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).

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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.

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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.

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The sawtooth barracuda Sphyraena putnamae, widely distributed in the Indo-Pacific region, is one of the commercially important barracuda species exploited by trawls in the Indian EEZ. The present study examined 2,135 S. putnamae collected during 2014-2020 from different fish landing centres along the Indian coast, to elucidate their reproductive and feeding behaviour. The fork length of sampled females and males varied from 12.5 to 130.9 cm and 16.5 to 90.0 cm respectively. Negative allometric growth was observed with a significant difference (p<0.05) between the sexes. The observed sex ratio (Female:Male) was 1.23:1, indicating the dominance of females. Size at sexual maturity for females and males were estimated at 55.3 and 45.4 cm fork length respectively. The higher proportion of spawning capable individuals and higher gonadosomatic index (GSI) values in females observed during March to May and November-December revealed the bimodal and protracted spawning nature of this species. Absolute fecundity increased with fork length and weight and varied from 70,080 to 10,18,068 oocytes with an average of 3,16,568 oocytes. The stomach vacuity index of females and males was 49.09 and 47.92% respectively. Fifty-nine prey items were identified in the diet, with a predominance of fishes confirming S. putnamae has a piscivorous feeding behaviour.

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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.

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