Gillnet Gear Research Articles

The The Effect of Using Led Lights (Light Emitting Diode) in the Operation of Bottom Gillnets on Catches In Pangandaran Waters, West Java

The objectives of the study were to analyse the response of dominant fish to different light colours that reflect the wavelength of light and to analyse the species composition of the gillnet catch to determine the fish that are positively phototaxis to LED light. Data collection was conducted using the experimental method. The experimental design used 1 unit of bottom gillnet gear with a mesh size of 4 inches, and used LED (Light Emitting Diode) lights. Trials using green LED lights and white LED lights were operated simultaneously between the control gillnet (without LED lights) and the experimental gillnet (with LED lights). The results of statistical analysis of gillnet catches with green LED light aids with white LED light aids and control nets have a significant effect on the number of gillnet catches. The results were: (1) The number of fish caught at a distance of < 1 m and at a distance of 1-2 m, this proves that many fish are attracted to light (positive phototaxis); (2) Proven by gill net fishing gear using green LED light aids obtained fish weighing up to 77.7 kg. (3) It is proven that the distance of the lamp with the position of the fish caught on the net sheet can produce the highest weight of fish caught, on green LED lights at a distance of <1 m the weight of the fish reached 30.89 kg.

Workplace Injuries Caused by Commercial Fishing Winches—Alaska, 2000–2020

ABSTRACT Objectives Deck machinery is a leading source of hospitalized injury for commercial fishing workers in Alaska. More detailed data are needed about the specific circumstances leading to injuries for developing targeted prevention efforts. Methods This study analyzed claims submitted to the Alaska Fisherman’s Fund (AFF) to identify patterns among injuries in Alaska from commercial fishing winches. Results During January 1, 2000–November 1, 2020, 125 traumatic injuries from commercial fishing winches were identified, mainly occurring among males (94%), frequently among fishermen aged 30 years or younger (54%). Over 80% of winch injuries occurred in salmon fisheries. By gear type, 40% of injuries occurred on vessels using purse seine gear, 30% on vessels using drift gillnet gear, and 12% among set gillnet operators. Most injuries involved a fisherman having a body part caught in or compressed by a winch or cables attached to a winch (67%). Injuries mainly affected upper extremities including fingers (50% of cases) or hands/wrists (together 22% of cases). Injury severity was not formally assessed, but injuries ranged from contusions, sprains, and strains to finger or hand crushing injuries, upper limb amputation, skull fracture, spinal fracture, and chest trauma. Most cases involved fractures (23%), amputations (18%), lacerations (16%), and contusions (16%). Of all injuries, 51% were caused by anchor winches, 32% were caused by deck winches, 9% were caused by trailer winches, and 9% were caused by other types of winches. Conclusions Practical solutions are needed for avoiding entanglement and struck-by hazards when operating fishing winches. Anchor winches warrant focused attention, having accounted for more than half of all winch injuries identified in this study. Engineering solutions, including emergency stop devices or other simple mechanical interventions depending on winch type, could help to avert potentially disabling injuries from winches. Administrative controls such as task-specific training for winches should be emphasized, especially for younger or less experienced commercial fishing crew, who may be at increased risk for injury.

Fisheries interactions and the challenges for target and nontargeted take on shark conservation in the Mexican Pacific.

Sharks have been of great cultural and socioeconomic importance in Mexico since the late 19th century, when the first fisheries were prosecuted in the Gulf of California to export fins to China. Mexican shark and ray fisheries are classified mainly by the size of the fishing vessel and include small- (7.5-10m), medium- (10-27m), and large-sized (>27m) fisheries. All are multispecies fisheries that use longline or gillnet gear, with their relative productivity varying over time. Off the Pacific coast, early shark small size vessel fisheries in the Gulf of California were driven by the need for vitamin A from livers, especially during World War II. As this fishery declined, new shark fishing opportunities arose because of government support and the development of the medium-sized fishery, which was capable of farther offshore excursions. Shark meat became an important part of the diets of poor and impoverished citizens during the 1950s and 1960s. The establishment of a Mexican Exclusive Economic Zone in 1976 pushed foreign vessels from Asia out of Mexican waters and led to the development of the large-sized vessel fishery to exploit pelagic sharks in offshore waters. By the early 1980s, Mexico shark fisheries were among the most productive in the world; however, a national economic crisis reduced effort and landings until the late 1980s, when several new fisheries emerged. Landings from Pacific states fluctuated between ~13,000 and 24,000t (dressed weight) during 1987-2012 but expanded steadily thereafter because of government support and offshore fleet expansion. Shark fisheries landings from the Mexican Pacific are currently at their highest recorded levels, exceeding 31,000t; however, a lack of species-specific landings and life history information has precluded population assessments of targeted stocks. In addition, though several recent management measures have been enacted to protect Mexican shark and ray fishery resources, the enforcement of these regulations is severely lacking. Therefore, the long-term sustainability of current fishing levels is unknown but should engender concern based on anecdotal evidence of serial depletion among historical elasmobranch targets in the Mexican Pacific.

Environmental associations of Pacific bluefin tuna (Thunnus orientalis) catch in the California Current system

AbstractWe investigate the impact of oceanographic variability on Pacific bluefin tuna (Thunnus orientalis: PBF) distributions in the California Current system using remotely sensed environmental data, and fishery‐dependent data from multiple fisheries in a habitat‐modeling framework. We examined the effects of local oceanic conditions (sea surface temperature, surface chlorophyll, sea surface height, eddy kinetic energy), as well as large‐scale oceanographic phenomena, such as El Niño, on PBF availability to commercial and recreational fishing fleets. Results from generalized additive models showed that warmer temperatures of around 17–21°C with low surface chlorophyll concentrations (<0.5 mg/m3) increased probability of occurrence of PBF in the Commercial Passenger Fishing Vessel and purse seine fisheries. These associations were particularly evident during a recent marine heatwave (the “Blob”). In contrast, PBF were most likely to be encountered on drift gillnet gear in somewhat cooler waters (13–18°C), with moderate chlorophyll concentrations (0.5–1.0 mg/m3). This discrepancy was likely a result of differing spatiotemporal distribution of fishing effort among fleets, as well as the different vertical depths fished by each gear, demonstrating the importance of understanding selectivity when building correlative habitat models. In the future, monitoring and understanding environmentally driven changes in the availability of PBF to commercial and recreational fisheries can contribute to the implementation of ecosystem approaches to fishery management.

Understanding Non-compliance With Protected Species Regulations in the Northeast USA Gillnet Fishery

Marine mammals and sea turtles in the United States are protected from commercial fishery interactions under the Marine Mammal Protection Act and the Endangered Species Act. To reduce harbor porpoise bycatch in the northeast sink gillnet fishery, fishermen are mandated to attach pingers to their nets in regulated areas. Although, pinger regulations have been in place for over a decade, in practice, enforcement is weak and the penalty for a violation is almost non-existent. In this scenario, the presence of normative factors may motivate a fisherman to comply with the pinger regulation. This study considers both economic and normative factors within a probit framework to explain a fisherman’s compliance decision. Model results indicate fishermen who previously violated pinger regulations, who are not completely dependent on gillnet gear and face a lower chance of being detected by an observer, are more likely to violate. Understanding the influence of normative factors on compliance decisions is a key component for higher compliance. That is, incorporation of these factors in the design of policy instruments may achieve higher compliance rates and thus more success in protecting these species. Our model findings were ground-truthed by conducting focus group research with fishermen using pingers; some preliminary findings are shared in the discussion in support of our model results. Finally, these results also suggest observer data can be used to support compliance and enforcement mechanisms in this fishery and possibly other fisheries as well.

Assessment of acid–base derangements among bonnethead (Sphyrna tiburo), bull (Carcharhinus leucas), and lemon (Negaprion brevirostris) sharks from gillnet and longline capture and handling methods

Blood gasses of wild bonnethead, bull, and lemon sharks were measured with the i-STAT clinical analyzer with the CG4+ cartridge immediately after capture; and again immediately prior to release after tagging, handling and morphometric measurements were taken. Relative reference ranges of post-capture status were established. Among species, stress response to capture was similar for all parameters; however, pH declined and lactate concentrations rose over time, indicating continued insult from capture and/or response to additional handling stress. pCO2 rose faster for S. tiburo than for C. leucas, and lactate concentrations rose faster for S. tiburo than for N. brevirostris. All species caught in gillnets experienced lower pH and higher lactate concentrations than on longlines. Discriminant analysis justified the use of blood gas analysis to assess physiological stress induced by different capture methods. From these results, we recommend 1) that gear be monitored closely and sharks be removed immediately, or suboptimally, that gear is deployed for the shortest soak time possible; 2) longline over gillnet gear; and 3) extra caution with sensitive species (e.g., S. tiburo), which may include the administration of blood buffers and other therapeutics if a shark is beyond the limits of relative reference ranges reported here.

Characteristics and magnitude of sea turtle bycatch in US mid-Atlantic gillnet gear

From 1995 to 2006, US federal fisheries observers deployed aboard commercial fishing vessels in the US mid-Atlantic region documented captures of loggerhead Caretta caretta, green Chelonia mydas, Kemp's ridley Lepidochelys kempii, and leatherback Dermochelys coriacea turtles in commercial sink gillnet gear. Data collected by these observers were used to characterize sea tur- tle bycatch in sink gillnet gear, including the temporal and spatial distribution, fishing characteristics, species composition, and sizes of turtles captured. In addition, these data were used to develop a gen- eralized additive model to evaluate and predict bycatch rates (turtles per metric ton of fish landed) of sea turtles. These rates were then applied to commercial gillnet landings over the same time period to estimate total bycatch of loggerhead turtles. Bycatch rates of loggerheads were correlated with lat- itude, sea surface temperature, and mesh size. Highest predicted bycatch rates occurred in warm waters of the southern mid-Atlantic, in large-mesh gillnets. From 1995 to 2006, the average annual bycatch estimate of loggerheads was 350 turtles (coefficient of variation = 0.20, 95% CI over the 12 yr period: 234 to 504). Characteristics and magnitude of bycatch can help inform population assess- ments, while the distribution of bycatch rates can be used to help inform bycatch mitigation options.

Establishment and closure of the directed Florida whiting (Menticirrhus americanus) fishery and implications for North Atlantic right whale (Eubalaena glacialis) conservation and management

Today, ocean and coastal marine resource management is extremely complex. Marine resource managers are charged with conserving and managing many diverse species. Southern kingfish ( Menticirrhus americanus ), commonly known as whiting, are found from southern New England to Florida. During the fall through winter, western North Atlantic right whales ( Eubalaena glacialis ) are primarily found in the coastal nearshore waters off South Carolina, Georgia, and Florida, overlapping the whiting's range and habitat. In January 2006, a right whale calf was discovered dead, as a result of gillnet entanglement, in close proximity to the Florida commercial whiting fishing grounds; thus, to assist the National Marine Fisheries Service (NMFS) with developing appropriated right whale conservation management measures, this study evaluated the newly established commercial Florida whiting fishery. Findings revealed that the whiting fishery was established in 2004 and the fishery was prosecuted during the time and area where right whales were found. Moreover, the study found that whiting landings, market value, catch-per-unit-effort (CPUE), dealers, and fishing effort significantly increased during 2000 through 2005. As a result of the right whale calf mortality and threat of gillnet gear to whales, the NMFS prohibited the use of gillnet gear in the US southeastern waters, which inevitably closed the newly established whiting fishery.

Cause-specific temporal and spatial trends in green sea turtle strandings in the Hawaiian Archipelago (1982–2003)

We investigated cause-specific temporal and spatial trends in sea turtle strandings in the Hawaiian Archipelago. Five species of sea turtle were recorded in 3,861 strandings over a 22-year period (1982–2003). Green turtles comprised 97% of these strandings with size and gender composition reflecting the demographic structure of the resident green turtle population and relative green turtle abundance in Hawaiian waters. The cause of strandings was determined by necropsy based on a complete gross external and internal examination. Totally 75% of the 3,732 green turtle strandings were from Oahu where strandings occur year-round. The most common known cause of the green turtle strandings was the tumour-forming disease, fibropapillomatosis (28%) followed by hook-and-line fishing gear-induced trauma (7%), gillnet fishing gear-induced trauma (5%), boat strike (2.5%), and shark attack (2.7%). Miscellaneous causes comprised 5.4% of strandings whereas 49% of green turtle strandings could not be attributed to any known cause. Green turtle strandings attributable to boat strike were more likely from Kauai and Oahu while fibropapilloma strandings were more likely from Oahu and Maui. Hook-and-line gear strandings were more likely from Oahu due to higher per capita inshore fishing effort. The specific mortality rate (conditional probability) for fibropapillomatosis was 88%, 69% for gillnet gear and 52% for hook-and-line gear. The probability of a dead green turtle stranding increased from 1982 but levelled off by the mid-1990s. The declining mortality risk was because the prevalence and severity of fibropapillomatosis has decreased recently and so has the mortality risk attributable to gillnet gear. Despite exposure to disease and inshore fishing gears, the Hawaiian green turtle stock continues to recover following protection since the late 1970s. Nevertheless, measures to reduce incidental capture of sea turtles in coastal Hawaiian fisheries would be prudent, especially since strandings attributable to hook-and-line fishing gear have increased steadily since 1982.

Lack of size selectivity for paddlefish captured in hobbled gillnets

A commercial fishery for paddlefish Polyodon spathula caviar exists in Kentucky Lake, a reservoir on the lower Tennessee River. A 152-mm (bar-measure) minimum mesh size restriction on entanglement gear was enacted in 2002 and the minimum size limit was increased to 864 mm eye-fork length to reduce the possibility of recruitment overfishing. Paddlefish were sampled in 2003–2004 using experimental monofilament gillnets with panels of 89, 102, 127, 152, 178, and 203-mm meshes and the efficacy of the mesh size restriction was evaluated. Following the standards of commercial gear used in that fishery, nets were “hobbled” (i.e., 128 m × 3.6 m nets were tied down to 2.4 m; 91 m × 9.1 m nets were tied down to 7.6 m). The mean lengths of paddlefish ( N total = 576 fish) captured in each mesh were similar among most meshes and bycatch rates of sublegal fish did not vary with mesh size. Selectivity curves could not be modeled because the mean and modal lengths of fish captured in each mesh did not increase with mesh size. Ratios of fish girth to mesh perimeter ( G: P) for individual fish were often less than 1.0 as a result of the largest meshes capturing small paddlefish. It is unclear whether lack of size selectivity for paddlefish was because the gillnets were hobbled, the unique morphology of paddlefish, or the fact that they swim with their mouths agape when filter feeding. The lack of size selectivity by hobbled gillnets fished in Kentucky Lake means that managers cannot influence the size of paddlefish captured by commercial gillnet gear by changing minimum mesh size regulations.

FISHING GEAR INVOLVED IN ENTANGLEMENTS OF RIGHT AND HUMPBACK WHALES

Interactions between marine mammals and fishing gear are an issue of global concern. Entanglements in the western North Atlantic are a major source of injury and mortality for endangered large whales. In this study, entanglements of 31 right whales (Eubalaena glacialis) and 30 humpback whales (Megaptera novaeangliae) were analyzed to determine the types and parts of gear involved. When gear was identified, 89% (n= 32) of the entanglements were attributed to pot and gill net gear; however, a wide range of specific gear types were implicated. Despite gear recovery, gear type was not identified in 20% (n= 9) of the cases. Although pot gear was recovered from both species equally, gill net gear was less frequently retrieved from right whales (n= 2) than humpback whales (n= 11). When gear part was identified, 81% (n= 21) involved entanglements in buoy line and/or groundline. For right whales, the most common point of gear attachment was the mouth (77.4%); for humpback whales, the tail (53%) and the mouth (43%) were common attachment sites. Four right and three humpback whales in this sample were known to have died subsequent to entanglement. However, when identified, the gear types and parts involved in lethal cases were not substantially different from entanglements with non-lethal outcomes. Large whales can become entangled in a wide variety of fishing gear types and parts, and additional insight will depend on continued efforts to document entanglements and recover associated gear.