Indian Scad, Decapterus russelli ....On its Fishery from Maharashtra Waters

lndia has a coastline of 8.129 km with a continental shelf of 4,14,868 sq. km. Its marine resources are spread in the lndian Ocean, Arabian Sea and in the Bay of Bengal. It has an Exclusive EconomicZone of 2.02 million square km comprising 0.86 million sq. km on the West coast, 0.56 million sq. km of the East coast and 0.60 million sq. km around Andaman and Nicobar Islands, with a harvestable fishery fishery potential of 3.9 million tonne

Reproductive biology of the Indian scad, Decapterus russelli (Ruppell, 1830) from Maharashtra waters, Northwest coast of India

The length at which 50% of females of Decapterus russelli attain maturity was estimated at 153 mm. The presence of mature, ripe and spent gonads was observed from June to October and December to April indicating prolonged spawning season. The sex-ratio varied from 1:0.43 in 140-149 mm to 1:1 in 110-119 mm length groups. Month-wise distribution of sex-ratio indicated significant predominance of male at 5% in April, May and November. The absolute fecundity ranged from 29,986 to 1,52,123 eggs. Based on the GSI studies it is inferred that the species has a prolonged spawning season probably falling between December to March and June to October. The relative condition factor value was highest in January which indicates the peak spawning month. Length-wise condition factor of males and females were maximum in the length range of 100-229 mm. In the present study size of ova diameter ranged from 0.01 to 0.97 mm. The species seems to spawn twice in a season and the period between two spawning may not be a long one

Morphometric relationship of the Indian scad, Decapterus ruselli (Ruppell, 1830) from Maharashtra waters, Northwest coast of India

The relationship of various morphometric characters of Decapterus russelli from Maharashtra water weres studied. The coefficient of correlation (r) for various morphometric characters ranged from 0.880 to 0.983 indicating high degree of relationship among the characters compared. Analysis of 15 morphometric characters revealed that the fork length had the fastest growth rate with reference to total length while snout length had fastest growth rate with reference to head length. Fin formula for D. russelli from Mumbai waters could be written as: B.6, D.8 | 1/27-31 + i, P.20 – 22, V.1/5,A.2 | 1/25-28+i,C.17-19, BS. 30-41, LI. 37-61. Key words: Morphometric relationships, meristic studies, Decapterus russelli, Carangids, Indian scad, Maharashtra

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Not Availablelndia has a coastline of 8.129 km with a continental shelf of 4,14,868 sq. km. Its marine resources are spread in the lndian Ocean, Arabian Sea and in the Bay of Bengal. It has an Exclusive EconomicZone of 2.02 million square km comprising 0.86 million sq. km on the West coast, 0.56 million sq. km of the East coast and 0.60 million sq. km around Andaman and Nicobar Islands, with a harvestable fishery fishery potential of 3.9 million tonnesNot Availabl

Stock assessment of the Indian scad, <i style="">Decapterus russelli</i> (Ruppell, 1830) from Mumbai waters

680-686Present study consists the Growth, mortality and the stock assessment of Decapterus russelli . ‘L∞’ was estimated as 277 mm and ‘K’ as 1.237/year. The to estimated by VBGF plot was – 0.3443 year. Growth in length of D. russelli described following von Bertalanffy growth equation as, Lt = 277[ 1-e -1.237{t-(-0.3443)}]. Longevity was estimated to be 2.42 years. Total mortality rate (Z), natural mortality rate (M) and fishing mortality (F) were estimated to be 6.66, 2.1 and 4.56 respectively. In this study, Z/K was found to be 5.38 indicating that the stock of D. russelli is presently mortality dominated in Mumbai waters. Exploitation rate (U) was calculated as 0.6838 and the Exploitation ratio (F/Z) as 0.6847. Thompson and Bell long-term prediction analysis indicated that there is no decline in yield of D. russelli even if the fishing effort is doubled. Present level of fishing has no deleterious effect on the fishery of D. russelli</i

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Not AvailableThe length at which 50% of females of Decapterus russelli attain maturity was estimated at 153 mm. The presence of mature, ripe and spent gonads was observed from June to October and December to April indicating prolonged spawning season. The sex-ratio varied from 1:0.43 in 140-149 mm to 1:1 in 110-119 mm length groups. Month-wise distribution of sex-ratio indicated significant predominance of male at 5% in April, May and November. The absolute fecundity ranged from 29,986 to 1,52,123 eggs. Based on the GSI studies it is inferred that the species has a prolonged spawning season probably falling between December to March and June to October. The relative condition factor value was highest in January which indicates the peak spawning month. Length-wise condition factor of males and females were maximum in the length range of 100-229 mm. In the present study size of ova diameter ranged from 0.01 to 0.97 mm. The species seems to spawn twice in a season and the period between two spawning may not be a long one.Not Availabl

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Parasitology Research

Not AvailableA novel myxozoan parasite is identified and described from mudskipper, Boleophthalmus dussumieri, collected from a brackishwater ecosystem in Maharashtra, India. Ellipsomyxa boleophthalmi sp. nov. was found in the gallbladder of 58 of 60 fish examined (96.7%). The parasite formed disporous plasmodia that varied in size and shape, and the thin-walled, ellipsoidal and elongated myxospores measured 9.0?10.7 ? 6.0?7.8 ?m. The two, spherical polar capsules measured 2.7 ?m in diameter and enclosed 3?4 coils of polar tubules. Histological observations of infected gallbladder revealed the attachment of disporous plasmodial stages of the parasite to the gallbladder wall with fine pseudopodia. Under the scanning electron microscope (SEM), the myxospores showed a distinct central sutural line and two distinct depressions on the opposite sides at the openings of polar capsules. SEM also revealed the engulfment of microvilli of gallbladder wall by pseudopodia of the plasmodial stages. Analysis of the partial fragment of the SSU rDNA region (1386 bp) showed less than 98% sequence similarity with the other reported Ellipsomyxa spp. In the phylogenetic tree, the present species formed as a distinct subclade within the major clade of Ellipsomyxa spp. The unique morphological and morphometric features of the myxospore, together with the molecular analysis, allowed us to conclude that the present myxozoan is a new species and is named Ellipsomyxa boleophthalmi sp. nov., after the generic name of the host. This is the first report on the occurrence of the genus Ellipsomyxa in B. dussumieri

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