A new conceptual framework based on satellite data, including chlorophyll (CHL), sea surface temperature (SST) fronts, relative winds, current vectors, Ekman transport, and eddies, has been developed to identify potential fishing zones (PFZ) in the Bay of Bengal (BoB). The framework aims to provide persistent forecasts, even under cloudy conditions, based on feature propagation. The validation of the PFZ was carried out using fish catch data collected by the Fishery Survey of India (FSI) between 2016 and 2018. Hooking rates (HR) from longlines and catch per unit effort (CPUE) from trawl nets were used to analyse the data points in hook rate categories (1.0–3.0 and > 3.0) and CPUE categories (50–100 kg and > 100 kg) and interpret them with the PFZ maps. The analysis showed that the high fish catch locations were consistent with persisting features in the BoB, such as high chlorophyll patches, SST fronts, and cyclonic eddies. The high fish catch locations based on hook rate and high CPUE were found to be collocated with the high chlorophyll persisting features and thermal gradients in the BoB. The regression analysis shows that availability of the food (CHL) had the strongest correlation with fish catch, followed by the comfort condition (fronts and eddies).

Read more...

Studies on elasmobranch trade have often focused on a single commodity, shark fins. Such a narrow focus can result in an incomplete understanding of the socio-cultural importance of sharks, limiting discussion on the range and efficacy of potential management interventions. Assessments must be performed across the value chain from fisher to retail vendor to better conserve vulnerable elasmobranch species, offering a broader view of capture, use, and trade. Here, we collate insights from shark value chain assessments conducted in eight countries (Mexico, Peru, Guinea-Bissau, India, Bangladesh, Sri Lanka, Indonesia and Fiji) spanning five continents. Approaches and processes implemented in a shark value chain analysis (VCA) were reviewed to: (1) understand better approaches and tools and (2) collate shared experiences. Our results demonstrate that VCAs broaden the outlook of fishery and trade assessments when capturing a more comprehensive range of economic and socio-cultural aspects (e.g., livelihoods, cultural use of commodities) of trade in all shark commodities. Time invested in various components of assessments produced different outcomes, with considerable returns from stakeholder selection, survey design, and assessor/stakeholder relationship building. Contrastingly, results demonstrated that efforts in communication with stakeholder groups and policymakers could be further streamlined to focus on key results using a variety of communication formats. Outcomes from this study offer guidance to those embarking on shark VCAs, facilitating improving the assessment process and outcomes.

Read more...

Nemipterus randalli, commonly known as Randall’s threadfin bream, is a commercially important marine finfish. Understanding its genetic structure is critical to effective management and conservation efforts. Previous investigations on population structure in this species were limited by geographic coverage. In this study, we utilized the mitochondrial Cytochrome b gene and nuclear Ribosomal protein gene intron Rp S7 sequences to investigate the population genetic structure, demography and genetic diversity of N. randalli along Indian waters. Our results revealed high haplotype diversity but low nucleotide diversity. AMOVA revealed that the variation among the population was highly significant. Hierarchical AMOVA provided further evidence of significant genetic differentiation between the west and east coasts, which was corroborated by the Bayesian tree and the median-joining network diagram. The mtDNA sequences revealed significant genetic structure between populations based on fixation index analysis following the isolation-by-distance model. Furthermore, the neutrality test and mismatch analysis suggest that N. randalli populations may have experienced a population expansion. However, nuclear marker RpS7, showed a high level of polymorphism, which obscured the population structuring observed with the mitochondrial marker. Consequently, concordant results were not obtained when comparing the mitochondrial and nuclear DNA sequences. The strong genetic differentiation between the east and west coast observed using mitochondrial marker could be attributed to a combination of geographic and environmental factors. These findings lay the groundwork for developing effective conservation and management strategies for N. randalli, considering its genetic structure.

Read more...

Artisanal fishers fishing in nearshore coastal waters off Visakhapatnam using motorised crafts and in estuaries of Krishna using non-motorised crafts were selected for the study. Their annual net operating income varied between US$ 469.63 (?39,040) and US$ 2698.42 (?2,24,320), respectively. Inspired by the potential of cage farming from the frontline demonstrations in marine and estuarine waters and after acquiring appropriate skills, 15 individuals from the Traditional Fishermen’s Co-operative Society, Visakhapatnam and 76 individuals from Yanadri Girijana Matsya Sakhara Sangam, Krishna embarked on cage aquaculture of Indian pompano in 15 and 70 cages, respectively. Marine cages were circular (6 m diameter) and estuarine cages were square (5 m X 5 m), and were stocked with hatchery-produced Indian pompano (Trachinotus mookalee) fingerlings of 22.6 g weight @ 2500 and 1500 numbers respectively, and were fed with floating pellets at 8-3% of biomass. Average body weight, survival and biomass production from marine and estuarine cages after eight months of culture were 843 and 666 g, 96.28 and 91.47% and 2029.0 and 913.85 kg respectively. Deducting all capital and operational expenses, annual net operating income per unit ranged from US$ 1247.44 (?1,03,700) to US$ 2632.02 (?2,18,800); which represented a substantial increase from that of capture fishery. Cluster-cage farming, as adopted, did not adversely impact the water and sediment quality. The current research offers novel insights into the bio-growth and economic factors pertinent to commercial cage farming of Indian pompano. Cage farming in marine and estuarine conditions holds a great promise as an alternative source of livelihood for artisanal fishers, thereby bolstering their economic sustainability.

Read more...

Deep investigations of host-associated microbiota can illuminate microbe-based solutions to improve production in an unprecedented manner. The poor larval survival represents the critical bottleneck in sustainable marine aquaculture practices. However, little is known about the microbiota profiles and their governing eco-evolutionary processes of the early life stages of marine teleost, impeding the development of suitable beneficial microbial management strategies. The study provides first-hand mechanistic insights into microbiota and its governing eco-evolutionary processes in early life stages of a tropical marine teleost model, Trachinotus blochii.

Read more...