• Journals
• OpenAccess

An investigation on the seasonal variation of household-based small-scale fisheries resource structure in the coastal waters off Penghu, Taiwan

This study systematically collected logbook data from household-based small-scale fishing vessels operating around Penghu between 2016 and 2020, and applied ecological indicators along with geographic information analyses to quantify the seasonal and spatial dynamics of fishing operations, catch composition, and catch rates. The three dominant catch species were Lethrinus nebulosus, Uroteuthis chinensis, and Epinephelus quoyanus, and the catch assemblage exhibited clear seasonal variation. Similarly, both the Alternated Index and Migratory Index revealed temporal shifts in community structure. Fishing activities were primarily concentrated in the Penghu Inner Sea, the southwestern coastal waters of the archipelago, the waters around the South Penghu Marine National Park, and the southwestern waters off Qimei Island. In addition, the seasonal movement of the fishing center of gravity showed consistent shifts along both east-west and north-south axes. Overall, the results demonstrated pronounced seasonal and interannual variability in catch assemblages and fishing-ground distribution, indicating that Penghu's small-scale fisheries are shaped by both environmental forcing and operational constraints. These findings provide essential scientific support for resource conservation and spatial management of coastal fisheries in the region.

• Journals
• OpenAccess

Synchrony in Abundance and Spatial Distribution Variability of Longline Commercial Species in the Indian Ocean

Tuna and billfishes are ecologically and economically important species in the Indian Ocean, and mainly caught by the longline fishery and recreational fisheries around the world. In this study, we clarify the spatiotemporal dynamics of five majors tuna and billfish species in the Indian Ocean, the fishery data which were collected from Indian Ocean Tuna Community longline fishery data from 1980 to 2022. The time series of standardized CPUE were developed to assess relative abundance trends and habitat distributions. The results revealed distinct temporal trajectories among species: yellowfin tuna and albacore exhibited recurrent fluctuations, while bigeye tuna and swordfish standardized CPUE increased around 2012 before declining. Especially, skipjack tuna displayed an overall increasing trend, whereas southern bluefin tuna showed high standardized CPUE in 2009. Spatially, the analysis demonstrated significant habitat segregation driven by latitudinal thermal gradients. A distinct tropical guild (yellowfin, bigeye, and skipjack) was confined to the warm equatorial band (10°N-20°S), primarily concentrated in the western Indian Ocean. In contrast, albacore dominated subtropical waters (25°S-40°S), while southern bluefin tuna was strictly restricted to high latitudes (>40°S). Furthermore, longitudinal partitioning was evident, with southern bluefin tuna exhibiting a unique eastward distribution (95°E-147.5°E) compared to the western-central governance of other species.

• Journals
• OpenAccess

Observations of Sea Water of Temperature and Salinity in the Yun-Chang Rise Area of the Taiwan Strait from 2019 to 2021

In this study, profiles of seawater temperature and salinity were collected and analyzed at research stations in the Yun-Chang Rise area of the central Taiwan Strait using the Fisheries Research Institute research vessel Fishery researcher NO.2. The results indicate that during spring, variability among stations was less than that observed in summer and autumn, suggesting weaker mixing and interaction among water masses during this period. Seasonal analyses further revealed that in spring, strong intrusion of the China Coastal Current reduced the influence of low-salinity terrestrial runoff along the Changhua coastal region. In contrast, during autumn, the study area was affected by South China Sea water masses of varying intensity, resulting in pronounced vertical salinity variability. From a spatial perspective, distinct hydrographic differences were observed between nearshore and offshore stations. Northern stations within the study area were more susceptible to seasonal forcing, leading to shifts in dominant water-mass characteristics. Overall, the Yun-Chang Rise area exhibits clear seasonal hydrographic variability driven by water-mass dynamics; however, the specific patterns differ among years and seasons. Long-term environmental changes in this region can therefore only be elucidated through integrated temporal and spatial hydrographic observations.

• Journals
• OpenAccess

Ecological Study of Dentex hypselosomus in Southwestern Waters of Taiwan

The Dentex hypselosomus is an important commercial demersal fish species in the coastal and offshore waters of Taiwan. Despite its economic value, biological and fishery information for this species in southwestern waters of Taiwan has long been insufficient. This study integrated fishery-dependent data and biological sampling obtained from bottom trawl, pole and line, and bottom longline fisheries operating in southwestern waters of Taiwan from 2022 to 2024. Monthly samples were collected to examine body length composition, sex ratio, length-weight relationships, gonadosomatic index (GSI), ovarian maturity stages, size at 50% maturity (L50), and seasonal and spatial fishing ground distribution. Results showed strong gear selectivity among fishing methods: bottom trawls mainly captured small-sized individuals (100-160 mm FL), whereas pole and lines and longlines selectively caught medium to large individuals (160-240 mm FL). Females dominated smaller size classes, while males were more prevalent in larger size classes. Female GSI and ovarian maturity indicated that the principal spawning season occurred from March to April. Fishing grounds exhibited clear seasonal shifts associated with depth and latitude. The results provide essential baseline information for stock assessment and fisheries management of D. hypselosomus in southwestern Taiwan.

• Journals
• OpenAccess

Abundance Variability and Environmental Drivers of Commercial Fish in the Northern South China Sea across ENSO Phases under Climate Change Scenarios

The El Niño-Southern Oscillation (ENSO) is a dominant driver of environmental variability in the Northern South China Sea (NSCS). Under climate change, understanding how these oscillations impact commercial fisheries is crucial for adaptive management. This study statistically quantifies the response of 21 commercial fish species in the Taiwan Bank upwelling region to ENSO phases under future warming scenarios (1951-2100). We forced the Dynamic Bioclimatic Envelope Model (DBEM) with environmental data derived from the ensemble mean of the GFDL ESM2M Earth System Model to isolate robust climate signals. Using Analysis of Variance (ANOVA) and univariate linear regression, we examined biomass variability across El Niño, La Niña, and Neutral phases. The results reveal that species abundance is significantly higher during La Niña events compared to El Niño and Neutral phases (p-value < 0.05). Univariate regression analyses identified Sea Surface Temperature (SST) and Net Primary Production (NPP) as the primary drivers, showing significant negative and positive correlations with biomass, respectively. These findings provide statistical evidence that La Niña-induced upwelling-characterized by cooler waters and enhanced productivity-creates a favorable "buffer" period for fishery resources. We suggest that fisheries management strategies should explicitly account for these ENSO-driven phase differences to mitigate risks during less favorable El Niño periods.

• Journals
• OpenAccess

Spatial distribution and catch composition of swimming crabs in trap fisheries of the Taiwan Strait

Swimming crabs (family Portunidae) constitute an important component of coastal trap fisheries in the Taiwan Strait, contributing significantly to regional fisheries production and economic value. Despite their importance, information on the spatial distribution and catch composition of swimming crabs derived from trap fisheries remains limited. This study analysed fishery inspection logbook data from 2018 to 2025 to characterise the catch composition, seasonal dynamics, and regional distribution of four target species (Charybdis feriatus, Charybdis natator, Portunus pelagicus, and Portunus sanguinolentus) across North, Central, and South Taiwan. P. sanguinolentus was the dominant species across all regions, though catch composition differed markedly between North and South: North and Central Taiwan were co-dominated by C. feriatus and P. sanguinolentus, whereas South Taiwan exhibited a more diverse assemblage with substantial contributions from C. natator and P. pelagicus. PCA confirmed this spatial structure, explaining 77.3% of compositional variance and separating regions along a gradient consistent with contrasting oceanographic regimes across the Taiwan Strait. Catches of C. feriatus, C. natator, and P. sanguinolentus peaked during autumn and winter, while P. pelagicus showed a distinctly different seasonal pattern. A general decline in catch and CPUE was observed from 2021 onwards; C. natator and P. pelagicus showed no signs of recovery, while partial rebounds in P. sanguinolentus and C. feriatus from 2023 coincided with tightened fisheries regulations. These findings provide baseline fishery information to support future monitoring and sustainable management of swimming crab resources in the Taiwan Strait.

• Journals
• OpenAccess

Nanoplastics in Aquatic Ecosystems: Toxicological Risks and Emerging Bacterial Strategies for Biodegradation

Naoplastics, defined as particles smaller than 1000 nm, are an emerging pollutant of increasing concern in aquatic environments. Their small size and high surface-area-to-volume ratio confer high reactivity and a strong capacity to adsorb other environmental contaminants, positioning them as a significant ecological risk, particularly for aquatic ecosystems, seafood safety, and fisheries productivity. In aquaculture systems, nanoplastics can accumulate in the tissues of economically valuable species like shrimp and shellfish, posing potential threats to food safety and trade viability. This review synthesizes current understanding of nanoplastics sources, properties, and toxicological mechanisms, with emphasis on their biological impact across multiple trophic levels. Particular focus is given to their interactions with fish and aquatic invertebrates, as well as their size-dependent toxicity and complex environmental behaviors. The review also explores microbial and enzymatic strategies for nanoplastics detection and biodegradation, highlighting bacterial species capable of producing key enzymes such as PETase and laccase. Additionally, biofilms are discussed as potential modulators of nanoplastics fate, influencing aggregation, transport, and biodegradability. Despite growing research interest, microbial approaches remain largely experimental. Critical challenges persist in detection standardization, in situ validation, and the characterization of degradation pathways. This review outlines emerging opportunities in microbial biotechnology and offers a roadmap for advancing nanoplastics research through interdisciplinary research in aquatic toxicology, microbiology, and sustainable fisheries.

• Journals
• OpenAccess

Microsatellites in Aquaculture Genetics: Foundations, Applications, and Future Directions for Sustainable Breeding

Aquaculture continues to expand globally every year to meet the nutritional needs across the world, but the sustainability of this industry is largely dependent on genetic diversity and breeding practices. This review explores the role of microsatellite markers (SSRs) in aquaculture genetics, and their applications in determining genetic diversity, monitoring inbreeding, and guiding selective breeding programs. It also examines practices such as broodstock selection and ecological influence on genetic differentiation and geneflow. With their high polymorphism and codominant inheritance: microsatellites can be used in parentage analysis, studying population structure and linkage mapping. Applications span diverse taxa; from shrimp and sturgeon to oysters and sea otters; demonstrating their versatility in both conservation and production contexts. Marker-Assisted Selection (MAS) and Quantitative Trait Loci (QTL) mapping are discussed as key strategies for improving traits such as growth, disease resistance, and reproductive efficiency. Despite their advantages, SSRs are also not without limitations. Limitations including genotyping errors, homoplasy, and reduced functional relevance compared to SNPs. However, recent advances in next-generation sequencing (NGS) have significantly enhanced the efficiency of SSR marker discovery, enabling large-scale development even in species lacking extensive genomic resources. When integrated with single nucleotide polymorphisms (SNPs) and genomic selection frameworks, these tools are expected to improve breeding precision and support the global harmonization of marker panels. The synergistic usage of SSRs, SNPs and functional genomics can pave the way to a new era of precision aquaculture that promotes high productivity and long-term sustainability.

• Journals
• OpenAccess

Evaluation of hybridization and spawning ground between Amphiprion ocellaris and Amphiprion ocellaris var.

The main objective of this study was to develop clownfish with specific body colors through hybridization experiments with Amphiprion ocellaris (female) and A. ocellaris var. (male). The experiment also investigated artificial pairing behavior, choice of artificial ovaries, spawning rates, and juvenile morphology. Four types of artificial spawning substrates-smooth tiles (A), rough tiles (B), ceramic flower pots (C), and plastic PVC pipes (P)-were placed in breeding tanks. A total of 12 pairs of broodstock were observed over a period of 16-months to monitor pairing behavior, spawning conditions, and willingness to choose spawning grounds. The results showed that B and C had a higher number of eggs, whereas no spawning was observed in A and P. The average number of eggs laid was 303 ± 0.27 on B and 332 ± 0.57 on C, with no significant difference between the two. These findings suggest that rough tiles and ceramic pots are more suitable spawning substrates than smooth tiles and PVC pipes for A. ocellaris breeding under artificial conditions. The body color of the juvenile fish is different from that of the parents. It has an orange-red chest, a brown body, and a three-white stripe pattern.

• Journals
• OpenAccess

Applications of plasma technology in aquaculture: antimicrobial effects, nitrogen removal, and toxicological implications of plasma-activated water

This study investigates the antimicrobial, nitrogen removal, and toxicity effects of plasma-activated water (PAW) in aquaculture systems. Plasma-activated water was generated using an atmospheric plasma system, which demonstrated potent antimicrobial activity against a range of aquatic pathogens. The bactericidal efficacy was primarily attributed to the synergistic effects of high oxidation-reduction potential (ORP) and low pH, with full pathogen inhibition observed after 5 to 10 minutes of plasma treatment. Oxygen PAW exhibited antimicrobial activity, albeit with lower potency, and showed significant improvements in the degradation of nitrogenous compounds without causing the accumulation of nitrite-N. Notably, atmospheric PAW resulted in the accumulation of nitrite-N, particularly in environments with atmospheric nitrogen, which can present challenges in nitrogen-sensitive aquaculture systems. Toxicity assessments revealed that atmospheric PAW caused 100% mortality in giant freshwater prawns within 2 h, primarily due to elevated nitrite-N levels. In contrast, oxygen PAW showed significantly lower toxicity, especially in seawater, and was deemed relatively safe for marine species such as orange-spotted grouper and white shrimp juveniles. However, oxygen PAW still induced high mortality in giant freshwater prawns, suggesting that plasma treatment remains highly toxic to certain freshwater organisms. These findings highlight the potential of oxygen PAW for nitrogen compound removal and safer application in aquaculture systems, while atmospheric PAW requires careful consideration due to its toxicity.