Journal of Fisheries

Effect of ploidy on growth, fillet composition and colour of large rainbow trout (Oncorhynchus mykiss) in the Black Sea

2024-04-24T08:02:24+00:00

The purpose of this study was to determine the growth performance and fillet quality parameters of large rainbow trout (Oncorhynchus mykiss) and of different ploidy (diploid-DTS and triploid- TTS) cultured in the Black Sea. This study was carried out in a commercial fish farm in Sinop, Black Sea of Turkey. Triploid groups had a higher weight and a better feed conversion rate than the DTS at the end of the 150-day study. Crude protein and crude fat ratios were respectively higher in the DTS and TTS groups; while ploidy affected the biochemical and fatty acid compositions of the large rainbow trout, it had no effect on the amino acid compositions. The colour of fillets was affected by the crude fat ratio of the fillet. This study indicated that large rainbow trout produced in the Black Sea, regardless of its ploidy, were of high quality, nutritious and healthy for human consumption. Furthermore, it demonstrated yet again that large rainbow trout is of sufficient quality to compete with other salmonid species in the national or international markets.

Stocking density optimisation for gulsha, Mystus cavasius farming in pond under drought prone area of Bangladesh

2024-04-24T08:02:30+00:00

Lack of appropriate stocking density is the constraint for aquaculture promotion of a potential species like gulsha, Mystus cavasius in ponds under drought prone area. With a view to addressing this problem, three different densities 98800, 123500 and 148200 gulsha individuals ha^–1 were tested under three treatments (T₁, T₂ and T₃) in ponds under Paba Upazila of Rajshahi district, Bangladesh. Treatments were replicated thrice. Hatchery produced gulsha seeds were grown for a period of six months from July – December 2021 with commercial feed containing 35% protein. Water quality and fish growth were monitored fortnightly. Significantly (p < 0.05) lowest value of dissolved oxygen and highest values of carbon di-oxide and ammonia-nitrogen were observed in T₃. Significantly lowest values of final weight, weight gain, specific growth rate and survival rate were also observed in T₃. However, significantly (p < 0.05) highest yield and cost-benefit ratio were obtained in T₂.

Factors affecting abundance and primary productivity of phytoplankton in a wetland ecosystem of Bangladesh

2024-04-24T08:02:40+00:00

Wetlands are the most productive, economically important and hydrologically variable ecosystems. In this study, the abundance of phytoplankton and its primary productivity were evaluated in Dingapota Haor of Bangladesh. A total of 41 phytoplankton genera belong to Chlorophyceae (15), Bacillariaophyceae (14), Cyanophyceae (8) and Euglenophyceae (4) were recorded whereas Bacillariaophyceae (37.02%) was the most dominant. The highest cell density (22.71×10⁴ cell L^–1) was recorded in pre-monsoon. Diversity indices were also significantly higher in pre-monsoon. The species diversity, evenness and richness varied from 2.51–3.79, 0.57–0.90 and 4.65–7.50 respectively. Difference in phytoplankton assemblage with an overall average dissimilarity value of 52.56 % was recorded. Cyclotella (3.60%), Bacillaria (3.13%), Volvox (2.95%), Spirulina (2.92%) and Euglena (2.88%) were the five most contributory species to the seasonal variation. Gross Primary Production, Net Primary Production and Community Respiration values ranged from 0.90–2.49, 0.68–1.60 and 0.35–0.89 mgCm^–3day^–1 respectively. Alkalinity and Chl-a showed significant positive correlation with GPP, NPP and CR. Pre-monsoon was the most productive phase whereas the monsoon season was the least productive. The current study produced valuable baseline data that will aid in the formulation of wetland conservation and management strategies.

Sustainability of the hookah diving fishery in Turkey

2024-04-24T08:02:45+00:00

Hookah diving is a traditional fishing method based on the hand collection of commercial benthic organisms. Fishers continue their profession without paying attention to their physical health and psychophysical fitness. Ignoring the diving safety and decompression rules underwater, using improvised diving systems, and economic concerns carry risks that can result in death. The long-term sustainability of work depends on nations’ ability to control fishing practices and promote good management. This study discusses the current situation of hookah divers in Turkey based on official statistics from the ministry and face-to-face interviews with hookah divers. The data were subjected to strengths, weaknesses, opportunities, and threats (SWOT) analysis and synthesised with the literature for strategic analysis. The sector’s contribution to the national economy, economic satisfaction of divers, and supporting rural employment were evaluated as strengths. Lack of expertise in the professional career and complex laws were identified as threats that require urgent solutions. Multidirectional national efforts are needed for sustainable fishing, including stakeholder networking, diving safety, hookah equipment, underwater fishing strategies, training curricula and professional career development. Our findings offer strategic and planning approaches for the sustainable development of hookah diving in Turkey.

Morphological relationships, growth patterns and some aspects of reproductive biology of Sind Danio Devario devario (Hamilton 1822)

2024-04-24T08:02:35+00:00

This study examined the morphological relationships, growth population factors and reproductive biology of Devario devario collected from the Atrai River of Dinajpur, Bangladesh, for sustainable management and conservation aspects. The length-weight relationships (LWRs) commonly indicated the isometric growth. The Fulton’s condition factor (CF_f) and relative body weight (BW_r) varied across sexes. A positive correlation was found in length-length relationships (LLRs); among total length (TL), standard length, head length and fork length. The asymptotic lengths were 7.5, 7.2 and 7.5 cm, with growth rates of 0.78‒1.8, 0.6‒3.4 and 1.8‒3.6 year^–1 while total mortality was 1.22‒3.06, 0.97‒7.07 and 3.70‒6.09 year^–1; fishing mortality was –0.87 to –1.04, –0.97 to 1.09 and –0.05 to –0.23 year^–1; natural mortality was 2.26–3.93, 1.94–5.98 and 3.93–6.14 year^–1 for female, male and combined sexes respectively. The highest probability of capture (L₅₀) was 5.74‒6.15 cm. The gonado-somatic index ranged from 32.75±1.82 to 44.12±2.73, with a peak in April to May. Fecundity was recorded from 3253±289 to 4831±342, with a significant correlation among TL, BW, gonad length (GL) and gonad weight (GW). These initial findings on D. devario will serve as the basis for future research and management.