Session 35: AES Fisheries, Conservation & Management IIRoom: Conference Theater2022-07-30 10:00 - 12:00 |
| Moderator: Nick Dulvy |
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1. 10:00 Refinement and Testing of a Microprocessor-Based Shark Bycatch Reduction Device (M-B BRD) Using an Academic-Industry Partnership. Sara Mirabilio*, NCSU North Carolina Sea Grant College Program; Richard Brill, Virginia Institute of Marine Science; Peter Bushnel, Indiana University South Bend; Amanda Wilson, Ocean Guardian semirabi@ncsu.edu
Reducing shark bycatch in U.S. pelagic longline fisheries is a NOAA Fisheries management priority as multiple coastal-pelagic species are overfished and/or experiencing overfishing. We contend shark bycatch can be reduced by taking advantage of the unique sensory biology of elasmobranch fishes, specifically their ability to perceive electric fields of less than five nanovolt per centimeter. Such signals are, however, undetectable by targeted teleost fishes which lack the electrosensory system (Ampullae of Lorenzini) of elasmobranch fishes. A National Sea Grant Office award (NA19OAR4170413) funded development of an industry-deployable, microprocessor-based, shark bycatch reduction device (M-B BRD). We evaluated its performance using a 150-hook, three-mile, bottom longline deployed from a commercial fishing vessel operating in coastal waters from Oregon to Hatteras inlets (North Carolina). Over the course of 15 fishing days (Aug. 2 – Oct. 1, 2021), a total of 141 sharks (across nine species) were captured with all but 34 on hooks near M-B BRDs that emitted no electric pulse (controls). This ratio is significantly different from the expected 1:1 ratio (p=0.0000000007). Although effectiveness was species-specific, in aggregate the presence of an active M-B BRD reduced shark catch by greater than 50%. These data support the hypothesis that weak electric stimuli generated by a M-B BRD can reduce shark bycatch in longline fisheries. Further, with a M-B BRD shark bycatch could be reduced without imposition of time-area closures, significant gear modifications, or mandated hook types, and with little or no effect on catches of non-electrosensitive target teleost fishes (e.g., swordfish and tunas). |
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2. 10:15 Commercial fishery bycatch risk for large juvenile and adult smalltooth sawfish (Pristis pectinata) in Florida waters. Jasmin Graham*, Minorities in Shark Sciences; Andrea Kroetz, NOAA National Marine Fisheries Service; Gregg Poulakis, Charlotte Harbor Field Laboratory; Rachel Scharer, Charlotte Harbor Field Laboratory; John Carlson, NOAA National Marine Fisheries Service; Susan Lowerre-Barbieri, University of Florida; Danielle Morley, Florida Fish and Wildlife Conservation Commission; Eric Reyier, Herndon Solutions Group, LLC; R. Dean Grubbs, Florida State University Coastal and Marine Laboratory learningwithjasmin@gmail.com
The smalltooth sawfish (Pristis pectinata) is endemic to the Atlantic Ocean and listed as Endangered in the US Endangered Species Act. One of its major threats is bycatch mortality in commercial fisheries. Acoustic and satellite tag data collected on 59 sawfish between 2011 and 2019 were analysed to assess commercial fishery bycatch risk for large juveniles and adults off Florida. This study focused on shrimp trawl, south‐east coastal gillnet, and shark bottom longline fisheries. Bycatch risk associated with the shrimp trawl fishery was significantly higher than the other fisheries, indicating that this fishery currently poses the greatest threat to recovery. Bycatch risk was concentrated in all seasons in the Gulf of Mexico adjacent to the lower Florida Keys for the shrimp trawl fishery, off Cape Canaveral in the south‐east coastal gillnet fishery, and in the Atlantic Ocean adjacent to the Florida Keys in the shark bottom longline fishery. Tagging location and sex were predictors of bycatch risk. Individuals tagged in Charlotte Harbor had the highest shrimp trawl bycatch risk. Females tagged in south Florida tended to reside in the deepest water, which is where shrimp trawl effort is highest. Therefore, females may be at more risk in these deeper waters. Results from this study indicate a year‐round closure of waters off south‐west Florida to the shrimp trawl fishery between Charlotte Harbor and the western Florida Keys would reduce sawfish bycatch, and thus mortality, which is in line with recovery plan goals. |
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3. 10:30 Marine Debris and Other Anthropogenic Effects on the Smalltooth Sawfish, Pristis pectinata. Dylan M. Yakich*, Charlotte Harbor Field Laboratory, Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission; Andrew K. Wooley, Charlotte Harbor Field Laboratory, Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission; Lukas B. Heath, Charlotte Harbor Field Laboratory, Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission; Gregg R. Poulakis, Charlotte Harbor Field Laboratory, Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission dylan.yakich@myfwc.com
The population of endangered smalltooth sawfish (Pristis pectinata) in the United States declined throughout the twentieth century due mainly to bycatch mortality from net fisheries. While conservation, management, and outreach efforts have reduced these threats, the species is still at risk from other direct anthropogenic effects such as entanglement in recreational and commercial fishing gear and various forms of marine debris. The impact of marine pollution on sawfish has increased in occurrence since research began on the species in the early 2000s. During 2017–2021, data from research and the U.S Sawfish Recovery Hotline (1-844-4-SAWFISH; sawfish@MyFWC.com) documented 176 reports of individuals that were entangled, injured, or dead from debris interactions. While recreational and commercial fishery gears (e.g., trawls, gill nets, cast nets, fishing tackle) remain the most frequent entanglement issues for sawfish, other household and miscellaneous items are increasingly present. A concerning number (at least 30) of sawfish with encircling debris (e.g., monofilament loops, rubber bands, hair ties, ball-bungee cords) around anterior parts of their bodies have been encountered in southwest Florida. The ball bungee cord issue has emerged in recent years and is likely related to increased numbers of covers on boat lifts. Collectively, these encircling items have caused severe injuries (e.g., interfered with spiracle, gill, and mouth function) and led to the death of at least one individual. Clearly, outreach will need to be an ongoing priority to help address these marine pollutants, their sources, and the impacts they can have on recovery of the species. |
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4. 10:45 High Site-Attachment of Caribbean Reef Sharks (Carcharhinus perezi), and Movements Relative to No-Take Marine Reserve Boundaries. Steven Kessel*, John G. Shedd Aquarium; Jill Brooks, Carlton University; Abby Nease, Broward County Sea Turtle Conservation Program; Bonnie Ahr, Fisheries Data Solutions, LLC skessel80@gmail.com
In 2021, Caribbean reef sharks (Carcharhinus perezi) were listed as ‘Endangered’ on the IUCN Red List, with the overall population decreasing. Taken as target and bycatch some populations have declined by up to 99%, however, where effective protection measures exist, they have remained stable since the 1980s. Increased understanding of their spatial ecology will help to assess existing spatial conservation designations and inform future development. Existing literature suggests high site-fidelity to discrete reef ecosystems, many fragmented by stretches of deep water. This study focused on Caribbean reef sharks at the Exuma Cays, Bahamas, which constitutes >180 km of uninterrupted shallow reef habitat. The aims were to a) investigate site-attachment in the absence of potential barriers to movement; and b) investigate movement relative to the boundaries of the Exuma Cays Land and Sea Park (ECLSP) no-take reserve. Between 2017-2018, 27 individuals were implanted with Vemco V16-H acoustic transmitters, and 33 receiver stations established, both inside and outside of the ECLSP. Between 2017-2019, 1,016,333 detections were recoded. Individuals, with >400 detections (n=16), showed strong site-attachment, with a mean of 97.8% (S.E. 1.27) of total detections recorded at the closest receiver to tagging location. Similarly, only four (of all 27) individuals transitioned across the ECLSP boundaries, with a mean of 97.2% (S.E. 1.51) of total detections consistent to tagging location (inside vs outside). High site-attachment in the absence of apparent barriers to movement was confirmed, suggesting effective design of Marine Protected Area networks can help sustain abundance. |
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5. 11:00 Potential Consequences of Climate Change-Driven Shifts in White Shark Nursery Habitat in the Northwest Atlantic Ocean. Tobey Curtis*, NOAA Fisheries; Daniel Crear, ECS Federal tobey.curtis@noaa.gov
Some shark species have high likelihoods of poleward distribution shifts under ongoing and projected ocean warming. Coastal waters off Long Island, New York, a region of rapid warming, are a summer nursery area for young-of-the-year (YOY) white sharks (Carcharodon carcharias). Thermal habitat suitability models were developed using electronic tracking data collected during 2016-2019 (N=22; 138-166 cm total length), and habitat suitability was projected over historical conditions (to 1965) and future conditions (to 2099) using climate scenario projections. Historical projections reveal that suitable summer nursery habitat has already shifted since 1965. Suitable nursery habitat is projected to continue to shift northeastward along the U.S. Atlantic coast by 2100. This shift would increase overlap with the summer distribution of adult white sharks – natural predators of YOY white sharks. Increased water temperatures are also projected to increase overlap with regional fisheries, potentially increasing bycatch susceptibility. Ironically, expansion of renewable energy infrastructure in the form of offshore wind farms along the U.S. Atlantic coast may also result in disturbance to white shark nursery habitat, but the long-term effects of such construction on sharks is largely unknown. Thus, climate change may result in increased fishing and natural mortality for YOY white sharks, potentially reducing recruitment to adult populations and destabilizing recent abundance increases. |
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6. 11:15 Using a Citizen-Science Approach to Characterize Shark Depredation in the Recreational Fisheries of the Southeast United States. Michael McCallister*, Harbor Branch Oceanographic Institute, Florida Atlantic University; Lauran Brewster, Harbor Branch Oceanographic Institute, Florida Atlantic University; Marcus Drymon, Coastal Research and Extension Center, Mississippi State University; Cliff Hutt, Highly Migratory Species Division, NOAA Fisheries; Matthew Ajemian, Harbor Branch Oceanographic Institute, Florida Atlantic University mmccallister@fau.edu
Shark depredation (i.e., partial removal of target catch prior to retrieval) is an emerging issue that is purportedly affecting several fisheries in the southeastern US. While NOAA Fisheries has begun assessment of shark depredation in commercial fisheries, there have been few attempts to quantify these interactions in the recreational sector. These data are needed to characterize the scale of the issue and determine the need for mitigation measures. To address this knowledge gap, we initiated a citizen-science-based project with goals to: 1) acquire depredation data in the recreational sector, and 2) evaluate fishermen perceptions of the issue. We are achieving these goals via multiple approaches, including data acquisition from an online survey of randomly selected Florida saltwater anglers, social media groups, and genetic sampling of depredated fish carcasses landed by participating charters. From July – December 2021, online angler surveys generated over 1000 responses and preliminary analyses indicate depredation is common. Most interactions were purportedly caused by bull sharks and depredated fish were too damaged for human consumption. Approximately 60% of reports came from anglers who were bottom fishing with natural baits on natural reefs, and most responded to depredation by moving locations or ending fishing for the day. Depredation apparently had little effect on how often or where anglers went fishing, although just over half of the respondents considered depredation rates to have increased in the last five years. While additional data collection is ongoing, these results will be imperative towards building a comprehensive understanding of this emerging human-wildlife conflict. |
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7. 11:30 Capturing Fishermen’s Knowledge to Better Characterize Shark Depredation in the US Gulf of Mexico. Marcus Drymon*, Mississippi State University; Amanda Jefferson, Mississippi State University; Mandy Karnauskas, NOAA Fisheries; Steven Gray, Michigan State University; Savannah Swinea, Northeastern University; Evan Prasky, Northeastern University; Steven Scyphers, Northeastern University marcus.drymon@msstate.edu
Depredation, defined as the partial or complete removal of a captured species by a non-target species, is a complex social-ecological issue impacting a diverse group of stakeholders. Rising concern about the impacts of shark depredation has driven recent research in this area, particularly in the US Gulf of Mexico (GoM). Given the perception that shark depredation is increasing, GoM fishermen have requested that resource managers take action. Therefore, the objective of this project was to co-produce a shared characterization of the impacts of depredation in the GoM reef fish fishery. This objective was accomplished through three phases. First, we gathered, analyzed, and interpreted existing GoM depredation-related datasets. Second, we designed and implemented a depredation-related electronic survey of commercial and recreational fishermen across the GoM. These outputs were used to assemble fuzzy-logic cognitive maps (i.e., mental models), or visual representations of fishermen’s beliefs about social and ecological impacts of depredation. Third, the data synthesis and mental models developed during the first and second phases of the project were presented to stakeholders at a collaborative mental modeling workshop. The workshop 1) allowed stakeholders to assess, discuss, and revise the mental models generated from the survey data, 2) facilitated in-person discussion and reciprocal learning among researchers, resource managers, and stakeholders about GoM reef fish depredation, and 3) identified knowledge gaps concerning GoM reef fish depredation. Collectively, this in-person integration of researchers, resource managers, and stakeholders provides a blueprint for how to effectively capture fishermen’s knowledge regarding complex social-ecological issues like depredation. |
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8. 11:45 Exploration of Machine Learning as a Tool for Pacific Sleeper Shark Population Assessment. Keith Fuller*, Alaska Pacific University; Cindy Tribuzio, NMFS- Alaska Fisheries Science Center diver9043@gmail.com
Electronic Monitoring (EM) technology has found extensive applications in the field of fishery sciences. While on-vessel video recording does allow for fleet coverage beyond what on-board observers could reasonably provide, the amount of data generated from these videos requires significant investment and time to review and disseminate. This has prompted exploration into machine learning technology as a tool to review EM data more quickly and accurately for fisheries assessments. The Pacific sleeper shark (Somniosus pacificus) are data-limited in Alaskan waters and may greatly benefit from increased EM coverage and improved, efficient processing. To test the utility of machine learning technology in the identification of S. pacificus from EM video data, we examined the accuracy of sleeper shark detection, tracking, and classification of a series of custom machine learning algorithms. Results suggest that machine learning has the potential to significantly increase EM processing capability with minimal loss of accuracy for S. pacificus and may strengthen our understanding of the S. pacificus population status throughout Alaskan waters. |