Fisheries Research最新文献

Globally, marine taxa and their associated ranges are negatively impacted by climate change, including ecologically and socioeconomically important marine mega-decapods. Given their ecological and socioeconomical importance, comprehending the current and future impacts of climate change on marine mega-decapod ranges is of the utmost importance. In this paper, a systematic literature review is conducted on Brachyuran, Anomuran, Astacidean, and Achelatan range responses to climate change. In total, 48 papers were included in this review, with 76 species and 101 range responses reported. We identified trends in study conductance, range responses and associated consequences. Our results show that there is a spatial discrepancy in the distribution of study locations, as well as a taxonomic bias towards studying Brachyuran species. Additionally, our results reveal that the majority of species’ ranges are affected, with range expansions, shifts and contractions being the most commonly recorded. Moreover, a general poleward movement into cooler waters is observed for many species, namely 69 % of all recorded range responses, whilst an offshore movement is witnessed to a lesser extent (18 %). Additionally, a greater number of observed range responses were reported than modelled/predicted range responses. Range shifts will cause a variety of negative ecological impacts, such as exacerbating population declines, increasing competition and spreading disease. Further, range shifts will also create a number of socioeconomic issues, due to commercial and non-commercial species being equally affected by climate change. This is the first and most detailed quantification of marine mega-decapod range responses to climate change and provides key data on range response trends, so that appropriate future conservation strategies can be formulated, and negative socioeconomic impacts can be mitigated.

Despite its significant economic importance and intensive exploitation worldwide, the Atlantic bluefin tuna (ABFT) lacks the essential parameters required to estimate its abundance using acoustic methods at the most used 38 kHz frequency. This paper presents in situ measurements of target strength (TS; dB re 1 m²) for ABFT in dorsal aspect obtained from a baitboat in the Bay of Biscay, using a 38-kHz split-beam echosounder. A linear regression model was fit between TS and fork length (FL; cm) based on data from nine live-bait fishing operations. To mitigate potential bias due to double counting, TS measurements were filtered with fish tracking. The range of modal TS values per set was from −38 to −17 dB for modal tuna body fork lengths between 55 and 150 cm, that is, a rather thorough range of sizes including ABFT juveniles and adults. The linear regression resulted in a TS-length relationship characterised by a slope of 36.9 dB and an intercept of −101.6 dB, with a coefficient of determination R² = 87 %. When the slope of the TS-length relationship was forced to 20, the intercept (b₂₀) was −68.5 dB (R² = 79.5 %). The acoustic parameters presented in this work are key to providing an alternative to the uncertainties associated with the traditionally used fishery-dependent abundance indices of ABFT in the Bay of Biscay and abroad.

Holothuria poli is one of the most in-demand sea cucumber species and has attracted the interest of markets in Mediterranean regions. The present study is the first attempt to determine the reproductive cycle of H. poli in a coastal area of the Central Aegean Sea. Samples of H. poli as well as environmental and biometric data were collected monthly for 1 year. The sample population exhibited a female predominance, a size at first maturation of 156.3 mm and a distinctive reproductive pattern that reached its mature stage in the summer months. These findings contribute to the overall understanding of the reproductive physiology of the species and provide information for the sustainable management of sea cucumber stocks in the Hellenic Seas.

Declining Bristol Bay red king crab (BBRKC) abundance has triggered recent closures of this iconic Bering Sea fishery and raised interest in bycatch in non-directed fisheries as a possible conservation concern. One particular concern is the effectiveness of static closed areas for bycatch fisheries in an era of climate warming and widespread distribution shifts. However, spatial data for supporting management decisions concerning bycatch is lacking, as fisheries-independent data are collected only in the summer, and the relationship to BBRKC distribution in the fall/winter/spring, when most bycatch occurs, is unknown. We filled this information gap by using fishery-dependent data to build predictive models of BBRKC bycatch distribution in non-pelagic trawl groundfish fisheries in the data-poor seasons. We trained Boosted Regression Tree models for bycatch occurrence and abundance of four BBRKC sex-size/maturity categories, and evaluation metrics indicated good to excellent predictive ability across all models. We found that flatfish directed-fishery CPUE, summer survey CPUE for BBRKC and flatfish, and depth were important predictors for bycatch occurrence and abundance. Physical variables (ice cover and temperature) were generally less important. We also found strong correlations between the mean latitude of observed bycatch and the summer survey for BBRKC, highlighting the ability of summer survey data to predict non-summer bycatch distributions. BBRKC bycatch prediction is a tractable problem, and our results are the first step towards operating models that may be used to evaluate proposed management actions. We also conclude that northward shifts in fishery-independent and -dependent data suggest the possible value of reassessing decades-old static closure areas for managing BBRKC bycatch.

The mahseer populations in various regions of India are undergoing rapid declines due to factors such as unregulated fishing of juveniles and brood stock, severe degradation of aquatic ecosystems, and the construction of barrages, dams, and weirs as part of river valley projects. Given the significance of this species, it is crucial to assign high conservation value to mahseers in India. To safeguard this important resources, efficient conservation and propagation strategies must be planned and implemented throughout the country. Conserving mahseer fishery resources demands integrated efforts, culture fisheries, blending capture, and environmental programs, with strict enforcement of environmental laws. Taxonomic clarity within the Tor and Neolissochilus genus is crucial for effective conservation planning, given the endangered status of all mahseer species. Conservation efforts should be embedded in new hydel projects, utilizing artificial breeding and pond culture, while adaptive fishing regulations are needed to protect vulnerable spawning populations. However, comprehensive knowledge of the genetic deviation and population structure of wild endangered mahseer populations is currently lacking. This paper aims to review the evolutionary history, present status, and the importance of conservation for mahseers, while emphasizing the function of biological conservation and genetics in preserving their germplasm, promoting sustainable utilization, and enhancing their populations. Additionally, we propose new ideas and suggestions that can contribute to the conservation efforts aimed at protecting these magnificent mighty mahseers across the country.

Management decisions for the eastern oyster (Crassostrea virginica) fishery in Maryland are made at a finer spatial scale than the spatial data resolution of the current stock assessment. This mismatch creates concerns that the consequences of management actions and fishing activities are not being adequately represented when assessing fishery status. To produce a model that could support a participatory modeling process intended to differentiate results of fine-scale management actions we developed a method for conditioning a down-scaled oyster stock assessment model to produce a spatially-explicit operating model at the scale of individual oyster bars for eastern oysters in Chesapeake Bay, Maryland. To ensure that parameter values of the operating model were consistent with data at multiple scales we fitted the model to bar-specific harvest data during 2004–2020 and regional abundance estimates from the current Maryland Oyster Stock Assessment during 1999–2020. The operating model can then predict effects of different management actions, such as planting hatchery-reared oysters, addition of substrate, or modifying fishing regulations, at a bar-specific scale and compare outcomes among different scenarios. Model outputs included a suite of management performance metrics, including but not limited to oyster abundance and fishery harvest, that were important to stakeholders. These bar-specific scenarios would not have been possible using an operating model with the same spatial resolution as the current Maryland Oyster Stock Assessment. Accounting for fine scale spatial processes can be important to engaging participants and our model provides an expedient option to develop an operating model that downscales stock assessment models.

Fish parasites are widely used as biological indicators of stocks and populations of their hosts. In this work we examine the stability of the stock structure of Argentine anchovy, Engraulis anchoita, after a period of three decades using parasite tags. A total of 295 anchovies were examined for parasites. Two samples were collected at Northern stock (Necochea and El Rincón), two from the Southern stock (Rawson and San Jorge Gulf), and two from the intermediate zone between Northern and Southern stocks (San Matías Gulf and boundary between Northern and Southern stock). The structure and composition of both parasite infracommunities and component communities were analysed by uni and multivariate statistics. Our results showed certain compositional homogeneity after three decades as well as the presence of three groupings, with those from San Matias Gulf being part of a “central” stock or population distributed also outside the gulf on the continental shelf. This newly identified stock was probably overlooked in the previous study since all parasites were considered in the multivariate comparisons, whereas the present data were restricted to long-lived, and therefore more suitable biological tags, parasitic species. Further studies based on other kinds of evidence and carried out at broader temporal and spatial scales are necessary to corroborate the occurrence of a population in San Matías Gulf. In such a case, considering the ecosystem relevance of E. anchoita, the establishment of its temporal dynamics will be a first step for the conservation and safeguarding of the entire marine ecosystem at a regional scale.

Handling of crustaceans can result in injuries such as limb damage, reducing post-release survival and subsequent growth. Quantifying the impact of handling damage can provide insight into the effects of increased handling, which can occur when undersized animals are released by fishers or during translocations of animals between areas. We investigated the impact of handling on the Southern Rock Lobster (Jasus edwardsii) using three decades of scientific tag-recapture data from a no-fishing reserve. We used a Bayesian modeling approach with a modified Von Bertalanffy growth model which is robust to measurement error and Cormack-Jolly-Seber capture-recapture model to estimate growth and survival probability parameters. We found that even low levels of damage (1–4 appendages) can decrease growth by ∼ 10 % in the subsequent moult. Male lobsters suffered greater effects of handling-induced damage than did females, potentially due to the additional energy reserves available to brooding females.

Biologists often manage abundant invasive Common Carp (Cyprinus carpio) populations for suppression below population density or biomass thresholds via commercial harvest that also removes large numbers of native Bigmouth Buffalo (Ictiobus cyprinellus). Thus, biologists need population estimates to monitor abundance but often avoid them due to the time and effort required to produce population estimates and pervading estimate imprecision. While population abundance of these fishes can be challenging to estimate, commercial fishers harvest large numbers of fish that could improve population estimates with less effort from biologists. Yet, how population estimates from fishery-dependent and fishery-independent data sources compare is unknown. We compared the precision of Schnabel fishery-independent (electrofishing) and Lincoln-Petersen fishery-dependent (commercial harvest) population estimates for Common Carp and Bigmouth Buffalo in seven northwest Iowa lakes. We then assessed how sampling effort and environmental factors affected the number of fish recaptured by electrofishing and how the number of fish marked and recaptured affected estimate variability. Lincoln-Petersen estimates were more precise and provided similar abundance estimates compared with Schnabel estimates for Bigmouth Buffalo, while both models provided comparable population estimates and precision for Common Carp. Common Carp electrofishing recaptures were positively related to electrofishing effort, number of fish tagged, lake size, and water temperature. Bigmouth Buffalo recaptures were positively related to number of fish tagged and negatively related to lake area and water temperature. Coefficient of variation for fishery-dependent estimates declined with number of fish tagged and recaptured; 750 Common Carp and 150 Bigmouth Buffalo needed to be marked at large to obtain precision of CV ≤ 0.25. Our results suggest Lincoln-Petersen estimates with fishery-dependent data represent an improvement over fishery-independent estimates for Bigmouth Buffalo while both techniques provided comparable estimates for Common Carp. Incorporating harvest data into population estimates can reduce sampling effort while improving or maintaining precision.

Climate change is expected to influence aquatic habitats and associated fish populations, yet we know little about the impact on recreational anglers. Our goal was to explore whether interannual fluctuations in waterbody surface area and other explanatory variables could be used as indicators of changes in angler fishing effort. Our approach leveraged a combination of remotely sensed waterbody surface area, environmental and fish population data, and onsite angler survey monitoring data for Devils Lake, North Dakota, USA during the open-water fishing period (May 1st to August 31st) for 9 years (1992–2021). The information was used to develop a dynamic waterbody size-angler effort model. Changes in waterbody surface area reliably predicted changes in angler effort (r² = 0.60). Increases in waterbody surface area led to increases in angler effort, and decreases in waterbody surface area led to decreases in angler effort. Our findings show promise that remotely sensed fluctuations in waterbody surface area could be used as an indicator of interannual angler effort dynamics. Dynamic waterbody size-angler effort models could provide managers the ability to predict changes in angler effort via climate-related hydrological cycles that affect the size and distribution of waterbodies on the landscape.