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Research about feeding ecology of fish is important to understand individual behavior and population development, which is also the basic to analyze trophic structure and function of aquatic ecosystems. Chaetrichthys stigmatias is one of the key species in the Haizhou Bay fisheries ecosystem, which has critical ecological niche within the food web. In this study, we collected samples through bottom trawl surveys during the fall of 2018 in the Haizhou Bay, and analyzed the feeding ecology of C. stigmatias based on both stomach content analysis and stable isotope technology. The results showed that the primary diet groups for C. stigmatias were Ophiuroidea and Shrimp, including Ophiothrix marenzelleri, Ophiopholis mirabilis, Ophiura sarsii, Penaeidae, and Alpheus japonicus. The range of δ13C values of C. stigmatias was from -19.39% to -15.74%, with an average value of (-18.07± 0.87)%, which had no significant correlation with body length. The range of δ15N values was from 8.16%c to 12.86%, with an average value of (10.14± 1.51)%, which was positively correlated with body length. The trophic level of C. stigmatias showed a positive relationship with body length, with an average value of (3.74±0.34) and a range value of 3.32 to 4.20 among different size groups. The contribution rates of different prey groups varied significantly. Based on the structural equation modeling, we found that the feeding intensity of C. stigmatias was primally influenced by body length, sea bottom salinity, sea bottom temperature, and water depth, with a particularly significant positive correlation with body length. The combination of stable isotope technology and stomach content analysis methods could contribute to comprehensive understanding on the feeding ecology of C. stigmatias, providing essential data and foundation for research on trophic structures and resource conservation in the Haizhou Bay ecosystem. [ABSTRACT FROM AUTHOR]

Trophic dynamics is one of the major regulators of fishery production in marine ecosystems, which is important for the implementation of ecosystem-based fisheries management. Based on data collected form bottom trawl surveys in Haizhou Bay and adjacent waters during autumn of 2011 and 2018, Delta-GAMMs (Delta-generalized additive mixed models) were constructed to evaluate the effects of biotic and abiotic factors on the predation of five key prey species (including Leptochela gracilis, Alpheus japonicus, Loligo spp., Larimichthys polyactis, and Oratos- quilla oratoria) in the Haizhou Bay. Percent frequency of occurrence and predation pressure index were used to identify their major predators. Variance inflation factor and full subsets regression were analyzed to quantiiy the degree of multicollinearity between these factors. The results showed that the occurrence frequency of keystone prey species in the stomach of predators ranged from 8.5% to 42.2%, and the weight percentage ranged from 4.2% to 40.9%. The average deviance explanation rate of' the "binomial" model was 16.1%, and the average deviance explanation rate of the "positive" model was 23.8%. Body length of predator, predator population density, and sea bottom temperature were important factors influencing prey-predator trophic interactions. Predator length was the most important factor, with feeding probability and weight percentage of keystone prey species all increasing with body length of predator. Feeding probability and weight percentage of key prey species decreased with predator population density. The effects of environmental factors such as sea bottom temperature, depth of water, latitude, and sea bottom salinity showed different trends, depending on the prey-predator assemblage. This study showed that the Delta-GAMMs was an effective method to explore the trophic interactions between prey and predators in marine ecosystems, and could provide a theoretical basis for the conservation and sustainable use of fisheries resources. [ABSTRACT FROM AUTHOR]

Occasional species are often neglected in community ecology studies due to low abundance and frequence. However, they are closely related to biodiversity maintenance and marine conservation. We used index of relative importance (IRI), distribution center of gravity and Mann-Kendall trend test to elucidate the spatial and temporal distributions and changing trends of occasional fishes in Haizhou Bay based on the fishery resources survey data collected from 2013 to 2019. The occasional fishes in Haizhou Bay was identified based on IRI. Nine of the occasional species were selected to analyze the spatial distribution and interannual trends of relative biomass and occurrence frequency. The results showed that a total of 93 fish species were recorded in the multi-year survey in Haizhou Bay. Among which, 61 species had IRI<10, indicating the existence of a large number of occasional fishes in Haizhou Bay. The nine selected occasional species had distinctive spatial distribution characteristics. Erisphex pottii, Azuma emmnion, and Raja porosa were mainly distributed in the eastern part of Haizhou Bay, with a wide habitat range. Sphyraena pinguis, Coilia nasus, and Zebrias zebra were distributed in the western and southern parts, respectively. The rest species were mainly distributed in the southwestern part. In terms of interannual variation, the biomass and occurrence frequency of Coilia mystus, R. porosa, A. emmnion, and S. pinguis showed fluctuating changes, while Odontamblyopus rubicundus and Ctenotrypauchen microcephalus showed an increasing trend. The biomass and occurrence of Z. zebra, C. nasus and E. pottii gradually decreased with no catch in recent years. This study would contribute to the understanding of the spatial and temporal distribution of occasional species, and provide guidance for the conservation of occasional biological resources and species diversity, especially for the establishment of marine protected areas. [ABSTRACT FROM AUTHOR]

Sustainable fisheries management is built on effective management strategies and informative data that are usually well defined for data‐rich fisheries. However, their counterparts in data‐limited fisheries remain inadequately evaluated due to insufficient data for stock assessments. This raises two questions: (1) can data‐limited management strategies achieve sustainable fisheries and (2) are certain types of data more informative than others are in developing sustainable data‐limited fisheries? To address these questions, we performed management strategy evaluation with data‐rich stocks to simulate data‐limited fisheries management. The performance of data‐limited management procedures (MPs) was compared with the performance of management strategies that are based on data‐rich stock assessments. We examined the informative nature of six data categories in data‐limited situations by developing a tier system that mimicked different data availability levels and evaluating their contributions to management success. Our study showed that it is possible to achieve maximum sustainable yield (MSY) with limited data, given the proper choice of MPs. In addition, the data categories were not equally informative to the development of sustainable data‐limited fisheries management. In our case study, the MPs using the data on stock size and quantitative management targets (target proxy) demonstrated the highest management success rates. The most effective (100% management success rate) while least data‐demanding MPs included minlenLopt1, SPMSY, MCD, Itarget1, and ICI. We also confirmed that the performance of the data‐limited MPs was closely related to historical stock dynamics and levels of data availability. We suggest considering historical stock trends and data availability levels as critical prerequisites in the management of data‐limited fisheries. [ABSTRACT FROM AUTHOR]

It is increasingly recognized that effective fisheries management needs to take into account not only the target species, but also the broader scope of biological, environmental, socio-economic and institutional factors pertaining to human utilization of fishery resources. This recognition has stimulated a global call for the Ecosystem-Based Fisheries Management (EBFM), with an increasing appreciation of its merits in the face of climate change. In this study, we applied the concept of EBFM to China's fisheries and tested the performance of various fisheries management strategies, including status quo management and alternative strategies with different objective priorities, under contrasting climate warming scenarios. We used the Ecopath with Ecosim (EwE) as an operating model, with an explicit consideration of trophic interactions, and specifically quantified the trade-offs across multiple metrics (i.e., sustainable fishery production, economic profitability, seafood security, and ecosystem health). No single strategy was superior across all the four dimensions. Importantly, the existing approach to fisheries management underperformed in most metrics, with the current fishing intensity exceeding the level that would maximize multispecies yields (f MSY) and total profits (f MEY). In contrast, an alternative harvest control rule (HCR) strategy, designed to respond to variations in biomass, provided inherent resilience of the ecosystem under climate warming, resulting in increased commercial fish biomass, improved profit and seafood supply, as well as enhanced ecosystem structure and function across various time-climate scenarios. From a tactic perspective, the multiple species management strategies of "f MSY " and "f MEY " can be better suited for the highly mixed fishery context in China. These alternatives also consistently demonstrated superior performance compared to the existing fisheries management strategy. Our work reveals potential trade-offs among diverse ecosystem services and provides a framework using EwE model for quantifying possible performance of management strategies under climate change, leading to more informed and transparent decision-making. • We employed an ecological model for fisheries management strategies evaluation. • Trade-offs were quantified among multiple objectives under climate change. • The status quo management underperformed in most metrics. • Harvest control rules would be effective under climate change. • Multiple species management strategies can be better suited for China's mixed fishery. [ABSTRACT FROM AUTHOR]