Leatherback aggregation and feeding in Placentia Bay Extension

Transcription

1 Leatherback aggregation and feeding in Placentia Bay Extension Potentially Harmful Activity (X) Potentially Harmful Stressor (X) Bottom trawl Oil pollution X Fishing Scallop dredges Marine Industrial effluent pollution Clam dredges Fishplant effluent Midwater trawl Sewage Gillnets (bottom) X Historic military waste Gillnets (pelagic) X Long range transport of nutrients Longline X Acid rain Seine (pelagic) X Persistent Organic Pollutants X Recreational cod fishery ( Eutrophication ) Crab pots X Ghost nets X Lobster pots Litter X Whelk pots X Other contaminants (specify) Other (specify) Ice distribution Otter trapping Climate Temperature change X Other Change Seal hunt Sea-level rise harvest Seabird hunt Ocean acidification Seaweed harvest Current shifts X Anchor drops/drags Increased storm events Seabed Ore spill Increased UV light alteration Fish offal dumping Oxygen depletion Finfish aquaculture Changes in freshwater runoff Dredge spoil dumping Other (specify) Dredging Green crab Mining/Oil & gas drilling Harmful Membranipora species Cables Golden Star Tunicate Freshwater diversion Violet Tunicate Coastal Subtidal construction Vase Tunicate alteration Intertidal/coastal Codium fragile construction Clubbed Tunicate Other (specify) Didemnum Vessel traffic X Harmful Algal Blooms Disturbance Ship strikes X Disease organisms (human waste) Ecotourism X Disease organisms (aquaculture) Marine construction Other (specify) Seismic surveys Navy sonar Other Other (specify) 1

2 Background Information The leatherback turtle is officially listed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) as endangered and Leatherback turtles are listed as Endangered under Schedule I of the Species at Risk Act (SARA), which results in legal protection and mandatory recovery requirements of priority species under the Act. The leatherback turtle is classified as critically endangered by the International Union for the Conservation of Nature (Atlantic Leatherback Turtle Recovery Team, 2006), and listed as a depleted and rare species in the LOMA (Fisheries and Oceans Canada, 2007). Distribution The leatherback turtle is the most widely distributed of all sea turtles, with individuals undertaking extensive migrations between tropical and temperate waters. At-sea field research confirms that leatherbacks from multiple nesting colonies aggregate annually off Canada s Atlantic coast. Therefore, Canadian efforts to promote recovery of this endangered reptile have global implications and include participation in international sea turtle conservation initiatives and reduction of incidental capture of leatherbacks in Canadian fisheries. Coastal and slope waters of the NW Atlantic provide high-use foraging habitat for leatherbacks. Waters off Nova Scotia are particularly important to this species, as indicated by the large seasonal aggregation of turtles that occurs there. Fisheries interactions are an important source of injury and mortality for leatherbacks in temperate waters.(james, M. C., Sherrill-Mix, S. A., & Myers, R. A., 2007). Figure 1.Occurrence of the leatherback turtle, Dermochelys coriacea, off eastern Canada. Shaded areas show the location of concentrations of observations and are taken from Goff and Lien (1988; A), Witzell (1999 and DFO, 2005; B), and James (2000; C).(Atlantic Leatherback Turtle Recovery Team, 2006) 2

3 Figure 2. Spatial use by 38 leatherback turtles equipped with Argos satellite tags in waters off Nova Scotia, Canada. Colour denotes the number of days turtle(s) were observed in each hexagon. (James, M. C., Ottensmeyer, C. A., & Myers, R. A., 2005) Although they do not nest in Canada, Canadian waters support one of the highest summer and fall densities of leatherbacks in the North Atlantic, and should be considered critical foraging habitat for this endangered species (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006; Templeman, N. D. & Davis, M. B., 2006). The Atlantic population appears to be relatively stable, but shows dramatic fluctuations in the number of nesting females from year to year. There are no good population estimates for leatherbacks in Canadian waters (COSEWIC & James, M. C., 2001). The relative density of leatherbacks in Canadian waters is likely much higher than Shoop and Kenney s (1992) estimate of a summer population of turtles in the large area they surveyed. From , fishers and other mariners reported 851 geo-referenced sightings of free-swimming or entangled leatherback turtles in Atlantic Canada. Sightings principally corresponded to the Scotian Shelf, mainly reflecting reporting by fishers in Nova Scotia. However, smaller number of sightings was also reported outside of the principal study area, including coastal Newfoundland and slope waters south of Nova Scotia (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006). Recent findings, satellite telemetry studies, and data from pelagic fisheries observer programs all point to coastal and slope waters of the western Atlantic north of 38_N as preferred summer and fall foraging habitat for leatherbacks (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006). Biology The leatherback turtle is the world s largest reptile, the only sea turtle with no claws on their flippers, and the only sea turtle that does not have a hard shell or scales (Fisheries and Oceans Canada, 2004). Since this species diet of gelatinous plankton is high in water and low in organic content with very little nutritive content, they must consume large quantities of food to fulfil their food energy requirements. This is the only known biological limiting 3

4 factor in Canadian waters (Atlantic Leatherback Turtle Recovery Team, 2006). Leatherbacks breathe air, and also spend time basking, resting and feeding at the sea surface. In Canadian waters satellite tracking studies have shown that leatherbacks spend between 1-35% of their time on the surface (James, M. C., Myers, R. A., & Ottensmeyer, C. A., 2005). The primary determinant of movement and behaviour of leatherbacks is the spatial and temporal distribution of their primary prey, jellyfish. In general jellyfish abundance is lower in pelagic vs. coastal waters, however, physical transport of jellyfish can create local aggregations, particularly at physical discontinuities such as shelf breaks and upwellings zones (James, M. C., Ottensmeyer, C. A., & Myers, R. A., 2005). Jellyfish are planktonic, generally floating in surface waters, but in deep offshore areas they may occur at considerable depths, and leatherbacks foraging in shelf waters off Canada appear to search for and capture much of their prey at depth, before returning to the surface to consume it (James, M. C., Myers, R. A., & Ottensmeyer, C. A., 2005). Figure 3. Diving behaviour of two leatherback turtles tagged in coastal waters off Nova Scotia, Canada: Proportion of time (per 6 h sample) spent in different depth ranges. This pattern of foraging behavior is consistent with the high proportion of time spent at the surface in northern waters. Increased surface time at northern latitudes may also reflect basking, as turtles have routinely been observed resting at the surface during the middle part of the day and evening with both front and rear flippers extended and their heads lowered in the water. There is evidence that leatherbacks do not feed exclusively at the surface. In fact turtles equipped with time-depth recorders have been recorded diving beyond 1000m. This deep diving behavior may reflect nocturnal foraging for jellyfish and other soft-bodied invertebrates within the deeper water layers (COSEWIC & James, M. C., 2001). Prey- Jellyfish (Cyanea and related species) Seasonal increases in water temperature have been shown to be important to both sexual development and the onset of reproduction in Cyanea and related species. Rapid spring increases in coastal water temperatures linked to exponential growth in C. capillata and A. aurita first occur in southern parts of eastern Canada, with more northerly areas reaching peak seasonal temperatures later in the season. The spatio-temporal seasonal patterns in leatherback distributions inferred from sightings data likely parallel the seasonal cycles of C. capillata and other gelatinous prey, with turtles exploiting emerging food resources and then 4

5 departing northern waters when prey densities decline. Similarly, variation in the temporal distribution of leatherback sightings between years may reflect inter-annual differences in the timing of various stages of development of Cyanea and other scyphomedusae. The present findings, satellite telemetry studies, and data from pelagic fisheries observer programs all point to coastal and slope waters of the western Atlantic north of 38_N as preferred summer and fall foraging habitat for leatherbacks (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006). The leatherback's diet of jellyfish may help conserve fish species. Leatherbacks help keep the jellyfish population under control. This is significant not only because jellyfish compete with larval fish for food (both eat zooplankton), but because jellyfish are also known predators of larval fish (James, M. C., Myers, R. A., & Ottensmeyer, C. A., 2005). Threats The leatherback s insatiable appetite and foraging curiosity also may lead to entanglement in fishing gear. Front flipper entanglement in ropes and cables is common, and this may result from turtles approaching buoys and biting at them. Leatherbacks may also become entangled after being attracted to the jellyfish that foul fishing gear (COSEWIC & James, M. C., 2001). Of all Atlantic sea turtle species, leatherbacks seem to be most vulnerable to entanglement in fishing gear such as pelagic longlines, lines associated with fixed ear (pots, traps, gillnets), buoy anchor lines, and other ropes and cables (Atlantic Leatherback Turtle Recovery Team, 2006). Leatherbacks are vulnerable to entanglement in northern coastal and shelf waters, where turtle fishery interactions represent a greater threat to this species than previously recognized. The global decline of leatherbacks has also been largely attributed to incidental capture in fisheries, with pelagic longlines proposed as a key threat. However, leatherbacks caught in pelagic longlines are normally entangled or hooked externally on this mobile gear and are usually capable of swimming to the surface to breathe. Therefore, for leatherback turtles, entanglement in pelagic longlines does not necessarily lead to mortality. In fact, observer data reveals that very few turtles are discovered dead on pelagic longlines, although post-release mortality remains unknown. Of 323 leatherbacks observed interacting with US pelagic longline gear in 2001 and 2002, only one (0.3%) was found dead. In contrast, as our data suggest, fishing gear anchored to the bottom (fixed gear) in shelf waters may lead to higher mortality per interaction because turtles entangled at depth or at the surface at low tide will almost certainly drown. As fixed gear fisheries receive relatively little observer coverage, the magnitude of the threat they pose to leatherbacks has not been adequately recognized nor addressed. As in Canadian waters, leatherbacks are regularly entangled in fixed gear in US waters off New York through Maine (James, M. C., Ottensmeyer, C. A., & Myers, R. A., 2005). Leatherbacks will readily consume a variety of edible and inedible slow-moving and buoyant objects. Though this behavior is adaptive in exploiting large concentrations of jellyfish, these turtles regularly mistakenly ingest plastic bags and other floating marine debris. Marine debris accumulates at convergence zones, where prey is also naturally concentrated. Ingestion of plastics, styrofoam and other waste can be fatal (COSEWIC & James, M. C., 2001). Their specialized diet may make leatherbacks vulnerable to ingestion of plastics and 5

6 other buoyant marine debris. These materials may resemble their soft-bodied prey, and the magnitude of this threat may be grossly underestimated (James, M. C. & Herman, T. B., 2001). A new study looked at necropsy reports of more than 400 leatherbacks that have died since 1885 and found plastic in the digestive systems of more than a third of the animals. Besides plastic bags, the turtles had swallowed fishing lines, balloon fragments, spoons, candy wrappers and more (Sohn, E., 2009). When dead leatherbacks wash ashore, plastics are commonly found in their digestive tracts. Leatherbacks are known to ingest plastic sheeting, tar halls, monofilament, styrofoam, and other marine debris of anthropogenic origin. These materials can directly affect the survival of marine turtles by causing fatal blockages in the digestive tract. Moreover, the potential toxic effects of such ingestion, while poorly understood, may be significant. Feeding behavior may also put leatherbacks at risk indirectly. Since the horizontal movement of jellyfish is largely passive, they tend to concentrate where currents converge. These same currents concentrate other buoyant objects, including marine debris (e.g., plastic bags, discarded and lost fishing gear, etc.). Therefore, leatherbacks foraging in areas where jellyfish are concentrated may encounter significant amounts of potentially harmful materials of anthropogenic origin. These convergence zones and other areas of high productivity also attract commercially valuable species of fish, inadvertently bringing leatherbacks into contact with fishing gear (James, M. C. & Herman, T. B., 2001). In Canada, aerial surveys are required to assess regional patterns and long-term trends in leatherback abundance, to help identify areas of turtle concentration at smaller scales, and to evaluate the spatial and temporal overlap between leatherbacks and the human activities that impact them (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006). Table 1: Treats to leatherback turtles (Atlantic Leatherback Turtle Recovery Team, 2006) 6

7 Table 2: Natural and anthropogenic impacts on sea turtles (NOAA, U. S. Department of Commerce, 2003) Scoping Gillnets (groundfish): Leatherbacks may become entangled after being attracted to the jellyfish that foul fishing gear (COSEWIC & James, M. C., 2001). These incidents can result in serious injuries (rope or cable cuts on the shoulders and front flippers) or death by drowning. The leatherback has never developed the ability to swim backwards. This poses some difficulty when it encounters fishing nets and lines in the ocean because it has no hope of backing out of them. Entanglement in fishing gear at any time can result in serious injuries to the turtles, including severe cuts and necrosis (death) of the tissue, which could lead to the loss of a flipper; entanglement can also lead to death by drowning. Unlike other smaller species of sea turtles, leatherbacks are sometimes strong enough to drag large amounts of fishing line and gear to the surface of the water, where they are discovered and released (Fisheries and Oceans Canada, 2004). Although the fine scale distribution and movements of turtles on the Grand Banks are not well known, data indicates that the edge of the shelf is an important area for sea turtles (Atlantic Leatherback Turtle Recovery Team, 2006). During a two-year programme of enhanced observer coverage levels, 22% of the entanglement records involved mooring or buoy lines associated with bottom gillnets, bait nets and pound nets of other fish traps. Bottom gillnets account for 62% of the landings in Placentia Bay, and leatherback turtles are prone to entanglement in fishing gear, including gillnets. Screened in. 7

8 Gillnets (pelagic): Leatherback turtles are highly vulnerable to this gear, but fishing of pelagic species such as herring, salmon and mackerel is minimal in Placentia Bay (Socio-economic overview 2001), and mobile gear (seines) are more frequently used. Screened out. Longline: Estimates of incidental capture of leatherback turtles in the entire Atlantic Ocean range from 30,000 to 60,000 for offshore pelagic longline fleets in 2000 (Atlantic Leatherback Turtle Recovery Team, 2006). Turtle interactions do not appear to occur in Canadian pelagic longline fisheries targeting shark, but are well documented in longline fisheries targeting swordfish and tunas (28 individuals swordfish 2001; 33 individuals swordfish 2002; 4 individuals offshore tuna 2002) (Atlantic Leatherback Turtle Recovery Team, 2006). Placentia Bay is subjected is subjected to low intensity (4% of total 3PS harvest). Screened out. Seine (pelagic): Leatherback turtles are not reportedly caught in seines, and fishing of pelagic species such as herring, and capelin which would use this gear is currently minimal in Placentia Bay (Community Resource Services Ltd & Jacques Whitford Environment Ltd, 2001). Screened out. Crab pots: Crab landings in Placentia Bay account for 19% of total landings for the EBSA (Appendix A, Table 17 and 25)(Fisheries and Oceans Canada, 2008). Crab pots are attached by ropes to surface buoys, and may be set singly or in strings. In Newfoundland waters, crab pots are generally linked together in a long chain by groundlines which float in the water column many meters off the bottom. Both groundlines and lines to surface buoys are responsible for frequent entanglement of large marine animals such as leatherback turtles. The use of lead (heavy) groundlines is a potential mitigation which can minimize entanglement in crab pots, but this mitigation is not widely adopted. Screened in. Whelk pots: Whelk pots can be set singly or in strings, and are attached by ropes to surface buoys. Both groundlines and lines to surface buoys are responsible for frequent entanglement of large marine animals such as leatherback turtles. The whelk fishery in Placentia Bay has been growing since 2004, but even in 2007 amounted to less than 2% of the total landings for the EBSA (see Appendix A, Tables 17 and 25) (Campbell, J. S. & Simms, J. M., 2009). Screened out. Vessel traffic (disturbance): Little is known about the hearing ability of the leatherback turtle and its response to acoustic disturbance (Atlantic Leatherback Turtle Recovery Team, 2006). Vessel traffic causes significant noise which affects the ability of cetaceans to feed and communicate, but there is no evidence that leatherbacks engage in complex acoustic communication, but it is likely that vessel traffic may cause disturbance of leatherbacks during feeding, basking or sleeping at the sea surface. A major shipping lane passes through the east side of Placentia Bay serving 8

9 the Come by Chance Oil refinery, the NL Transshipment Terminal and the Ferry Terminal at Placentia as well as other sites. Total annual vessel movements in Placentia Bay in 2004 totalled 8,286 including 1,276 oil tankers, 62 chemical tankers, 522 cargo ships, 2,046 tug boats 1,501 ferry movements, and 1,589 fishing boats and other vessels under 20m (Transport Canada, 2007). Since the EBSA encompasses a 7,398km 2 area, 8286 vessel transits annually corresponds to 1.1transit/ km 2 /year, or transits/ km 2 /day. Clearly some areas will have many more transits than other areas, and the summer season is likely to be busier than the winter (NS ferry and many fishing vessels do not operate in winter), but even so, this level of vessel traffic density is not expected to cause significant harm to leatherbacks within Placentia Bay. Screened out. Ship strikes: Leatherback turtles breathe air, feed on planktonic jellyfish, bask at the sea-surface and so spend much of their time in the upper water column where they are vulnerable to ship strikes. While no incidences of collisions with boats are documented in Atlantic Canada, they have been known to occur in some areas of the U.S. and may have an impact on the leatherback turtle population that also uses Canadian waters. In areas where recreational boating, commercial fishing and ship traffic are concentrated, propeller and collision-related injuries may represent a source of mortality. However, in situations where there is evidence of a collision, it is difficult to infer whether the collision itself led to the death of the turtle in question, or if the turtle was hit after it died of other causes. Leatherback turtles are known to bask at the surface for extended periods of time when foraging in temperate waters and, therefore, may be vulnerable to collisions with marine traffic (Atlantic Leatherback Turtle Recovery Team, 2006). Although ship strikes are not considered to be a major source of mortality in Placentia Bay, any risk of serious injury or mortality is a concern for this rare species. Screened in. Eco-tourism: Cape St. Mary s bird sanctuary is the primary eco-tourist attraction in Placentia Bay, but the viewing sites are land-based and well monitored and do not appear to negatively affect marine organisms (Community Resource Services Ltd & Jacques Whitford Environment Ltd, 2001). Three tour-boat operators, based out of North harbour, Woody Island and Arnold s Cove, offer whale and bird watching tours and there are guided kayaking tours from Spanish Room (Community Resource Services Ltd & Jacques Whitford Environment Ltd, 2001), but considering the large size of the bay, this level of activity is minimal, and impacts are not considered significant. Screened out. Oil pollution: Placentia Bay has a relatively high risk of oil pollution with numerous sources of chronic oil (ports, urban runoff) and sources of accidental spills (tanker traffic, shipping, fishing, oil storage, refining and transhipment). The leatherback is relatively resistant to the effects of oil due to its thick leathery hide and lack of sensitive features such as fur, feathers or gills, and its high mobility. It is therefore not considered a key stressor. Screened out. 9

10 Persistent organic pollutants (POPs): Leatherback turtles are large, but feed very low on the food chain, with jellyfish being their preferred prey. As a result, they do not tend to accumulated POPS to any significant extent, unlike the smaller piscivorous whales and fish such as belugas and tunas. Screened out. Ghost nets: Since the 1960s when non-biodegradable synthetic ropes, buoys and netting gradually replaced traditional biodegradable materials, lost fishing nets known as ghost nets, have become a serious threat to marine ecosystem health. Ghost nets can continue to fish for years, capturing tonnes of fish, lobster, crab, and marine mammals. In shallow coastal waters, lost nets may become rapidly filled with dead fish, and sink, becoming snagged on the bottom, where they are a serious threat to bottom dwelling species. Gillnets are considered to be the major source of ghost nets in Placentia Bay. Gillnets were used extensively in the inshore groundfish fishery, and for pelagic species such as salmon. Following closure of the cod and salmon fisheries in the 1990s, use of gillnets decreased substantially, but still account for 62% for the landings in the EBSA (see Appendix A, Tables 17, 25)(Fisheries and Oceans Canada, 2008). Various initiatives have been launched to try to retrieve ghost nets. One such project in Placentia Bay, recovered 60 nets that contained lumpfish, seal, redfish, flounder, lobster and 30,000 lbs. of rotting cod (CBC News, 2000). Leatherbacks are typically surface feeders, and there is no evidence of significant entanglement in ghost nets in the EBSA. Entanglement in active gillnets is usually associated with surface buoys. Screened out. Litter: Plastic debris occurs in considerable quantities throughout the world s oceans, and incidents of ingestion by leatherback turtles may be significantly underestimated (Barreiros, J. & Barcelos, J., 2001; Simpson, M. R., Miri, C. M., & Busby, C., 2008). Negative impacts related to plastic litter are documented in 267 marine species including 86% of all sea turtle species (Derraik, J. G. B., 2002). DFO marine debris surveys of beaches in Placentia Bay found significant accumulations of litter on southwest-facing beaches. Plastic was the most common material found, and included fishing-related items such as ropes, buoys, netting, and buckets (Fisheries and Oceans Canada, 2005). Ingestion of persistent plastic, particularly floating plastic bags which resemble jellyfish, and entanglement in netting and rope fragments are thought to be serious stressors to leatherback sea turtles (Derraik, J. G. B., 2002). Screened in. Temperature change: A global increase in air and sea temperature is predicted as a result of increased atmospheric concentrations of greenhouse gases, with polar regions most affected (IPCC, 2007). Drinkwater (Drinkwater, K. F., 2005) predicts a 2-4 o C temperature change in southern Newfoundland marine waters by 2100 based on IPCC models. This temperature rise is not predicted to be linear, but will escalate over time. For the purposes of this analysis, we will assume a maximum increase in water temperature of o C over the next ten years. 10

11 While in Canadian waters, leatherbacks forage on large jellyfish species which mainly occur in northern coastal areas. Seasonal increases in water temperature have been shown to be important to both sexual development and the onset of reproduction in Cyanea and related species. Rapid spring increases in coastal water temperatures are linked to exponential growth in C. capillata and A. aurita, which first occur in southern parts of eastern Canada, with more northerly areas reaching peak seasonal temperatures later in the season. The spatio-temporal seasonal patterns in leatherback distributions likely parallel the seasonal cycles of C. capillata and other gelatinous leatherback prey, with turtles exploiting emerging food resources and then departing northern waters when prey densities decline (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006). Temperature change is unlikely to have a significant impact on jellyfish/leatherback distribution in Placentia Bay over the next ten years, and effects are likely to be beneficial, providing an earlier abundance of jellyfish, but further monitoring is recommended. Screened out. Current shifts: Changing ocean currents have been linked to localized changes in temperature and salinity, and changes development and overturn of thermoclines- all of which may affect leatherback aggregation and feeding. Ocean currents are predicted to change as a result of the warming of polar waters and associated influx of freshwater - ocean circulation is driven by sinking of cold, salty (dense) water at the high latitudes which is replaced by warmer salty water from lower latitudes. Researchers in both Greenland and Antarctica have found the sinking of super-cooled water has weakened significantly, with Greenland now less than one quarter its former strength, and Antarctica one third of what it was a century ago (Gribbin, J., 2001; Leake, J., 2005). Leatherbacks normally inhabit areas where prey productivity is high, along oceanic frontal systems and along vertical gradients located at oceanic fronts. In eastern Canada, the distribution and movements of leatherback are thought to be closely associated with seasonally abundant prey, particularly Cyanea sp, their principle jellyfish prey (Atlantic Leatherback Turtle Recovery Team, 2006). Therefore, adult leatherback habitat may be determined by prey abundance, with turtles moving from offshore waters into coastal areas to exploit the seasonal production of jellyfish (Atlantic Leatherback Turtle Recovery Team, 2006). These changes may affect the production or distribution of jellyfish within Placentia Bay Extension, and consequently may affect leatherback abundance and distribution, but any affects are not expected to be significant over the next ten years. Screened out. Key Activities/Stressors: Gillnets (groundfish) Crab pots Ship strikes Litter 11

12 Reference List 1. Atlantic Leatherback Turtle Recovery Team (2006). Recovery Strategy for Leatherback Turtle (Dermochelys coriacea) in Atlantic Canada (Rep. No. Species at Risk Act Recovery Strategy Series ). Ottawa: Fisheries and Oceans Canada. 2. Barreiros, J. & Barcelos, J. (2001). Plastic Ingestion by a Leatherback Turtle Dermochelys coriacea from the Azores (NE Atlantic). Marine Pollution Bulletin, 42, Campbell, J. S. & Simms, J. M. Status Report on Coral and Sponge Conservation in Canada. Oceans, Habitat and Species at Risk Report Series (in press). 4. CBC News (2000). Ghost nets wreak havoc in Placentia Bay. [Announcement posted on the World Wide Web]. from the World Wide Web: 5. Community Resource Services Ltd & Jacques Whitford Environment Ltd (2001). Socio-Economic Overview of Placentia Bay, Newfoundland. 6. COSEWIC & James, M. C. (2001). COSEWIC Assessment and Update Status Report on the Leatherback Turtle Dermochelys coriacea in Canada Ottawa: Committee on the Status of Endangered Wildlife in Canada. 7. Derraik, J. G. B. (2002). The pollution of the Marine Environment by Plastic Debris:a review. Marine Pollution Bulletin, 44, Drinkwater, K. F. (2005). The Response of Atlantic cod (Gadus morhua) to future climate change. ICES Journal of Marine Science, 62, Fisheries and Oceans Canada. Underwater World Aquatic Species at Risk - The Leatherback Turtle Ottawa, Ont. Ref Type: Pamphlet 10. Fisheries and Oceans Canada. Marine Debris, Trashing our Oceans, Trashing our Future (poster) St. John's, NL. Ref Type: Pamphlet 11. Fisheries and Oceans Canada (2007). Placentia Bay-Grand Banks Large Ocean Management Area Conservation Objectives (Rep. No. 2007/042). Canadian Science Advisory Secretariat Science Advisory Report. 12. Fisheries and Oceans Canada LMNOP4R Effort and Catch. Policy and Economics Branch. [Newfoundland and Labrador Region Catch and 12

13 Effort] Fisheries and Oceans Canada. Ref Type: Data File 13. Gribbin, J. (2001). Ocean Forces Threaten our climate. First Science [Announcement posted on the World Wide Web]. from the World Wide Web: IPCC (2007). A report of Working Group I of the Intergovernmental Panel on Climate Change: Summary for Policymakers Cambridge, United Kingdom and New York, NY, USA: Cambridge University Press. 15. James, M. C. & Herman, T. B. (2001). Feeding of Dermochelys coriacea on Medusae in the Northwest Atlantic. Chelonian Conservation and Biology, 4, James, M. C., Myers, R. A., & Ottensmeyer, C. A. (2005). Behaviour of leatherback sea turtles, Dermochelys coriacea, during the migratory cycle. Proceedings of the Royal Society B, 272, James, M. C., Ottensmeyer, C. A., & Myers, R. A. (2005). Identification of high-use habitat and threats to leatherback sea turtles in northern waters: new directions for conservation. Ecology Letters, 8, James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A. (2006). Canadian waters provide critical foraging habitat for leatherback sea turtles. Biological Conservation, 133, James, M. C., Sherrill-Mix, S. A., & Myers, R. A. (2007). Population characteristics and seasonal migrations of leatherback sea turtles at high latitudes. Marine Ecology Progress Series, 337, Leake, J. (2005). Britain faces big chill as ocean current slows. The Sunday Times. 21. NOAA, U. S. D. o. C. (2003). Oil and Sea Turtles: Biology, Planning and Response U.S. Department of Commerce, National Oceanic and Atmospheric Administration. 22. Simpson, M. R., Miri, C. M., & Busby, C. (2008). Assessment of Thorny Skate (Amblyraja radiata Donovan, 1808) in NAFO Divisions 3LNO and Subdivision 3Ps (Rep. No. SCR Doc. 08/43, Serial No. N5545). Northwest Atlantic Fisheries Organization. 23. Sohn, E. Plastic Found in One-Third of Leatherback Tutles. Discovery News Discovery Channel Ref Type: Generic 13

14 24. Templeman, N. D. & Davis, M. B. (2006). Placentia Bay-Grand Banks Ecosystem Overview and Assessment Report (DRAFT) Newfoundland & Labrador: Fisheries and Oceans Canada. 25. Transport Canada (2007). Synopsis Report - Environmental Oil Spill Risk Assessment for the South Coast of Newfoundland (Rep. No. TC ). 14

15 Leatherback aggregation and feeding in Placentia Bay Extension Gillnet (bottom) Magnitude of Interaction Areal extent: Leatherback turtles have not been systematically surveyed around Newfoundland and distribution maps rely largely on opportunistic reporting and tracking of small numbers of individual leatherbacks. The primary determinant of movement and behaviour of leatherbacks is the spatial and temporal distribution of their primary prey, gelatinous plankton generally known as jellyfish. In general, jellyfish abundance is highest in coastal waters (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006). James et al. identified spatial use of leatherbacks in the western Atlantic through satellite tracking tags on 38 turtles (Fig. 1, below): Figure 1. Spatial use of leatherbacks in the Western Atlantic (James, M. C., Ottensmeyer, C. A., & Myers, R. A., 2005). This data was updated by the Turtle Expert Working Group in 2007: Figure 2. Habitat use by Leatherback Turtles on foraging Grounds in the northwest Atlantic (Turtle Expert Working Group, 2007). 1

16 Figure 3.Occurrence of the leatherback turtle, Dermochelys coriacea, off eastern Canada. Shaded areas show the location of concentrations of observations (Atlantic Leatherback Turtle Recovery Team, 2006). This information indicates that leatherbacks are broadly distributed, and could be found throughout the EBSA. Gillnet fisheries make up 62% of the total landing within the EBSA. Geo-referenced fishing locations are available for vessels over 35ft (Fig. 4 below) with major fisheries in Placentia Bay targeting cod, plaice and skate. Figure 4. Areal extent of gillnet fisheries (vessels > 35ft), Newfoundland Region fisheries, (Fisheries and Oceans Canada, 2008). Areal extent of gillnet (4,277km 2 ) Gillnet vessels over 35ft account for 10% of the total landings in the EBSA from , with an area of overlap (4,277 km 2 /7398km 2 ) =57.8%. There is also a significant inshore gillnet fishery (vessels <35ft), largely targeting cod, lumpfish and winter flounder, accounting for 52% of the total landings for the EBSA from The distribution of these fisheries is shown on Fig. 5 below: 2

17 Figure 5. Distribution of lumpfish, winter flounder, and Atlantic cod gillnet fisheries in Placentia Bay from (Community Resource Services Ltd & Jacques Whitford Environment Ltd, 2001). Based on this information we have estimated an area of overlap of 65%. Score 6.5 Contact: Quantitative Fishing Gear Scores (Fisheries and Oceans Canada, 2007) for contact between bottom gillnets and leatherback are low (0-25%). Turtle fishery interactions represent a greater threat to leatherback turtles than previously recognized. Data suggest that fishing gear anchored to the bottom (fixed gear) may lead to higher mortality per interaction because turtles entangled at depth or at the surface at low tide will almost certainly drown. As fixed gear fisheries receive relatively little observer coverage, the magnitude of the threat they pose to leatherbacks has not been adequately recognized. Leatherbacks are regularly entangled in fixed gear in Canadian waters (James, M. C., Ottensmeyer, C. A., & Myers, R. A., 2005). Since entanglement in fishing gear has been identified as a significant threat to leatherbacks in the region (Atlantic Leatherback Turtle Recovery Team, 2006; Griffin, E., Miller, K. L., Harris, S., & Allison, D., 2008; Ledwell, W. & Huntington, J., 2007), have selected a score at the high end of the low range. Score 3.5 Duration: Leatherbacks are typically present in the EBSA from June to October (Atlantic Leatherback Turtle Recovery Team, 2006) Gillnet fishing occurs from May 1 to Feb 28 or 100% of the time occupied by the CP. Score 10 Intensity: Halpern et al. (2008) have developed maps showing the global intensity of several anthropogenic stressors including a range of fisheries. These maps can be used to provide guidance in scoring the intensity of a stressor in relation to maximum (100%) intensity in a global context, in accordance with the scale provided below. Halpern s map of demersal non-destructive fisheries with high bycatch, which include gillnets, is shown in Fig. 6 below. 3

18 Map colour Red Orange Yellow Light Blue Dark Blue Intensity % 60-80% 40-60% 20-40% 0-20% Figure 6. Global intensity of demersal non-destructive fisheries with high bycatch, which include gillnets (adapted from (Halpern, B. S. et al., 2008). Figure 6 shows a medium (yellow) intensity relative to global levels for a score range of 40% to 60% for the EBSA. Gillnet fisheries account for 62% of the total landings in the EBSA from (Fisheries and Oceans Canada, 2008a), and gillnets have historically been the dominant gear used in Placentia Bay, therefore we have selected the highest score in the global range. Score 6 Magnitude of Interaction: (6.5 x 3.5 x 10 x 6)/1000 = 1.4 Sensitivity Sensitivity of the CP to acute impacts: Quantitative Fishing Gear Scores (Fisheries and Oceans Canada, 2007) for harm resulting from an interaction between bottom gillnets and sea turtles are low (occasionally 1-25%), but in Atlantic-wide bottom gillnet fisheries, scores are high (> 75% of the time). Incidental capture in fisheries is considered as a leading cause of population decline (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006). The susceptibility of leatherbacks to entanglements may result from their large body size, long pectoral flippers and soft shell. Leatherbacks are unable to swim backwards, and this reduces their ability to avoid entanglement or free themselves once they become entangled (Fisheries and Oceans Canada, 2004) Acute impacts due to entanglement may vary in severity from trivial to lethal, depending on the extent of the entanglement. Entanglement of leatherbacks beneath the surface generally leads to death through drowning since the turtle is unable to reach the surface to breath. Even if the turtle is able to free themselves, serious injuries may be sustained, or gear may remain attached to the turtle leading to chronic impacts (Atlantic Leatherback Turtle Recovery Team, 2006). Data suggests that fishing gear anchored to the bottom (fixed gear) may lead to higher mortality per interaction because turtles entangled at depth or at the surface at low tide 4

19 will almost certainly drown. As fixed gear fisheries receive relatively little observer coverage, the magnitude of the threat they pose to leatherbacks has not been adequately recognized nor addressed. Leatherbacks are regularly entangled in Canadian waters (James, M. C., Ottensmeyer, C. A., & Myers, R. A., 2005). Based on this information we have selected a score in the moderate range. Score 5 Sensitivity of the CP to chronic impacts: A long lifespan, very high rates of egg and hatchling mortality, and a late age of maturity makes this species unusually vulnerable to even small increases in rates of mortality of adults and older juveniles. Generation time is estimated at <30 years (COSEWIC & James, M. C., 2001) The leatherback turtle is classified as critically endangered by the International Union for the Conservation of Nature and as endangered by the Committee on the Status of Endangered Wildlife in Canada. Leatherbacks have experienced a dramatic population decline of more than 60 per cent since Currently, the total number of nesting females is thought to be less than 35,000 worldwide (Fisheries and Oceans Canada, 2004). The Atlantic population appears to be stable, but shows dramatic fluctuations from year to year. The relative density of leatherbacks in Canadian waters has been estimated at turtles (during summer), but this is likely low, as there are no accurate population estimates for leatherbacks in Canadian waters (COSEWIC & James, M. C., 2001). Chronic impacts of entanglement can range from minor rope scars, to debilitating injuries, or moderate to severe morbidity due to gear remaining attached or imbedded in the turtle. In these cases, the ability of the animal to move and feed may be compromised by injuries, infection, interference with vital body functions (rope/netting confining limb, neck or mouth movement) or by the weight of gear. In severe cases, death may occur months or even years later as a result of starvation or chronic infection (Atlantic Leatherback Turtle Recovery Team, 2006) Turtles towing gear for any length of time are unlikely to free themselves, and are more likely to become entangled again. Given the poor recovery rate for serious interactions, and low reproductive rates of leatherbacks, we have selected a moderate score (5.5) for chronic sensitivity. Leatherbacks are listed as a depleted species for the LOMA (add 1 point). Score 6.5 Sensitivity of ecosystem to harmful impacts to the CP: Leatherbacks depend on prey with very little nutritive content and since this species diet of jellyfish is high in water and low in organic content, they must consume large quantities of food to fulfill their energy requirements (Atlantic Leatherback Turtle Recovery Team, 2006). Jellyfish are generally considered a nuisance species, which can foul fishing gear and force the closure of swimming beaches. Jellyfish also compete with larval fish for food 5

20 Despite their relatively small numbers, leatherbacks represent a significant biomass due to their large size, and contribute significantly to the energetics of the marine ecosystem. Leatherbacks are highly mobile, and their large scale movements contribute to the transfer of energy and biomass from seasonally productive areas to distance marine systems. Due to their large size and habit of basking on the sea surface, leatherbacks have long attracted interest, and their presence within the EBSA contributes to ecotourism opportunities. Canadian waters support one of the highest summer and fall densities of leatherbacks in the North Atlantic, and should be considered critical foraging habitat for this endangered species (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006). Although the EBSA has been identified as an important area for leatherback aggregation and feeding, leatherbacks are widely distributed within the LOMA during the summer months and other areas may be of equal or greater importance. Based on this information, we have selected a score in the medium range to reflect the importance of leatherback aggregation and feeding within the EBSA in relation to the LOMA as a whole. Score 5 Sensitivity: ( )/3 = 5.5 Risk of Harm: 1.4 x 5.5 = 7.7 6

21 Certainty Checklist Answer yes or no to all of the following questions. Record the number of NO s to the 9 questions, and record certainty according to the scale provided below: 1 No s = High certainty 2-3 No s = Medium certainty > 4 No s = Low certainty Y/N Y Is the score supported by a large body of information? N Is the score supported by general expert agreement? N Is the interaction well understood, without major information gaps/sources of error? Y Is the current level of understanding based on empirical data rather than models, anecdotal information or probable scenarios? Y Is the score supported by data which is specific to the region, (EBSA, LOMA, NW Atlantic? Y Is the score supported by recent data or research (the last 10 years or less)? N Is the score supported by long-term data sets (ten years or more) from multiple surveys (5 years or more)? Y Do you have a reasonable level of comfort in the scoring/conclusions? N Do you have a high level of confidence in the scoring/conclusions? Score: Low For interactions with Low certainty, underline the main factor(s) contributing to the uncertainty Lack of comprehensive data Lack of expert agreement Predictions based of future scenarios which are difficult to predict Other (provide explanation) Suggest possible research to address uncertainty: 7

22 Reference List 1. Atlantic Leatherback Turtle Recovery Team (2006). Recovery Strategy for Leatherback Turtle (Dermochelys coriacea) in Atlantic Canada (Rep. No. Species at Risk Act Recovery Strategy Series ). Ottawa: Fisheries and Oceans Canada. 2. Community Resource Services Ltd & Jacques Whitford Environment Ltd (2001). Socio-Economic Overview of Placentia Bay, Newfoundland. 3. COSEWIC & James, M. C. (2001). COSEWIC Assessment and Update Status Report on the Leatherback Turtle Dermochelys coriacea in Canada Ottawa: Committee on the Status of Endangered Wildlife in Canada. 4. Fisheries and Oceans Canada. Underwater World Aquatic Species at Risk - The Leatherback Turtle Ottawa, Ont. Ref Type: Pamphlet 5. Fisheries and Oceans Canada (2007). Placentia Bay-Grand Banks Large Ocean Management Area Conservation Objectives (Rep. No. 2007/042). Canadian Science Advisory Secretariat Science Advisory Report. 6. Fisheries and Oceans Canada LMNOP4R Effort and Catch. Policy and Economics Branch. [Newfoundland and Labrador Region Catch and Effort] Fisheries and Oceans Canada. 7. Griffin, E., Miller, K. L., Harris, S., & Allison, D. (2008). Trouble for Turtles: Trawl Fishing in the Atlantic Ocean and Gulf of Mexico Washington, DC: Oceana. 8. Halpern, B. S., Walbridge, S., Selkoe, K. A., Kappel, C. V., Micheli, F., D'Agrosa, C., Bruno, J. F., Casey, K. S., Ebert, C., Fox, H. E., Fujita, R., Heinemann, D., Lenihan, H. S., Madin, E. M. P., Perry, M. T., Selig, E. R., Spalding, M., Steneck, R., & Watson, R. (2008). A Global Map of Human Impact on Marine Ecosystems. Science, 319, James, M. C., Ottensmeyer, C. A., & Myers, R. A. (2005). Identification of high-use habitat and threats to leatherback sea turtles in northern waters: new directions for conservation. Ecology Letters, 8, James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A. (2006). Canadian waters provide critical foraging habitat for leatherback sea turtles. Biological Conservation, 133, Ledwell, W. & Huntington, J. (2007). Whale and leatherback sea turtles incidental entrapment in fishing gear in Newfoundland and Labrador and a 8

23 summary of the Whale Release and Strandings Program during 2006 A Report to the Department of Fisheries and Oceans, St. John's, Newfoundland and Labrador, Canada. 9

24 Leatherback aggregation and feeding in Placentia Bay Extension Crab pots Magnitude of Interaction Areal extent: Leatherback turtles have not been systematically surveyed around Newfoundland and distribution maps rely largely on opportunistic reporting and tracking of small numbers of individual leatherbacks. The primary determinant of movement and behaviour of leatherbacks is the spatial and temporal distribution of their primary prey, gelatinous plankton generally known as jellyfish. In general, jellyfish abundance is highest in coastal waters (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006). James et al. identified spatial use of leatherbacks in the western Atlantic through satellite tracking tags on 38 turtles (Fig. 1, below): Figure 1. Spatial use of leatherbacks in the Western Atlantic (James, M. C., Ottensmeyer, C. A., & Myers, R. A., 2005). This data was updated by the Turtle Expert Working Group in 2007: Figure 2. Habitat use by Leatherback Turtles on foraging Grounds in the northwest Atlantic (Turtle Expert Working Group, 2007). 1

25 Figure 3.Occurrence of the leatherback turtle, Dermochelys coriacea, off eastern Canada. Shaded areas show the location of concentrations of observations (Atlantic Leatherback Turtle Recovery Team, 2006). This information indicates that leatherbacks are broadly distributed, and could be found throughout the EBSA. Snow crab pots harvested 19% of the total landing within the EBSA, from (Fisheries and Oceans Canada, 2008). Geo-referenced fishing locations are available for vessels over 35ft are shown on Fig. 4 below: Figure 4. Areal extent of crab pots (vessels > 35ft) by Newfoundland Region fisheries, (Fisheries and Oceans Canada, 2008). Areal extent (4,467km 2 ). For snow crab vessels over 35ft, the area of overlap (4,277 km 2 /7398km 2 ) =57.8%. 2

26 There is also a significant inshore fishery (vessels <35ft), accounting for the majority of the total landings for the EBSA from The distribution of the inshore fisheries is shown on Fig. 5 below: Figure 5. Distribution of snow crab fisheries in Placentia Bay from (Community Resource Services Ltd & Jacques Whitford Environment Ltd, 2001). Based on this information, we have estimated an area of overlap of 60%. Score 6 Contact: Quantitative Fishing Gear Scores (Fisheries and Oceans Canada, 2007a) for contact between snow crab pots and leatherbacks are rare (< 1% of the time), but scores are higher for other types of pots such as hagfish, rock crab and toad crab. Of all Atlantic sea turtle species, leatherback seem to be most vulnerable to entanglement in fishing gear such as pelagic longlines, lines associated with fixed ear (pots, traps, gillnets), buoy anchor lines and other ropes and cables (Atlantic Leatherback Turtle Recovery Team, 2006). Surface buoy lines appear to be most problematic (Atlantic Leatherback Turtle Recovery Team, 2006). The Newfoundland and Labrador Whale Release and Strandings Program (Ledwell, W. & Huntington, J., 2007) and other researchers report significant entrapment of leatherbacks in crab pots (COSEWIC & James, M. C., 2001);(Atlantic Leatherback Turtle Recovery Team, 2006). The leatherback s insatiable appetite and foraging curiosity also may lead to entanglement in fishing gear. Front flipper entanglement in ropes and cables is common, and this may result from turtles approaching buoys and biting at them. (COSEWIC & James, M. C., 2001). Based on this information we have selected a score at the high end of the low range. Score 3.5 Duration: Leatherbacks are typically present in the EBSA from June to October (Atlantic Leatherback Turtle Recovery Team, 2006) 3

27 Snow crab fishing is open within the EBSA from April 10 to June 15 (Table 9,(Fisheries and Oceans Canada, 2008) or 15days/ 150days. This amounts to 10% of the time occupied by the CP. Score 1 Intensity: Halpern et al. (2008) have developed maps showing the global intensity of several anthropogenic stressors including a range of fisheries. These maps can be used to provide guidance in scoring the intensity of a stressor in relation to maximum (100%) intensity in a global context, in accordance with the scale provided below. Halpern s map of demersal non-destructive fisheries with high bycatch, which include crab pots, is shown in Fig. 6 below. Map colour Red Orange Yellow Light Blue Dark Blue Intensity % 60-80% 40-60% 20-40% 0-20% Figure 6. Global intensity of demersal non-destructive fisheries with high bycatch, which include crab pots (adapted from (Halpern, B. S. et al., 2008). Figure 6 shows a medium-low (light blue) intensity relative to global levels for a score range of 20% to 40%. Crab fisheries within the EBSA represent an average of 19% of the landings from (Appendix A, Table 17 and 25) (Fisheries and Oceans Canada, 2008), therefore we have selected a high score in this range. Score 4 Magnitude of Interaction: (6x 3.5 x 1 x 4)/1000 = 0.1 Sensitivity Sensitivity of the CP to acute impacts: Quantitative Fishing Gear Scores (Fisheries and Oceans Canada, 2007b) for harm resulting from an interaction between crab pots and leatherbacks are low (occasionally 1-25%), but scores are higher for other types of pots such as hagfish, rock crab and toad crab. 4

28 The Newfoundland and Labrador Whale Release and Strandings Program reported significant entanglement of leatherbacks in crab pots (Ledwell, W. & Huntington, J., 2007). Acute impacts due to entrapment may vary in severity from trivial to lethal, depending on the extent of the entanglement. Data suggests that entanglement in fixed gear may lead to high mortality per interaction because turtles entangled at depth or at the surface at low tide will almost certainly drown. As fixed gear fisheries receive relatively little observer coverage, the magnitude of the threat they pose to leatherbacks has not been adequately recognized nor addressed. As in Canadian waters, leatherbacks are regularly entangled in fixed gear in US waters off New York through Maine (James, M. C., Ottensmeyer, C. A., & Myers, R. A., 2005) Based on this information, we have selected the highest score within the low range. Score 3.5 Sensitivity of the CP to chronic impacts: A long lifespan, very high rates of egg and hatchling mortality, and a late age of maturity makes this species unusually vulnerable to even small increases in rates of mortality of adults and older juveniles. Generation time is estimated at <30 years (COSEWIC & James, M. C., 2001) The leatherback turtle is classified as critically endangered by the International Union for the Conservation of Nature and as endangered by the Committee on the Status of Endangered Wildlife in Canada. Leatherbacks have experienced a dramatic population decline of more than 60 per cent since Because male turtles do not return to land, it is not possible to accurately count them. Scientists determine the population of sea turtles by counting nesting females. Currently, the total number of nesting females is thought to be less than 35,000 worldwide (Fisheries and Oceans Canada, 2004). The Atlantic population appears to be stable, but shows dramatic fluctuations from year to year. The relative density of leatherbacks in Canadian waters has been estimated at turtles (during summer), but this is likely low, as there are no accurate population estimates for leatherbacks in Canadian waters (COSEWIC & James, M. C., 2001). Chronic impacts of entanglement can range from minor rope scars, to debilitating injuries, or moderate to severe morbidity due to gear remaining attached or imbedded in the turtle. In these cases, the ability of the animal to move and feed may be compromised by injuries, infection, and interference with vital body functions (rope/netting confining limb, neck or mouth movement) or by the weight of gear. In severe cases, death may occur months or even years later as a result of starvation or chronic infection (Atlantic Leatherback Turtle Recovery Team, 2006) Turtles towing gear for any length of time are unlikely to free themselves, and are more likely to become entangled again. Given the poor recovery rate for serious interactions, and low reproductive rates of leatherbacks, we have selected a moderate score (5.5) for chronic sensitivity. Leatherbacks are listed as a depleted species for the LOMA (add 1 point). Score 6.5 5

29 Sensitivity of ecosystem to harmful impacts to the CP: Leatherbacks depend on prey with very little nutritive content and since this species diet of jellyfish is high in water and low in organic content, they must consume large quantities of food to fulfill their energy requirements (Atlantic Leatherback Turtle Recovery Team, 2006). Jellyfish are generally considered a nuisance species, which can foul fishing gear and force the closure of swimming beaches. Jellyfish also compete with larval fish for food (both eat zooplankton), and are also known predators of larval fish (James, M. C., Ottensmeyer, C. A., & Myers, R. A., 2005). Leatherbacks help keep the jellyfish population under control, and may therefore help conserve fish species, as well as contributing to pest control within the EBSA. Despite their relatively small numbers, leatherbacks represent a significant biomass due to their large size, and contribute significantly to the energetics of the marine ecosystem. Leatherbacks are highly mobile, and their large scale movements contribute to the transfer of energy and biomass from seasonally productive areas to distant marine systems. Due to their large size and habit of basking on the sea surface, leatherbacks have long attracted interest, and their presence within the EBSA contributes to ecotourism opportunities. Canadian waters support one of the highest summer and fall densities of leatherbacks in the North Atlantic, and should be considered critical foraging habitat for this endangered species (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006). Although the EBSA has been identified as an important area for leatherback aggregation and feeding, leatherbacks are widely distributed within the LOMA during the summer months and other areas may be of equal or greater importance. Based on this information, we have selected a score in the medium range to reflect the importance of leatherback aggregation and feeding within the EBSA in relation to the LOMA as a whole. Score 5 Sensitivity: ( )/3 = 5 Risk of Harm 0.1 x 5 = 0.5 6

30 Certainty Checklist Answer yes or no to all of the following questions. Record the number of NO s to the 9 questions, and record certainty according to the scale provided below: 1 No s = High certainty 2-3 No s = Medium certainty > 4 No s = Low certainty Y/N Y Is the score supported by a large body of information? N Is the score supported by general expert agreement? N Is the interaction well understood, without major information gaps/sources of error? Y Is the current level of understanding based on empirical data rather than models, anecdotal information or probable scenarios? Y Is the score supported by data which is specific to the region, (EBSA, LOMA, NW Atlantic? Y Is the score supported by recent data or research (the last 10 years or less)? N Is the score supported by long-term data sets (ten years or more) from multiple surveys (5 years or more)? Y Do you have a reasonable level of comfort in the scoring/conclusions? N Do you have a high level of confidence in the scoring/conclusions? Score: Low For interactions with Low certainty, underline the main factor(s) contributing to the uncertainty Lack of comprehensive data Lack of expert agreement Predictions based of future scenarios which are difficult to predict Other (provide explanation) Suggest possible research to address uncertainty: 7

31 Reference List 1. Atlantic Leatherback Turtle Recovery Team (2006). Recovery Strategy for Leatherback Turtle (Dermochelys coriacea) in Atlantic Canada (Rep. No. Species at Risk Act Recovery Strategy Series ). Ottawa: Fisheries and Oceans Canada. 2. Community Resource Services Ltd & Jacques Whitford Environment Ltd (2001). Socio-Economic Overview of Placentia Bay, Newfoundland. 3. COSEWIC & James, M. C. (2001). COSEWIC Assessment and Update Status Report on the Leatherback Turtle Dermochelys coriacea in Canada Ottawa: Committee on the Status of Endangered Wildlife in Canada. 4. Fisheries and Oceans Canada. Underwater World Aquatic Species at Risk - The Leatherback Turtle Ottawa, Ont. Ref Type: Pamphlet 5. Fisheries and Oceans Canada (2007a). Draft proceedings of the Workshop on Qualitative Risk Assessment of Fishing Gears. In Government of Canada. 6. Fisheries and Oceans Canada (2007b). Placentia Bay-Grand Banks Large Ocean Management Area Conservation Objectives (Rep. No. 2007/042). Canadian Science Advisory Secretariat Science Advisory Report. 7. Fisheries and Oceans Canada LMNOP4R Effort and Catch. Policy and Economics Branch. [Newfoundland and Labrador Region Catch and Effort] Fisheries and Oceans Canada. 8. Halpern, B. S., Walbridge, S., Selkoe, K. A., Kappel, C. V., Micheli, F., D'Agrosa, C., Bruno, J. F., Casey, K. S., Ebert, C., Fox, H. E., Fujita, R., Heinemann, D., Lenihan, H. S., Madin, E. M. P., Perry, M. T., Selig, E. R., Spalding, M., Steneck, R., & Watson, R. (2008). A Global Map of Human Impact on Marine Ecosystems. Science, 319, James, M. C., Ottensmeyer, C. A., & Myers, R. A. (2005). Identification of high-use habitat and threats to leatherback sea turtles in northern waters: new directions for conservation. Ecology Letters, 8, James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A. (2006). Canadian waters provide critical foraging habitat for leatherback sea turtles. Biological Conservation, 133, Ledwell, W. & Huntington, J. (2007). Whale and leatherback sea turtles incidental entrapment in fishing gear in Newfoundland and Labrador and a summary of the Whale Release and Strandings Program during 2006 A Report to the Department of Fisheries and Oceans, St. John's, Newfoundland and Labrador, Canada. 8

32 12. Turtle Expert Working Group (2007). An Assessment of the Leatherback Turtle Population in the Atlantic Ocean (Rep. No. NOAA Technical Memorandum NMFS-SEFSC-555). U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southeast Fisheries Science Center. 9

33 Leatherback aggregation and feeding in Placentia Bay Extension Ship strikes Magnitude of Interaction Areal extent: Leatherback turtles have not been systematically surveyed around Newfoundland and distribution maps rely largely on opportunistic reporting and tracking of small numbers of individual leatherbacks. The primary determinant of movement and behaviour of leatherbacks is the spatial and temporal distribution of their primary prey, gelatinous plankton generally known as jellyfish. In general, jellyfish abundance is highest in coastal waters (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006) James et al. identified spatial use of leatherbacks in the western Atlantic through satellite tracking tags on 38 turtles (Figure 1, below): Figure 1.. Spatial use of leatherbacks in the western Atlantic (James, M. C., Ottensmeyer, C. A., & Myers, R. A., 2005). This data was updated by the Turtle Expert Working Group in 2007, and is shown in Fig. 2 below: Figure 2. Habitat use by leatherback turtles on foraging grounds in the northwest Atlantic (Turtle Expert Working Group, 2007). 1

34 Leatherback occurrence was also mapped by the Atlantic Leatherback recovery Team in 2006 and is shown in Fig. 3 below: Figure 3. Occurrence of the leatherback turtle, Dermochelys coriacea, off eastern Canada. Shaded areas show the location of concentrations of observations (Atlantic Leatherback Turtle Recovery Team, 2006). This information indicates that leatherbacks are broadly distributed, and could be found throughout the EBSA. The primary source of detailed local data on marine traffic for the LOMA is maintained by the Canadian Coast Guard (CCG), and is based on a mandatory reporting system for all commercial vessels over 500t (or carrying pollutants or dangerous cargo) transiting within Canada s 12 nautical mile territorial sea (Fig. 4 below). Figure 4. Commercial shipping, traffic density (from ECAREG data) (Fisheries and Oceans Canada, 2007). 2

35 A major shipping lane passes through the east side of Placentia Bay serving the Come by Chance Oil refinery, the NL Transshipment Terminal and the Ferry Terminal at Placentia as well as other sites. Total annual vessel movements in Placentia Bay in 2004 totalled 8,286 including 1,276 oil tankers, 62 chemical tankers, 522 cargo ships, 2,046 tug boats 1,501 ferry movements, and 1,589 fishing boats and other vessels under 20 (Transport Canada, 2007). Based on this information, the annual vessel traffic is for the EBSA is considered to be high. Score 9 Contact: While incidents of collisions with leatherbacks have not been documented in Atlantic Canada, they have been known to occur in US waters (Atlantic Leatherback Turtle Recovery Team, 2006), and collisions with cetaceans are well documented (Elvina, S. S. & Taggart, C. T., 2008; Jensen, A. S. & Silber, G. K., 2004; Laist, D. W., Knowton, A. R., Meade, J. G., Collet, A. S., & Podesta, M., 2001; Vanderlaan, A. S., Taggart, C. T., Serdynska, A. R., Kenney, R. D., & Brown, M. W., 2008). Leatherbacks breathe air, and also spend time resting and feeding at the sea surface (James, M. C., Myers, R. A., & Ottensmeyer, C. A., 2005). Diving behaviour of leatherbacks in continental slope waters of northeastern US and eastern Canada suggests that they spend 43 to 50% of their time at the water surface (Transport Canada & RMRI (Canada), 2007). Leatherback turtles are known to bask at the surface for extended periods of time when foraging in temperate waters and, therefore, may be vulnerable to collisions with marine traffic. In areas where recreational boating, commercial fishing and ship traffic are concentrated, propeller and collision-related injuries may represent a source of mortality (Atlantic Leatherback Turtle Recovery Team, 2006). The likelihood of contact is therefore considered high. Score 8 Duration: Leatherbacks are typically present in the LOMA from June to October (Atlantic Leatherback Turtle Recovery Team, 2006) Most vessel traffic is relatively consistent throughout the year, with the exception of fishing and passenger vessels which are greatly reduced in the winter (December to March) (Pelot, R. & Wootton, D., 2004). Since peak vessel traffic coincides with leatherback occurrence in the LOMA, duration is 100% Score 10 Intensity: Halpern et al. (2008) have developed maps showing the global intensity of several anthropogenic stressors including commercial shipping. These maps can be used to 3

36 Figure 6. Commercial shipping activity in PBGB LOMA (Halpern, B. S. et al., 2008). Based on Figure 6, shipping intensity within the EBSA can be considered moderate (40-60%) on a global scale, as the shipping density is predominantly yellow in colour. Since fishing and shipping intensity within Placentia Bay is high relative to other areas of the LOMA, we have selected a high score within the moderate range Score 6 Magnitude of Interaction: (9 x 8 x 10 x 6)/ 1000 = 4.3 Sensitivity Sensitivity of the CP to acute impacts: Leatherbacks breathe air, and also spend time resting and feeding at the sea surface (James, M. C., Myers, R. A., & Ottensmeyer, C. A., 2005). Leatherback turtles are known to bask at the surface for extended periods of time when foraging in temperate waters and, therefore, may be vulnerable to collisions with marine traffic. In areas where recreational boating, commercial fishing and ship traffic are concentrated, propeller and collision-related injuries may represent a source of mortality (Atlantic Leatherback Turtle Recovery Team, 2006). While incidents of collisions with leatherbacks have not been documented in Placentia Bay or even Atlantic Canada, they have been known to occur in US waters (Atlantic Leatherback Turtle Recovery Team, 2006), and collisions with cetaceans are well documented (Elvina, S. S. & Taggart, C. T., 2008; Jensen, A. S. & Silber, G. K., 2004; Laist, D. W., Knowton, A. R., Meade, J. G., Collet, A. S., & Podesta, M., 2001; Vanderlaan, A. S., Taggart, C. T., Serdynska, A. R., Kenney, R. D., & Brown, M. W., 2008) The highest incidents of vessel strikes to large whales in North American waters occurred in the US east coast, and was nearly 5 times higher than the frequency reported in Eastern Canada (Jensen, A. S. & Silber, G. K., 2004). This may also hold true for leatherbacks, but there is little or no reporting of collision incidents. While all sizes and types of vessels can collide with whales, most lethal or severe injuries are caused by vessels >80 m in length (Laist, D. W., Knowton, A. R., Meade, J. G., Collet, A. S., & Podesta, M., 2001). Historical records suggest that fatal ship strikes 4

37 Large vessel traffic within the EBSA include tankers (oil, chemical), cargo vessels (bulk, general, container), and passenger vessels (ferries, cruise ships, tour boats) (Fisheries and Oceans Canada, 2002). Acute impacts from ship strikes are likely low, but this may be largely the result of the low density of leatherbacks in the EBSA and globally, rather than a reflection of their vulnerability. Based on this information we have selected a score at the high end of the low range. Score 3 Sensitivity of the CP to chronic impacts: A long lifespan, very high rates of egg and hatchling mortality, and a late age of maturity makes this species unusually vulnerable to even small increases in rates of mortality of adults and older juveniles. Generation time is estimated at <30 years (COSEWIC & James, M. C., 2001) The leatherback turtle is classified as critically endangered by the International Union for the Conservation of Nature and as endangered by the Committee on the Status of Endangered Wildlife in Canada. Leatherbacks have experienced a dramatic population decline of more than 60 per cent since Because male turtles do not return to land, it is not possible to accurately count them. Scientists determine the population of sea turtles by counting nesting females. Currently, the total number of nesting females is thought to be less than 35,000 worldwide (Fisheries and Oceans Canada, 2004). The Atlantic population appears to be stable, but shows dramatic fluctuations from year to year. The relative density of leatherbacks in Canadian waters has been estimated at turtles (during summer), but this is likely low, as there are no accurate population estimates for leatherbacks in Canadian waters (COSEWIC & James, M. C., 2001). Although ship collisions with leatherbacks have not been recorded within the LOMA, and are likely rare, even the occasional death of a leatherback is a concern due to their depleted status. Non-lethal incidents and propeller injuries may also occur, and are much less likely to be reported. Since small inshore fishing boats (<35 ) make up close to 90% of fishing vessels in the region (Fisheries and Oceans Canada, 2002), and small boat traffic is most common in coastal areas (Pelot, R. & Wootton, D., 2004) such as Placentia Bay, minor collisions and propeller injuries are an additional concern. Chronic sensitivity is considered to be in the low range (2). Leatherbacks are listed as a depleted species for the LOMA (add 1 point). Score 3 5

38 Sensitivity of ecosystem to harmful impacts to the CP: Leatherbacks depend on prey with very little nutritive content and since this species diet of jellyfish is high in water and low in organic content, they must consume large quantities of food to fulfill their energy requirements (Atlantic Leatherback Turtle Recovery Team, 2006). Jellyfish are generally considered a nuisance species, which can foul fishing gear and force the closure of swimming beaches. Jellyfish also compete with larval fish for food (both eat zooplankton), and are also known predators of larval fish (James, M. C., Ottensmeyer, C. A., & Myers, R. A., 2005). Leatherbacks help keep the jellyfish population under control, and may therefore help conserve fish species, as well as contributing to pest control within the EBSA. Despite their relatively small numbers, leatherbacks represent a significant biomass due to their large size, and contribute significantly to the energetics of the marine ecosystem. Leatherbacks are highly mobile, and their large scale movements contribute to the transfer of energy and biomass from seasonally productive areas to distance marine systems. Due to their large size and habit of basking on the sea surface, leatherbacks have long attracted interest, and their presence within the EBSA contributes to ecotourism opportunities. Canadian waters support one of the highest summer and fall densities of leatherbacks in the North Atlantic, and should be considered critical foraging habitat for this endangered species (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006). Although the EBSA has been identified as an important area for leatherback aggregation and feeding, leatherbacks are widely distributed within the LOMA during the summer months and other areas may be of equal or greater importance. Based on this information we have selected a score in the medium range to reflect the importance of leatherback aggregation and feeding within the EBSA in relation to the LOMA as a whole. Score 5 Sensitivity: 3+3+5/3=3.7 Risk of Harm: 4.3 x 3.7 =

39 Certainty Checklist Answer yes or no to all of the following questions. Record the number of NO s to the 9 questions, and record certainty according to the scale provided below: 1 No s = High certainty 2-3 No s = Medium certainty > 4 No s = Low certainty Y/N Y Is the score supported by a large body of information? N Is the score supported by general expert agreement? N Is the interaction well understood, without major information gaps/sources of error? Y Is the current level of understanding based on empirical data rather than models, anecdotal information or probable scenarios? N Is the score supported by data which is specific to the region, (EBSA, LOMA, NW Atlantic? Y Is the score supported by recent data or research (the last 10 years or less)? N Is the score supported by long-term data sets (ten years or more) from multiple surveys (5 years or more)? Y Do you have a reasonable level of comfort in the scoring/conclusions? N Do you have a high level of confidence in the scoring/conclusions? Score: Low For interactions with Low certainty, underline the main factor(s) contributing to the uncertainty Lack of comprehensive data Lack of expert agreement Predictions based of future scenarios which are difficult to predict Other (provide explanation) Suggest possible research to address uncertainty: 7

40 Reference List 1. Atlantic Leatherback Turtle Recovery Team (2006). Recovery Strategy for Leatherback Turtle (Dermochelys coriacea) in Atlantic Canada (Rep. No. Species at Risk Act Recovery Strategy Series ). Ottawa: Fisheries and Oceans Canada. 2. COSEWIC & James, M. C. (2001). COSEWIC Assessment and Update Status Report on the Leatherback Turtle Dermochelys coriacea in Canada Ottawa: Committee on the Status of Endangered Wildlife in Canada. 3. Elvina, S. S. & Taggart, C. T. (2008). Right whales and vessels in Canadian waters. Marine Policy, 32, Fisheries and Oceans Canada (2002). Statistical Services - Commercial Licenses - Vessels Information. Fisheries and Oceans Canada [Announcement posted on the World Wide Web]. from the World Wide Web: tm 5. Fisheries and Oceans Canada. Underwater World Aquatic Species at Risk - The Leatherback Turtle Ottawa, Ont. Ref Type: Pamphlet 6. Fisheries and Oceans Canada The Grand Banks of Newfoundland: Atlas of Human Activities. The Grand Banks of Newfoundland: Atlas of Human Activities (in press). 7. Halpern, B. S., Walbridge, S., Selkoe, K. A., Kappel, C. V., Micheli, F., D'Agrosa, C., Bruno, J. F., Casey, K. S., Ebert, C., Fox, H. E., Fujita, R., Heinemann, D., Lenihan, H. S., Madin, E. M. P., Perry, M. T., Selig, E. R., Spalding, M., Steneck, R., & Watson, R. (2008). A Global Map of Human Impact on Marine Ecosystems. Science, 319, James, M. C., Myers, R. A., & Ottensmeyer, C. A. (2005). Behaviour of leatherback sea turtles, Dermochelys coriacea, during the migratory cycle. Proceedings of the Royal Society B, 272, James, M. C., Ottensmeyer, C. A., & Myers, R. A. (2005). Identification of high-use habitat and threats to leatherback sea turtles in northern waters: new directions for conservation. Ecology Letters, 8, James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A. (2006). Canadian waters provide critical foraging habitat for leatherback sea turtles. Biological Conservation, 133,

41 11. Jensen, A. S. & Silber, G. K. (2004). Large Whale Ship Strike Database (Rep. No. NMFS-OPR-25). U.S. Department of Commerce. 12. Laist, D. W., Knowton, A. R., Meade, J. G., Collet, A. S., & Podesta, M. (2001). Collisions Between Ships and Whales. Marine Mammal Science, 17, Pelot, R. & Wootton, D. (2004). Maritime traffic distribution in Atlantic Canada to support an evaluation of a Sensitive Sea Area proposal (Rep. No ). Maritime Activity & Risk Investigation Network. 14. Transport Canada (2007). Synopsis Report - Environmental Oil Spill Risk Assessment for the South Coast of Newfoundland (Rep. No. TC ). 15. Transport Canada & RMRI (Canada) (2007). Quantitative Assessment of Oil Spill Risk for the South Coast of Newfoundland and Labrador (Rep. No. CAN/0179/R003). Transport Canada. 16. Turtle Expert Working Group (2007). An Assessment of the Leatherback Turtle Population in the Atlantic Ocean (Rep. No. NOAA Technical Memorandum NMFS-SEFSC-555). U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southeast Fisheries Science Center. 17. Vanderlaan, A. S., Taggart, C. T., Serdynska, A. R., Kenney, R. D., & Brown, M. W. (2008). Reducing the risk of lethal encounters: vessels and right whales in the Bay of Fundy and on the Scotian Shelf. Endangered Species Research, 4,

42 Leatherback aggregation and feeding in Placentia Bay Extension Litter Magnitude of Interaction Areal extent: Leatherback turtles have not been systematically surveyed around Newfoundland and distribution maps rely largely on opportunistic reporting and tracking of small numbers of individual leatherbacks. The primary determinant of movement and behaviour of leatherbacks is the spatial and temporal distribution of their primary prey, gelatinous plankton generally known as jellyfish. In general, jellyfish abundance is highest in coastal waters (James, M. C., Sherrill-Mix, S. A., Martin, K., & Myers, R. A., 2006). James et al. identified spatial use of leatherbacks in the western Atlantic through satellite tracking tags on 38 turtles (Fig. 1, below): Figure 1. Spatial use of leatherbacks in the Western Atlantic (James, M. C., Ottensmeyer, C. A., & Myers, R. A., 2005). This data was updated by the Turtle Expert Working Group in 2007: Figure 2. Habitat use by Leatherback Turtles on foraging Grounds in the northwest Atlantic (Turtle Expert Working Group, 2007). 1

43 Figure 3.Occurrence of the leatherback turtle, Dermochelys coriacea, off eastern Canada. Shaded areas show the location of concentrations of observations (Atlantic Leatherback Turtle Recovery Team, 2006). This information indicates that leatherbacks are broadly distributed, and could be found throughout the EBSA. It is estimated that 6.4 million tonnes of garbage go into the world s oceans every year (Keep Sweden Tidy Foundation, 2003). Up to 80% of marine debris comes from the land, blowing and washing off beaches and carried to the sea by rivers, sewage systems, and storm drains. The remaining 20% is lost or discarded from boats and ships of all types and sizes (Federal-Provincial-Territorial Committee on NPA, 2000). Marine litter within Placentia Bay comes from many sources, including vessels, surface currents, and land-based sources which can be related to population density. Average annual marine traffic density in the EBSA is considered high (Pelot, R. & Wootton, D., 2004). Although the population (25,000 residents) is relatively low, Placentia Bay hosts a number of major industrial sites and tourist attractions which bring a considerable number of non-residents to the area on a daily basis, and therefore population density is considered to be moderate. Beach surveys conducted in 2004 in Placentia Bay revealed large accumulations of plastic debris on southwest-facing beaches of the bay where they are deposited by prevailing southwest winds and counterclockwise currents (Fisheries and Oceans Canada, 2005). Based on the pollution potential of the area (moderate to high) and existing data for the area, we have estimated the areal extent at the low end of the high range. Score 8 Contact: Leatherbacks breathe air, and also spend time basking, resting and feeding at the sea surface. In Canadian waters, satellite tracking studies have shown that leatherbacks spend between 1-35% of their time on the surface (James, M. C., Myers, R. A., & Ottensmeyer, C. A., 2005). 2

44 Although there is evidence that leatherbacks do not feed exclusively at the surface, they feed mainly on planktonic jellyfish floating in surface waters, and are generally thought of as surface feeders, particularly in coastal waters. Plastic particles and scraps of ropes, netting, six pack rings and related materials persist in the marine environment, floating in surface waters where they interact with leatherbacks feeding at the sea surface. Feeding behavior may also put leatherbacks at risk indirectly. Since the horizontal movement of jellyfish is largely passive, they tend to concentrate where currents converge. These same currents concentrate other buoyant objects, including marine debris (e.g., plastic bags, discarded and lost fishing gear, etc.). Therefore, leatherbacks foraging in areas where jellyfish are concentrated may encounter significant amounts of potentially harmful materials of anthropogenic origin (James, M. C. & Herman, T. B., 2001). The likelihood of contact is therefore considered high. Score 9 Duration: Leatherbacks are typically present in the EBSA from June to October (Atlantic Leatherback Turtle Recovery Team, 2006) Litter is considered a chronic stressor which occurs every year, and so is given a score in the medium range. Since marine litter is persistent, consisting largely of plastic debris, and sources of litter (land-based activities, fishing boats, ships and winds/currents) are present throughout the year, we have selected a score at the top of the medium range. Score 7 Intensity: Halpern et al. (2008) have developed maps showing the global intensity of several anthropogenic stressors including ocean pollution. This map can be used to provide guidance in scoring the intensity of a stressor in relation to maximum (Fisheries and Ocean Canada, 2007) intensity in a global context in accordance with the scale provided below. Map colour Red Orange Yellow Light Blue Dark Blue Intensity % 60-80% 40-60% 20-40% 0-20% Figure 4. Global intensity of ocean pollution, adapted from (Halpern, B. S. et al., 2008) 3