Indian Council of Agricultural Research
CENTRAL MARINE FISHERIES RESEARCH INSTITUTE

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Holistic Approach to Upwelling and Downwelling along the South-West Coast of India

An attempt has been made to develop a holistic understanding of upwelling and downwelling along the south-west coast of India. The main objective was to elucidate the roles of different forcings involved in the vertical motion along this coast. The south-west coast of India was characterized by upwelling during the south-west monsoon (May to September) and by downwelling during the north-east monsoon and winter (November to February). The average vertical velocity calculated along the south-west coast from the vertical shift of the 26 ?C isotherm is 0.57 m/day during upwelling and 0.698 m/ day during downwelling. It was concluded that upwelling along the south-west coast of India is driven by offshore Ekman transport due to the alongshore wind, Ekman pumping, horizontal divergence of currents and by the propagation of coastally trapped waves. Whereas downwelling along the coast is driven only by convergence of currents and the propagation of coastally trapped Kelvin waves. Along the west coast of India, the downwelling-favorable Kelvin waves come from the equator and upwelling-favorable waves come from the Gulf of Mannar region.


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Captive maturation, breeding and seed production of Pink ear emperor in recirculating aquaculture system

Pink ear emperor, Lethrinus lentjan (Lacepede, 1802), belonging to the family Lethrinidae (oder: Perciformes) is an important food fish in India, Arabian Gulf and other South East Asian countries. The present communication gives detailed information on its captive broodstock maturation in RAS, natural spawning, larval rearing and seed production for the first time. Fertilized eggs (714.21 ±11.91 ?) were transparent, pelagic, non-adhesive with single oil globule (146.63± 3.51?). Green water system was used for larval rearing. Size of hatchling ranged from 1355.1 ? to 1534.6 ? and mouth (110 - 148.2 ?) opened on 2nd dph . Larvae were reared using copepods, rotifer, artemia and micro diet. Squamation and intense pigmentation on the body began by 22 dph and by 25-30 dph larvae started moving from pelagic to benthic realm. Larvae became juvenile (length - 19.2 mm; weight - 0.096 g) after 35 dph resembling the adult fish colourations and by 46 dph, they attained an average body length of 27.83 mm and average body weight of 0.276 g. Fishes spawned throughout the year in RAS without any hormonal manipulation. Average percentage survival at seed stage was 2.85 ±1.41.


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Seasonal and positional variations in the rate of nacre coating in Indian pearl oyster Pinctada fucata

Recently technology has been perfected for the production of quality image pearls (mabe pearls) in India which fetches a good price ranging from $20-50 per pearl. This study focused on variations in the rate of nacre coating during different seasons when implanted with image pearl nucleus in different positions of the pearl oyster shell. The implantation was done at three positions at P1, P2 and P3 in both shells and the experiments were repeated in three seasons namely pre monsoon, monsoon and post monsoon. Among the positions, the position P2 which is the wide marginal mantle region gave the maximum nacre coating rate. Hydrological parameters such as atmospheric and water temperature, salinity, pH, turbidity, ammonia, nitrite, nitrate, phosphate, silicate, dissolved oxygen, primary productivity and chlorophyll a were also recorded during the study. Rate of nacre coating was found to be maximum (6.79 ± 2.07 ?/ day) during post monsoon months corresponding to maximum productivity (Net Primary Production of 204.40 ± 45.86 mgC/m3/day and Gross Primary Production of 361.40 ± 96.92 mgC/m3/day) and chlorophyll concentration (2.79 ± 0.13 mg/m³). The rate of coating was minimum (2.19 ± 0.17 ?/day) during pre monsoon season. The influence of hydrological parameters and positions of the implanted nuclei on the nacre coating were statistically analysed and discussed in the present paper.


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Larval development and growth of Red Saddleback Anemonefish under captive conditions

On the 1st day of hatching, the body of the larva was transparent and all the fins were fused together to form a single fin fold. Hatchlings measured 4.96 mm in total length. On the 10th day, all the fins were visible and body colouration had begun to develop, the larvae then measured 7.08 mm in total length. The banding began to appear from the 10th day and on the 15th day, the head and middle band were clearly visible. From the 25th day onwards, the larva measured 9.66 mm in total length. On the 30th day, adult pigmentation had begun to appear in the larva. After the 45th day, the bands started to disappear. By the 160th day, the middle band had completely disappeared. On the 310th day all the bands had disappeared and now the juvenile has transformed into an adult fish.


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Longtail tuna fisheries in the northern Arabian Sea off the north-west coast of India

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.


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Highly oxygenated antioxidative 2H-chromen derivative from the red seaweed Gracilaria opuntia

Phytochemical investigation of the thalli of ethyl acetate-methanol extract of the red seaweed Gracilaria opuntia led to isolation of a substituted 2H-chromen derivative of unusual structure possessing highly oxygenated carbon skeleton, characterised as 2-acetoxy-2-(5- acetoxy-4-methyl-2-oxotetrahydro-2H-pyran-4-yl)ethyl 4-(3-methoxy- 2-(methoxymethyl)-7-methyl-3,4,4a,7,8,8a-hexahydro-2H-chromen-4- yloxy)-5-methylheptanoate, which have not been reported in nature. The chemical structure was resolved by detailed spectroscopic analysis. The anti-inflammatory activity of the newly reported metabolite was determined by pro-inflammatory cyclooxygenase and 5-lipoxygenase inhibitory assays. The anti-inflammatory selectivity index of the title compound recorded greater value (SI: anti-cycloxygense-1IC50 /anti-cycloxygense-2IC50 ~ 1.26) than synthetic NSAIDs (aspirin and ibuprofen, SI: 0.02 and 0.44, respectively), and consequently, appeared to be safer. The antioxidative activity of the title compound was significantly greater as determined by 2, 2-diphenyl-1-picrylhydrazyl and 2, 2?-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging activities (IC50 0.26–0.32 mg/mL) compared to ?-tocopherol (IC50 > 0.6 mg/mL), and was comparable to the synthetic antioxidants butylated hydroxytoluene and butylated hydroxyanisole (IC50 ~ 0.25–0.34 mg/mL).


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