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Angling for hairtail Trichiurus lepturus using lights is common around the Korean Peninsula. Typically, metal halide (MH) lamps are used to attract fish during the fishing process. We investigated the fishing performance and fuel consumption using light-emitting diode (LED) lamps instead of MH lamps off the coast of Jeju Island, Republic of Korea. We conducted a total of 19 fishing trips using LED lamps, at a depth of 100–145 m during the winter fishing season of 2012–2013. The catch by the LED-lamp vessel (21.6 kW) was similar to the catch by the MH-lamp vessels of similar sizes (9.77 GT) but higher light power (45–84 kW). Fuel consumption per trip for the LED-lamp vessel was 454.2 l, and fuel consumption per hour for fishing operations (excluding steaming) was 9.2–11.3 l, with an average of 10.3 l. Catch intensity, defined as catch per kW of light power (kg kW −1 ) of LED-lamp vessel was significantly higher than MH-lamp vessels of all size classes. The break-even point for the vessels to install LED lamps instead of MH lamps is 109 trips per year when the fuel price is at the 2012 level of USD 0.82 l −1 . In addition, through the reduction of fuel use, CO 2 emission can be reduced by approximately 27,553.0 kg for each vessel in the fishery.

The Antarctic krill ( Euphausia superba ) is one of the most abundant resources in the ocean, which provides food for several important species in the Antarctic Ocean, and is targeted commercially by humans for many decades. To sustainably manage and harvest the species, energy-efficient, catch-efficient, and selective fishing gears should be developed for the Antarctic krill trawl fishery. This study investigates the effect of twine area and the liner length on the engineering performance of trawl through flume tank testing of trawl model to predict the performance of the full-scale midwater trawl used in the Antarctic krill fishery. Four 1/35th scale trawl model nets with varying lengths of the liner, based on the traditional trawl used in the Antarctic krill fishery, were designed using modified Tauti’s law and were tested in a flume tank at different towing speed, door spread, heavy bob weight, and the ratio of buoyancy to the fishing line (F/G). The results showed that the reduction in liner length by 25 and 50% from the traditional trawl net led to the decrease in twine area by 11.01 and 19.31% and, consequently, resulted in reductions in the lower bridle tension by 12.44 and 19.78%, and increases in energy efficiency by 17.98 and 25.73%, respectively. In addition, the reduction in liner length by 25 and 50% were found to increase the net mouth opening by 2.63 and 5.38% and the swept area by 6.52 and 8.38%, respectively, both of which are proportional to catch rates. Although the trawl net with 50% liner length is more energy-efficient and large mouth opening than those of the trawl net with the liner length over 75% of the trawl body, the large mesh section without a liner can result in the escape of the krill from the trawl, reducing overall catch efficiency. We, therefore, recommend the trawl with 75% of liner length as a suitable design for Antarctic krill considering energy efficiency and catch efficiency.

Abandoned, lost, and discarded fishing gear (ALDFG) is a problem that is increasingly of concern to global fisheries resources and the aquatic environment. Nearly 2% of all fishing gear used in marine fisheries is lost to the ocean annually. This has negative impacts on the aquatic ecosystem, which includes but not limited to ghostfishing mortality to commercial, recreational and protected species, degradation of benthic habitat, and change to the ecosystem. Fishing gear left in the sea can drift ashore affecting recreational use of beaches and shorelines and poses hazards to navigation. Most of the research on ALDFG has been in the marine fisheries of the developed world with very few studies in the inland fisheries, mostly in the developing world of sub-Saharan Africa and Asia. This paper reviews and synthesizes literature about the status of ALDFG in inland fisheries globally. Only 16 studies, between 1970 to 2023, that referenced ALDFG causes, levels, impacts, and preventive measures were found. Thus, this review highlights that ALDFG in inland fisheries remains a highly understudied area of aquatic plastic pollution. Further studies are recommended to fully understand its status, extent, and potential environmental impacts.

Dynamic responses of tuna purse seine to currents were numerically studied with regard to the vertical subsidence and global load distribution, and determinant attributes were identified. We rebuilt the submerged geometry of a purse seine net using the lumped mass method with hydrodynamic coefficients obtained from measurements of the prototype material, as well as a mesh grouping method, which corrects the twine diameter and netting material density for the equivalent net by introducing the compensation coefficient. Uneven tension distribution showed that it was vulnerable to high loads in the bunt area at shooting and along the lead line at pursing. High loads were present at the convex sections of net circles in the direction of the current. Higher shooting speeds resulted in well-balanced sinking, while a reduced hanging ratio of netting panels was beneficial to faster sinking. While large mesh sizes reduce water resistance and increase sinking velocity, extensive use should be cautioned in terms of the sensibility to stress. Comparing two options of different proportions of large-mesh panels, mesh sizes doubled for 15 strips versus 5 strips, suggesting that the 15 strip option would pose a higher risk of strand vulnerability, while the 5 strip option may be a more balanced alternative with a lower mesh density and a lower mesh stress.

ObjectiveAlewife Alosa pseudoharengus and Blueback Herring A. aestivalis, collectively referred to as river herring, are anadromous clupeids inhabiting the North American Atlantic coast. Although the seasonal patterns of their spawning migration are well studied and predictable, the fine-scale movements are still poorly resolved.MethodsThis study used high-resolution acoustic imaging to study the fine-scale behavior of river herring during their spring spawning migration in two coastal rivers in Massachusetts, United States.ResultObservations suggest that seasonal patterns of migration appear to be influenced by temperature, while fine-scale patterns in migration were associated with the time of day, tidal state, and their interaction. River herring were consistently observed during both day and night, with elevated peaks of activity in the early morning and late afternoon. Daytime movement consisted of the intermittent passage of large, dense schools, while nighttime movement consisted of the frequent passage of individuals or small groups. The highest numbers of herring observations were associated with flood and high tides. Additionally, the interactions between time of day and tidal state resulted in synergistic positive effects during crepuscular incoming tides, which were favorable to movement, and synergistic negative effects during midday low tides, which inhibited fish movement.ConclusionThe changing relationship between the time of day and tidal state within the season manifested in changing periodicity in fish movement to correlate with favorable movement conditions. Since movements may be related to both time of day and tide, previous run size estimates from visual counts made only during the day may be too low. Sampling methodologies that collect information during all 24 h would likely produce the most accurate run size estimates. This study highlights the need to view river herring migration in a holistic context predicated by multiple environmental and biological factors that vary at several temporal scales (i.e., seasonally, daily, and hourly).

Shrimp locomotion includes walking, swimming, and tail-flipping, all essential for survival. Understanding the pathway and use of energy during different modes of locomotion is important in understanding the strategy and evolution of locomotion. We explored the mechanisms of energy supply during swimming and tail-flipping locomotion modes in the whiteleg shrimp Litopenaeus vannamei (Boone, 1931). We studied the metabolic pathways of glycogen and triglycerides and the regulation of glycolytic enzyme on glycolysis, and analyzed their relationship with the behavior modes of locomotion. Swimming includes sustained and prolonged modes, where the shrimp were forced to swim at a speed of 10 cm s⁻¹ for 200 min (sustained), and at 20 cm s⁻¹ until fatigue (prolonged). In tail-flipping locomotion, shrimp were forced to tail-flip by tapping the animal until fatigue. The results showed that the hydrolysis of glycogen in pleopod muscle increased with the rate of pleopod strokes due to increased energy demand during fast swimming. Similarly, glycogen breakdown in abdominal muscles was increased during tail-flipping. Glycogen and triglycerides were utilized in aerobic metabolism pathway as a result of the lower rate of pleopod strokes during sustained swimming. Prolonged and tail-flipping modes of locomotion were powered by anaerobic glycolysis because oxygen supply probably was not sufficient to meet the requirements of glycogen and triglyceride oxidation. Lactate accumulation due to increased glycolysis consequently resulted in locomotion fatigue. These findings highlight our understanding of physiology and behavior of locomotion in shrimps, essential during migration, foraging, and escape from predators.

The construction of dams and tide gates on waterways has altered the physical structure of many coastal, estuarine, and freshwater systems. These changes have come at a cost to fish populations, most notably diadromous species, which rely on connectivity between marine and freshwater systems. These anthropogenic structures can have direct effects on migrating fish, such as blocking fish passage, or have more subtle effects, such as changing movement patterns. This study used a high‐resolution Adaptive Resolution Imaging Sonar to examine the behavior of Striped Bass Morone saxatilis, a large coastal predator, and Alewife Alosa pseudoharengus and Blueback Herring Alosa aestivalis (collectively known as river herring), which are forage fish, below a tide gate structure on the Herring River in Wellfleet, Massachusetts, during the river herring spring spawning run. Striped Bass were persistently present downstream of the tide gate and exhibited strong diurnal and tidal patterns. Activity of Striped Bass was highest at night and during ebb tides. During peak outflow periods, river herring were observed milling downstream of the dam in a scour pool, indicating delayed upstream passage. River herring upstream migration was primarily associated with daytime and during incoming tides. Downstream‐migrating river herring were primarily observed during nighttime hours. While it was documented that the tide gates provided a physical impediment to migration, their effect on predator behavior could pose an additional challenge to migrating river herring, further complicating their recovery efforts. Due to the prevalence of obstructed waterways, studying the behavior of fish around anthropogenic structures is important in understanding the full range of impacts that these systems have under varying ecological conditions and on ecological relationships.

The swimming endurance of Atlantic cod (Gadus morhua), native to the cold waters off the east coast of Newfoundland and Labrador, was investigated under laboratory conditions. Using a swimming flume, endurance was tested at swimming speeds ranging from 0.6 to 1.3 m·s -1 using water temperatures from 0.0 to 9.8°C ( mean = 3.2°C, SD = 2.8) and fish lengths from 41.0 to 86.0 cm ( mean = 57.8 cm, SD = 10.5). The results revealed that swimming speed was the only significant factor affecting the endurance of cod. The maximum sustained swimming speed (U ms ) was predicted to be 0.66 m·s -1 . Statistical analysis of the data was conducted using failure time analysis. The hazard, or risk of exhaustion, was found to increase rapidly with increasing swimming speed, i.e., there was a decrease in the probability of cod achieving a given swimming endurance. Probability curves for the endurance of cod were calculated for different swimming speeds. The findings suggest that the catching efficiency of commercially targeted cod (>41.0 cm) by otter trawls may be highly sensitive to changes in towing speed while being independent of both fish length and water temperature.

Based on the evaluation, the document proposed a framework for marking these fishing gears and FADs, based on the principles outlined in the FAO Voluntary Guidelines on the Marking of Fishing Gear. The VGMFG not only stipulates that fishing gear be marked, but also provides guidance on the reporting of gear loss, the recovery of ALDFG and the disposal of end-of-life gear. 1.1.2 IOTC's work towards the implementation of fishing gear marking Following the endorsement of the Voluntary Guidelines on the Marking of Fishing Gear by COFI, the European Union, a Member of Indian Ocean Tuna Commission (IOTC), put forward a proposal for a resolution on the marking of fishing gear in 2019, with due consideration of Annex V of the International Convention for the Prevention of Pollution from Ships (MARPOL), which prohibits the discharge of all garbage at sea, including from fishing vessels (IOTC, 2019). [...]given the CPCs' diverse economic development stages and varying levels of fishery management, the report outlines a number of strategies for raising awareness and capacity building in CPCs, particularly developing states. Fish aggregating device (FAD) is a permanent, semi-permanent or temporary object, structure or device of any material, man-made or natural, which is deployed and/or tracked, for the purpose of aggregating target tuna species