Abstract. Bianchi, Alan John. Effects of Fishing Practices, Gear Parameters and Gear

Transcription

1 Abstract Bianchi, Alan John. Effects of Fishing Practices, Gear Parameters and Gear Configurations on Target and Incidental Catch in the Southern Flounder (Paralichyths lethostigma) Gillnet Fishery of Pamlico Sound, North Carolina (Under the direction of Dr. BJ. Copeland) In North Carolina, the southern flounder (Paralichyths lethostigma) fishery is one of the most valuable finfish fisheries in the state. A large portion of this fishery occurs during the fall (September 15 to December 15) in the southeastern area of Pamlico Sound, North Carolina, and is conducted with gillnets. The increase in the number of gillnets employed in this fishery has begun to raise concerns among fishery managers and conservationists. These concerns include the reputation that gillnets have for catching large amounts of bycatch, an increase in the number of stranded sea turtles in the area during the southern flounder fall gillnet season, the incidental take of seabirds during gillnet operations and the incidental capture of red drum in southern flounder gillnets. This study was conducted during the 2000 and 2001 fall southern flounder season to determine the impacts of gillnets on sea turtles, seabirds, red drum, other finfish and invertebrates in Pamlico Sound, North Carolina. The purpose of this study is to examine the catch-per-unit-effort (CPUE) of the target (southern flounder) and bycatch species that is occurring in the southern flounder gillnet fishery of southeastern Pamlico Sound, North Carolina. It is hypothesized that the CPUE of the target and bycatch species will differ between the two areas (deep and shallow), the halves of the fishing season, gear parameters, soak time and gear configurations. The objectives of this study are: 1) To characterize the bycatch composition and distribution that is occurring in the southern

2 flounder gillnet fishery, 2) To test experimental gillnet configurations in an effort to reduce bycatch (emphasis on sea turtle bycatch) without reducing target catch in the deep area of the fishery, and 3) To suggest reasonable and prudent regulations for the fishery. The sea turtle bycatch was mostly composed of juveniles and subadults Kemp s ridley, green and loggerhead turtles. The majority of the finfish bycatch was composed of Atlantic menhaden and weakfish. Horseshoe crabs composed the majority of the invertebrate bycatch. Data analyzed from this study has determined that area was a significant factor affecting sea turtle and red drum bycatch. Other factors significantly affecting sea turtle bycatch included length and height of gillnet fished. Mesh size and length were significant factors in red drum and seabird bycatch. Effort was the only significant variable in the finfish analysis. Analysis of the southern flounder CPUE determined that twine size, length, height and soak time are all significant variables. Even though fishing season was not a significant factor in the analysis, the majority of observed sea turtle, seabird and red drum interactions occurred in the first half of the fishing season. Tie down configuration was an insignificant factor in the sea turtle, seabird and finfish CPUE analysis. However, it was a significant factor in the southern flounder CPUE analysis. Analysis of the experimental gear configurations determined that configuration was a significant variable. The low-profile configuration caught significantly less finfish and invertebrate bycatch than the control and double-lead line configurations. The low-profile configuration also caught significantly less southern flounder than the control.

3 I suggest that the following regulations be implemented to reduce bycatch of all species in the fall southern flounder gillnet fishery of Pamlico Sound, NC. 1) Move the starting date of the fishery back to October 1. 2) Raise the minimum mesh size to 14.6 cm and lower the maximum mesh size to 16 cm. 3) Implement the use of the low profile configurations for the deep area of the fishery.

4 EFFECTS OF FISHING PRACTICES, GEAR PARAMETERS AND GEAR CONFIGURATIONS ON TARGET AND INCIDENTAL CATCH IN THE SOUTHERN FLOUNDER (PARALICHYTHS LETHOSTIGMA) GILLNET FISHERY OF PAMLICO SOUND, NORTH CAROLINA BY ALAN JOHN BIANCHI A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the Degree of Master of Science ZOOLOGY Raleigh 2002 APPROVED BY: Dr. BJ Copeland, (chair) Dr. James A. Rice Dr. Lundie Spence

5 Biography Alan John Bianchi was born on November 21, 1974 in Rochester, Michigan to Laura and John Bianchi. He lived in the suburbs of Detroit until he was 13 years old and his family moved to Maumee, Ohio. He attended Maumee High School for 3 years and moved back to the suburbs of Detroit to finish his high school career at Henry Ford II High School. He graduated with honors in Alan attended the University of Michigan for one semester in the fall of In 1994 his family moved to Greensboro, North Carolina. In Greensboro, he met his future wife, Sabrina. Sabrina and Alan wed on April 29, 1995 and on August 24, 1995 his daughter Meagan was born. In the spring of 1996, Alan attended the University of North Carolina at Greensboro. He remained there until the fall of 1997 when he transferred to North Carolina State University and finished his Bachelor s of Science Degree in Zoology in During his undergraduate career, Alan was elected to Phi Beta Kappa and Phi Sigma Theta and obtained Summa Cum Laude honors. In the spring of 2000, Alan applied to the Zoology Graduate Program at North Carolina State University. Alan was accepted and began working with Dr. BJ Copeland in the summer of 2000 on his master s research. ii

6 Acknowledgements I could not have accomplished the completion of this project and this degree without the support of my family. I want to take this time to thank my parents for their support and encouragement. I also wish to thank my beautiful wife and daughter, Sabrina and Megan Bianchi for their support, love and belief in my abilities to complete this project. I also want to thank my committee, Dr. B J Copeland, Dr. James Rice and Dr. Lundie Spence for their invaluable encouragement, advice and counsel. I also wish to thank Bob Barwick, Corey Oakley, Larissa Bailey, Rob Aguilar, Jason Robinson and the rest of the Zoology Graduate Students for their support. I also wish to thank Jeff Gearhart, John Alexander, Chris Braddy and Parks Lewis at the North Carolina Division of Marine Fisheries for their help in gathering and editing the data necessary to complete this project. This project was supported from a grant received from the National Oceanic and Atmospheric Administration. Support for this project was received from the North Carolina Division of Marine Fisheries, National Marine Fisheries Service, North Carolina Sea Grant Program and North Carolina State University. iii

7 Table of Contents LIST OF TABLES LIST OF FIGURES vi vii I. INTRODUCTION Background on the Flounder Fishery 1 Bycatch in the Southern Flounder Fishery 3 Background on the Target and Bycatch Species 4 Southern Flounder (Paralichyths lethostigma) 4 Sea Turtle Bycatch 5 Seabird Bycatch 7 Finfish Bycatch 8 Gillnet Parameters and Gear Configurations 10 Management Strategies Currently Employed to Manage Commercial Fisheries 11 Goals and Objectives 13 Works Cited 15 II. METHODS Description of the Study Area 24 Observers and Observer Training 24 Study Design and Data Recorded 25 Statistical Analysis 27 Works Cited 31 III. RESULTS Observer Coverage 32 Sea Turtle Bycatch 32 Fishing Practices 33 Gear Parameters 33 Seabird Bycatch 34 Fishing Practices 34 Gear Parameters 35 Red Drum Bycatch 35 Fishing Practices 36 Gear Parameters 36 Other Finfish 37 Fishing Practices 37 Gear Parameters 38 iv

8 Southern Flounder 38 Fishing Practices 38 Gear Parameters 39 Gear Configuration 39 Tie Down Length 39 Experimental Gear Configuration 40 IV. DISCUSSION Characterization of the Bycatch in the Southern Flounder Gillnet Fishery of Pamlico Sound, NC 67 Management Strategies for the Southern Flounder Gillnet Fishery 70 Bycatch and Management Strategies in Other Gillnet Fisheries 73 Conclusion 76 Suggested Regulations and Needed Research 78 Works Cited 79 v

9 List of Tables Table 1 Number of trips and gears observed by area during the 2000 Pamlico Sound southern flounder gillnet fishery. 43 Table 2. Number of trips and gears observed by season during the 2000 Pamlico Sound southern flounder gillnet fishery. 43 Table 3. Total number of sea turtle interactions observed during the fall 2000 southern flounder gillnet fishery of Pamlico Sound, NC. 43 Table 4. Paired t-test analysis between sea turtle CPUE for 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 43 Table 5. Total number of seabird interactions in the 2000 southern flounder gillnet fishery of Pamlico Sound, NC. 46 Table 6. Total weight of the finfish bycatch during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 229). 59 Table 7. Species composition by number and weight sampled during the 2001 southern flounder gillnet fishery of Pamlico Sound, North Carolina (n = 90). 60 Table 8. Species composition by number and weight for control configured gillnets for the 2001 southern flounder gillnet fishery of Pamlico Sound, North Carolina (n = 90). 62 Table 9. Species composition by number and weight for double lead line configured gillnets for the 2001 southern flounder gillnet fishery of Pamlico Sound, North Carolina (n = 90). 63 Table 10. Species composition by number and weight for low profile configured gillnets for the 2001 southern flounder gillnet fishery of Pamlico Sound, North Carolina (n = 90). 64 Table 11 Percent catch by number for three experimental gear configurations in the 2001 southern flounder gillnet fishery of Pamlico Sound, NC relative to the control configuration (n = 90). 66 Table 12. Percent catch by number for three experimental gear configurations In the 2001 southern flounder gillnet fishery of Pamlico Sound, NC relative To the control configuration (n = 90). 66 vi

10 List of Figures Figure 1. Illustration of a sink gillnet employing a tie down Configuration (reproduced with permission from Gearhart 2001; NMFS 1996). 14 Figure 2. The Pamlico Sound Gillnet Restricted Area (reproduced with permission from NCDMF 2000). 29 Figure 3. Deep and Shallow water southern flounder gillnet fisheries of Pamlico Sound, North Carolina (reproduced with permission from NCDMF 2001). 30 Figure 4. Probability of a Sea Turtle Interaction (± std. error) vs. Area during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC as estimated by logistic regression (n = 377). 44 Figure 5. Probability of a Sea Turtle Interaction (± std. Error) vs. Season During the 2000 southern flounder gillnet fishery of Pamlico Sound, NC as estimated by logistic regression (n = 377). 44 Figure 6. Sea Turtle Interaction vs. Effort during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 45 Figure 7. Sea Turtle Interaction vs. Meters of net during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 45 Figure 8. Probability of a Sea Turtle Interaction (± std. error) vs. Height during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC as estimated by logistic regression (n = 377). 46 Figure 9. Seabird CPUE (± std. error) vs. Species during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 229). 47 Figure 10. Seabird CPUE (± std. error) vs. Area during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 229). 47 Figure 11. Seabird CPUE (± std. error) vs. Season during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 229). 48 Figure 12. Seabird CPUE vs. Meters of net during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 229). 48 Figure 13. Seabird CPUE (± std. error) vs. Mesh Size during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 229). 49 vii

11 Figure 14. Red Drum CPUE (± std. error) vs. Life Status during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 49 Figure 15. Red Drum CPUE (± std. error) vs. Area during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 50 Figure 16. Red Drum CPUE (± std. error) vs. Season during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 50 Figure 17. Red Drum CPUE vs. Meters of net during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 51 Figure 18. Red Drum CPUE (± std. error) vs. Mesh Size during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC. (n = 377) 51 Figure 19. Finfish CPUE (± std. error) vs. Area during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 229). 52 Figure 20. Finfish CPUE (± std. error) vs. Season during the 2000 southern flounder gillnet fisher of Pamlico Sound, NC (n = 229). 52 Figure 21. Finfish CPUE vs. Effort during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 229). 53 Figure 22. Southern flounder CPUE (± std. error) vs. Area during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 53 Figure 23. Southern flounder CPUE (± std. error) vs. Season during the 2000 Southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 54 Figure 24. Southern flounder CPUE vs. Meters of net during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 54 Figure 25. Southern flounder CPUE (± std. error) vs. Soak during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 55 Figure 26. Southern flounder CPUE (± std. error) vs. Height during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 55 Figure 27. Southern flounder CPUE (± std. error) vs. Twine Size during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 377). 56 Figure 28. Probability of a Sea Turtle Interaction (± std. error) vs. Tie Down Length during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC as estimated by logistic regression (n = 156). 56 viii

12 Figure 29. Seabird CPUE (± std. error) vs. Tie Down Length during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 91). 57 Figure 30. Finfish CPUE (± std. error) vs. Tie Down Length during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 91). 57 Figure 31. Southern flounder CPUE (± std. error) vs. Tie Down Length during the 2000 southern flounder gillnet fishery of Pamlico Sound, NC (n = 156). 58 Figure 32. Southern flounder CPUE (± std. error) vs. Experimental Gillnet Configuration during the 2001 southern flounder gillnet fishery of Pamlico Sound, NC (n = 90). 58 Figure 33. Finfish CPUE (± std. error) vs. Experimental Gillnet Configuration during the 2001 southern flounder gillnet fishery of Pamlico Sound, NC (n = 90). 65 Figure 34. Invertebrate CPUE (± std. error) vs. Experimental Gillnet Configuration during the 2001 southern flounder gillnet fishery of Pamlico Sound, NC ( n = 90). 65 ix

13 Introduction Bycatch is a major problem in both commercial and recreational fisheries around the world (Northridge 1991; Alverson et al. 1994). A large amount of bycatch occurs in gillnet fisheries operated around the world, including the United States (Northridge 1991; Alverson et al. 1994). Marine mammals, sea turtles, seabirds, endangered fish and invertebrates often compose the bycatch in many of these fisheries (Northridge 1991; Alverson et al. 1994). The effects of this incidental harvest can result in declining populations of the incidentally harvested species, devastating ecological interactions, disruptions in food web dynamics and the loss of a sustainable fishery (Northridge 1991; Alverson et al. 1994). Background on the Flounder Fishery The flounder fishery was one of the top ten commercial fisheries in the United States in both landings (177, 808 metric tons) and income ($96,802,000) in (NMFS 1999). On the Atlantic coast, flounders or flukes consist of several species; summer flounder (Paralichyths dentatus), gulf flounder (Paralichthys albigutta) and southern flounder (Paralichyths lethostigma). In North Carolina, the southern flounder fishery is one of the most valuable finfish fisheries in the state, generating almost $7 million in 1995 (NCDMF 1997). A large portion of this fishery occurs during the fall (September 15 to December 15) in the southeastern area of Pamlico Sound, North Carolina (G. Meekins, pers. comm. 2000). At this time of year, southern flounder are migrating out of the estuarine habitat to their spawning grounds offshore (Burke et al. 1

14 1991; Matlock 1991; Burke 1995; Monaghan and Armstrong 2000). Commercial fishermen take advantage of this natural phenomenon and set their gear in an attempt to intercept the flounder during their annual migrations. Historically, the most common gear utilized in the fishery was the pound net (Watterson 2000; Monaghan 2001). However, over the past 10 years gillnets have become the most predominate gear (Watterson 2000; Gearhart 2001; Monaghan 2001). The increase in the participation of the gillnet fishery has been due to an increase in the demand for flounder and the recruitment of displaced fishermen from other states (Watterson 2000; Monaghan 2001). A significant portion of this increase has occurred in the southeastern portion of Pamlico Sound (G. Meekins, pers. comm. 2000). The gillnet fishery that occurs in this portion of Pamlico Sound can be broken into two areas, a deep area in which the water depth is greater than 3 m and a shallow area in which the water depth is less than 3 m (Gearhart 2001; NCDMF 2001a). These two areas can be characterized by the size of the fishing vessels, effort employed, and fishing practices that occur during the fall season (Gearhart 2001; NCDMF 2001a). Fishing vessels in the deep water fishery typically range from m while shallow water vessels are typically m (Gearhart 2001; NCDMF 2001a). In the deep water fishery, fishermen employ tie downs that are m long. A tie down is a short length of heavy twine or cable that connects the top of the gillnet to the bottom of the gillnet (Figure 1; Dander 1996; Montgomery 2002). In the southern flounder gillnet fishery of Pamlico Sound, tie downs are placed within the entire length of the net and are generally spaced 7-9 m apart (Dander 1996; Montgomery 2002). The utilization of a tie down configuration is believed to enhance catch production by creating loose webbing that will increase the 2

15 entanglement rate of southern flounder (J. Gearhart, pers. comm. 2001). This configuration allows the gillnet to fish only the lower portion of the water column and is utilized to reduce bycatch (Dander 1996; Keefe 2000; Montgomery 2002). Deep water fishermen typically set a few thousand meters of net with a soak duration of up to three days (Gearhart 2001; NCDMF 2001a). The shallow water fishery is conducted without tie downs and fishermen will generally set m of net which rarely soak longer than overnight (Gearhart 2001; NCDMF 2001a). Bycatch in the Southern Flounder Gillnet Fishery The increase in the amount of gillnets in the fall Pamlico Sound portion of the fishery has begun to raise concerns among conservationists and fisheries managers. A portion of this concern stems from the reputation gillnets have for catching large amounts of bycatch and for causing excessive mortality to a large diversity of species (Northridge 1991; Alverson et al. 1994). Bycatch is the unintended catch of non-target species and age groups (Alverson et al. 1994; NCDMF 1997; Crowder and Murawski 1998) and can range from invertebrate species to marine mammals (Northridge 1991; Crowder and Murawski 1998). Another source of concern is the corresponding increase of sea turtle strandings in the southeastern portion of Pamlico Sound with the increase in the use of gillnets (NCDMF 2000; Gearhart 2001; NCDMF 2001a). Due to this growing concern, observer trips were conducted in the fall of 1999 by the North Carolina Division of Marine Fisheries (NCDMF) to examine two gillnet fisheries operating in the southeastern area of Pamlico Sound (NCDMF 2000; Gearhart 2001; NCDMF 2001a). Observers implicated the southern flounder gillnets as a possible cause of the increase in strandings when two Kemp s Ridley (Lepidochelys kempii) sea 3

16 turtles were observed taken on flounder trips and no sea turtle interactions were recorded during spotted trout trips (NCDMF 2000; Gearhart 2001; NCDMF 2001a). The species composition of the bycatch component associated with the southern flounder gillnet fishery is very diverse and includes species that are mainly benthic and species that forage on benthic organisms (Dander 1996; Evans 2001; Montgomery 2001). It includes sea turtles, seabirds, numerous species of finfish, and multiple species of invertebrates (Dander 1996; Evans 2001; Montgomery 2001). The sea turtle composition of the bycatch includes Kemp s ridleys, loggerheads (Caretta caretta), and greens (Chelonia mydas). The most common seabirds taken incidentally in this fishery are the double-crested cormorant (Phalacrocorax auritus) and the common loon (Gavia immer). The finfish component of the bycatch is predominately composed of sciaenids and Atlantic menhaden (Brevoortia tyrannus) (Evans 2001; Montgomery 2001). Of the sciaenid species, red drum (Sciaenops ocellatus) is a concern because of stressed populations (Evans 2001, Thorpe et al. 2001). Horseshoe crabs (Limulus polyphemus) make up the bulk of the invertebrate bycatch species, although the incidental catch of blue crabs (Callinectes sapidus), whelks (Melongenidae) and jellyfish (Scyphozoa) is common (Evans 2001; Montgomery 2001). Background on the Target and Bycatch Species Southern Flounder (Paralichyths lethostigma) The target species, southern flounder (P. lethostigma) occur in the coastal waters from Virginia to northern Mexico, except for the southern tip of Florida where they appear to be absent (Reagan and Wingo 1985; Robins et al. 1986; NCDMF 1997; Monaghan and Armstrong 2000). They are often one of the most abundant predators in 4

17 the estuarine environment (Wright et al. 1993) preying on benthic macroinvertebrates during their juvenile life stages and preying on spot (Leiostomus xanthurus), Atlantic menhaden and other fish as they grow (Powell and Schwartz 1979; Reagan and Wingo 1985; Wright et al. 1993; Burke 1995; Fitzhugh et al. 1996). Adult southern flounder migrate out of the estuaries and sounds in the fall to their spawning grounds offshore (Reagan and Wingo 1985; Burke et al. 1991; Matlock 1991; Burke 1995; Monaghan and Armstrong 2000). Migrating larvae enter the estuarine nursery grounds from December through February (Allen and Baltz 1997; Hettler et al. 1997; Hettler and Hare 1998) during nighttime flood tides (Burke et al. 1991). Sexual dimorphism is exhibited by this species with the female larger than the male (Matlock 1991; Fitzhugh et al. 1996; Smith et al. 1999). This species has been documented to exhibit a complicated life history pattern, including nine larval developmental stages (van Maaren and Daniels 2000). Southern flounder mature at about 2-3 years of age (Matlock 1991; Smith et al. 1999; Monaghan and Armstrong 2000) and may grow to a length of 76 cm (Robins et al. 1986). Sea Turtle Bycatch All sea turtles are federally listed as endangered or threatened under the Endangered Species Act of 1973 as amended (NRC 1990; NMFS and USFWS 1991a,b; NMFS and USFWS 1992; NMFS and USFWS 1993a,b; Heppell and Crowder 1998). Of the five species of sea turtles common in the Atlantic, the three species afore mentioned are known to utilize the estuaries along the coast of North Carolina (NRC 1990; NMFS and USFWS 1991a,b; NMFS and USFWS 1992). The loggerhead sea turtle is the most common sea turtle on the Atlantic coast of the United States (NMFS 2001a) while the Kemp s Ridley is the most endangered (NRC 1990; NMFS and USFWS 1992; McDaniel 5

18 et al. 2000). The green turtle is the largest of the sea turtles commonly encountered in Pamlico Sound, capable of reaching a length of cm straight carapace length (SCL) and a weight of 150 kg (Behler and King 1985; NMFS and USFWS 1991b; Wynne and Schwartz 1999). Loggerheads may reach a size of 92 cm SCL and a weight of 113 kg (Behler and King 1985; NMFS and USFWS 1991a; Wynne and Schwartz 1999). The smallest of the three is the Kemp s ridley reaching a size of cm SCL and a weight of 80kg (Behler and King 1985; NMFS and USFWS 1992; Wynne and Schwartz 1999). These three species can be easily identified from one another by examining their heads and flippers. The age at maturity for sea turtles is still not known but it is believed that green turtles mature at an older age (20-50 years) than loggerheads (12-30 years) or Kemp s ridleys (6-7 years) (NMFS and USFWS 1991a,b; NMFS and USFWS 1992). All three species are believed to mate offshore of the nesting beach or during nesting migrations (NMFS and USFWS 1991a,b; NMFS and USFWS 1992). In the Atlantic, these turtles tend to nest from early spring to mid-summer and females may nest from 1-7 times in one season laying approximately eggs per nest (Hirth 1980; NRC 1990; NMFS and USFWS 1991a,b; NMFS and USFWS 1992). Loggerheads and greens are found circumglobally (NMFS and USFWS 1991a,b) while the Kemp s ridley is mainly confined to the Atlantic, Gulf of Mexico, and the Caribbean (NMFS and USFWS 1992). All three species prefer temperate and tropical waters (NRC 1990; NMFS and USFWS 1991a,b; NMFS and USFWS 1992). Adults and subadults of each species prefer to inhabit the continental shelf and estuarine waters (NRC 1990; NMFS and USFWS 1991a,b; NMFS and USFWS 1992). Loggerheads are 6

19 known to utilize many different types of habitat from turbid, detritus-laden bays to clear waters (NMFS and USFWS 1991a). Green turtles are known to inhabit and flourish around sea grass beds (NMFS and USFWS 1991b; Mortimer 1995) and Kemp s ridleys are known to utilize mud and sandy environments conducive to decapod crustaceans (NMFS and USFWS 1992). These sea turtles utilize these habitats seasonally in Pamlico Sound and will migrate out of them in late fall and winter as the water temperature begins to drop. Southern flounder also utilize these habitats during their fall spawning migrations. Thus, the flounder are subjected to commercial fishing pressure resulting in sea turtle and gillnet interactions. Seabird Bycatch There is a large variety of seabird species that occur in Pamlico Sound during the fall southern flounder fishery. One of the most common of the diving seabirds is the double-crested cormorant. The double-crested cormorant is a large seabird reaching a length of 83 cm (Peterson 1980; Farrand 1988). It is a widespread aquatic bird found in both freshwater and marine environments with a range extending from Nova Scotia to Florida (Peterson 1980; Farrand 1988). As a result, it has a very wide breeding range nesting in the interior of North America as well as along the coast (Rail and Chapdelaine 1998). This species is an excellent swimmer (Farrand 1988) and is almost exclusively piscivorous (Brugger 1993; Thompson 1993 et al.; Rail and Chapdelaine 1998; Simmonds et al. 2000). Unlike sea turtles, the population of the double-crested cormorant has increased during the past 20 years (Vermer and Rankin 1984) and because of its diet is now a major concern for inland fisheries that are subjected to this 7

20 tremendous predation pressure (Brugger 1993; Derby and Lovvorn 1997; Simmonds et al. 2000). Like the double-crested cormorant, the common loon is a large seabird reaching a length of cm (Peterson 1980; Farrand 1988). However, unlike the double-crested cormorant, the populations of the common loon have been declining during the past several decades (Parker 1988; Belant et al. 1993; Caron and Robinson 1994). This bird uses the North Carolina coast as a suitable environment during its winter migrations from the north (Peterson 1980; Farrand 1988). Like the double-crested cormorant, this bird is an excellent swimmer and forages on fish, amphibians and aquatic invertebrates (Farrand 1988; Parker 1988; Caron and Robinson 1994; Barr 1996; Gingras and Paszkowski 1999). Finfish Bycatch Finfish is the largest bycatch component in the Pamlico Sound southern flounder fishery (Dander 1996; Evans 2001; Montgomery 2001). However, a large portion of this component is composed of marketable fish, most notably fish in the family Sciaenidae, commonly known as the drums (Connaughton 1996; Evans 2001; Montgomery 2001). Marketable species that occur in this family include Atlantic croaker (Micropogonias undulates), black drum (Pogonias cromis), kingfishes (Menticirrhus spp.), spot, weakfish, and red drum. Because of their recent population declines (Reagan 1985; McEachron et al. 1993; NCDMF 2001b), red drum is a special concern and there has been a growing interest to determine how many red drum are taken incidentally in both commercial and recreational gillnet operations (Evans 2001; Thorpe et al. 2001). Red drum can reach a size of 1.3 m 8

21 and a weight of 42 kg (Robins et al. 1986). The juvenile life stage of this species inhabits a wide variety of environments including seagrass beds, oyster reefs, sand, mud, river mouths, bays and passes (Adams and Tremain 2000; NCDMF 2001b). Adults come inshore to mate during the late summer and early fall (Reagan 1985; McEachron et al. 1993; Ross et al. 1995; Scharf and Schlicht 2000). Larvae are transported through passes into estuaries by tidal currents into shallow nursery areas where they remain through their juvenile stage (Scharf and Schlicht 2000). These fish have an extensive range from Massachusetts to Mexico (Reagan 1985; Robins et al. 1986; Ross et al. 1995; NCDMF 2001b). Red drum are voracious predators on benthic macroinvertebrates, including blue crab and paneiid shrimp, and on juvenile finfish (Regan 1985; Scharf and Schlicht 2000; NCDMF 2001b). Weakfish are another important sciaenid (Connaughton 1996), reaching a length of 91 cm and a weight of 8 kg (Robins et al. 1986). These fish are common from Nova Scotia to northern Florida (Robins et al. 1986; Mercer 1989; Lowerre-Barbieri et al. 1995; NCDMF 1997; Daniel and Armstrong 2000). Adult weakfish spawn near the inlets and inside the sounds from March through September (Mercer 1989; NCDMF 1997; Daniel and Armstrong 2000). Weakfish begin to migrate out of the inshore waters and into oceanic waters in the fall and return to the estuaries during spring (Mercer 1989; Lowerre-Barbieri et al. 1995; NCDMF 1997; Daniel and Armstrong 2000). Weakfish mature at about one year of age (Mercer 1989; NCDMF 1997; Daniel and Armstrong 2000) and is a major predator on other fish and benthic invertebrates (Mercer 1989; Hartman and Brandt 1995; Lankford and Targett 1997; Paperno et al. 2000). 9

22 Atlantic menhaden belong in the family Clupeidae, commonly known as the herrings (Reintjes 1969; Rogers and Van Den Avyle 1983; Robins et al. 1986; Rogers and Van Den Avyle 1989). Atlantic menhaden are found from Nova Scotia to Florida (Reintjes 1969; Rogers and Van Den Avyle 1983; Rogers and Van Den Avyle 1989). Menhaden are very important ecologically in that they are the major prey for commercially important species such as southern flounder (Reagan and Wingo 1985), weakfish (Reintjes 1969; Hartman and Brandt 1995) and red drum (Reagan 1985). Menhaden can reach a size of 35 cm (Robins et al. 1986) and forage mostly on phytoplankton, zooplankton and detritus (Reintjes 1969; Rogers and Van Den Avyle 1983; Rogers and Van Den Avyle 1989). Adults will migrate out of the estuaries and to spawning grounds offshore from November to March (Reintjes 1969; Rogers and Van Den Avyle 1983; Rogers and Van Den Avyle 1989). Menhaden larvae are then transported through the inlets into estuarine waters by currents were they remain until they reach the juvenile life stage (Reintjes 1969; Rogers and Van Den Avyle 1983; Rogers and Van Den Avyle 1989). Gillnet Parameters and Gear Configurations Gillnets are among the most commonly used gears to commercially harvest and to scientifically sample fish populations (Hamley 1975; Pierce et al. 1994; Guy et al. 1996; NCDMF 1997). Gillnets are a type of passive fishing gear, meaning that they are not moved through the water during operation. Gillnets are highly size selective (Hamley 1975; Hovgard 1996a,b; Petrakis and Stergiou 1996; Monaghan 2001a). The size selectivity of a gillnet depends on its mesh size, twine size, height and length (Hamley et al. 1975; Pierce et al. 1994; Hovgard 1996b; Monaghan 2001a). However, the catch 10

23 production of a gillnet will depend on its gear configuration (utilization of a tie-down), the ecological interactions occurring in the area and on the fishing practices being employed (Hamley 1975; Monaghan 2001a). Management Strategies Currently Employed to Manage Commercial Fisheries Fisheries managers regulate commercial fisheries by setting restrictions that affect the fishing practices or gear parameters typically employed for that fishery (Watterson 2000; Monaghan 2001a,b; Mumford 2001; Watterson 2001). Common management strategies that can affect the fishing practices of a fishery include time/area closures, quota limits, incidental take limits and limited entry into a fishery (Watterson 2000; Monaghan 2001b; Mumford 2001; Watterson 2001). Gear restrictions, such as a minimum mesh size, and gear configurations, such as the use of a tie-down, are examples of regulating fishing gear (Watterson 2000; Monaghan 2001a; Mumford 2001; Watterson 2001). By using a combination of these restrictions, fisheries managers attempt to regulate commercial fisheries in order to reduce bycatch and maintain a sustainable harvest of the target catch. Unfortunately, developing management strategies for a commercial fishery is not a simple process, especially when management strategies are being developed to reduce bycatch. The process is complicated when management strategies are needed to reduce the bycatch of numerous species (Melvin et al. 1999). For example, management strategies developed to reduce bycatch of one species may actually increase the bycatch of another species (Melvin et al. 1999; Crouse 2000). As a result, management strategies must be formulated that will reduce bycatch of all species or for as many species as possible (Melvin et al. 1999). If management strategies that reduce bycatch of all species 11

24 cannot be developed then the formulation of management strategies has to be weighted for the species in the most peril. In light of this, the National Marine Fisheries Service (NMFS) has developed an incidental take limit for fisheries that commonly interact with marine mammals (Waring et al. 1997, 1999; LeBoeuf 1999), sea turtles (NCDMF 2000; NCDMF 2001a) and seabirds (USFWS 1998a,b). Once a fishery hits the limit for the bycatch of any species of marine mammal, sea turtle (Gearhart 2001), or seabird this fishery is closed for the remainder of the season. Determination of the number of incidental takes allowed for a fishery differs among marine mammals, sea turtles and seabirds. The Potential Biological Removal (PBR) concept is utilized to determine the number of incidental takes allowed for marine mammals within a specified fishery (Waring et al. 1997; LeBoeuf 1999). For sea turtles and seabirds, the number of observed interactions during previous years and current stock assessments is used to determine the estimated incidental take levels for upcoming years (USFWS 1998a,b; NMFS 2000, 2001b,c, d; NCDMF 2001a). For fisheries that do not have previous data on the number of incidental takes but are known or believed to be interacting with sea turtles, the number of strandings that has occurred in the fishing area is used as an index to determine the number of allowed takes (NCDMF 2000). If a fishery is estimated to exceed the allowed number of incidental takes determined from observer data, then the fishery is subjected to a biological opinion conducted by NMFS in which new regulations are developed to reduce the number of incidental takes (NMFS 2000). 12

25 Goals and Objectives The goal of this study is to examine the catch-per-unit-effort (CPUE) of the target (southern flounder) and bycatch species (sea turtles, seabirds, finfish, and invertebrates) that is occurring in the southern flounder gillnet fishery of southeastern Pamlico Sound, NC. It is hypothesized that the CPUE of the target and bycatch species will differ between the deep and shallow areas, the fishing season, gear parameters, soak time and gear configurations. The objectives of this study are: 1). To characterize the bycatch composition and distribution, both temporally and spatially, that is occurring in the southern flounder gillnet fishery; 2). To test experimental gillnet configurations in an effort to reduce bycatch (emphasis on sea turtle bycatch) without reducing target catch; and, 3). To suggest reasonable and prudent management options for the fishery. 13

26 Figure 1. Illustration of a sink gillnet employing a tie down configuration (reproduced with permission from Gearhart 2001; NMFS 1996). 14

27 Works Cited Adams, D. H. and D. M. Tremain Association of Large Juvenile Red Drums, Sciaenops ocellatus, with an Estuarine Creek on the Atlantic Coast of Florida. Environmental Biology of Fishes 58: Allen, R. L. and D. M. Baltz Distribution and Microhabitat use by Flatfishes in a Louisiana Estuary. Environmental Biology of Fishes 50: Alverson, D.L., M. H. Freeberg, J. G. Pope, and S. A. Murawski A Global Assessment of Fisheries Bycatch and Discards. FAO Fisheries Technical Paper. No Rome, FAO. 233 pp. Barr, J. F Aspects of Common Loon (Gavia immer) Feeding Biology on its Breeding Ground. Hydrobiologia 321: Behler, J. L. and F. W. King The Audubon Society Field Guide to North American Reptiles and Amphibians. Alfred A. Knopf, New York. 743 pp. Belant, J. L., J. F. Olson, and R. K. Anderson Evaluation of the Single Survey Technique for Assessing Common Loon Populations. Journal of Field Ornithology 64(1): Brugger, K. E Digestibility of Three Fish Species by Double-Crested Cormorants. Condor 95: Burke, J. S Role of Feeding and Prey Distribution of Summer and Southern Flounder in Selection of Estuarine Nursery Habitats. Journal of Fish Biology 47: Burke, J. S., J. M. Miller, and D. E. Hoss Immigration and Settlement Pattern of Paralichthys Dentatus and P. Lethostigma in an Estuarine Nursery Ground, North Carolina, U.S.A. Netherlands Journal of Sea Research 27(3/4): Caron, J. A., Jr., W. L. Robinson Responses of Breeding Common Loons to Human Activity in Upper Michigan. Hydrobiologia 279/280: Connaughton, M. A Drumming, Courtship, and Spawning Behavior in Captive Weakfish, Cynoscion regalis. Copeia 1996(1): Crouse, D After TEDS: What s Next?? In: F. A. Abreu-Grobois, R. Briseno- Duenas, R. Marquez and L. Sarti (compilers). Proceedings of the Eighteenth International 15

28 Sea Turtle Symposium. U. S. Dep. Commer. NOAA Tech. Memo. NMFS-SEFSC pp. Crowder, L. B. and S. A. Murawski Fisheries Bycatch: Implications for Management. Fisheries 23(6): Dander, R Test Multiple Tie-Down Flounder Nets: Observation of By Catch Relative to Tied Down Height. North Carolina Fisheries Resource Grant. Project 95 FEG pp. Daniel, L. B., III and J. L. Armstrong Reproductive Ecology of Selected Marine Recreational Fishes in North Carolina: Weakfish, Cynoscion regalis. Completion Report Grant F-60. Segments 1-2. North Carolina Division of Marine Fisheries, Morehead City, North Carolina. 9 pp. Derby, C. E. and J. R. Lovvorn Predation on Fish by Cormorants and Pelicans in a Cold-Water River: A Field and Modeling Study. Canadian Journal of Fisheries and Aquatic Sciences 54: Ehrhart, L. M A Review of Sea Turtle Reproduction In: K. A. Bjordnal (ed). Biology and Conservation of Sea Turtles, revised edition. Smithsonian Institute Press, Washington D. C Evans, W. G North Carolina Fisheries Resource Grant. Project 98 FEG pp. Farrand, J. Jr Eastern Birds: An Audubon Handbook. McGraw Hill, New York. 484 pp. Fitzhugh, G. R., L. B. Crowder, and J. P. Monaghan, Jr Mechanisms Contributing to Variable Growth in Juvenile Southern Flounder (Paralichthys lethostigma). Canadian Journal of Fisheries and Aquatic Sciences 53: Gearhart, J Sea Turtle Bycatch Monitoring of the 2000 Fall Flounder Gillnet Fishery of Southeastern Pamlico Sound, North Carolina. NCDMF Completion Report for Incidental Take Permit NCDMF, Morehead City, North Carolina. 26 pp. Gingras, B. A. and C. A. Paszkowski Breeding Patterns of Common Loons on Lakes with Three Different Fish Assemblages in North-Central Alberta. Canadian Journal of Zoology 77: Guy, C. S., D. W. Willis, and R. D. Schultz Comparison of Catch per Unit Effort and Size Structure of White Crappies Collected with Trap Nets and Gill Nets. North American Journal of Fisheries Management 16: Hamley, J. M Review of gillnet selectivity. Journal of the Fisheries Research Board of Canada 32(11):

29 Hartman, K. J. and S. B. Brandt Trophic Resource Partioning, Diets, and Growth of Sympartic Estuarine Predators. Transactions of the American Fisheries Society 124: Heppell, S. S. and L. B. Crowder Prognostic Evaluation of Enhancement Programs Using Population Models and Life History Analysis. Bulletin of Marine Science 62(2): Hettler Jr., W. F., D. S. Peters, D. R. Colby, and E. H. Laban Daily Variability in Abundance of Larval Fishes Inside Beaufort Inlet. Fishery Bulletin 95: Hettler Jr., W. F. and J. A. Hare Abundance and Size of Larval Fishes Outside the Entrance to Beaufort Inlet, North Carolina. Estuaries 21(3): Hirth, H. F Some Aspects of the Nesting Behavior and Reproductive Biology of Sea Turtles. American Zoologist 20: Hovgard, H. 1996a. A Two-Step Approach to Estimating Selectivity and Fishing Power of Research Gill Nets Used in Greenland Waters. Canadian Journal of Fisheries and Aquatic Sciences 53: Hovgard, H. 1996b. Effect of Twine Diameter on Fishing Power of Experimental Gill Nets Used in Greenland Waters. Canadian Journal of Fisheries and Aquatic Sciences 53: Lankford, T. E. and T. E. Targett Selective Predation by Juvenile Weakfish: Post- Consumptive Constraints on Energy Maximization and Growth. Ecology 78(4): LeBoeuf, N. (ed.) Marine Mammal Protection Act of 1972 Annual Report: January 1, 1998 to December 31, National Marine Fisheries Service, Office of Protected Resources, Silver Spring, MD. 101 pp. Lowerre-Barbieri, S. K., M. E. Chittenden, Jr., L. R. Barbieri Age and Growth of Weakfish, Cynosion regalis, in the Chesapeake Bay Region with a Discussion of Historical Changes in Maximum Size. Fishery Bulletin 93: Keefe, S. G Evaluating the Effects of Striped Bass Bycatch Using Tied-Down Gillnets in Winter Perch Fishery. North Carolina Fisheries Resource Grant. Project 98- FEG pp. Matlock, G. C Growth, Mortality, and Yield of Southern Flounder in Texas. Northeast Gulf Science 12(1):

30 McDaniel, C. J., L. B. Crowder, and J. A. Priddy Spatial Dynamics of Sea Turtle Abundance and Shrimping Intensity in the U.S. Gulf of Mexico. Conservation Ecology 4(1): 15 [online] URL: McEachron, L. W., C. E. McCarty, and R. R. Vega Successful Enhancement of the Texas Red Drum (Sciaenops ocellatus) Population In: M. R. Collie and J. P. Mcvey (eds). Interactions Between Cultured Species and Naturally Occurring Species in the Environment: Proceedings of the 22 nd U.S.-Japan Aquacultural Panel Symposium. UJNR Technical Report No. 22. Alaska Sea Grant Report AK-SG Mercer, L. P Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Mid-Atlantic)-weakfish. U. S. Fish and Wildlife Service. Biological Report 82(11.109). U. S. Army Corps of Engineers, TR EL pp. Melvin, E. F., J. K. Parrish and L. L. Conquest Novel Tools to Reduce Seabird Bycatch in Coastal Gillnet Fisheries. Conservation Biology 13(6): Monaghan, Jr., J. P. and J. L. Armstrong Reproductive Ecology of Selected Marine Recreational Fishes in North Carolina: Southern Flounder, Paralichthys lethostigma. Completion Report Grant F-60, Segments 1-2. North Carolina Division of Marine Fisheries, Morehead City, North Carolina. 17 pp. Monaghan, R. 2001a. Minimum Distance Between Gill Nets and Pound Nets in the Southern Flounder Fishery. NCDMF, Morehead City, North Carolina. 3 pp. Monaghan, R. 2001b. Minimum Distance Between Gill Nets and Pound Nets in the Southern Flounder Fishery. North Carolina Division of Marine Fisheries, Morehead City, NC. 3 pp. Montgomery, G By-Catch Comparison of Flounder Gill Nets Utilizing Different Denier Webbing. North Carolina Fisheries Resource Grant. Project 99-FEG pp. Montgomery, G Catch Comparison of Three Gill Net Designs in the N.C. Flounder Gill Net Fishery. North Carolina Fisheries Resource Grant. Project 01-FEG pp. Mortimer, J. A Feeding Ecology of Sea Turtles In: K. A. Bjorndal, (ed). Biology and Conservation of Sea Turtles, revised edition. Smithsonian Institute Press, Washington D. C Mumford, D Recreational Restrictions for Southern Flounder. NCDMF, Morehead City, North Carolina. 13 pp. 18

31 National Marine Fisheries Service Fisheries Sampling Branch-Observer Manual. Northeast Fisheries Science Center, 166 Water St., Woods Hole, MA pp. National Marine Fisheries Service Fisheries of the United States, Current Fishery Statistics No Silverspring, Maryland. National Marine Fisheries Service Biological Opinion, Section 7 Consultation on Authorization to take Listed Marine Mammals Incidental to Commercial Fishing Operations Under Section 101(a)(5)(E) of the Marine Mammal Protection Act for the California/Oregon Drift Gillnet Fishery. NMFS, Marine Mammal Division, Office of Protected Species. National Marine Fisheries Service. 2001a. Endangered Species Act Section 7 Consultation, Biological Opinion. Reinitation of Consultation on the Federal Lobster Management Plan in the Exclusive Economic Zone [Consultation No. F/NER/2001/ National Marine Fisheries Service, Sustainable Fisheries Division, Northeast Region. June National Marine Fisheries Service. 2001b. Biological Opinion, Section 7 Consultation on Authorization of Fisheries Under the Monkfish Fishery Management Plan [Consultation No. F/NER/2001/00546]. NMFS, Northeast Region Protected Resources Division. National Marine Fisheries Service. 2001c. Biological Opinion, Section 7 Consultation on Authorization of Fisheries Under the Spiny Dogfish Fishery Management Plan [Consultation No. F/NER/2001/00544]. NMFS, Northeast Region Protected Resources Division. National Marine Fisheries Service. 2001d. Biological Opinion, Section 7 Consultation, Reinitiation of Consultation on the Atlantic Highly Migratory Species Fishery Management Plan and Its Associated Fisheries. NMFS, Office of Protected Resources, Endangered Species Division. National Marine Fisheries Service and U.S. Fish and Wildlife Service. 1991a. Recovery Plan for U.S. Population of Loggerhead Turtle. National Marine Fisheries Service, Washington, D. C. 64 pp. National Marine Fisheries Service and U.S. Fish and Wildlife Service. 1991b. Recovery Plan for U.S. Population of Atlantic Green Turtle. National Marine Fisheries Service, Washington, D. C. 52 pp. National Marine Fisheries Service and U.S. Fish and Wildlife Service Recovery Plan for the Kemp s Ridley Sea Turtle (Lepidochelys kempii). National Marine Fisheries Service, St. Petersburg, Florida. 40 pp. 19

32 National Marine Fisheries Service and U.S. Fish and Wildlife Service. 1993a. Recovery Plan for Hawksbill Turtles in the U.S. Caribbean Sea, Atlantic Ocean, and Gulf of Mexico. National Marine Fisheries Service, St. Petersburg, Florida. 52 pp. National Marine Fisheries Service and U.S. Fish and Wildlife Service. 1993b. Recovery Plan for Leatherback Turtles in the U.S. Caribbean, Atlantic and Gulf of Mexico. National Marine Fisheries Service, Washington, D.C. 65 pp. National Research Council Decline of the Sea Turtle: Causes and Prevention. National Academy Press, Washington D. C. 259 pp. North Carolina Division of Marine Fisheries Assessment of North Carolina Commercial Finfish Fisheries, North Carolina Department of Environment and Natural Resources, Division of Marine Fisheries, Morehead City, NC. North Carolina Division of Marine Fisheries. 2001a. Application for an Individual Incidental Take Permit Under the Endangered Species Act of North Carolina Division of Marine Fisheries, Morehead City, NC. 29 pp. North Carolina Division of Marine Fisheries. 2001b. Red Drum Fishery Management Plan. North Carolina Division of Marine Fisheries, Morehead City, North Carolina. North Carolina Division of Marine Fisheries Application for and Individual Incidental Take Permit Under the Endangered Species Act of North Carolina Division of Marine Fisheries, Morehead City, NC. 25 pp. Northridge, S. P Driftnet fisheries and their impacts on non-target species: a worldwide review. FAO Fisheries Technical Paper, No Rome, FAO. 115 pp. Paperno, R., T. E. Targett, and P. A. Grecay Spatial and Temporal Variation in Recent Growth, Overall Growth, and Mortality of Juvenile Weakfish (Cynoscion regalis) in Delaware Bay. Estuaries 23(1): Parker, K. E Common Loon Reproduction and Chick Feeding on Acidified Lakes in the Adirondack Park, New York. Canadian Journal of Zoology 66: Peterson, R. T Peterson Field Guides: Eastern Birds. Houghton Mifflin Co., New York, New York. 383 pp. Petrakis, G. and K. I. Stergiou Gill Net Selectivity for Four Fish Species (Mullus barbatus, Pagellus erythrinus, Pagellus acarne and Spicara flexuosa) in Greek Waters. Fisheries Research 27:

33 Pierce, R. B., C. M. Tomcko, and T. D. Kolander Indirect and Direct Estimates of Gill-Net Size Selectivity for Northern Pike. North American Journal of Fisheries Management 14: Powell, A. B. and F. J. Schwartz Food of Paralichthys dentatus and P. lethostigma (Pisces: Bothidae) in North Carolina Estuaries. Estuaries 2(4): Rail, J-F. and G. Chapdelaine Food of Double-crested Cormorants, Phalacrocorax auritus, in the Gulf and Estuary of the St. Lawrence River, Quebec, Canada. Canadian Journal of Zoology 76: Reagan, R. E Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Gulf of Mexico)- red drum. U. S. Fish and Wildlife Service. Biological Report 82(11.36). U. S. Army Corps of Engineers, TR EL pp. Reagan, R. E., Jr. and W. M. Wingo Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Gulf of Mexico)- southern flounder. U. S. Fish and Wildlife Service. Biological Report 82(11.30). U. S. Army Corps of Engineers TR EL pp. Reintjes, J. W Synopsis of Biological Data on the Atlantic Menhaden, Brevoortia tyrannus. FAO Species Synopsis No. 42. Circular 320. Washington, D. C. 30 pp. Robins, C. R., G. C. Ray, and J. Douglas Peterson Field Guides: Atlantic Coast Fishes. Houghton Mifflin Co., New York, New York. 354 pp. Rogers, S. G. and M. J. Van Den Avyle Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (South Atlantic)- Atlantic Menhaden. U. S. Fish and Wildlife Service, Division of Biological Services, FWS/OBS-82/ U. S. Army Corps of Engineers, TR EL pp. Rogers, S. G. and M. J. Van Den Avyle Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (South Atlantic)- Atlantic Menhaden. U. S. Fish and Wildlife Service. Biological Report 82(11.108). U. S. Army Corps of Engineers, TR EL pp. Ross, J. L., T. M. Stevens and D. S. Vaughan Age, Growth, Mortality, and Reproductive Biology of Red Drums in North Carolina Waters. Transactions of the American Fisheries Society 124: Scharf, F. S. and K. K. Schlicht Feeding Habits of Red Drum (Sciaenops ocellatus) in Galveston Bay, Texas: Seasonal Diet Variation and Predator-Prey Size Relationships. Estuaries 23(1):

34 Simmonds Jr., R. L., A. V. Zale, and D. M. Leslie, Jr Modeled Effects of Double- Crested Cormorant Predation on Simulated Reservoir Sport and Forage Fish Populations in Oklahoma. North American Journal of Fisheries Management 20: Smith, T. I. J., D. C. McVey, W. E. Jenkins, M. R. Denson, L. D. Heyward, C. V. Sullivan, and D. L. Berlinsky Broodstock Management and Spawning of Southern Flounder, Paralichthys lethostigma. Aquaculture 176: Thorpe, T., D. Beresoff, and K. Cannady Gillnet Bycatch Potential, Discard Mortality, and Condition of Red Drum (Sciaenops ocellatus) in Southeastern North Carolina. North Carolina Fishery Resource Grant Program 00-FEG pp. United States Fish and Wildlife Service. 1998a. Endangered Species Act Formal Section 7 Consultation for Hook-and-Line Groundfish Fisheries of the Gulf of Alaska and Bering Sea and Aleutian Islands Area. United States Fish and Wildlife Service. 1998b. Endangered Species Act Formal Section 7 Consultation for Pacific Halibut Fisheries in Waters Off Alaska. Van Maaren, C. C. and H. V. Daniels A Practical Guide to the Morphological Development of Southern Flounder, Paralichthys lethostigma, from Hatchery Through Metamorphosis. Journal of Applied Aquaculture 10(2): 1-9. Vermeer, K. and L. Rankin Population Trends in Nesting Double-Crested and Pelagic Cormorants in Canada. Murrelet 65:1-9. Waring, G. T., D. L Palka, K. D. Mullin, J. H. W. Hain, L. J. Hansen and K. D. Bisack U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments NOAA Technical Memorandum NMFS-NE pp. Waring, G. T., D. L. Palka, P. J. Clapham, S. Swartz, M. C. Rossman, T. V. N. Cole, L. J. Hansen, K. D. Bisack, K. D. Mullin, R. S. Wells, D. K. Odell and N. B. Barros U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments NOAA Technical Memorandum NMFS-NE pp. Watterson, C Achieving Target Level Fishing Mortality/Biomass. North Carolina Division of Marine Fisheries, Morehead City, North Carolina. 8 pp. Watterson, C Flounder Bycatch in the Crab Trawl Fishery. North Carolina Division of Marine Fisheries, Morehead City, NC. 13 pp. Wright, R. A., L. B. Crowder, and T. H. Martine The Effects of Predation on the Survival and Size-Distribution of Estuarine Fishes: An Experimental Approach. Environmental Biology of Fishes 36:

35 Wynne, K. and M. Schwartz Guide to Marine Mammals and Turtles of the U.S. Atlantic and Gulf of Mexico. Rhode Island Sea Grant, Narragansett, Rhode Island. 114 pp. 23

36 Methods Description of the Study Area About 78% of the inshore commercial fisheries harvested in North Carolina occur in Pamlico Sound (Copeland et al. 1984; Copeland 1989). Pamlico Sound covers an area of about 5,335 km 2 and it is estimated that the total volume of water in the sound averages about 26 billion m 3 (Stanley 1989; Stanley 1992). The average depth of Pamlico Sound is about 4.9 m with a maximum depth of only 7.3 m (Stanley 1989; Stanley 1992). The surface sediments present in the area are primarily composed of fine sand, silts and clay (Stanley 1989; Stanley 1992). The salinity inside the sound ranges from 15 ppt (around the Pamlico and Neuse River mouths) to 30 ppt (around the inlets of the barrier islands) (Stanley 1989; Stanley 1992). Submerged aquatic vegetation present in the sound includes eelgrass (Zostera marina), shoalgrass (Halodule wrightii), and widgeon grass (Ruppia maritime) (Ferguson et al. 1989). By using the high number of sea turtle strandings that occurred in Pamlico Sound in 1999, the area east of W and south of N was identified as the main area for sea turtle interactions with southern flounder gillnets (NCDMF 2000; Figure 2). This area has been designated the Pamlico Sound Gillnet Restricted Area (PSGRA) (G. Meekins pers. comm. 2000; NCDMF 2000). The PSGRA is composed of two primary areas, shallow (<3 m) and deep (>3 m) (Gearhart 2001), separated by a sandbar or reef that parallels the barrier islands (G. Meekins pers. comm. 2000; Figure 3). The shallow area is located on the island side of the reef while the deep area is located on the opposite side (Figure 3). Observers and Observer Training 24

37 The use of observers was instrumental in this study. There were two different types of observers, NMFS protocol trained observers and employees from the NCDMF. I participated in this study as a NMFS protocol trained observer. Observers that were trained according to the protocol developed by NMFS were required to take a 10-day class conducted at the Northeast Fisheries Science Center in Woods Hole, Massachusetts. During this class, observers attended workshops and were tested on how to identify finfish, sea turtles, seabirds, marine mammals, shellfish and other invertebrates. Observers were also trained on how to fill out NMFS observer data logs and appropriate data recording techniques along with how to use field guides and the NMFS observer manual when needed. Employees from the NCDMF were not required to attend such a class because they only recorded a limited amount of data (see below). However, these observers were familiar with the target and bycatch species in the area and were comfortable identifying these species. Study Design and Data Recorded This study was conducted during the 2000 and 2001 fall southern flounder gillnet fishery of Pamlico Sound, North Carolina. During the 2000 season observer data were used to compare the CPUE of target and bycatch between shallow and deep areas, first and second halves of the fishing season, and gear parameters. Each individual gear observed was considered a single observation. In some instances, one gear might have been composed of several different nets in which mesh sizes, twine sizes, or other parameters could have differed (Figure 1). When this occurred, these parameters were averaged for the gear as a whole and used for the final analysis. In the 2001 season, observer data was used to compare the CPUE of target and bycatch between different 25

38 experimental gillnet gear configurations, developed by the North Carolina Division of Marine Fisheries. Each individual gear was composed of three different types of experimental gillnet: control, shallow and double-lead line. The control net was the standard commercial gillnet typically fished for flounder in Pamlico Sound. The shallow net was only 12 meshes deep (approximately half as tall as the control) and did not employ a tie-down. The double-lead line net had an extra lead line as its float line. Each individual net was 274 m long making each gear 822 meters long. All other parameters of the experimental gillnets were held constant. Commercial fishermen were then contracted to fish the experimental gillnets and were given 3 gears, with the order of the nets in each gear different. The gears were then fished side by side as instructed by the terms of the contract. All observers were required to gather a large amount of data about the type of gear and how it was used, along with biological data on all species captured. The data recorded during the 2000 fall southern flounder season can be broken into two broad categories, gear characterization and biological. When recording gear characterization data, observers from NCDMF were required to record the following: location of nets by latitude and longitude, number of nets, length of nets (yards), soak time (days), tie-down length (feet) if employed, depth of net (feet), stretched mesh size (inches), height (meshes deep) and twine size. Biological data included: number of sea turtles caught per net, exact location of sea turtle caught (latitude and longitude), species of sea turtle caught, pounds of flounder caught per net, number of red drum and striped bass per net. Observers trained under NMFS protocol recorded all of the same information and much more. Gear characterization data that were recorded by NMFS trained observers and not 26

39 by NCDMF observers included stretched mesh size range of each net (inches), net material, height (feet) and color of the twine. NMFS trained observers also recorded much more biological data including, random length frequencies and weights of kept and discarded finfish species, location of all sea turtle and seabird interactions, and biological measurements on all sea turtles. During the 2001 fall southern flounder season, experimental gillnet testing was initiated. Data recorded during this part of the study included the position (latitude and longitude) of each gear, the weight in kilograms of each species caught in each gear, the number of each species caught by each gear, and the length frequencies of as many finfish as possible (both target and bycatch). Statistical Analysis Multiple regression analysis (Steel et al. 1997; Rao 1998), employing a backward model selection procedure, was used to determine which variables and interactions were the most significant in predicting target and bycatch CPUE (Rawlings et al. 1998). When employing a backward model selection procedure, all variables are placed in a regression analysis (Rawlings et al. 1998). Variables are then dropped from the model when they do not meet some criterion until the model contains all variables that meet the criterion or only one variable remains (Rawlings et al. 1998). In this analysis, variables were dropped from the model when they did not meet the p-value = 0.05 criterion. Analysis was divided into fishing practices and gear parameters because these methods are the most commonly used in fisheries management (Copeland, pers. comm. 2002). Factors included in fishing practices include area, season and the total fishing effort (soak time in days * meters of net fished). Mesh size, twine size, height, tie down 27

40 length, soak time and length of net were regarded as gear parameters. A multiple regression analysis was run with only fishing practices factors and another with only gear parameters to determine which variables were the most significant in predicting target and bycatch CPUE. ANOVA was used to determine which experimental gillnet configuration caught the least amount of bycatch and target catch. All analyses were run in SAS with PROC GLM except for the sea turtle data gathered from the 2000 season (SAS 1985). Due to the rare occurrence of a single net catching more than one sea turtle, this analysis was run with PROC GENMOD as a logistical regression where 0 represented a gillnet without an interaction and 1 represented a sea turtle take (SAS 1985; Boos, pers. comm. 2002). 28

41 Figure 2. The Pamlico Sound Gillnet Restricted Area (reproduced with permission from NCDMF 2000). 29

42 Figure 3. Deep and shallow water southern flounder gillnet fisheries of Pamlico Sound, North Carolina (reproduced with permission from NCDMF 2001). 30