Browsing by Subject "Entanglement"
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Item Open Access A Review of Aquaculture Gear Characteristics and Impacts on Entanglement Risk for Protected Species(2021-04-22) Eynon, JohnEntanglement in fishing gear is the cause of death for hundreds of thousands of marine mammals and sea turtles every year. There are relatively few documented cases of protected species entanglement in aquaculture gear, but events are likely underreported. Interactions with aquaculture are expected to increase in the United States as demand for seafood drives industry growth, new technologies enable farming further offshore, and clarified regulatory processes reduce barriers to entry. Despite this, little attention has been paid to how characteristics of aquaculture gear impact entanglement risk. This research a) catalogs the gear elements thought to influence detection, contact, entanglement, entanglement sustainment, and/or injury severity, and b) summarizes the state of knowledge on how each identified characteristic influences entanglement risk. I find that many of the characteristics are correlated and/or interact in their influence on entanglement. By highlighting relevant gear elements, this review supports future research into system-specific strategies for mitigating entanglement risk.Item Open Access Analysis of North Atlantic Right Whale Swimming Behavior during Bottom Foraging Events to Assess Entanglement Risk(2005) Maresh, Jennifer L.The western North Atlantic right whale, Eubalaena glacialis, is critically endangered throughout its range. With approximately 300 individuals remaining, this population suffers significant impacts from entanglement in commercial fishing gear that are impeding the species ability to recover from historic hunting pressures. The purpose of this study was to evaluate the circumstances surrounding serious entanglements. Data collected from foraging right whales tagged in 2001 and 2002 were analyzed to identify behavior(s) that may increase the risk of entanglement in certain types of gear at certain depths. Results suggest that foraging right whales display risky behaviors that may increase their chances of becoming entangled, including swimming at depths where floating loops of line from bottom-fixed gear extend into the water column, and increased rolling behavior through vertical line during the ascent and descent portions of the dive cycle. This work could contribute to current conservation efforts on behalf of the whale by informing the design of more 'whale-friendly' fishing gear, as well as help managers determine more effective mitigation strategies to reduce the risk that fishing gear poses to right whales.Item Open Access ASSESSMENT OF SPATIAL OVERLAP OF FIXED FISHING GEAR AND RIGHT WHALES, EUBALAENA GLACIALIS, IN THE GULF OF MAINE(2007-05) Hurley, Brendan JRight whale, Eubalaena glacialis, entanglement in fixed fishing gear remains one of the most crucial threats to the survival of the species today. Aerial surveys conducted by the National Marine Fisheries Service (NMFS) from 2002- 2005 from the Gulf of Maine to the New York Bight recorded sighting events of right whales as well as fixed fishing gear buoys. These data were used to assess the presence or absence of spatial overlap between right whale sightings and fixed gear sightings to provide locations where whales most likely are encountering gear within the survey area. Preliminary results show persistent between-year overlap in spring, and within-year overlap in the summer, fall, and winter. This is the first study to utilize NMFS sightings of both right whales and fixed fishing gear. The resulting interaction zones can inform managers and possibly identify important areas for entanglement mitigation such as time area closures.Item Open Access Entaglement of Humpback Whales in Fishing Gear: Description of Injuries and Entanglement Patterns(2003) Mooney, Melissa SIn the Gulf of Maine, the entanglement of humpback whales in fishing gear is a substantial source of human-caused mortality. The current mortality and serious injury of humpback whales in the Gulf of Maine is twice the Potential Biological Removal (PBR) level set for this population. Researchers and managers are challenged to reduce entanglement to below PBR without extensive information on many important factors. The goal of this study was to describe entanglement injuries and investigate whether different fishing gear types, particularly pot and net fisheries, resulted in distinctive entanglement patterns of humpback whales from the Gulf of Maine. I searched the Center for Coastal Studies' entanglement database for whales that fit the following criteria: the entanglement occurred between 1995 and 2002, the whale was photographed during the disentanglement, and the gear type or line type of the entangling gear was known. Sixteen cases were identified that fit the criteria. Three cases involved entanglements in pot fishery gear, four in net gear, and nine cases with known line type. I qualitatively analyzed photographs from these sixteen cases to describe the injuries and to investigate whether any entanglement patterns could be determined based on gear type in terms of location of entanglement on whale, presence of trailing gear, presence of buoys or high flyers, free swimming versus anchored in gear, disentanglement success, or type of injury. I was unable to find a relationship between entangling gear type and any of the factors assessed. I discuss potential reasons for the finding of no relationship as well as considerations for future research in this area.Item Open Access Reducing the Mortality and Serious Injury of North Atlantic Right Whales in the Gulf of Maine(2021-04-22) Stoni, TaylorThe North Atlantic right whale (Eubalaena glacialis) is one of the most critically endangered baleen whales. The most pressing threat to this declining population is entanglement. The Atlantic Large Whale Take Reduction Team recommended measures to reduce the entanglement risk to right whales in fixed gear fisheries in the Gulf of Maine. The central recommendation was to reduce the breaking strength of vertical lines used in these fisheries. We collected data on the breaking strength of unmodified line and lines modified with weak points to develop options for Maine fishermen to reduce entanglement risk to right whales. Our study had three goals: (1) develop a baseline dataset of breaking strength for ropes used in Maine; (2) determine the efficacy of five weak point options in reducing the breaking strength of line to the breaking strength target of 1700 pounds of force (lbsf); and (3) examine if a time tension line cutter (TTLC) could be used as a physical weak point. We tested 140 pieces of straight line and 950 weak point samples. As expected, straight line samples were stronger than those with a weak point. All weak points reduced the breaking strength of each type of line, but no weak point option was successful in reducing all samples to 1700 lbsf. The TTLC could be used as a physical weak point in the fishery, but further studies should be conducted on its ease of use for fishermen. Two of the weak points tested effectively reduced breaking strengths across all rope types, but our results suggest the Maine lobster fishery will require a variety of solutions to reduce risk to right whales.Item Open Access Spatial Ecology of the North Atlantic Right Whale (Eubalaena Glacialis)(2008-04-24) Good, CarolineDespite decades of protection, the endangered North Atlantic right whale (Eubalaena glacialis) has failed to recover, primarily due to interactions with fishing gear and ship strikes. Right whales range along the U.S. east coast, foraging year round in the Gulf of Maine while a subset of the population travels to the South Atlantic Bight each year to calve. The habitat requirements of the right whale are poorly understood. I investigated the relationship between the distribution of right whales and physical oceanographic conditions in an effort to create predictive models of essential right whale habitats. Additionally, the distribution of right and humpback whales (Megaptera novaeangliae) relative to fixed fishing gear was examined to assess spatio-temporal overlap. Habitat preferences were assessed using aerial survey data of whale locations and a range of topological and satellite derived physical parameters including bathymetry, sediment type, sea surface temperature, thermal gradients and surface roughness. A suite of non-parametric quantitative techniques including Mantel tests, log likelihood functions, Generalized Additive Models, Spearman Rank Correlations and the Williamson's spatial overlap index were used to assess relationships between whales and habitat variables. Our findings indicate that suitable calving habitat along the east coast may extend much farther to the north than is currently recognized. Our model correctly identified several well documented current and historic calving grounds in the eastern Atlantic but failed to fully identify a heavily used calving area off Argentina, which is characterized by lower surface water temperatures than the other calving regions. In the Gulf of Maine, right whale distribution was correlated primarily with sea surface temperature, sediment type and bathymetry. Predictive models offered insights into right whale habitat preferences for foraging but failed to wholly capture the physical factors underlying right whale distribution. I found the relative density of right and humpback whales and fixed fishing gear in the Gulf of Maine to be negatively correlated in most seasons and areas. These findings demonstrate that the regular co-occurrence of high densities of whales and gear is not a prerequisite for entanglement. Prohibiting entangling lines in areas where whales are known to forage could substantively reduce entanglement.