Journal of Fisheries and Environment

Assessing the Accuracy of Sentinel-2A and the Van Hengel-Spitzer Algorithm for Bathymetry Mapping in Shallow Waters: A Case Study of Bokori Island, Indonesia

Muh Abdul Rahman Hadimu — 2026-04-01

Multispectral remote sensing is a proven tool for mapping shallow waters, but accurately capturing seabed color signatures remains a significant challenge due to water- column effects, atmospheric interference, and complex interactions between inherent and apparent optical properties. Our study explores whether Sentinel-2A satellite imagery, processed with the Van Hengel-Spitzer (VHS) algorithm, offers a practical solution for bathymetric mapping. We collected field depth measurements using echo-sounders and adjusted these for tidal variations. Applying the VHS algorithm generated relative depths, which we then calibrated to absolute depths using a linear regression model based on our in-situ data. The results are promising: the combined VHS and Sentinel-2A approach delivered robust depth estimates down to 12 meters. The relationship between satellite-derived depths and in situ measurements was strong (R² = 0.683). When we tested accuracy, nearly 80% (79.66%) of the satellite estimates fell within ±3 meters of the actual depths. The data also showed higher precision, with 54.24% of estimates accurate within ±2 meters and 32.2% within just ±1 meter of the measured depths. These findings confirm that Sentinel-2A provides a viable option for moderately accurate, efficient bathymetric mapping in clear, shallow marine environments. This approach holds significant potential for supporting coastal zone management and environmental monitoring efforts.

Effects of Feed Type, Temperature and Light Conditions on Rearing Performance of Ornate Spiny Lobster (Panulirus ornatus) Phyllosoma Larvae in Thailand

Rungtiwa Konsantad — 2026-04-01

The ornate spiny lobster Panulirus ornatus is a valuable but challenging aquaculture species, with larval survival—particularly of the phyllosoma stage—being a primary constraint. This study evaluated the effects of feed types and environmental conditions (light and temperature) on feeding performance and survival of primary phyllosoma larvae. Results show that providing appropriate live feed significantly enhances nursery performance (p<0.05). Larvae in the 1^st P stage fed Artemia nauplii (AN) exhibited the highest mean survival from day 3, surpassing those fed with S-type rotifer (SR) or a mixed AN+SR regime. In the absence of feeding, survival dropped with complete mortality by day 7. Notably, 1^st P larvae fed exclusively on AN demonstrated the longest survival duration. In contrast, artificial feed (AF) yielded a lower survival, with all individuals dying within 7 days, and combined AN+AF survival remaining below 15 days. Temperature profoundly affected feeding and mortality: at 30 °C, Artemia intake peaked (9.9 individuals·day^-1) with the lowest mortality (12.56 %·day⁻¹), whereas 33 °C produced the highest daily mortality. Light conditions did not significantly influence daily feeding or mortality rates. Collectively, these findings advance understanding of factors governing 1^st P survival and offer evidence-based guidelines to optimize larval rearing and future productivity of P. ornatus.

Size Variation and Survival after Transplantation of the Tropical Box Marine Mussel Septifer bilocularis on the Three Coastal Sites of North Sulawesi, Indonesia

Medy Ompi — 2026-04-01

Box mussels exhibit patchy distribution patterns across intertidal and subtidal zones, where environmental contrasts strongly influence their physiology and ecology. Intertidal box mussels experience frequent air exposures, variable salinity, acidity, and turbidity during low tide, whereas subtidal mussels generally experience more stable conditions. However, with rising sea temperatures related to global climate change, these stressors may intensify, disrupting the mussel’s activities. Consequently, their roles in marine ecosystems may change, yet knowledge of box mussel responses to environmental change remains limited. This study investigated the effects of site, time (monthly intervals), and position (intertidal vs. subtidal) on mussel growth and survival. Box mussels were transplanted to intertidal and subtidal seabeds at three sites in North Sulawesi: Tiwoho, Tongkaina, and Blongko, from August to November 2023. Shell length and survival rates were analyzed using a three-way ANOVA, with site, time, and position as main factors. The results showed that mean shell length was significantly influenced by all three factors. The box mussels grew rapidly from August to September, followed by slower growth from October to November. The final mean size was higher at Tongkaina compared to Blongko, while Tiwoho did not differ significantly from Tongkaina. Survival declined steadily, averaging 22–40% by November, and was influenced by time and position but not by site. Ascidians were observed attaching to the cages in November. Seawater temperature, ascidian presence, and food availability may influence mussel size and survival. Finally, although the tropical mussel, S. bilocularis, exhibits higher thermal tolerance, it remains vulnerable to ocean warming.

Size Selection of Short-necked Clam (Paphia undulata) Dredge in Thai Waters: An Application of Selectivity Model to Improve the Fishery Management

Watcharapong Chumchuen — 2026-04-30

The short-necked clam (Paphia undulata) has been a commercially important marine species throughout the Indo-Pacific region for centuries. Recently, the sieve sizes of the short-necked clam dredge still need to be reconsidered by fishery managers and stakeholders to ensure the sustainability of this resource. This study aimed to (i) review the short-necked clam fisheries in Thailand, (ii) apply a parametric selectivity model to the short-necked clam dredge, and (iii) assess the catches to determine the suitable sieve size based on size selectivity, maturity size, and marketable size. This study reviewed and analyzed secondary data, including fishery statistics, fishing gears and operations, short-necked clam dredge experiments, and information on maturity and marketable sizes. Our findings indicated that short-necked clam fishery in Thailand dates back to the 19^th century, evolving from hand-collecting to dredging by fishing vessels both in the Gulf of Thailand and the Andaman Sea. The parametric model was applied to three different sieve sizes (8 mm, 10 mm, and 12 mm) to enhance the precision of size selectivity estimation. The results revealed that the shell length selectivity of the short-necked clam dredge was 26.0 mm, 30.0 mm, and 36.5 mm for the 8 mm, 10 mm, and 12 mm sieve sizes, respectively, with an estimated selection factor of 3.20. The catch assessment demonstrated that a 10 mm or larger sieve size is optimal for reducing the capture of immature and unmarketable short-necked clams and supporting effective fishery management and sustainable resource utilization.

Effects of Stocking Density on Fish and Rice Yields in Semi-intensive Rice-fish Culture of Climbing Perch (Anabas testudineus) in Rain-fed Rice Paddies

Minoru Saito — 2026-04-30

We investigated the feasibility of culturing air-breathing carnivorous fish, climbing perch (Anabas testudineus), in a semi-intensive rice-fish system in Northeast Thailand. Fingerlings of two initial size classes (ca. 1 and 6 g per fish) were reared for 2.5 or 3.5 months to evaluate the effects of stocking density (0–80 fish∙m⁻²) on fish growth, fish yield, and rice yield. Fish reached market size (100 mm total length and 20 g wet weight) at all stocking densities. Total fish yield increased proportionally with stocking density, at least up to 60 fish∙m⁻², yielding 1.8–2.0 kg∙m⁻², indicating that climbing perch did not experience density-related constraints within this range. Trade-off existed between fish and rice yields, with rice yield declining significantly at stocking densities of ≥20 fish∙m⁻²(mean: 200 g∙m⁻²) compared to the no-fish control and 10 fish∙m⁻²treatments (mean: 520 g∙m⁻²). Fish revenue was comparable to, or slightly lower than, the combined costs of fingerling purchase and feed under concurrent culture conditions, with fingerling costs accounting for nearly 40% of this production cost. Overall, this study demonstrates that semi-intensive rice-fish culture of climbing perch is feasible in terms of fish production; however, further optimization of culture conditions is necessary to sustain both fish and rice yields at higher stocking densities. Specifically, extending the culture duration and/or improving fish growth performance are necessary to enhance profitability.

Hermit Crabs of the Family Diogenidae Ortmann, 1892 (Crustacea: Decapoda: Anomura) in Indonesia: Diversity, Distribution and Habitat

Tyani Fitrian — 2026-04-30

Hermit crabs of the family Diogenidae are ubiquitous organisms along the coasts of the Indonesian archipelago. This study aims to contribute additional data to enhance the current understanding of the geographical distribution patterns, bathymetric distribution, and habitat preferences of diogenid hermit crab species within the framework of Indonesia’s marine ecoregions. Distributional data of Diogenidae in Indonesian waters were obtained from scientific literature, dissertations, and unpublished Museum Zoologicum Bogoriense (MZB) specimen data. The diversity analysis of the family Diogenidae in Indonesia identified 116 species in 13 genera. These hermit crabs are widely distributed throughout the country, occurring in all 12 previously defined marine ecoregions. They are found across a broad depth range, and most species are found in more than one substrate such as rocky shores, sand flats, and muddy bottoms, as well as ecosystems including seagrass beds, mangroves, and coral reefs. Seventy percent of species inhabit the littoral zone, which extends from 0 to a depth of 50 m. Among the species studied, Paguropsis andersoni exhibited the broadest vertical distribution, ranging from the littoral zone down to the bathyal zone, with recorded depths between 30 and 548 m. The genera Diogenes and Clibanarius comprise the highest number of species, with 27 and 26 respectively. Among the ecoregions analyzed, the Banda Sea shows the greatest species richness, with a total of 66 identified species of Diogenidae. The most commonly found species in Indonesian waters is Clibanarius striolatus.

Enhancing Water Quality in Intensive Asian Seabass (Lates calcarifer) Aquaculture Using Green Mussels (Perna viridis): A Biomass‒Normalized Apparent Reduction

Roongparit Jongjaraunsuk — 2026-04-30

Integrated multi‒trophic aquaculture (IMTA) is a promising strategy to mitigate water quality deterioration in intensive marine aquaculture, although continuous water renewal may obscure the role of extractive species. This study evaluated green mussel (Perna viridis) integration with Asian seabass (Lates calcarifer) under simulated marine IMTA conditions. A 60-day experiment with four mussel biomass treatments was conducted at constant seabass density, with routine water exchange (50% every three days). Key water quality parameters, including dissolved oxygen (DO), temperature, power of hydrogen (pH), salinity, total ammonia nitrogen (TAN), nitrite‒nitrogen (NO₂^-‒N), nitrate‒nitrogen (NO₃⁻–N), alkalinity (ALK), total suspended solids (TSS), and turbidity, were monitored throughout the experiment. Asian seabass growth performance, survival, and biomass production were also assessed. Mussel‒integrated treatments showed significantly lower concentrations of ALK, TAN, TSS, and turbidity, along with higher NO₃⁻–N, compared with the control (p<0.05), whereas DO, temperature, pH, NO₂^-‒N, and salinity did not differ significantly among treatments. Despite identical water‒exchange regimes, the presence of mussels contributed to improved water quality stability. Fish growth, survival, and biomass production were enhanced in mussel‒integrated systems, particularly at intermediate to high mussel biomass. These results demonstrate that green mussels can enhance water quality and production performance in intensive Asian seabass culture beyond the effects of routine water exchange alone, supporting the application of biomass‒based IMTA as a practical approach for sustainable marine aquaculture.

Effect of Salinity Differences on Growth and Chlorophyll a Content in Caulerpa racemosa

Firdha Pebrian Nissa — 2026-04-30

Caulerpa racemosa (sea grapes) is a commercially valuable green macroalga widely cultivated in Indonesia for its nutritional and economic potential. Salinity is among the most critical environmental factors governing its growth and photosynthetic pigment production, yet the optimal salinity range for Indonesian pond cultivation systems remains poorly defined. This study aimed to determine the effect of different salinities on the growth and chlorophyll a content of C. racemosa and to identify the salinity level that best supported its growth and chlorophyll a content. This study used an experimental method with a Completely Randomized Design (CRD) consisting of four treatments and three replications: S24 (24 ppt), S27 (27 ppt), S30 (30 ppt), and S33 (33 ppt). The C. racemosa cultivation system used the off-bottom method, with an initial weight of 50 g and a water volume of 12 L and was maintained for 43 days. The collected data included morphological observations, absolute growth, specific growth rate (SGR), chlorophyll a content, and water quality. The results showed that salinity had a significant effect (p<0.05) on absolute growth, SGR, and chlorophyll a content, with the highest values observed in treatment S27. Based on the study, the S27 treatment (27 ppt) produced the highest absolute growth (133.28±16.26 g), SGR (3.01±0.21 %·day⁻¹), and chlorophyll a content (452.16±0.19 µg·mL⁻¹), indicating that maintaining salinity around 27 ppt can optimize physiological performance and enhance biomass yield in C. racemosa cultivation.

Aquafeed Innovation: Utilization of Insects for Sustainable Fish Nutrition: A Review

Hesham Abozaid — 2026-04-01

Rapid global population growth has increased food demand, placing pressure on conventional agriculture and highlighting the need for sustainable protein sources. Aquaculture contributes significantly to global food security by supplying animal protein, yet its expansion is constrained by the high cost and environmental impact of traditional feed ingredients such as fishmeal and soybean meal, which are associated with overfishing and deforestation. These challenges have encouraged the exploration of alternative, environmentally responsible feed resources. Insects have emerged as a promising ingredient in aquaculture diets due to their high-quality protein, balanced amino acid profile, and beneficial lipid composition. Insect-based meals offer economic advantages while reducing reliance on conventional feed sources, potentially improving both sustainability and resource efficiency within the sector. This review evaluates the nutritional benefits and environmental implications of incorporating insect-derived ingredients into aquafeeds and examines their potential to enhance sustainable aquaculture production. The review also discusses key barriers to large-scale adoption, including regulatory limitations, cultural acceptance, production scalability, and logistical challenges. Safety considerations such as microbial risks, allergenic potential, and the accumulation of undesirable substancesare analyzed within current regulatory frameworks. Additionally, existing knowledge gaps, species-specific responses, digestibility concerns, and optimal inclusion levels are addressed, alongside consumer perception and market acceptance. Overall, continued research, investment, and supportive policy development are essential to facilitate the integration of insect-based feeds into mainstream aquaculture. Advancing these efforts can support environmentally sustainable aquaculture practices while helping meet the growing global demand for protein.