AQD Journal Articles

Effect of season, culture system, and stocking density on growth performance and limb loss in blue swimming crab (Portunus pelagicus) from instar to early juvenile stage

Tue, 20 May 2025 00:00:00 GMT

Effect of season, culture system, and stocking density on growth performance and limb loss in blue swimming crab (Portunus pelagicus) from instar to early juvenile stage Lames, Jenalyn; Traifalgar, Rex Ferdinand; Parado-Estepa, Fe D.; Estante-Superio, Erish; Santander-Avancena, Sheryll; Balinas, Vicente T. The study investigated the growth, survival rates, and limb loss occurrence of blue swimming crabs (BSC), Portunus pelagicus from crab instar to the early juvenile stage at different culture systems (outdoor tanks, net cages in ponds, and net cages in pens), and varying stocking densities (30, 50, and 100 individuals/m²). These variables were assessed during the wet and dry seasons for 21 days following a 2 × 3 × 3 factorial design. Survival showed a significant interaction between culture systems and seasons (p < 0.001). However, no significant differences were found between culture systems and stocking densities, or between stocking densities and seasons (p > 0.05). Results showed that pond and pen systems, particularly at moderate densities (30–50 individuals/m²), yielded significantly higher growth, survival, and biomass production compared to tank systems (p < 0.05). Survival rates were significantly higher in ponds (76.69% ± 2.58) than in pens (54.97% ± 2.10), and tanks (38.32% ± 4.61). Moreover, BSC juveniles exhibited limb loss (%) ranging from 11.43% to 35.17%, with loss of a single limb being the most common, occurring in 49–70% of the crabs. Overall, the study recommends the use of pond and pen systems with moderate stocking densities for optimal nursery production of P. pelagicus, contributing valuable insights for improving aquaculture protocols and supporting stock enhancement initiatives toward sustainable fisheries.

The impact of indoor biofloc-based system on water quality, growth, and disease resistance of black tiger shrimp

Wed, 01 Oct 2025 00:00:00 GMT

The impact of indoor biofloc-based system on water quality, growth, and disease resistance of black tiger shrimp Estante-Superio, Erish; de la Peña, Leobert D.; Geanga, Therese Marie M.; Castellano, Jose Louis A.; Cordero, Christian P.; Berlin, Sharmen C.; Lazado, Carlo C. The present study investigates the efficiency of an indoor biofloc-based system for the intensive culture of black tiger shrimp (Penaeus monodon). Water quality, growth performance, and disease resistance of black tiger shrimp (0.35 ± 0.07 g) were evaluated after 90 days of rearing in a zero-water exchange system. Shrimp were stocked at 180 individuals/m³ in nine 5-ton concrete tanks under three treatments: biofloc with molasses (M), biofloc with wheat flour (WF), and a control group reared in a conventional clear water (CW) flow-through system. The WF treatment resulted in significantly higher final weight and improved FCR compared to CW (p < 0.05). Survival was also significantly higher in both biofloc-based treatments despite elevated concentrations of total ammonia nitrogen, nitrite-nitrogen, and nitrate-nitrogen levels in the WF group (p < 0.05). Additionally, Kaplan–Meier survival analysis indicated that shrimp reared and challenged in the biofloc system exhibited better resistance to Vibrio parahaemolyticus (VP_AHPND1212), as evidenced by higher survival rates. Although total hemocyte count, prophenoloxidase, and respiratory burst activities were not significantly different from the control group (p > 0.05), they were consistently elevated in the biofloc-based treatments. Overall, biofloc-based treatments, specifically WF, proved effective in biofloc formation, contributing to improved water quality, enhanced immune response and disease resistance, and superior growth performance in P. monodon. This study highlights the potential of indoor biofloc systems as a sustainable strategy for intensive P. monodon culture in indoor biofloc tanks.

Effects of seawater temperature fluctuations on local communities through kelp production in the Pacific coastal area of eastern Hokkaido, Japan

Mon, 01 Jan 2024 00:00:00 GMT

Effects of seawater temperature fluctuations on local communities through kelp production in the Pacific coastal area of eastern Hokkaido, Japan Ito, Sayaka; Kuroda, Hiroshi; Onitsuka, Toshihiro; Hasegawa, Natsuki; Fukuda, Hiroki; Shirafuji, Norio Data on the landing value for each of the eight fisheries commodities in small-scale coastal fisheries in Nemuro City was collected and analyzed to understand the importance of kelp fishery in local communities along the Pacific coast of eastern Hokkaido. Over the past 25 years from 1991 to 2015, a trend in small-scale coastal fisheries in the region has significantly varied. However, in all year groups, the landing value of the kelps accounted for about 40% of its total value, indicating no significant change in its importance. The kelp fishery always has a profit center within the small- scale fisheries operations in the region. The influences of seawater temperature and the physical environmental factors of the seafloor on kelp production were investigated using GIS. Mean seawater temperatures in July, September, and October of the year before the harvest negatively correlated with the kelp harvest in Nemuro City from 2006 to 2014. The kelp length was mainly explained by the water temperatures in September and July of the year before the harvest, bottom current velocity, and water depth. These results indicate that the water temperature during summer and the seafloor physical environment have significant effect on kelp growth. Recent increases in seawater temperature along the Pacific coast of eastern Hokkaido during summer would significantly impact the local socio-economy through reduced kelp production.

Investigating stocking density, culture duration, and the combination ratio of artificial feed and fresh feed for mangrove crab Scylla serrata megalopae reared in pond-based net cages

Tue, 01 Apr 2025 00:00:00 GMT

Investigating stocking density, culture duration, and the combination ratio of artificial feed and fresh feed for mangrove crab Scylla serrata megalopae reared in pond-based net cages Caballero, Pedrita; Alava, Veronica R.; Regatalio, Kyle Dymer; Dayrit, Rheniel; Faisan, Jr.; Mamauag, Roger Edward; Maceren-Pates, Mercedes; Pates, Gaudioso S., Jr. To address the crablet supply shortage for grow-out ponds, two experiments were conducted. The first aimed to identify the optimal combination of stocking density (SD) and culture duration (CD), while the second utilized this combination to determine the most effective ratio of artificial feed (F) to mussel meat (M) for nursery rearing of mangrove crab (Scylla serrata) megalopae into crablets. Each pond-based net cage (1 m² area) was provided with 1 unit each of shelter and feeding tray. The first experiment assessed four SDs (50, 100, 200, and 300 ind.m⁻²) at two CDs (3 and 4 weeks). Results showed that crablets at 50 ind.m⁻² had carapace width (CW) of 17.3 mm and final body weight (FBW) of 0.65 g after 4 weeks while the highest specific growth rate (SGR) of 19%/day was observed at 3 weeks. Although survival rates were higher (80–84%) at SD 50, 100, and 200 ind.m⁻², a higher final harvested number of crablets was achieved at higher SD 200–300 ind.m⁻² of 162 and 215 ind.m⁻², respectively. Using the SD 200 ind. m⁻², the second experiment evaluated 50F:50 M, 70F:30 M, 80F:20 M, and 100F alone on megalopa reared for 3 weeks. Results indicated that the 70F:30 M treatment obtained the highest SR of 69.9%, FBW of 0.28 g, CW of 12 mm, and SGR of 21.33%/day (p > 0.05). Our results indicate that a SD of 200–300 ind.m² and a feed ratio of 70F:30 M for 3 weeks are recommended for optimal growth and maximizing crablet production of Scylla serrata megalopae in nursery rearing.