Fisheries Management and Ecology最新文献

Estuarine fisheries are of high regional socio-economic importance worldwide, by providing an important livelihood for many families. The Portuguese green crab (Carcinus maenas) fishery was assessed using a socio-economic assessment to understand the importance of the fishery and a stock assessment analysis to determine the exploitation status of the fishery during 1960–2020. Fisher knowledge revealed that crab fishing was a family affair that provided a livelihood for hundreds of families directly targeting crabs, with catches exported to Spain during 1960–1990s, and in later years, crab demand increased as bait for octopus fishing. Despite its socio-economic importance, the fishery was regulated without a scientific basis and economic value of crabs remained similar through time. Annual landings never exceeded sustainable catch rates, but engagement in the crab fishery declined due to low economic value of crabs compared to other fisheries and regulatory hurdles. Consequently, the number of fishermen declined to 20–30 elderly men fishing on the largest estuaries, with the fishery currently on the verge of extinction. Fishers pointed to a reduction in the minimum landing size and enforcement of crab-specific trap regulations as ways to avert fishery decline. Such changes would stimulate recruitment of new crab fishers, while reducing fishing pressure on other estuarine resources through fisheries diversification.

This paper outlines the scientific achievements of Gordon H. Copp (1956–2023) in fish biology and invasion science as presented in his Doctor of Science portfolio. Gordon's mentorship began during his postdoctoral research and expanded to involve students, early-career researchers as well as prominent fish biologists in a vast number of research projects. Early in his career, Gordon was involved in the study of floodplain fish communities for which he developed a novel technique for sampling young-of-year (0+) fish and in the early ontogeny of fishes. Gordon's later involvement in non-native species policy has been pivotal, from developing risk analysis schemes for freshwater fishes to advising on EU and UK regulations. Gordon's research throughout his entire career on the pumpkinseed sunfish Lepomis gibbosus as a model species highlights his focus on understanding and predicting invasiveness under varying climate conditions, contributing to a broader understanding of non-native species impacts.

Saltwater angling is a culturally significant and economically vital coastal recreational activity, particularly in the Gulf of Mexico that attracts enthusiasts worldwide and contributes significantly to the well-being of Gulf Coast communities. However, angling can threaten ecologically important species, notably sea turtles, which are federally protected under the Endangered Species Act. In commercial fisheries, using circle hooks over traditional “J” hooks and using specific bait types can reduce sea turtle bycatch and fishing gear interactions. However, angler willingness to use these techniques is unknown. Our study aimed to assess the willingness of recreational anglers to adopt tackle modifications to support sea turtle conservation. A mixed-mode survey was used to gather data on angler knowledge, behaviors, and attitudes toward sea turtle conservation. Generalized linear models were used to examine factors associated with angler willingness to adopt sea turtle-friendly practices. Factors such as gender, state residency, recreational and fishing motivations, and ecological knowledge influenced angler willingness to adopt sea turtle-friendly tackle modifications. We conclude that conservation strategies and educational outreach must be tailored to specific fishery management objectives.

We estimated relative abundance of South Atlantic Swordfish (Xiphias gladius), a highly migratory marine species, from commercial fishing data using a three-step analysis protocol. First, we modeled catch rate based on variables affecting the catch rate to rule out effects of catchability-related factors. Next, we analyzed residuals to identify autocorrelation. Last, we used an area-weighed recursive algorithm that considered spatial autocorrelation for each year within the analysis period. Commercial South Atlantic swordfish catch data from the Brazilian pelagic longline fleet were analyzed. Swordfish accounted for the highest spatial dependence in distance in 2005 (456 km), 2008 (111 km), 2012 (80 km), and 2014 (443 km), as well as for the lowest in 2011 and 2013 (average = 15.45 km). A downward trend in swordfish abundance between 2010 and 2017 was detected several years earlier than conventional standardized indices, so our proposed index is an alternative, and potentially more accurate, index of swordfish population dynamics in the South Atlantic. Our findings highlight the need to integrate multiple approaches into assessments of the abundance of marine species.

Gillnets are the most commonly used fishing gear targeting black rockfish (Sebastes schlegeli) and fat greenling (Hexagrammos otakii) in the artificial reef area in coastal China. However, a minimum mesh size (MMS) has not yet been established for this fishery, which is unfavorable for sustainable development and effective management of fishery resources. We compared size selectivity and catch efficiency of gillnets of four commonly used mesh size (stretched mesh size; 40, 50, 60, and 70-mm) in a typical artificial reef area in the Yellow Sea, China. Increasing the mesh size improved size selectivity of gillnets for black rockfish and fat greenling by reducing the proportion of undersized individuals. Further, changes in mesh size affected catch efficiency of target-sized individuals. To protect juveniles, while maintaining catch efficiency for target-sized fish, we recommend 60-mm as the MMS for this fishery. Our study will contribute to the development of MMS regulations in reef fisheries management in China.

Rainbow trout have been translocated from North America worldwide for more than 150 years, but have not reproduced in the wild in Europe in the last 100 years. In recent decades, several examples of successful reproduction have become public. This study reports scientific evidence of natural reproduction of North American rainbow trout (Oncorhynchus mykiss) in three alpine rivers in Bavaria, Germany. Eggs collected from spawning redds were determined to be rainbow trout in all study rivers. In the river Leitzach, where spawning was exclusively observed in spring, electrofishing revealed a balanced length-frequency distribution with a high abundance of rainbow trout and a high proportion of individuals < 10 cm. In the rivers Isar and Traun, spawning was observed in winter and supposedly also in spring, according to local reports. Rainbow trout < 10 cm were also observed in these two rivers during electrofishing surveys but were less abundant than in the river Leitzach. Genetic factors and river-specific environmental and climatic conditions may have contributed to the success or failure of rainbow trout reproduction. Effects of rainbow trout on native fish vary widely, from severe negative impacts to minimal niche overlap, so further studies of genetic and environmental factors that determine rainbow trout naturalisation are needed to better inform fisheries management.

The cobia (Rachycentron canadum) is important to fisheries in Northeastern Brazil. To restore stocks in Rio Grande do Norte, cobia were stocked and the fishery was monitored over 4 years. We evaluated effects of stocking on cobia size composition in this data-limited fishery to understand stocking limitations and explore possibilities for future projects. Total length of cobia was significantly shorter after stocking than before stocking, with mostly small fish caught mainly by nets, an unusual pattern for cobia. Total length also varied significantly among bottom types. Most of the cobia harvested were below the size at first maturity, which suggests that stocking increased the catch, but most fish harvested were immature, thereby potentially hindering stock recovery. For future projects, we recommend against the use of plastic tags for tagging hatchery cobia and propose releases that emulate natural spawning dynamics, alongside releasing fish at older ages. Further, we recommend robust post-stocking fishery monitoring, and management strategies, such as a release of net-caught cobia in the initial 2 years and incorporating validated fisher knowledge into decision-making.