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Gear selectivity is crucial in fisheries management because it influences the size and species of fish caught, with traditional methods often basing optimal mesh size on the mature length of a target species. However, to ensure sustainable fisheries, both biological aspects of resource protection and fishing operation efficiency must be considered. This study aimed to determine the ideal mesh size for trap fishing of marbled flounder (Pseudopleuronectes yokohamae) in Gyeongsangnam‐do, South Korea, by using biological and economic factors for sustainable fisheries management. We sampled fish caught in traps of varying mesh sizes (35, 50, 65, 80, and 100 mm) and developed two models based on fish maturity, bycatch ratio, and CPUE. Model 1 used a maturity criterion of 17.8 cm, and Model 2 used the legal minimum length limit of 20 cm. Net selectivity curves indicated that the optimal mesh size ranged 50–65 mm based only on a minimum mature body length of 17.8 cm. In contrast, the optimal mesh size based on both biological and economic factors ranged 57.5–90 mm. Our findings could guide policymakers in enhancing marble flounder population management strategies through policy adjustments in mesh size and gear restrictions. [ABSTRACT FROM AUTHOR]

Objective: We assessed the relative proportions of wild‐ and hatchery‐origin summer steelhead Oncorhynchus mykiss caught by sport anglers in the Deschutes River, Oregon. Our objective was to evaluate if steelhead of wild or hatchery origin were equally or disproportionately captured by sport anglers relative to the overall run composition. Methods: We conducted access‐based angler creel surveys of the Deschutes River steelhead fishery during 2000–2019 and 2021 to observe reported catch of wild and hatchery steelhead. We collated fishery‐independent hatchery‐wild composition data from three locations (two dams and one fish trap) bounding the fishery area we creel sampled. We then used a series of mixed‐effect logistic regression models fit to compare angler catch of wild‐ and hatchery‐origin steelhead relative to their composition at the fishery‐independent sampling locations. Result: The best‐fit model suggests that anglers were more than twice as likely to observe a wild steelhead in their catch as compared with the chance of the fishery‐dependent sampling sites to observe a wild steelhead. Across all years, wild steelhead were 27–31% of the stock composition at the fishery‐independent sampling sites yet averaged 65% of angler catch. Conclusion: Disproportionately high encounter rates of wild‐origin summer steelhead suggest that any adverse impacts associated with catch‐and‐release fishing may be magnified by this effect. We explore some potential mechanisms that could account for this difference and hypothesize that a difference in catchability between wild and hatchery steelhead is the most likely mechanism driving the observed patterns. Regardless of the mechanism, annual catch of wild steelhead is proportionally greater than expectations, given wild steelhead run size compared with that of hatchery steelhead. Impact statementUnderstanding catch of wild and hatchery steelhead is important for balancing sport angling and conservation. Wild summer steelhead in the Deschutes River, Oregon, were more frequently caught than hatchery steelhead and disproportionately supported angler success. In addition to species conservation, maintaining wild steelhead abundance is critical to angler success in the Deschutes River steelhead fishery. [ABSTRACT FROM AUTHOR]

Acanthopsoides molobrion is a freshwater previously known to be spread across Malaysia and Borneo. This study aimed to record for the first time the occurrence of the A. molobrion in Bangka Island, Indonesia, and update the geographic distribution of this species. This new record of freshwater fish provides an important contribution to the comprehension of the biogeography of the species. The purpose sampling approach was employed for this study to collect specimens. The species were then identified morphologically by the application of morphometric and meristic methods, and molecularly through the employ of DNA Barcoding. On 20th January 2023, two A. molobrion specimens were collected from the Bumang Kemuja River, Bangka Island using a fish trap. The new record of A. molobrion found here is the southernmost record for this species, expanding its geographic distribution. In addition, the latest record site is about 500 km south of the nearest locality in Peninsular Malaysia, and about 750 km southwest of the nearest locality in Borneo. The new record of A. molobrion has expanded the species' recorded distribution range, which has added to our understanding of this species. Furthermore, we present an updated record for the A. molobrion DNA sequence based on the COI gene. This sequence is the first DNA Barcode to Indonesia. Subsequently, the DNA sequence was registered into NCBI Genbank with the access code OR144414. This DNA barcode will be used as a standard for identifying A. molobrion and will aid in DNA and biotechnology-based studies in the future. [ABSTRACT FROM AUTHOR]

Religious wildlife release is prevalent worldwide, especially in Asia countries. It is one of the anthropogenic pathways to cause biological invasions. Religious fish release is common on the Qinghai-Tibetan Plateau, yet few studies have assessed the influences of religious fish release on local species. In Yushu, a city on the Qinghai-Tibetan Plateau, we interviewed local people, conducted fish trap surveys in local rivers, and examined the diet of Eurasian otters Lutra lutra using a fecal DNA metabarcoding approach. We found that fish release started at least in 1980–1990s in Yushu. Tibetan residents released fish in large amounts and released fish were usually exotic commercial fish purchased from market. Despite such long-term and intensive fish release activities, released fish were few in local rivers. On the other hand, Eurasian otters mainly prey on fish and released fish accounted for ~20% of relative read abundance of prey DNA in otters' diet, indicating their high preference on released fish. Our study suggested that religious fish release may provide additional food resources for otters, whereas otters, as a top predator in local rivers, may deplete non-native fish once they were released and, therefore, reduce the probability of colonization of released fish, although further studies are required to assess otters' impact. Our study revealed otters' diet in Yushu, providing basic information for local otter management and conservation. Furthermore, it represents a case showing that native predators prey on religious released animals, implying a probable direction for controlling invasive species through native predator conservation. [ABSTRACT FROM AUTHOR]

The right to a healthy environment reflects fundamental values such as the right to life, the right to health, and the right to a healthy and standard quality life that belongs to different generations of humans in the present and future. Trawl net fishing has been carried out in the Persian Gulf for some time, which, according to experts, violates the right to a healthy environment and its fundamental values. In trawl net fishing, a large fish trapping net in the shape of a funnel is used, which is attached to the back of a floating vessel and catches marine organisms at different depths with a coverage coefficient of 90%, causing serious damage to the marine ecosystem. Preservation of the environment is done by supporting the protection, improvement of the environment and preventing and prohibiting any kind of pollution and destructive action that disturbe the balance and suitability of the environment. Preservation of various animal species, including aquatic animals, is an example of environmental protection. In this research, through a descriptive and library method of investigation, by analysing laws and regulations,we aim to answer the question whether it is possible to impose restrictions or prohibitions on this type of fishing in the Iranian legal system? Which laws and regulations can be relied upon to address the damage caused by trammel net fishing to the environment and natural resources? To this end, the constitution, ordinary laws and regulations are first examined, followed by the general policies of the Islamic Republic of Iran, the 1404 Vision Document and the Environmental Protection and Restoration Act. Finally, regional and international conventions and international documents are studied. [ABSTRACT FROM AUTHOR]

The Florida Keys reef tract has rapidly shifted from a structurally complex, hard coral-dominated reef to a less rugose, soft coral-dominated reef. This transition has been facilitated by persistent anthropogenic stressors including recreational and commercial fishing and increased anthropogenic marine debris. During the summers of 2020-2022, benthic censuses were conducted to identify substrate and marine debris composition for 30 reefs in the middle Florida Keys. Inshore reefs contained higher rugosity, coral cover, and marine debris abundance primarily comprised of monofilament and rope from fishing traps. Plastic items (e.g., ropes and monofilament) overall had the highest species diversity. Additionally, marine debris appears to promote turf algae growth on inshore reefs. While is it not yet possible to determine if this pattern of high debris nearshore is due to proximity to onshore debris sources, accumulation due to higher rugosity snagging debris, or increased debris removal efforts offshore, these differences in marine debris types and abundances suggest variability in potential impacts of debris on marine biota on inshore versus offshore reefs. Therefore, the differential use of marine debris by associated biota should be considered in marine debris management practices. [ABSTRACT FROM AUTHOR]

Fishing activities by fishermen in Kebumen Regency experience major obstacles related to oceanographic conditions and the uncertainty of the fishing season. When it's not in season, some fishermen have other livelihoods, namely farming, animal husbandry, and others. However, not all fishermen have this ability, many fishermen depend only as fishermen for their livelihood. The aim of this research is to identify the potential of the region as an alternative economic activity for fishermen and provide recommendations for appropriate alternative livelihoods for fishermen in Kebumen Regency, for example the case in Jogosimo Village. Data collection on opportunities for alternative economic activities was carried out through regional potential surveys and literature studies. These results were then carried out with a focus group discussion (FGD) to obtain input regarding fishermen's views on these alternative livelihoods. Data analysis was carried out descriptively based on the results of field surveys and FGDs. The results of field identification and literature study showed that alternative economic activities that fishermen could carry out were fishing activities at river mouths with traps, cultivating/rearing mangrove crabs, and river tourism. The results of the FGD provided input on the need for innovation so that trap fishing equipment is not lost when the river flows fast. The condition of the mangroves in Jogosimo Village needs to be replanted so that the population is higher, so that mangrove crab cultivation or rearing can be carried out. The recommendation that can be given is the need to develop river tourism through the integration of fishing activities, maintenance and rearing of mangrove crabs, as well as culinary tourism and marketing of local products. [ABSTRACT FROM AUTHOR]

Estimates of recreational fishing effort and catch are needed to inform fisheries management, but such estimates can be challenging to obtain. We combined a zig‐zag line transect survey of buoys, a fisheries enforcement survey and a drone survey to estimate recreational effort in the open‐access trap fishery for signal crayfish (Pacifastacus leniusculus) in the sixth largest lake in Europe, Lake Vättern, Sweden. Using supporting variables such as size of nearby ports and bathymetry, our model‐assisted estimate of total effort was 6400 (±4300 CI) buoys during the three‐weekend season. Using the frequency of buoys to traps as a constant, the total number of crayfish traps was estimated to be 25,500 (±17,000 CI). The sampling design and methods presented are useful for ecologists and resource managers to design future multi‐source surveys of recreational trap fishing effort. [ABSTRACT FROM AUTHOR]

This study analysed the catches of trap fishing in the Canary Archipelago, NE Atlantic Ocean. This study was conducted from October 2016 to September 2017, April to November 2018 and September 2020, in five ports (San Cristóbal, Taliarte, Castillo del Romeral, Arguineguín and Mogán).The primary gear were traps with small mesh size (31.6 mm) and large mesh size (50.8 mm). A total of 2587 small mesh size traps and 141 large mesh size traps were analysed from 20‐ to 130‐m depth.The main target species were Dentex gibbosus and Stephanolepis hispidus.Catches of traps with large mesh size showed D. gibbosus above first maturity and S. hispidus in small mesh size traps. Both species exhibit larger specimens during reproductive periods.The most effective traps for D. gibbosus (large mesh) were located on the western coast (>30‐m depth), with the highest catch per unit of effort (CPUE) in Mogán (857.7 g trap−1 day−1). The most effective traps for S. hispidus (small mesh) were located in southern areas, especially in sandy habitats (124.9 g trap−1 day−1 in Castillo del Romeral, 102.9 g trap−1 day−1 in Arguineguín).The highest catchability of D. gibbosus was observed in April (CPUE of 962.8 g trap−1 day−1), and the highest catchability of S. hispidus was found in June (CPUE of 165.9 g trap−1 day−1).The traps with small mesh size showed a great selectivity of sizes for S. hispidus; though high catch rates of immature specimens of D. gibbosus pose a threat to species conservation.The management recommendations' proposed measures include revising minimum catch sizes for both species. Additionally, we suggested depth limitations for mesh sizes of traps.The study highlights the need for new management strategies to ensure the conservation of targeted demersal species, with special emphasis on addressing the threat posed by small mesh sizes to immature D. gibbosus.The findings provide valuable insights for adapting fishery management practices to sustainably conserve the targeted species in the Canary Archipelago. [ABSTRACT FROM AUTHOR]

Traps (or pots) are one of the oldest and most widespread scientific survey gears for fish and decapod crustaceans around the world. Here, I review and synthesize the extensive scientific literature describing the various benefits and drawbacks of using traps as a survey gear in scientific studies. The widespread use of traps in fish and decapod surveys is due to several characteristics like their low cost, flexible design, ease of use, ability to fish unattended, and being amenable to pairing with other gears. However, there are a number of significant drawbacks of using traps, including highly variable catches due to environmental fluctuations or behavioral interactions or lost traps that continue catching and killing animals, that must be considered and accounted for when initiating trap surveys. This study highlights the types of habitats and species most and least suited for monitoring by traps, and emphasizes the importance of matching the goals and objectives of a trap survey with the correct trap design, mouth entrance, bait type, soak time, and pairing of gears. Pilot studies are also recommended before surveys are initiated to quantify the selectivity patterns of traps and identify the various factors that may influence trap catch. [ABSTRACT FROM AUTHOR]

The management of fish aggregating devices (FAD) creates heated debates in tuna fishery management organizations striving to reduce the number of deployed floating objects. Through several econometric models and a machine learning approach, we evaluate the consequences of three management scenarios on the catch and profit of the French purse‐seine fleet operating in the Indian Ocean: (1) a half reduction in the number of authorized buoys per vessel, (2) a 72‐day closure of FAD fishing with and (3) without re‐allocation of effort on free schools. The results show a significant decrease of fleet profits by 7%, 10% and 18% respectively. We hypothesize an "economic trap" of FAD fishing caused by the far greater efficiency of this harvesting technique for larger vessels searching for economies of scale, and by the overfished status and catch limitation of yellowfin (Thunnus albacares) and bigeye (Thunnus obesus) tunas in the Indian Ocean. The results are compared with other studies looking at the impact of FAD management measures in other oceans. [ABSTRACT FROM AUTHOR]

The taillight shiner, Notropis maculatus (Hay in Proc United States Natl Museum 3:488-515, 1881), primarily occurs in the southeastern United States, with rare occurrences in Illinois, where it is state listed as endangered. The first observation in Illinois was in 1987 and the species was last seen in the state in 1988. However, the taillight shiner was recently rediscovered in Buttonland Swamp within the Cache River watershed in September 2020 during fish community surveys. A total of 311 taillight shiners were captured from September 2020 to October 2022 within Buttonland Swamp using electrofishing, mini fyke nets, and light traps from the fish community surveys. Habitat associations were assessed using repeated measures mixed models and a conditional inference tree was developed to assess the probability of taillight shiner occurrence in electrofishing samples based on habitat variables and dissolved oxygen. We also assessed differences in taillight shiner length among years and seasons. Emergent vegetation was particularly important in predicting the occurrence of taillight shiners in samples, with dissolved oxygen and silt/clay also being important. Taillight shiner length distributions were similar among years and significantly different among seasons. Spawning occurred in spring, while post-spawn mortality occurred between June and August. This study provides important information regarding habitat associations, probability of occurrence in samples, recruitment, and timing of post-spawn mortality of taillight shiners in Illinois, which could inform future sampling efforts in Illinois and adjacent states. This rediscovery indicates that the taillight shiner is still present in Illinois and further search efforts to assess the species' status in Illinois are needed. [ABSTRACT FROM AUTHOR]

Trap‐and‐transport of migratory fish is commonly used to bypass in‐river obstructions. On the River Conon in Scotland, Atlantic salmon (Salmo salar) smolts are transported around two hydropower facilities. Smolt release occurs during daylight, when predation rates can be high. A novel automatic release cage (ARC) was designed to release smolts at night. Smolts were fitted with acoustic tags (n = 99) to compare survival. High post‐release mortality was identified in the day‐release group, with night‐release survival >40% higher. ARCs can provide fishery managers with a cost‐effective and reliable method of improving smolt survival. [ABSTRACT FROM AUTHOR]

Iteroparity represents an important but often overlooked component of life history in anadromous Atlantic salmon. Here, we combined individual DNA profiling and scale reading to identify repeat spawners among ~8000 adult salmon captured in a fish trap in the river Etne, Norway, in the period 2015–2019. Additionally, 171 outward migrating kelts were captured in the spring of 2018–2020 and identified using molecular methods to estimate weight loss since ascending the river to spawn. The overall frequency of repeat spawners identified using molecular methods and scale reading combined was 7% in females and 3% in males (5% in total). Most of these (83%) spent one full year reconditioning at sea before returning for their second spawning, with a larger body size compared with their size at first spawning, gaining on average 15.9 cm. A single female migrating back into the river for a fifth breeding season was also identified. On average, kelts lost 40% bodyweight in the river, and more female than male kelts were captured during outward migration. The date of arrival in the upstream fish trap was significantly but moderately correlated between maiden and second entry to the river for alternate and consecutive spawners. The estimated contribution from repeat spawners to the total number of eggs deposited in the river each year varied between 2% and 17% (average 12%). Molecular‐based methods marginally underestimated the number of repeat spawners compared with scale reading (5% vs 7%) likely due to a small number of returning spawners not being trapped and sampled. Differences between the methods were most evident when classifying the spawning strategy (alternate or consecutive‐year repeat spawners), where the scale method identified proportionally more consecutive‐year repeat spawners than the molecular method. This unique data set reveals previously unstudied components of this life history strategy and demonstrates the importance of repeat spawners in population recruitment. [ABSTRACT FROM AUTHOR]

The eastern Australian flatback mangrove goby Mugilogobius platynotus (Günther 1861) is recorded for the first time from Aotearoa, New Zealand. Three voucher specimens (two males and one female) were collected using fish traps submerged in tidal drains of a saltmarsh wetland edged by mangroves adjacent to Ngunguru River, Northland. Key characters for identification: the colour of freshly thawed specimens, meristic counts, and morphometric measurements are presented and compared with the same characters described by Larson (2001) for all Mugilogobius. We discuss this major range extension from its natural Australian distribution, concluding it is an adventive species, probably carried across the Tasman Sea into New Zealand waters by shipping, not ocean currents. Our analysis of goby species recorded from northern New Zealand mainland waters concludes seven (86%) are probably adventive and introduced from Australia. We recommend a further survey of mangrove and saltmarsh estuary habitats to discover if this new goby has established a breeding population and is expanding its current limited distribution within northern New Zealand. [ABSTRACT FROM AUTHOR]

Humpback whales Megaptera novaengliae undertake annual migrations along eastern Australia, where they can be susceptible to entanglement in set fishing gear. This can potentially result in both sublethal and fatal outcomes for the whales, and financial losses for the fishing industry, including loss of gear and catch. Interannual fluctuations in entanglement records suggest that dynamic oceanographic features may be associated with the whales' migration path, and therefore, risk of entanglement. Using records of demersal fish traps off the coast of New South Wales (NSW), we identify two areas of high fishing pressure and entanglement risk overlap. Within each area, we combine entanglement observations with metrics associated with the East Australian Current (EAC) and climate (i.e., southern oscillation index). We show that the strength and position of the EAC was associated with the likelihood of entanglement in set fishing gear. In northern NSW (30.3° S), entanglement risk was highest between July and October when the EAC is relatively close to the coast. In contrast, there was no evidence suggesting that oceanography further south in the separation zone of the EAC (33.8° S) was associated with risk of entanglement. In the years following a strongly negative SOI (i.e., El Niño events), entanglement risk was also reduced. While we provide clear linkages with regional oceanographic dynamics and entanglement risk off NSW, if a dynamic ocean management approach to reducing entanglements is to be realized, further research into the fine‐scale movements of humpback whales is needed. [ABSTRACT FROM AUTHOR]

Australian waterscapes were fashioned to meet human needs during the ancient Aboriginal past through the construction of weirs, fish traps and small dams and accompanying socio-cultural practices and institutions. Exemplary amongst Australian water cultures was that of the Gunditjmara of western Victoria, who for thousands of years practiced a sophisticated form of swamp engineering and eel farming in the volcanic landscapes of Budj Bim. Within 150 years of European colonisation, frontier violence, dispossession and hydrological alteration had put an end to the most extensive and oldest aquaculture system in the world. Recent land and water restitution measures enacted in collaborative partnerships with the wider watershed community have enabled the Gunditjmara to restore the Budj Bim wetlands and rebuild their nation. This process entails re-storying engineering and eeling: cultural practices and connections are being retold to gain recognition for the capacity to negotiate change and adapt to geological, climatological and imperial forces. Critical theory and concepts relating to waterscapes, hydro-social relations and the Anthropocene assist in interpreting the resilient efforts of a rural community to retrieve its history and find new ways to care for the past as well as the future. [ABSTRACT FROM AUTHOR]

Objective: Create and test the effectiveness of a new light‐emitting‐diode (LED) light trap for sampling early life stages of fishes in relation to a chemical light stick (CL) lit light trap. Methods: Laboratory experiments compared light intensity of the LED and CL light sources and LED‐ and CL‐lit light trap capture and retention probabilities of Razorback Sucker Xyrauchen texanus and Fathead Minnow Pimephales promelas. Field experiments compared LED‐ and CL‐lit light trap captures of all fishes and Razorback Sucker larvae in both paired and unpaired analysis. Result: The LED light source had a greater and more stable light intensity over time than the CL light source, and LED‐lit traps had similar capture and retention probabilities in laboratory experiments. However, in field experiments LED‐lit traps captured more fish and Razorback Sucker than CL‐lit traps. Conclusion: LED‐lit light traps are as or more effective at sampling early life stages of fishes compared to CL‐lit light traps. Biologists should consider adopting this innovative design to increase sampling effectiveness while eliminating light stick waste. Impact statementThis study demonstrates the ability of newly designed LED‐lit traps to outperform traditional chemical‐light‐stick‐lit traps in capturing the early life stages of fishes. This new design has and will continue to help managers improve data collection, sharpen time‐sensitive decisions, and promote sustainable and effective sampling techniques. [ABSTRACT FROM AUTHOR]

Abstract Humpback whales Megaptera novaengliae undertake annual migrations along eastern Australia, where they can be susceptible to entanglement in set fishing gear. This can potentially result in both sublethal and fatal outcomes for the whales, and financial losses for the fishing industry, including loss of gear and catch. Interannual fluctuations in entanglement records suggest that dynamic oceanographic features may be associated with the whales' migration path, and therefore, risk of entanglement. Using records of demersal fish traps off the coast of New South Wales (NSW), we identify two areas of high fishing pressure and entanglement risk overlap. Within each area, we combine entanglement observations with metrics associated with the East Australian Current (EAC) and climate (i.e., southern oscillation index). We show that the strength and position of the EAC was associated with the likelihood of entanglement in set fishing gear. In northern NSW (30.3° S), entanglement risk was highest between July and October when the EAC is relatively close to the coast. In contrast, there was no evidence suggesting that oceanography further south in the separation zone of the EAC (33.8° S) was associated with risk of entanglement. In the years following a strongly negative SOI (i.e., El Niño events), entanglement risk was also reduced. While we provide clear linkages with regional oceanographic dynamics and entanglement risk off NSW, if a dynamic ocean management approach to reducing entanglements is to be realized, further research into the fine‐scale movements of humpback whales is needed.

During two campaigns, one in the Kattegat (Denmark) in 2018, and the other off Namibia in 2019, the same fish baited trap was applied to catch scavenging amphipods at two stations each. The water depths in both areas were between 50 and 130 m. In addition to very few individuals of other species (Isopoda and Amphipoda), the samples consisted mainly of Scopelocheirus sp. The species from the Kattegat was identified as S. hopei. The question arises as to whether it is possible that the same species could dominate scavenging communities in sea areas more than 10,000 km apart. At first glance, the scopelocheirid amphipods of the northern and southern hemispheres appear identical, but subtle morphological and large genetic differences led to the conclusion that we are dealing with a previously undescribed species off Namibia. We have named it Scopelocheirus sossi sp. nov. [ABSTRACT FROM AUTHOR]

In lentic ecosystems (e.g., lakes and ponds), anthropogenic shoreline alterations, such as concrete embankments, severely degrade habitat, affecting fish assemblage structure. Since fishes have a significant influence on lake ecosystems, it is, however, also essential to assess the response of fish behavior to this degradation to better understand the impact of shoreline alteration on lake ecosystems. Here, we investigated freshwater fish migration behavior in 12 small lakes of norther Japan, in which shorelines are environmentally altered, to assess how the habitat alterations can affect fish emigration from the lake to its connecting channels. We collected fishes using traps installed in lake inflow channels and five focal species were selected for the analysis. A generalized linear mixed model showed that emigration of three of five focal fish increased with the increasing proportion of concrete embankment on the lake shorelines. This result suggests that anthropogenic alteration of a lake shoreline structure significantly impacts fish behavior and affects to their emigration from lakes. Further, this finding indicates that behavioral changes caused by anthropogenic alteration are important for understanding the dynamics of small lake ecosystems. [ABSTRACT FROM AUTHOR]

Fish catch captured by fishers is slightly low, it cause fishers not able to cover their daily needs. Improvement is required to increase dragon trap productivity, one of the ways is using bait. This study aims to describe the dragon traps fishing unit, counting species caught in dragon traps using bait and without bait, and counting the revenue of the dragon traps fishing business. This research was in bondet coastal fishing port (PPP) waters from March to April 2022. Research method was experimental fishing with 20 repetitions (trips) using trash fish namely goldstripe sardinella (Sardinella gibbosa) and pony fish (Leighnatus equulus) as bait. Results show that the 20 dragon traps used in the research have size (50 cm Î 37 cm Î 35 cm) with a length trap of 10 m. Dragon trap without bait catch 82.53 kg (672 fish) from 11 species, meanwhile total catch of dragon traps with bait was 131.721 kg (904 fishes) from 11 species. Based on profit analysis that calculated the dragon trap fishing business deserves to be continued. Because dragon traps with bait catch more fish than dragon traps without bait, trash fish can be used as a suitable technology applied for dragon traps. [ABSTRACT FROM AUTHOR]

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Fish that exhibit high foraging activity or bold behavior can be particularly vulnerable to angling. If these traits are heritable, selection through harvest can drive phenotypic change, eventually rendering a target population less vulnerable to angling and consequently impacting the quality of the fishery. In this study, we used parental-based tags to investigate whether vulnerability to angling might be heritable in steelhead trout (Oncorhynchus mykiss) spawned at a hatchery in western Oregon, USA. We found modest evidence to support the hypothesis that vulnerability to angling is a heritable trait in steelhead. However, our data unexpectedly revealed that steelhead collected with in-river traps produced nearly twice as many adult offspring as steelhead collected by anglers. This difference in adult-to-adult production is explained in part through lower egg-to-fry survival of steelhead produced with angler-caught broodstock, possibly related to collection stress and greater time in captivity experienced by angler-caught broodstock. Our findings suggest that managers could improve broodstock fitness and program efficiencies by preferentially spawning fish collected with traps, and limiting use of broodstock collected by anglers. Additional research is needed to identify mechanisms contributing to higher juvenile mortality of steelhead produced with angler-caught broodstock. [ABSTRACT FROM AUTHOR]

Fish traps and fish weirs built by Indigenous people in the Barwon‐Darling River system of the Murray Darling Basin (MDB), south‐eastern Australia, are an important component of their traditional social, spiritual and economic systems. The celebrated Brewarrina stone fish traps (Ngunnhu) on the Barwon River are the largest and best documented stone fish traps in the Basin. However, there has been minimal research on the many other stone fish traps in this system. This paper focusses on the in‐stream stone fish traps downstream of Brewarrina along the Darling (Baaka) River, some still partly extant, remembered, or documented in historical material. Wooden and earthen bank fish traps and weirs, while not as enduring and archaeologically visible as stone fish traps, were frequently used on the Darling (Baaka) floodplain lakes, swamps and billabongs. Archaeological evidence, traditional cultural knowledge and historical materials are utilised to document the complex social processes and modification of landscapes associated with fish traps and weirs. By demonstrating that Barkandji were active and successful managers of the river and its ecology prior to colonisation, and that much of this cultural knowledge is retained by current generations, the authors make a case for them to renew their custodianship and a decision‐making role in water management. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the seasonal variation of zooplankton diversity and abundance in the Nokoué Lagoon in southern Benin. Through extensive sampling, a total of 109 zooplanktonic taxa were identified and quantified. The average zooplankton abundance was found to be 60 individuals per liter, with copepods and rotifers being the most dominant groups, comprising 68.1% and 29.1% of the total abundance, respectively. The key factor identified as driving the structure of the zooplanktonic assemblages was salinity, which showed significant seasonal variation. The results revealed that during the high water period, when the lagoon was filled with fresh water, rotifers were dominant, zooplanktonic diversity was highest, and abundances were quite high. Conversely, during the low water period, when the lagoon was characterized by brackish water, diversity was minimal, and abundance decreased slightly. The study also found that some areas of the lagoon showed high abundances independent of salinity levels, suggesting that other factors such as riverine inputs or the presence of acadjas (home-made brush parks used as fish traps) may also have notable effects on the zooplankton community. Overall, the findings of this study provide valuable insights into the functioning of one of the most biologically productive lagoons in West Africa. [ABSTRACT FROM AUTHOR]

The current study reports on the second record of a wild population of the invasive alien red swamp crayfish Procambarus clarkii in South Africa following a report from Mimosa Dam in the Free State Province. Sampling for crayfish was conducted over an 18 month period (June 2018 to November 2019) using various methods in order to determine the extent of the invasion as well as to obtain preliminary information on the population structure within Mimosa Dam. Additionally, a gear and bait comparison experiment was conducted to determine their efficiency in mechanical removal of the P. clarkii. Three sampling approaches were compared: promar collapsible traps baited with either dog food or fish; and rectangular traps baited with fish, all which have been historically used in crayfish surveys. A total of 1901 crayfish with a total biomass of 27.32 kg were caught during the study and 65% of those were juveniles. The female to male sex ratio (1:1.2) in Mimosa Dam was skewed towards males. Fish head bait provided a higher catch per unit effort (CPUE) (1.2 ± 0.57 and 0.71 ± 0.08 for rectangular and promar traps, respectively) which was significantly higher than that of the dog food bait (0.14 ± 0.04). The fish bait should hence be optimised for intensive population suppression. Complete eradication of P. clarkii is virtually impossible, as shown by this study, but population suppression can be concentrated on months of crayfish population surges to minimise associated impacts on native biota. [ABSTRACT FROM AUTHOR]

The Australian Aboriginals built fish traps and weirs over a long period of time, and there is a wide variety of structures. Herein this study focuses on rock fish traps constructed in inland waterways. A common shape was a horseshoe design convex in shape and opened downstream. In this study, some basic physical modelling of rock fish trap models was conducted under controlled flow conditions. A generic horseshoe element shape was selected, with a range of porosity, consistent with the rock fish trap construction. Flow conditions were tested from low partial submergence to complete submergence, corresponding to large flood events. The results give some seminal insights into the hydrodynamics of these fish traps and provide some physically-based understanding of their operation and purpose. Article Highlights: Semi-circular horseshoe elements open downstream were tested physically. A broad range of free-surface flow patterns were observed with porous and impervious elements. The element porosity modified the recirculation region and flow patterns. Interactions between adjacent horseshoe structures were tested experimentally. [ABSTRACT FROM AUTHOR]

A number of seabird species have been known to peck, displace, and ingest various plastic items including expanded polystyrene, for reasons that remain largely conjectural. Ingestion of polystyrene parts potentially causes lethal or sublethal effects on birds. Pecking can also result in the damage of polystyrene items, resulting in increased market turnover and environmental build-up, or economic consequences for stakeholders. In January and February, 2022, fishers in a portion of the western Adriatic Sea coast reported pecking damage caused by gulls (Laridae) to polystyrene buoys used to float, signal, and retrieve static fishing nets and traps. We investigated the magnitude of this phenomenon in four fishing harbours of Italy by scoring damage to 470 buoys and interviewing 29 fishers (encompassing 42% of the relevant fleet). Information was complemented by opportunistic observations at sea. Our preliminary assessment suggests that offshore polystyrene pecking increases in winter months, and it occurs sporadically among years. The overall economic damage to the static net fishery appeared generally modest (approximately 3–4 Euro to replace one buoy), with wide variations in the extent of reported damage. We reviewed the hypotheses behind polystyrene pecking, but none of them provide a clear explanation for the observed behaviour. Finally, we discuss potential effects on seabirds and advocate monitoring to investigate causal factors and mitigate damage to seabirds, fisheries, and marine environment. [ABSTRACT FROM AUTHOR]

Entrapment and subsequent drowning in fish fykes poses an anthropogenic mortality hazard to Eurasian otters (Lutra lutra). Different concepts on how to solve this problem have been debated in the past. To proactively prevent future fatal interactions and increase acceptance among fishers, this study tested two exit mechanisms for otters to safely escape from fyke nets, while still retaining full trap functionality for inland fisheries. Both exit options, a tearable latex lacing around flexible metal wires (100% success rate, n = 6) and a steel hoop‐spring construction (90%, n = 10) were successfully tested in 16 otter escape trials and 30 additional tests for fish (pike, eel, and common bream) retention (100%). The results indicate that the modifications of the fish traps were effective for otter conservation and commercial fisheries. Thus, both options can be recommended as equally good otter protection measures for fyke‐net fisheries of the tested type and similar sizes. However, these data were yielded under controlled conditions and it is possible that field results could differ. Hence, the presented results should be additionally verified under field conditions. [ABSTRACT FROM AUTHOR]

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Downstream displacement and stranding of fish are key impacts in hydropeaked rivers, adversely affecting the organisms and, subsequently, the population. While these phenomena have been extensively studied for salmonid fish, few studies have been conducted on cyprinids, particularly at heterogeneous river banks that provide nursery areas for the earliest life cycle stages. This study examines the effects of rapid flow decreases (i.e., down-ramping) on downstream displacement and stranding of common nase, Chondrostoma nasus, larvae at two river bank morphologies (a flat gravel bar and a heterogeneous river bank consisting of a sill and ditch) and daytime periods (day and night) in a mesocosm facility. For a subset of the sill and ditch experiments, stranding location was noted to quantify the trapping effect of the structure. The results show that nase larvae's downstream displacement and stranding rates were higher at the sill and ditch than at the flat gravel bar. In addition, the effects of down-ramping were more visible at night than during the day. The displacement and stranding rates were the highest for the sill and ditch structure at night. In this case, the stranding rate was four times higher in the ditch area compared to other available areas of the mesocosm. Riverbank depressions can increase the stranding risk when disconnected and dewatered from the main channel after down-ramping, constituting potential ecological traps for fish larvae. These findings highlight the need to integrate riverbank morphology and flow schemes in hydropeaking mitigation frameworks to reduce fish displacement and stranding risks. [ABSTRACT FROM AUTHOR]

Rhodeus atremius suigensis is an extremely endangered bitterling fish, designated as one of the Nationally Endangered Species of Wild Fauna and Flora by the Ministry of Environment of Japan. To prevent its extinction, effective ecological survey methods are necessary in order to guide habitat management. Recently, environmental DNA (eDNA) analysis has proven useful for detection and censusing of endangered aquatic species that are difficult to locate and capture. In this study, we developed and evaluated a semi-quantitative system to track R. a. suigensis using eDNA. We designed primers and a fluorescent probe specific to the mitochondrial gene for NADH dehydrogenase subunit 1 (ND-1) of R. a. suigensis for quantitative real-time PCR. We first confirmed the utility of this analysis in aquarium experiments, before performing field surveys. We sampled water for eDNA analysis and set fish traps at 48 points in an agricultural channel in the Ashida River basin, inhabited by R. a. suigensis, and examined the relationship between fish occurrence and eDNA concentration. The concentration was correlated with the distance downstream from the point where specimens of R. a. suigensis were captured, indicating that the eDNA concentration reflects distribution and abundance of R. a. suigensis. These results not only demonstrate the reliability of this method, but also suggest its feasibility for conservation measures. [ABSTRACT FROM AUTHOR]

Commercial fishery harvest is a powerful evolutionary agent, but we know little about whether environmental stressors affect harvest-associated selection. We test how parasite infection relates to trapping vulnerability through selective processes underlying capture. We used fish naturally infected with parasites, including trematodes causing black spots under fish skin. We first assessed how individual parasite density related to standard metabolic rate (SMR), maximum metabolic rate (MMR) and absolute aerobic scope (AAS)—then used laboratory fishing simulations to test how capture vulnerability was related to parasite density. We further explored group-trapping dynamics using experimental shoals containing varying proportions of infected fish (groups of six with either 0, 2, 4 or 6 infected individuals). At the individual level, we found a positive relationship between parasite presence and SMR, but not MMR or AAS. While we saw no relationship between individual metabolic capacity and vulnerability to trapping, we found the length of time fish spent in traps increased with increasing parasite density, a predictor of trapping-related capture probability. At the group level, the number of infected individuals in a shoal did not affect overall group trapping vulnerability. Our results suggest that parasite infection has some capacity to shift individual vulnerability patterns in fisheries, and potentially influence the evolutionary outcomes of fisheries-induced evolution. [ABSTRACT FROM AUTHOR]

(1) Background: Coleoptera is one of the most diverse insect lineages. The beetle species live in many ecosystems around the globe and their roles in ecosystems are very diverse; thus, it is important to know the local and regional fauna varieties, especially for protected areas, such as nature reserves and national parks. (2) Methods: The materials were collected from the territory of the Khvalynsky National Park (European Russia, Saratov region), mainly over the last 30 years (1994–2022). The beetles were collected using different means (manual collection; the use soil traps, fermental crown traps, and Malaise traps; light fishing; sweeping with an entomological net on plants and under water, etc.). (3) Results: The dataset presents data on 914 species and subspecies of Coleoptera from 67 families found in the Khvalynsky National Park. The number of studied specimens was 7445. Four families (Cerylonidae, Byturidae, Phalacridae, and Sphindidae) and 95 species were recorded for the Khvalynsky National Park for the first time. Thirty-two species were recorded for the Saratov region for the first time. (4) Conclusions: The general biodiversity of Coleoptera in the Khvalynsky National Park includes 1203 species from 71 families. [ABSTRACT FROM AUTHOR]

Ecological traps can be caused when partial restoration leads organisms to make maladaptive habitat choices. One example of this is fishways (e.g., fish ladders) that provide upstream passage at dams but are not paired with adequate downstream passage. We tested the hypothesis that attracting anadromous fishes to spawn above a dam, but blocking downstream passage of their offspring leads to an ecological trap. Using passive integrated transponder (PIT) tags, we monitored the movements of steelhead (Oncorhynchus mykiss) at a dam and fishway on the central California coast. We found that downstream passage for juveniles and kelts was limited by four factors: migration delay, loss in the reservoir, avoidance of the downstream bypass, and water depths on the spillway. Based on the spillway-passage depth thresholds, we estimated that the ability for fish to pass downstream was limited to only half of the migration season in 55% of the past 20 years (2002–2021). Our results support the ecological trap hypothesis, which may explain why restoration using fishways has failed to produce recovery gains in this population and elsewhere. [ABSTRACT FROM AUTHOR]