Fishery Resources Research Articles

RUSNet: Robust fish segmentation in underwater videos based on adaptive selection of optical flow

Fish segmentation in underwater videos can be used to accurately determine the silhouette size of fish objects, which provides key information for fish population monitoring and fishery resources survey. Some researchers have utilized underwater optical flow to improve the fish segmentation accuracy of underwater videos. However, the underwater optical flow is not evaluated and screen in existing works, and its predictions are easily disturbed by motion of non-fish. Therefore, in this paper, by analyzing underwater optical flow data, we propose a robust underwater segmentation network, RUSNet, with adaptive screening and fusion of input information. First, to enhance the robustness of the segmentation model to low-quality optical flow inputs, a global optical flow quality evaluation module is proposed for evaluating and aligning the underwater optical flow. Second, a decoder is designed by roughly localizing the fish object and then applying the proposed multidimension attention (MDA) module to iteratively recover the rough localization map from the spatial and edge dimensions of the fish. Finally, a multioutput selective fusion method is proposed in the testing stage, in which the mean absolute error (MAE) of the prediction using a single input is compared with that obtained using multisource input. Then, the information with the highest confidence is selected for predictive fusion, which facilitates the acquisition of the ultimate underwater fish segmentation results. To verify the effectiveness of the proposed model, we trained and evaluated it using a publicly available joint underwater video dataset and a separate DeepFish public dataset. Compared with the advanced underwater fish segmentation model, the proposed model has greater robustness to low-quality background optical flow in the DeepFish dataset, with the mean pixel accuracy (mPA) and mean intersection over union (mIoU) values reaching 98.77% and 97.65%, respectively. On the joint dataset, the mPA and mIoU of the proposed model are 92.61% and 90.12%, respectively, which are 0.72% and 1.21% higher than those of the advanced underwater video object segmentation model MSGNet. The results indicate that the proposed model can adaptively select the input and accurately segment fish in complex underwater scenes, which provides an effective solution for investigating fishery resources.

The protection and development of marine resources under the perspective of the sustainable development concept

PurposeIn this study, suggestions on the protection and development of marine resources, sea area use and management, improvement of laws and regulations, monitoring of marine resources and impact assessment of marine environment are put forward.Design/methodology/approachLiterature research method.FindingsA major factor contributing to the decline in fishery resources is excessive fishing. At present, there are many problems to be solved in the exploitation and utilization of marine mineral resources in China. The pollution problem of marine tourism resources is becoming increasingly serious. Overmining of coastal sea resources has led to planning and management failures.Originality/valueThis paper discusses the current situation of marine resource exploitation and protection in China and analyzes the reasons for excessive resource exploitation from three aspects of marine concept, laws and regulations and marine management.

Toward “climate-driven”: innovation on legislation of modern marine fisheries law under era of blue carbon

Abstract Over the past decade, there has been increasing interest in the blue carbon project, which uses marine activities and organisms to take up carbon dioxide from the atmosphere and store it in ocean. Important question in contemporary and future fisheries management is how to coordinate the relationship among the offshore fishery, the fisheries resource conservation and blue carbon projects. Through comparative studies and normative analysis, this study explores the legislative aims of some representative international and national fisheries legislation and their creative reforms in recent years. The legislative purpose of fisheries laws has traditionally been to keep fishery resources above the Maximum Sustainable Yield (MSY) standard, while marine carbon sink resource protection is marginally inadequate. Given that the blue carbon project is inseparable from future fisheries industry development, the protection of marine carbon sink resources needs to be incorporated into the legislative aim of fisheries law in the future.

Growth Patterns of Small Pelagic Fish in West Africa

Small pelagic fishes play important ecological roles in marine ecosystems, constitute some of the most economically valuable fisheries resources, and play a vital role in West African food security. Often living in upwelling regions, these species appear to have developed mechanisms to cope with environmental variability, such as opportunistic reproductive tactics, enhancing their growth performance, or increasing their egg production by following the more predictable system attributes of seasonal cycles. To test this hypothesis, we investigated size-dependent patterns of the two growth mechanisms (i.e., growth rate) of two West African small pelagic populations (Ethmalosa fimbriata and Sardinella maderensis) in upwelling environments. These results were discussed with other areas in African tropical Atlantic waters. The monthly mean length of both species showed a large variation over the study period. Based on the fish length-frequency data and a coastal upwelling index, we found that the growth peaks of the species tended to occur during the most intense periods of upwelling (March–April). This study showed a significant decrease in size compared with other species found in other regions. It demonstrates how the geographical distribution of the same species, together with location-specific variation in temperature and food, can combine to determine local and regional growth responses in pelagic fish. Changes in growth rate may be an adaptive tactic in response to environmental change, as well as phenotypic plasticity in fish. This knowledge is essential to predict future changes in fish productivity and distribution vs. climate and to provide effective advice for ecosystem-based management.

The establishment, persistence, and scaling of marine community-based natural resource management in four coastal districts in Tanzania

Community-based natural resource management (CBNRM) is common in most types of ecosystems that are characterized by common property practices. However, the emergence and spread of CBNRM has varied across geographies and contexts. This study explores factors that have enabled the modern emergence, persistence, and spread of marine CBNRM in four coastal districts in Tanzania. It also investigates how CBNRM—particularly local ownership and management of marine resources —is implemented and developed. It draws on a document review of the grey and scientific literature, and in-depth qualitative field work carried out in four coastal districts on mainland Tanzania. The field work involved 15 key informant interviews, 12 focus groups discussion, and participant observation, documenting the perceptions of resource users. The findings indicate that marine CBNRM – operationalized largely through local organizations called Beach Management Units (BMUs) – have strong support from local communities, but emerged, persist, and scaled largely through government and donor led initiatives. The local communities' strong desire to safeguard fisheries resources and reduce overexploitation, caused by illegal harvesting practices, promoted the quick expansion of BMUs, which in turn ensured the continuation of CBNRM. The positive experience and lessons learned from BMUs established early in the process encouraged the spread and ultimately scaling out of CBNRM. Expanding and sustaining marine CBNRM beyond its current form, which relies heavily on external support, will require innovative approaches that foster collective action, identify sustainable financing mechanisms, provide clarity in roles and responsibilities, and identify cost-effective and scalable CBNRM approaches.

The Environmental Niche of the Light Purse Seine Fleet in the Northwest Pacific Ocean Based on Automatic Identification System Data

Ecosystem-based fisheries management requires high-precision fisheries information to provide relevant data for natural resource management, assessment, and marine spatial planning. This study utilizes Automatic Identification System (AIS) data from light purse seine vessels from the Chinese mainland that were collected from May to November between 2020 and 2022, along with the corresponding environmental data. By applying boosted regression trees (BRTs) and generalized additive models (GAMs), this study establishes nonlinear relationships between fishing intensity and predictor variables and explores the ecological and environmental drivers behind the spatial distribution of light purse seine vessels from the Chinese mainland in the Northwest Pacific. This research identifies the key influencing factors and reveals significant seasonal preferences for different marine environments in various months, with chlorophyll-a being the primary influencing factor. The predicted fishing effort closely resembles observed data, providing valuable information to support fisheries resource management and planning.

Living Along Distribution Margins: Differences in the Body and Biochemistry of Red Squat Lobster Morphotypes (Grimothea monodon) from the Humboldt Current System

Grimothea monodon, an important fishery resource in the Humboldt Current marine ecosystem (HCE), present two contrasting morphotypes (PM, pelagic morphotype; BM, benthic morphotype). The fishery management of G. monodon is focused on understanding only fishery aspects that apply to a limited area, and there are currently no studies that evaluate the nutritional status of these morphotypes. This study evaluated the biological performance of PM and BM, analyzing the body (size, CL; weight, W; condition factor, Kn) and biochemical condition (glucose, G; proteins, P; lipids, L; fatty acids, FAs). The results reveal that G. monodon showed differences in CL and W between morphotypes, with higher values in BM than PM. The Kn was different between morphotypes with a tendency of isometric growth. In turn, the G contents were higher in PM than BM, while the contents of P, L, and FAs showed an opposite tendency, with higher contents recorded in BM than PM. Our findings suggest that the Kn should be included to strengthen the biological parameters and their relationships used in fishery management models. Differences in the biochemical condition between morphotypes can be considered potentially adaptive, in response to the combined effect of environmental factors that vary in the HCE.

Sustainability of Small-Scale Capture Fisheries Based on Coastal Vulnerability in Pangpang Bay, Banyuwangi Regency, Indonesia

Graphical Abstract Highlight Research Climate change impacts on coastal vulnerability. Low coastal vulnerability in Pangpang Bay, Banyuwangi Regency. Sustainability of small-scale capture fisheries based on vulnerability. Sustainable small-scale fisheries management. Abstract Teluk Pangpang is one of the water areas that has considerable capture fisheries potential in Banyuwangi Regency, Indonesia. On the other hand, climate change impacts the vulnerability of coastal areas and coastal communities, especially small-scale fishers. This study aims to analyse the coastal vulnerability of Pangpang Bay and formulate a sustainable development of small-scale capture fisheries in Pangpang Bay. The research method used a descriptive method with a quantitative approach. Data collection techniques used geographic information systems and focus group discussions (FGDs). The data analysis used was Coastal Vulnerability Index (CVI) analysis with spatial approach and Participatory Prospective Analysis (PPA). From the CVI analysis, through the assessment of geomorphological parameters, erosion/accretion, coastal slope, distance of plants from the beach, wave height, and average tide range, the level of coastal vulnerability of Teluk Pangpang is included in the low category. Meanwhile, the PPA analysis resulted in seven variables that most influence the sustainability of small-scale capture fisheries, namely climate change, coastal vulnerability, coral reef area and density, number of small-scale fishers, catches, human resources of small-scale fishers, and management of small-scale fisheries resources. Furthermore, for the formulation of the sustainability scenario of small-scale capture fisheries in Pangpang Bay, is to minimise the impact of climate change and conduct disaster mitigation, improve the human resources of small-scale fishers, and equalise perceptions as outlined in the commitment between all interested parties and small-scale fishing communities.

DNA barcode reference library of the fish larvae and eggs of the South China Sea: taxonomic effectiveness and geographic structure

Fish early-stages constitute useful indicators of the states of marine ecosystems, as well as important fishery resources. Given the spectacular phenotypic changes during ontogeny, and the paucity of diagnostic morphological characters at the species level, the identification of fish early-stages is a challenging task. DNA barcoding, the use of the mitochondrial gene of the cytochrome c oxidase subunit I (COI) as an internal species tag, opened new perspectives for the identifications of both larval fish and fish eggs. However, the accuracy of the identifications assisted by DNA barcoding are dependent of the completeness of the DNA barcode reference libraries used to assigned unknown sequences to known species. Here, we built a DNA barcode reference library for 113 species of larval fish and 85 species of fish eggs involving the production of 741 newly generated DNA barcodes from South China Sea (63 localities). Together with 514 DNA barcodes mined from Genbank for 116 species from the South China Sea regions, a reference library including 1255 DNA barcodes for 308 species (248 locations) was assembled. The present study emphasizes the importance of integrating DNA barcoding to large scale inventories of early stages, as DNA-based species delimitation analyses delimited 305 molecular operational taxonomic units (MOTUs) and multiple cases of discordance with morphological identifications were detected. Cryptic diversity is detected with 14 species displaying two MOTUs and a total of 23 species were lumped into 11 MOTUs due to low interspecific divergence and/or mixed lineages.

A trophic modelling framework: Key metrics for the ecological assessment of artificial structures

As the global population expands, marine coastal ecosystems face mounting pressures from human activities, that have led to habitat deterioration and dwindling fishery resources. In this context, Artificial Reefs (ARs) have emerged as one of the promising solutions. They are generally implemented to provide habitat, to create a protective, physical boundary, to support sustainable fisheries and to facilitate ecosystem rehabilitation. Evaluating their ecological performance is crucial to ensuring they meet their objectives. Initially, assessment relied on comparing ARs to natural reefs using mainly ecological metrics which focused on fish assemblage and dynamics. Despite there being more research and documentation on effectiveness today, assessing ARs remains challenging due to the number of environmental factors that can affect the ecological systems. Moreover, ecological studies mainly used metrics that investigated the reef fish populations or ecological metrics such as fish assemblages or trophic structure that are often overlooked in studies that primarily focus on commercial fishery dynamics. Therefore, new ways of assessing artificial reef performance and the set-up of comprehensive metrics which integrate this level of complexity are needed. In this study, we focused on the "Rade de Cherbourg" in the English Channel, employing a trophic modeling approach using Ecopath with Ecosim (EwE). The study emphasizes the importance of Ecological Network Analysis (ENA) metrics for evaluating changes in the systems’ properties—such as complexity, flow diversity, and recycling capacity— which result from AR implementation. Furthermore, we identified which metrics are suitable for assessing specific AR objectives. The proposed metrics serve as a command-and-control tool for AR site managers, enabling them to evaluate the performance of each AR objective effectively. With the anticipated increase in AR projects, especially those which compensate for human impact like the Cherbourg ARs, this research offers valuable insights and future perspectives to continuously improve the ecological performance of ARs.

Monetary Value of Surf Zone Fishery Resources on the SouthWest Iberian Peninsula

ABSTRACTBeaches are among the world's most important coastal ecosystems, within which surf zones are crucial providers of essential ecosystem services to humans. We completed the first estimate of current and potential monetary value of fishery resources in surf zones of beaches on the southwestern Iberian Peninsula. Over 1 year, five beaches in the Gulf of Cádiz were sampled using a beach seine. For monetary valuation, average first‐sale prices were used, with a capital update based on the Consumer Price Index (CPI). The 189.16 kg of 38 commercial species captured had a potential monetary value (PMV) of 408.63 €/ha. The annual value of adult fish (19 species) averaged 115.05 €/ha and juvenile fish (33 species) averaged 293.58 €/ha. Our findings highlight the value of surf zones and beaches as fishery resources, similar to other marine ecosystems. Our findings are useful for ongoing monitoring and research to enhance knowledge of these areas and the array of ecosystem services they provide.

Law Enforcement on Fishery: Prohibition of Trawl Nets as an Effort to Protect Small Fisherman Fairly

The sea and its resources, especially fishery resources, are a gift from God Almighty for the welfare of all Indonesian people. Based on the state's right to control the earth and the natural resources contained therein, which originates from Article 33 paragraph (3) of the 1945 Constitution of the Republic of Indonesia, the government must regulate fishery resources for the greatest prosperity of all people. The use of fishery resources is carried out with various legal products ranging from laws, government regulations, and presidential decrees to ministerial rules. Regulations on using fishery resources include prohibiting using trawl nets to catch fish in certain waters. This prohibition aims to prevent damage to the marine environment, ensure the sustainability of fishery resources, and protect small fishermen. However, in its implementation, it is still hampered by the problem of law enforcement, which is hindered by disharmony of regulations, the availability of professional law enforcement officers, and the lack of support for facilities and infrastructure considering the vast area of law enforcement. One thing that is no less important in enforcing the law on the prohibition of the use of trawl nets is the low legal awareness of fishing communities, especially industrial fishermen who only care about themselves without paying attention to the preservation of marine ecosystems, the sustainability of fishery resources, and the protection of small fishermen or traditional fishermen.

New Insights into Fish Diversity in the Yellow and Bohai Seas Based on Environmental DNA Technology

Marine biodiversity is increasingly threatened by overfishing and marine pollution. A comprehensive understanding of the biodiversity in the Yellow and Bohai Seas is essential for resource conservation. This study conducted a large-scale survey of fishery resources in the Yellow and Bohai Seas to investigate fish community structure and diversity using eDNA technology. The results showed that 57 and 65 fish species were recorded in spring and summer, respectively, with 46 species identified in both seasons. A total of nine dominant species were identified in spring, mainly belonging to Perciformes, while seven dominant species were identified in summer, primarily from Clupeiformes. In different regions, no significant differences in fish α diversity were observed between spring and summer. However, significant seasonal differences were found in both α and β diversity. At the spatial level, fish species in the Yellow and Bohai Seas occupied similar ecological niches. However, at the temporal level, there are certain differences in the ecological niches of fish communities between seasons. Phylogenetic diversity showed no significant differences at the spatial scale, yet notable seasonal variations were observed at the temporal scale, with spring (661.46) significantly exceeding summer (540.30). The Mantel test indicated that nitrate and salinity were key environmental factors influencing α diversity. RDA analysis revealed that the dominant species in spring were mainly influenced by chlorophyll-a and water temperature, while those in summer were mainly affected by water depth, nitrite, water temperature, and salinity.

Trophic Structure of Fish Community in Artificial Reef Ecosystem Based on Body Mass Using Stable Isotope

Artificial reefs are widely recognized for their role in improving the ecological environment and creating protected habitats for marine organisms, ultimately enhancing biodiversity within the food web and fisheries resources. This study utilizes stable isotopes to analyze fish samples ranging from 3.4 to 1067 g in body mass, collected within the artificial reef area of Haizhou Bay. The objective is to determine if the δ15N-based fish body mass acts as a driving factor in shaping the food web structure. The results showed a certain level of overlap among all trophic guilds, suggesting that most trophic guilds within this region share similar living environments and feeding habits. The multiple linear regression showed a slight increasing trend between δ15N values and body mass. Furthermore, the predator–prey mass ratio (PPMR) was calculated to be 430:1 based on the δ15N–body mass relationship. This implies that larger reef fish within this artificial reef ecosystem tend to have higher δ15N values compared to smaller fish, indicating a shorter food chain in this ecosystem. In summary, this analysis provides valuable insights into the fish community structure within artificial reef ecosystems. Therefore, it is recommended that future studies focus on further characterizing the fish community structure using body mass information.

Seasonal variations of microbial communities and viral diversity in fishery-enhanced marine ranching sediments: insights into metabolic potentials and ecological interactions

BackgroundThe ecosystems of marine ranching have enhanced marine biodiversity and ecological balance and have promoted the natural recovery and enhancement of fishery resources. The microbial communities of these ecosystems, including bacteria, fungi, protists, and viruses, are the drivers of biogeochemical cycles. Although seasonal changes in microbial communities are critical for ecosystem functioning, the current understanding of microbial-driven metabolic properties and their viral communities in marine sediments remains limited. Here, we employed amplicon (16S and 18S) and metagenomic approaches aiming to reveal the seasonal patterns of microbial communities, bacterial-eukaryotic interactions, whole metabolic potential, and their coupling mechanisms with carbon (C), nitrogen (N), and sulfur (S) cycling in marine ranching sediments. Additionally, the characterization and diversity of viral communities in different seasons were explored in marine ranching sediments.ResultsThe current study demonstrated that seasonal variations dramatically affected the diversity of microbial communities in marine ranching sediments and the bacterial-eukaryotic interkingdom co-occurrence networks. Metabolic reconstruction of the 113 medium to high-quality metagenome-assembled genomes (MAGs) was conducted, and a total of 8 MAGs involved in key metabolic genes and pathways (methane oxidation - denitrification - S oxidation), suggesting a possible coupling effect between the C, N, and S cycles. In total, 338 viral operational taxonomic units (vOTUs) were identified, all possessing specific ecological characteristics in different seasons and primarily belonging to Caudoviricetes, revealing their widespread distribution and variety in marine sediment ecosystems. In addition, predicted virus-host linkages showed that high host specificity was observed, with few viruses associated with specific hosts.ConclusionsThis finding deepens our knowledge of element cycling and viral diversity in fisheries enrichment ecosystems, providing insights into microbial-virus interactions in marine sediments and their effects on biogeochemical cycling. These findings have potential applications in marine ranching management and ecological conservation.DRyDF7ykR-XALqAtu34uZtVideo

Use of Environmental DNA to Evaluate the Spatial Distribution of False Kelpfish (Sebastiscus marmoratus) in Nearshore Areas of Gouqi Island

This study aims to explore the spatial distribution of false kelpfish (Sebastiscus marmoratus) in the mussel farming area, artificial reef areas of Gouqi Island (Shengsi, China), and natural areas using eDNA detection methods. Surface and bottom water samples were collected at 12 stations in November 2022 and April 2023, totaling 52 samples. We used species-specific primers and probes for quantitative PCR (qPCR) detection of Sebastiscus marmoratus eDNA. The eDNA concentrations differed seasonally (p < 0.05) and did not differ (p > 0.05) among the three sampling areas and two water layers. The greatest eDNA concentrations occurred in the surface layer during the spring. Higher concentrations of Sebastiscus marmoratus eDNA were also found in the mussel aquaculture area. Temperature exhibited a significant positive correlation with Sebastiscus marmoratus eDNA concentration (p < 0.05). Additionally, we developed linear equations predicting the relationship between environmental factors and environmental factors, providing a reference for future fishery resource surveys.

Assessment of climatic and environmental parameters on fish abundance of an afro-tropical reservoir

This study assessed the impacts of climatic parameters (rainfall and temperature) and environmental variables (transparency, depth, chloride, TS, TSS, TOC) on the abundance of commercially important fish species in Esa-Odo. The research question was to find out if climatic and environmental factors influence the abundance of fish species in an afro-tropical reservoir. Fish species were collected on a monthly basis for two annual cycles covering both dry and rainy seasons. GIS-based climatic data was used to determine the relationship between climatic conditions and fish species abundance. Results showed that the highest abundance of fish was recorded during the rainy season, with Oreochromis niloticus being the most dominant species throughout the sampling period. Trend analysis revealed that variations in climate and environmental parameters influenced the abundance of different fish species in the reservoir. Mann-Kendal analysis indicated that an increase in rainfall led to an increase in reservoir depth, a decrease in transparency levels, and a reduction in temperature, with a Sen’s slope value of -38. Additionally, CCA and correlation matrix results demonstrated that climate and environmental parameters significantly influenced fish species abundance. The study emphasized the importance of climatic and environmental factors in the abundance of fish species in the reservoir, providing valuable information for future research on fishery resources. Governments and stakeholders were urged to prioritize the conservation and management of the reservoir’s fish population to prevent declines.

The Influence of Income, Family Consumption and Technology on the Welfare of Fishermen in Tanjung Benoa Bali

The high potential of fishery resources owned by Tanjung Benoa Village is a positive thing and can be a good source of income for the community. However, the fact is that this potential has not been able to provide the expected welfare. The purpose of this study is to analyze 1) The simultaneous effect of income, family consumption, and technology on the welfare of fishing families; 2) Partial effect of income, family consumption, and technology on the welfare of fishing families; 3) Variables that have a dominant effect on the welfare of fishing families in Tanjung Benoa Village. This research uses an associative quantitative approach. The type of data used primary data with a population of 140 fishermen in Tanjung Benoa Village. Data analysis techniques included descriptive statistics and multiple linear regression analysis using Stata software. The results of the analysis showed that: 1) income, family consumption, and technology have a significant effect simultaneously on the welfare of fishing families; 2) income, family consumption, and technology have a significant effect partially on the welfare of fishing families; 3) the technology variable is the dominant variable affecting the welfare of fishing families. Technology variable is the variable that has a dominant effect on the welfare of fishing families in Tanjung Benoa Village. Based on the results of the study, it is expected that the fishing community is expected to pay attention to the technology variables used in helping the process of catching seafood owned in order to increase their income so as to be able to generate a general level of welfare.

Food Preference of Purple‐Spotted Bigeye (Priacanthus tayenus Richardson 1846) in Northern Coast of Java, Indonesia

ABSTRACTDiet is one of the essential information used in the management of fisheries resource. The objective of this study was to assess the dietary preferences, index of preponderance, trophic level, food niche breadth, and food overlap of purple‐spotted bigeye (Priacanthus tayenus) caught from the northern coast of Java, Indonesia. A total of 407 fish samples were collected from July to October 2023. Each fish sample was measured for total length and body weight. Fish were then dissected to determine sex, gut length, gut volume, and diet composition. Data analysis included relative gut length, diet composition, frequency of occurrence, trophic level, index of preponderance, food niche breadth, and food overlap. The result showed that the purple‐spotted bigeye is a carnivorous fish (trophic level ranges from 3.88 to 4.18), whose main food is fish and shrimp. Based on the niche breadth value, purple‐spotted bigeye from East Java were more diverse in finding food (niche breadth = 0.26) than from West Java (niche breadth = 0.06) and Central Java (niche breadth = 0.09). The purple‐spotted bigeye species from West Java and Central Java exhibited a high level of competition in their search for food, as indicated by a food overlap value of 0.998.

Seasonal Distribution of Key Small-Sized Fish in the South Inshore of Zhejiang, China

Small-sized fish are a vital food source for large predatory commercial fish and play a key role in marine food webs, bridging lower and higher trophic levels. They are indispensable in maintaining the energy flow and material cycling within aquatic ecosystems. This study utilized bottom-trawl survey data from 2017 to 2020 along the south inshore of Zhejiang, China, complemented by concurrent environmental data, to examine the influence of environmental factors on the resource density and seasonal distribution patterns of four dominant small-sized fish species. The research findings indicated that SSH (sea surface height) and Chl (chlorophyll-a concentration) emerged as the key environmental factors influencing resource densities, with all four species exhibiting similar preferences toward these variables. However, significant disparities were observed in their preferences for SST (sea surface temperature), SSS (sea surface salinity), and DO (dissolved oxygen). The various species’ resource density and distribution patterns underwent significant seasonal variations. Additionally, the seasons and regions with the highest resource densities consistently aligned, occurring predominantly in autumn within the northern waters of the study area. This research further elucidated the environmental predilections and seasonal spatial distribution traits of small-sized fish in the south inshore of Zhejiang, an important feeding ground for economic fish species in the East China Sea. This provides scientific backing for forecasting alterations in coastal fishery resources under environmental and climate change scenarios and supports ecosystem-based fisheries management strategies.