Journal of Fisheries

Assessing shellfish harvesting and stakeholder perspectives on trade in Bangladesh’s largest wetland

2025-11-12T06:45:48+00:00

The trade of freshwater shellfish is growing but has received insufficient attention from researchers. In this study, we examined various aspects of shellfish harvesting (catch amount and composition, socio-economic profiles of shellfish collectors, distribution channels and perceptions of major stakeholder groups) over a six-month period (October 2023 to March 2024) in the largest wetland of Bangladesh, the Chalan Beel. The daily shellfish catch was higher during the low-water period (October – December; 10.7 ± 3.3 kg person^–1) than during the dry period (January – March; 0.6 ± 0.2 kg person^–1) (t-test: t = –32.4, p < 0.001). Catch composition varied significantly across groups (ANOVA: F = 10823, p < 0.001). Freshwater snails (primarily Pila globosa) contributed the most (70.1%) to the total catch, followed by mussels (primarily Lamellidens marginalis; 19.7%) and crab (Cancer pagurus; 10.2%). Three key actor groups involved in shellfish distribution were crab collectors, traders and consumers. Most collectors (65%), traders (54%) and consumers (89%) disagreed that shellfish are an important component of the aquatic environment. All traders and 96% of collectors agreed that shellfish collection and trade are profitable, whereas all consumers maintained a neutral standpoint. All consumers agreed that shellfish are good food, while the majority of collectors (93%) and traders (93%) remained neutral. Additionally, all consumers and most collectors (67%) and traders (73%) supported harvesting shellfish from other aquatic ecosystems. The results of this study are expected to be useful in formulating appropriate policies for wetland and resource management.

Optimising feed management for green tiger shrimp (Penaeus semisulcatus) in a biofloc system: impacts on growth performance, body composition and antioxidant activities

2025-11-11T06:46:03+00:00

This study conducted over a 45-day period examined how different feeding strategies affect green tiger shrimp (Penaeus semisulcatus) development in biofloc aquaculture systems. The investigation focused on juvenile shrimp with an initial mean weight 2.85 ± 0.22 g, distributed across various experimental conditions. Five distinct treatment groups were considered, each consisting of tanks with a volume of 150 L of filtered seawater. Each tank was stocked with 53 shrimp, maintaining a stocking density of ~1 g L^–1. Four groups utilised biofloc technology (BFT) with varying feeding levels: 0% (BFT0), 2% (BFT2), 4% (BFT4) and 6% (BFT6) of body weight per day. One additional group served as control, using a clear water system with feeding level of 6% (CW6) body weight daily. The BFT systems successfully maintained optimal water parameters despite minimal water exchange requirements. Performance metrics indicated that shrimp in the BFT4 and BFT6 groups achieved higher biomass production and survival rates. Biochemical analyses demonstrated enhanced nutritional profiles (protein, lipid and ash) in BFT-treated specimens. Antioxidant enzyme activity was significantly elevated in BFT systems, indicating improved overall health status. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities were significantly higher in BFT groups than control. These findings suggest that feeding juvenile green tiger shrimp at 4% body weight within a BFT system represents an optimal strategy, achieving balanced growth performance while maintaining superior water quality and enhanced animal health indicators without compromising survival rates or body composition.

First report of Halimeda magnicuneata Verbruggen & Dumilag 2020 from the northern coast of Sri Lanka

2025-11-11T06:46:21+00:00

The genus Halimeda is a group of calcifying green algae that play a crucial role in sediment production and reef stabilisation. During a field survey in November–December in Mathagal, Northern Sri Lanka, the previously unreported species Halimeda magnicuneata was identified. This marks the first record of the species in Sri Lankan waters and was confirmed through morphological analysis, segment cross-sections and comparisons with established taxonomic descriptions. The collected specimens had segment widths of 8–21 mm (mean 13.1±4.6 mm), lengths of 9–17 mm (mean 9.9±3.8 mm) and thicknesses of 0.50–1.25 mm (mean 0.75±0.31 mm). The holdfast measured 4–8 mm (mean 6.17±2.02 mm), with an overall algal height of 95–110 mm (mean 102.3±7.51 mm). The branching pattern was dichotomous, a typical characteristic of the genus. The species was found attached to coral rubble in shallow waters (~3 m depth). The microscopic view of segment surface showed hexagonal cells with thick cell walls and cross-section of segment revealed medulla and cortex which consists of layers of primary and inflated secondary utricles. These microscopic characteristics further authenticated the species identification. The present finding contributes to the growing knowledge of the region’s marine biodiversity and highlights the importance of continuous biodiversity assessments. The documentation of H. magnicuneata underscores the need for further studies on its ecological interactions, distribution patterns and response to environmental changes.

Spawning dynamics and maturity patterns of the Indian squid, Uroteuthis (Photololigo) duvaucelii (A. d'Orbigny, 1835), along the southeastern coast of India

2025-11-11T06:46:41+00:00

Uroteuthis (Photololigo) duvaucelii (A. d’Orbigny, 1835), is an economically important squid species along the southeastern coast of India. This study presents a comprehensive analysis of its reproductive biology, based on the specimens collected during an exploratory fishery resources survey in the region. The results provide valuable insights into the reproductive patterns of this important fishery resource. The overall sex ratio was 0.9:1 (Male:Female), indicating a predominance of females over males. The length at 50% maturity (L₅₀) was estimated at 138 mm dorsal mantle length (DML) for Males, and 118 mm for females, showing that females tend to mature earlier. Observation of maturity stages revealed that sexually mature (stage V) males and females were found throughout the year, with a reproductive peak in April, though no spent individuals were observed during the study. The maximum number of total eggs recorded in the ovary was 69,629 with 841 mature ova. Potential fecundity ranged from 544 to 20,865 eggs, with an average of 9,114. Relative fecundity (RF) value ranged from 8 to 115, while potential reproductive investment (PRI) values ranged from 0.01 to 0.196. The maximum egg weight was observed between 1.6 and 1.7 mg. Histological examination of the ovary and oviduct (stages IV and V) confirmed that this species follows an iteroparous spawning strategy, characterised by multiple spawning events throughout the year.

Effects of carbon sources on production performance, enzymatic efficiency and biochemical indices of Nile tilapia under biofloc culture system

2025-11-11T06:47:10+00:00

Biofloc technology (BFT) is a sustainable aquaculture system based on the principle of nutrient recycling. This study evaluated the effects of starch, molasses and corn flour as carbon sources on water quality, growth performance, proximate body composition, hematological indices, immune responses and antioxidant status of Nile tilapia in biofloc system. A 12-week trial was conducted with juvenile Nile tilapia (25.3 ± 0.6 g), which were randomly assigned to four treatments. The treatments were BFT with corn flour (BFT+CF), molasses (BFT+M), starch (BFT+S) and a control group. Physicochemical parameters of water were affected by the carbon sources but remained within the optimal range for tilapia culture, with the highest biofloc volume (34.1 mL L^–1) observed in BFT+M. Growth performance was significantly increased in BFT+M, which yielded the superior weight gain (125 g), survival rate (99.03%) and the lowest feed conversion ratio (17.1). Proximate analysis revealed the highest crude protein levels in fish reared under BFT+M and BFT+S. Hematological parameters (hematocrit, hemoglobin, WBCs and RBCs) and non-specific immune responses (albumin, globulin, immunoglobulin and lysozyme activity) were significantly improved in BFT+M and BFT+S groups compared to the control. In conclusion, the supplementation of biofloc system with molasses and starch as carbon sources significantly improved growth performance, hematology, immunity and antioxidant capacity of Nile tilapia.