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The majority of tropical fish stocks lack sufficient data for conventional fish stock assessment, making them data-poor fisheries. The status of stock assessment is even more dismal for the low value fishes or crustaceans landed by the trawlers in a significant quantity. Crustaceans like non-edible small crabs (Charybdis spp) and stomatopods form a significant component of the low-value bycatch landed along the northwest coast. Despite the high ecological importance of these groups and the recent declining trend in catches (2007-19), no attempts so far have been made to evaluate the stock status of these groups from the study region. As reliable time series catch and effort data for the individual species are not available, a recently developed length-based approach, LBB (Length Based Bayesian Biomass) estimation method is adopted for the present study. Two of the evaluated stocks, Charybdis hoplites and Miyakella nepa were found abundant (B/BMSY>1.1), whereas Oratosquillina interrupta (B/BMSY=0.94) was found slightly overfished. The sufficient number of larger individuals were found lacking in all three species (L95th/L∞<

Mud spiny lobsters, Panulirus polyphagus (Herbst, 1793), were reared at four different stocking sizes and stocking densities in open sea cages to evaluate their effects on growth performance. To evaluate the effect of stocking size on the growth performance, the lobsters were segregated into four different treatment groups according to size and were stocked at a density of 300 animals per cage. To evaluate the effect of stocking density on the growth performance, lobsters of 81–100 g were stocked in four different stocking densities, i.e. 16/m2, 24/m2, 32/m2 and 40/m2. The results showed that the growth rate of (60–80 g) size group, was significantly higher compared to the size groups, i.e. 101–120 g and 121–140 g comprising of larger individuals. The final body weight, though significantly higher in 81–100 g as compared to 60–80 g, the growth performance (i.e. weight gain percentage (WG %) and specific growth rate (SGR)) were not significantly different. The density‐dependent influence on growth performance was evident in this study. The WG % and SGR during 90 days’ culture period was significantly higher in 24/m2 compared to other groups. This study provides crucial information about the appropriate stocking density and stocking size of lobsters at the field level, which would help to promote sustainable lobster cage farming by maximizing the production potential of the system.

The mid-water multiday trawl fishery along the north-west coast of India generally targets adult largehead hairtail, Trichiurus lepturus. Bycatch landed by the commercial mid-water multiday trawlers operated from Veraval harbor during August 2017–December 2019 was investigated by analyzing catch composition with respect to its spatial and temporal patterns. A total of 834 bycatch sample observations from mid-water trawl fishery were examined. Bycatch comprises of 123 species and account for 53.36% of the total catch. Highest composition in bycatch comprises of teleosts (62.09%), cephalopods (35.88%), crustaceans (1.47%) and elasmobranchs (0.56%) respectively. Uroteuthis duvaucelii, Sepia elliptica, Nemipterus japonicus, Otolithes cuvieri, S. pharaonis, Priacanthus hamrur, Sepiella inermis and Saurida tumbil were the dominant species with high annual average catches; and together contributed 50.30% of total bycatch. Discards formed 6.32% of total catch and consisted of 62 species belonging to 29 families. The most common discards were juveniles of S. tumbil, N. japonicus, Platycephalus indicus, O. cuvieri, Johnius glaucus and T. lepturus. CPUE of bycatch differed significantly between the seasons with the lowest being in summer and highest in post-monsoon period. Minimum bycatch rates were observed in the offshore waters than inshore waters. Endangered, Threatened and Protected (ETP) species listed in CITES as well as IUCN were also observed. The present study revealed that quantities of bycatch landed off northwest coast of India in the Arabian Sea were relatively higher than that landed by mid-water trawlers operating in other parts of the world. Hence the mid-water trawl fishery operating in north-west coast of India and targeting largehead hairtail needs to be closely monitored to mitigate and reduce the quantity of bycatch landed by them.

Longtail tuna (Thunnus tonggol, Bleeker, 1851), the largest growing species among neritic tunas have a unique distribution pattern globally. Northern Arabian Sea together with the Oman Sea and Persian Gulf in the north-western Indian Ocean is considered to be the major area where the species is abundant and form sizeable fisheries globally. India has an artisanal tuna fishery and contributes nearly 10% of the longtail tuna landing in the region, with Gujarat alone contributing nearly 80%. The paper updates on the longtail tuna fisheries in the region with focus on the north-west coast of India together with its spatial characteristics. Clues on the areas of abundance of the species along Gujarat coast over the seasons and temporal movements of different ontogenetic stages in the shelf areas are revealed. The study sets prelude to a cost effective and participatory collection of spatially referred data on the artisanal and small scale fisheries in the region.

Longtail tuna Thunnus tonggol (Bleeker, 1851) is the major tuna resource in the neritic realms of the northern Arabian Sea and forms considerable fishery in the coastal nations in the region. Gujarat, on the north-west coast is the major province landing longtail tuna in India. The paper attempts to add to the hitherto sparse knowledge base on biology of the longtail tuna fished along the north-west coast of India, through a study spanning from 2011 to 2015. Reproductive biology, spawning, food and feeding dynamisms of the species were investigated. Sex ratio of the species was estimated as 1:2.1 and depicted an increase in male preponderance as the size increased. The fish attains maturity at 607 mm and it spawns during summer months starting from May. The fish is typically a non-selective feeder and over 22 taxa comprising of fishes, cephalopods and crustaceans formed the diet at varying rates over the year. Variation in feeding intensity at different reproductive stages is discussed besides the constraint posed by the large presence of unidentifiable, partially digested gut content.

The largehead ribbonfish, Trichiurus lepturus Linnaeus, 1758 forms a major fishery along north-west coast of India comprising the two coastal states of Gujarat and Maharashtra. Diet composition was analysed for five years (2010-2014) to understand shifts if any in the prey items. Seasonal changes in the prey items were studied for three years (2012-2014) to explore the temporal dynamics of prey availability in the ecosystem and in largehead ribbonfish guts. Feeding indices viz., Stomach fullness index (SFI), empty stomach ratio (ESR), gastrosomatic index (GaSI) and relative gut length (RLG) explained the feeding behaviour, seasonal dynamics and ontogenetic shifts in prey items. The Vacuity Index (VI) was estimated as 37.56%, indicating that T. lepturus is a carnivore and relatively edacious. Diet of T. lepturus comprised of fishes (47.16%), crustaceans (45.22%), molluscs (4.33%) and miscellaneous items (3.28%). Acetes sp. was the most dominant prey item during the study period. Feeding intensity was found to be high during the post-monsoon months which coincided with the period of gonadal maturation of the fish. Significant variations (pecology-based fishery management models/tools.