Marine ecosystems are undergoing life-history adaptations with impacts on productivity, resilience, and economic value due to Fisheries-Induced Evolution (FIE). Long-term and often intense selective commercial harvesting has led to truncations in population structure and evolutionary changes in key life-history traits. However, the consequences for different functional groups have rarely been evaluated, especially in the context of rebuilding depleted marine stocks. This study uses an individual-based eco-genetic modeling approach to investigate the effects of FIE during shifts in fishing intensity. We focus on functional groups of three types of pelagic fish and three types of demersal fish with different life histories in the China Seas, proposing and evaluating two types of evolving trait response indicators to FIE, and assessing the influence of fishing intensity during the population rebuilding phase. Our results indicate that FIE has a more pronounced impact on biomass recovery in demersal fishes compared to pelagic fishes. The recovery time ranges from 10 to 40 years and strongly correlates with length at 50% vulnerability (L50). Reductions in fishing intensity facilitate biomass recovery, particularly in demersal fishes. In conclusion, our study suggests that adopting a management approach tailored to the needs of distinct functional groups is highly beneficial for promoting the efficient recovery of declining demersal fisheries. This understanding is crucial for developing effective fishery management strategies that integrate the evolutionary responses of different functional groups.

Myctophid fishes represent an important trophic link between zooplankton and higher trophic level predators in the oceanic ecosystems of the Southern Ocean. The Antarctic lanternfish (Electrona antarctica) is one of the most abundant myctophids in the Southern Ocean; however, information on their feeding habits is sparse, representing a key area of uncertainty in efforts to model Southern Ocean food web dynamics. Using a classification tree approach based on stomach content data, we explored the feeding strategy of E. antarctica in the Amundsen and Cosmonaut Seas during January and March 2021, as well as its variation in relation to ontogenetic stage and sampling area. An ontogenetic shift in the feeding preference of E. antarctica was identified in the Cosmonaut Sea: Fish smaller than 48 mm fed on ostracods and copepods, while larger fish (SL > 62 mm) relied primarily on krill. Conversely, there was no ontogenetic shift in the diet of E. antarctica in the Amundsen Sea, and this species feeds almost exclusively on Themisto gaudichaudii. The diet composition of E. antarctica presented spatial differences: Copepods (48% IRI) and krill (24% IRI) were consumed more in the Cosmonaut Sea, while amphipods (91% IRI) were consumed more in the Amundsen Sea. The spatial differences in the prey of E. antarctica are related to the oceanographic environment and the variety of plankton prey in different regions. We determined that the size of E. antarctica, sea surface temperature (SST), latitude, and chlorophyll-a concentration (Chl) were the most important variables associated with dietary differences. When the fish size is larger than 55 mm and the krill abundance is high, E. antarctica mainly preys on krill. Since E. antarctica occupies a key position in the mesopelagic fish community, increased knowledge of the trophic ecology of this fish would contribute to a comprehensive understanding of its response to environmental changes.

Balanced harvest (BH) proposes moderate fishing mortality rates across all species or sizes in proportion to productivity, serving as a possible strategy for ecosystem-based fisheries management. Fishing patterns in some developing countries (e.g. China, the largest producer of seafood) closely resemble BH, where catches have been highly diversified by unselective gears due to market demand for almost all species. In this study, we employed an OSMOSE ecosystem model developed for the Yellow Sea in China to investigate the potential occurrences and advantages of BH in this region with highly exploited multispecies fisheries. Simulations were carried out under four types of fishing scenarios, where various levels of fishing mortality rates for all species or specific functional groups were implemented. Results indicated that the occurrences of BH depended on fishing pressure and targeted functional groups, and that size-level BH was significantly correlated with biomass and yield for most species. In particular, varying fishing pressure for certain functional groups resulted in BH, which produced a high yield for specific species and ensured their biomass sustainability. We concluded that the benefits of BH could be potentially achieved by adjusting fishing pressure for certain functional groups based on the existing fishing pattern in over-exploited ecosystems.

The composition of catch is affected by exploited fishing gear and its selectivity, and long-term selective harvest induces the change in biological characters and economic value of exploited population. Stow net is the main fishing gear to capture commercially important fish species small yellow croaker ( Larimichthys polyactis ) in Haizhou Bay, China. Long-term stow net selective harvest affects both the biological characters and economic benefits of small yellow croaker. Therefore, an appropriate harvest scenario that can achieve the high economic benefits and the sustainable use of resource needs to be explored. In this study, we develop a bio-economic model for small yellow croaker and focus on different harvest scenarios for obtaining maximum economic benefit and sustainable utilization of resource. Our results indicate that the increase in mesh size has positive effects on the protection of small yellow croaker population, and optimal harvest scenario achieves the short- or long-term economic benefits to different stakeholders. Fishing with small mesh size gets high economic value in short-term, while fishing with large mesh size achieves better economic value and effectively protect small yellow croaker resource under long-term fishing pressure. This study provides evidence to balance the long-term economic benefits and sustainable utilization of fishery resource, and it also offers a basis for the scientific formulation of fishery policy.