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

2025-09-03T14:39:57+07:00

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

2026-02-23T15:49:49+07:00

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

2025-12-17T15:53:35+07:00

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.

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

2025-10-16T14:45:03+07:00

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.