RELATIVE ABUNDANCE OF JUVENILE SMALL TOOTH SAWFISH

Transcription

1 Final Report RELATIVE ABUNDANCE OF JUVENILE SMALL TOOTH SAWFISH Beau G. Yeiser and Tonya Wiley* Center for Shark Research Mote Marine Laboratory 1600 Ken Thompson Parkway Sarasota, FL NOAA purchase order number: WC133F07CN0247 Contractor: Mote Marine Laboratory Project start date: September, 2007 Submitted to: National Marine Fisheries Service Southeast Regional Office th Avenue South St. Petersburg, Florida Mote Marine Laboratory Technical Report # 1307 December 2008

2 *Current contact information: Beau Yeiser 6365 Bridge Brook Overlook Cumming, Georgia Phone: Tonya Wiley Texas Parks and Wildlife Department Coastal Fisheries Division Dickinson Marine Lab 1502 FM 517 E Dickinson, Texas Phone: tonya.wiley@tpwd.state.tx.us

3 Project Purpose: The smalltooth sawfish was listed as Endangered under the Endangered Species Act in They were once common in the GulfofMexico and east coast of the United States. Decades of fishing pressure, both commercial and recreational, and habitat loss caused the population to decline significantly during the second half of the twentieth century and today they exist mostly in southern Florida. The completion of the Smalltooth Sawfish Recovery Plan in early 2006 has heralded a new phase of management for the US DPS ofthis species. Research and monitoring priorities identified in the Recovery Plan now need to be implemented. One of the high priority tasks to be identified in the plan was the monitoring ofthe number of sawfish in nursery regions throughout Florida. The most important nursery region for smalltooth sawfish is the section of coast from Marco Island (Naples) to Florida Bay. This region encompasses the coast of the Ten Thousand Islands and Everglades National Park, which is outside of the areas covered in the fishery independent monitoring program run by the Florida Fish and Wildlife Research Institute (FWRI). This project carried out a broad survey of this area when juvenile sawfish are pupped in this region (February through May) to identify appropriate sampling locations, techniques and timing. This report includes results of the survey and a recommended sampling schedule for future ongoing surveys of this region to document juvenile sawfish numbers. Results: Sawfish Nursery Surveys Design The location and timing of surveys within four regions of the coast of Florida were determined: Ten Thousand Islands, Everglades Coast, Shark RiverlWhitewater Bay/Coot Bay, and Florida Bay. Areas within these regions have been identified from the MML National Smalltooth Sawfish Encounter Database and previous MML fieldwork as potential nursery areas. Ten Thousand Islands Backcountry Region: This region includes the backcountry waters from Naples to Chokoloskee, encompassing the northern portion of Everglades National Park. Five areas within this region have been identified: Grocery Creek, Faka Union Bay, Mud Bay, Sunday Bay, and House Hammock Bay. Shark RiverlWhitewater Bay/Coot Bay Region: This region extends from the Gulf of Mexico at Ponce de Leon Bay through the backwaters of Everglades National Park to Coot Bay near Flamingo. Four areas within this region have been identified: Shark River, Whitewater Bay, Coot Bay, and Ponce de Leon Bay. Ten Thousand Islands and Everglades Gulf Coast Region: This region covers the coastal waters of the Ten Thousand Islands and northern Everglades National Park. Four areas within this region have been identified: Gullivan to Pavilion Key, Rodgers River mouth, Lostmans River mouth, and Sara's Hole.

4 Florida Bay Region: This region contains the waters along the southern tip of the Florida peninsula from Key Largo to the Gulf of Mexico. Five areas within this region have been identified: Black Betsy Keys, Madeira Bay, Eagle Key, Bradley Key, and Lake Ingraham. Sawfish Nursery Surveys Results Sampling occurred from late January to early May, 2008 using longlines, short bottom gill nets, and rod and reel from Marco Island to northeast Florida Bay (Figure 1). Thirtyeight juvenile smalltooth sawfish were captured (Table 1). The Mud Bayffumer River area was surveyed with 13 gillnet sets January 23 in response to a public sawfish encounter report (Figure 2). Seven sawfish were captured in Mud Bay. Captain Mike Weinhofer of Compass Rose Charters was hired to sample the area from the Marquesas Keys to Key West February 5-6 (Figure 1). Areas sampled with rod and reel and 8 long line sets include the Marquesas Keys, Lakes Passage, Seven Sisters and Jack's Channel. One sawfish was captured on longline at the southeast entrance to the Marquesas Keys, and fitted with a Wildlife Computers Pop-Off Archival Transmitter (PAT tag) in collaboration with John Carlson of National Marine Fisheries Service Panama City Lab. Turner River was surveyed with 3 gillnet sets February 7 in response to a public sawfish encounter report (Figure 2). Four sawfish were captured at the left fork of the Turner River. The Ten Thousand Islands and upper Everglades Coast were surveyed February with 16 gillnet sets (Figures 2 & 3). Areas sampled include Faka Union Bay, Last Huston Bay, Huston Coves, Grocery Creek, and Turner River. Five sawfish were captured. Northeast Florida Bay was surveyed March with 21 gillnet and 4 longline sets (Figure 4). Areas sampled include Eagle Key, Little Madeira Bay, Shell Key and Park Key. One sawfish was captured at Eagle Key. The Ten Thousand Islands and upper Everglades Coast were surveyed April (Figures 2 & 3) with 34 gillnet and 5 longline sets. Areas sampled include Faka Union Bay, Last Huston Bay, Mud Bay, Huston Coves, Whitehorse and Gullivan Keys, and Grocery Creek (Figures 2 & 3). Ten sawfish were captured. The upper and middle Everglades Coast was surveyed April (Figure 2) with 15 gillnet and 1 longline sets. Areas sampled include Little Pavilion Key, Sara's Hole, Last Huston Bay, Cross Bay and Mud Bay. Ten sawfish were captured. The lower Everglades Coast was surveyed May 1-4 (Figure 5) with 13 longline and 9 gillnet sets. Areas sampled include Whitewater Bay, Coot Bay, Shark River, East Cape, Middle Cape, and the Middle Grounds. No sawfish were captured.

5 Table 1. Spring survey smalltooth sawfish capture details. VVeight Age Date location Gear pel Fl Tl STl (kg) Sex class* M /2008 Mud Bay, Turner River Gillnet M Mud Bay, Turner River Gillnet M Mud Bay, Turner River Gillnet F 0-1 1/ Mud Bay, Turner River Gillnet F 0-1 1/ Mud Bay, Turner River Gillnet F Mud Bay, Turner River Gillnet M /2008 Mud Bay, Turner River Gillnet F Marquesas Keys longline F /2008 Turner River left fork Gillnet F Turner River left fork Gillnet M Turner River left fork Gillnet F Turner River left fork Gillnet F 1-2 2/ Faka Union Bay Gillnet F 0-1 2/26/2008 Last Huston Bay cove Gillnet F 0-1 2/ Turner River left fork Gillnet F Turner River left fork Gillnet F /2008 Turner River left fork Gillnet F 1-2 3/ E~le Key, Florida Bay Gillnet M 1-2 4/14/2008 Faka Union Bay Gillnet M 0-1 4/16/2008 Mud Bay, Turner River Gillnet F 0-1 4/ Mud Bay, Turner River Gillnet F 0-1 4/ Mud Bay, Turner River Gillnet F 0-1 4/16/2008 Mud Bay, Turner River Gillnet M 0-1 4/16/2008 Mud Bay, Turner River Gillnet F 1-2 4/16/2008 Mud Bay, Turner River Gillnet F 0-1 4/ Turner River left fork Gillnet F 0-1 4/ Turner River left fork Gill net F /2008 Grocery Creek Gill net M 0-1 4/30/2008 Mud Bay, Turner River Gillnet I.l M 0-1 4/30/2008 Mud Bay, Turner River Gill net M 0-1 4/ Mud Bay, Turner River Gill net M 0-1 4/ Mud Bay, Turner River Gill net M 0-1 4/ Mud Bay, Turner River Gill net F 0-1 4/30/2008 Mud Bay, Turner River Gill net F 0-1 4/ Mud Bay, Turner River Gillnet F 0-1 4/30/2008 Mud Bay, Turner River Gillnet F 0-1 4/ Mud Bay, Turner River Gillnet M 0-1 4/30/2008 Mud Bay, Turner River Gillnet * Age classes based 00 Sunpfeodorrer, c.a., Poulakis, G.R., O'Donnell, P.M., and Wiley, T.R Growth rates of juvenile smalltooth sawfish, Pristis pectinata, in the western Atlantic. Journal offish Biology 72,

6 Figure 1. Spring survey sampling (red circles) and sawfish capture (yellow triangles) locations, 24.. ~.~--~----~--~----~----~---r----r----r----~---t----t---~ 12.. ' 12.' 1t'5I' IN' 11'31' am' 11'11' 11'11'.'SI'.~'.'31'.'ZO'

7 Figure 2. Everglades Coast Region spring survey sampling (red circles) and sawfish capture (yellow triangles) locations. 11'%5' 1m' 11'15'... Irs' 11'10'

8 Figure 3_ Ten Thousand Islands Region spring survey sampling (red circles) and sawfish capture (yellow triangles) locations_ IN- 11'3S- 11'31- am-

9 Figure 4, Florida Bay Region spring survey sampling (red circles) and sawfish capture (yellow triangles) locations, ".0 ~ <I..... II " a.. <> ~.oj', op ~ R.-. " [) at'ii'.'s5'.'51'.~'. ',w'.'35'.'30'

10 Figure 5. Shark River Region spring survey sampling (red circles) locations.... c::::> \) (] Q ~ \ \, 0 = '" ~ '" " an' m' l1'li' "'55'.. 'SO'

11 Recommended Relative Abundance Monitoring Protocol: Gillnets were the most effective gear for capturing small juvenile sawfish «200 cm) in very shallow water «1m). Longlines were effective at capturing larger juveniles (> 200 cm) in deeper water (> I m). Therefore, for effective sampling for all juveniles it is recommended that gillnets be set in very shallow areas adjacent to the shoreline over sand bars/mud flats, and longlines be set in areas of deeper water. The following locations by region are recommended for annual spring sampling for monitoring the relative abundance of juvenile smalltooth sawfish in southwest Florida. Recommended sampling schedule is provided in Table 2. Ten Thousand Islands Backcountry Region: Grocery Creek, Faka Union Bay, Mud Bay, and Last Huston Bay Ten Thousand Islands and Everglades Gulf Coast Region: Lostman's River mouth, Sara's Hole, and Huston Coves Shark RiverlWhitewater Bay/Coot Bay Region: Whitewater Bay and Coot Bay Florida Bay Region: Black BetsylEagle Keys, Madeira Bay, and Lake Ingraham/East Cape Additional areas should continue to be scouted for further nursery areas in these regions; suggested additional areas are included in Table 2.

12 Table 2. Recommended Sampling locations and timing. Region: Location: Feb March April May Ten Thousand Islands Backcountry Grocery Creek Faka Union Bay Mud Bay Sunday Bay House Hammock Last Huston Bay Shark River Shark River Whitewater Bay Coot Bay Ponce de Leon Bay Ten Thousand IslandslEverglades Rodgers River Coast Lostmans River Sara' s Hole Gullivan Key Pavilion Key Huston Coves Florida Bay Black Betsy Keys Madeira Bay Eagle Key Bradley Key Lake Ingraham

13 The following maps show specific locations for recommended sampling:

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