On the occurrence of Decapterus macrosoma in trawl catches at fisheries harbour, Cochin

The scads (Decapterus spp.) locally known as 'Thiriyan' forms an important carangid fishery in 'trawls' at Fisheries Harbour, Cochin contributing about 45.09 and 60.67 % of the carangids caught in trawls during 1987 and 1988 respectively. D. macrosoma contributed upto 50% of the catches with the maximum catch per effort of 44.50 kg. This species represented by an abundant catch of juveniles and sub adults also contributing upto an estimated catch of 2,941 kg (catch/effort: 17 kg)

Fishery and population dynamics of the obtuse barracuda Sphyraena obtusata (Cuvier) landed by trawlers at Cochin, south-west coast of India

Fishery and population characteristics of the obtuse barracuda Sphyraena obtusata (Cuvier) landed by mechanised trawlers off Cochin were studied for the period 2010-2012. The average annual landings of barracuda was 184 t of which S. obtusata formed 65%. Seasonal peak in catch and catch rate was recorded during August, followed by February and May. The von Bertalanffy growth parameters (VBGF) estimated using ELEFAN were L∞ = 34.2 cm, K = 0.71 year-1 and t0 = -0.0000000025. The lengths attained at the end of 1, 2, 3, 4 and 5 years were 17.4, 25.9, 30.1, 32.2 and 33.2 cm, respectively. Recruitment was almost round the year with a major peak during February-May and a minor peak during July, together accounting 80% of the total recruitment. Natural mortality (M), fishing mortality (F) and total mortality (Z) were 1.35, 1.54 and 2.89 respectively. The length at first capture was 23.5 cm (age 1.64 years). The optimum length for exploitation (Lopt) was 20.9 cm at the age of (topt) of 1.3 years. Mean size in the catch (25.1 cm) was higher than Lopt. The resource is being exploited at a level marginally higher than E50 (E = 0.53), indicating optimal exploitation. Though the annual average yield is only marginally (6%) higher than the MSY estimated, there is no need for reducing the fishing effort from the prevailing rate. Instead, as the yield and biomass per recruit and yield and biomass curves showed that the maximum yield and yield per recruit could be obtained by increasing the present level of fishing, marginal increase in the effort is prescribed to sustain the fishery

Heavy landings of juvenile lizard fishes and silverbellies at Neendakara

On 25.2.2008, a heavy landing of lizard fish of about 1,000 kg along with silverbellies by trawlers was recorded at Neendakara (Fig. 1). The catch was from Chavara area (off Neendakara) caught from 10-20 m depth. Among the lizardfish catch, Saurida undosquamis and among the silverbellies, Leiognathus elongatus were the dominant species

Stock dynamics of the brushtooth lizardfish Saurida undosquamis (Richardson, 1848) from a tropical multispecies fishery in the southeastern Arabian Sea

The brushtooth lizardfish Saurida undosquamis (Richardson, 1848) is a high trophic level benthic predator and is one among the most exploited demersal finfish species from eastern Arabian Sea by Indian trawlers. However, in recent years, the landings of many top predator fishes including S. undosquamis showed a declining trend resulting in a steady decline in the mean trophic levels of the fishes caught commercially in the region. We investigated the growth, mortality and stock dynamics of S. undosquamis harvested by mechanised trawls in the southeastern Arabian Sea, using length-based methods for the data collected during 2012–2016. Besides, Bayesian state-space implementation of the Schaefer model (BSM) and catch-based MSY (CMSY) estimation were also made using the data for the period 1985–2016. Total length of the fish ranged from 5.5 to 34.5 cm with average annual mean length of 22.0 cm during 2012–2016. The growth parameters L∞ and K were 37.3 cm and 0.41 year�1, respectively. The natural, fishing and total mortality coefficients were 0.92, 2.58 and 3.5, respectively and exploitation ratio was 0.82. The length at first maturity was estimated at 21.4 cm for females. The mean size in the catch is lower than the optimum length for exploitation. Fisheries reference points (MSY, Fmsy, Bmsy) as well as relative stock size (B/Bmsy) and exploitation (F/Fmsy) estimated from catch data and broad priors for resilience (r), implies an exploitation of 30% below Bmsy level. Results from the length-based Thompson and Bell prediction model indicates that reducing the present level of fishing effort by 40% would lead to a harvest of the species at a sustainable level. As “fishing down food web” is reported in recent years from eastern Arabian Sea, the exploitation of top predators need to be maintained at sustainable levels to prevent ecosystem changes along the region

कोचीन मात्स्यिकी पोताश्रय में वर्ष 2010 के दौरान अवतरण किये सुरा और शंकुशों की प्रचुरता और विविधता पर विशेष परामर्श के साथ केरल की उपास्थिमीन मात्स्यिकी

कृपया पूरा लेखा पढ

Agarolytic activity in the enzyme extracts of Oscillatoria sp.

Oscillatoria sp. growing as epiphyte on the thallii of Gracilaria edulis was known to contain enzymes endowed with agarolytic properties. The alkaline PO, buffer(0.1 ml, pH 7.5) extracts containing protein concentration of 600 pg/ml exhibited maximum activity of agar solublization (490 pg) on 1% agar slants within the first three hours. However, at pH 6.0 the enzyme extract exhibited low rate of agarolytic activity. The in vim activity of this extract was also studied on the bits of fresh thallus of G. edulis for cell seperation. The results are discussed in the light of possibilities of applying this cost effective marine source of enzyme on protoplast isolation and somatic hybridization of Indian agarophytes

Decadal analysis of the flatfish fishery of India

Decadal analysis of the flatfish fishery of Indi

Landing of the mesopelagic fish Chlorophthalmus agassizi at Cochin Fisheries Harbour

Mesopelagic fishes distributed in the upper aphotic zone beyond 200 m depth range are seldom encountered in commercial landings. Exploratory surveys have shown that they are available in plenty in the 200 to 600 m depth range in the Indian EEZ. In spite of the fact that they have a nutritive value at par with the quality fishes, these fishes are not popular as food because of their non-accessibility to commercial fishery. Nevertheless, on 28-8-1995, a large quantity of the mesopelagic fish, Chlorophthalmus agassizi Bonaparte was landed by the commercial trawlers at Cochin Fisheries Harbou

Indescriminate destruction of juveniles of spiny cheek grouper Epinephelus diacanthus (Valenciennes) off Quilon, Kerala

An incidence of juvenile capture of Epirleplrelus diacantlrus (Val.) (Family: Serranidae) off Quilon, South west Coast of India is reported. They formed 65% of the discards landed on 13-10-2005 with an estimated catch of 2,610kg. The juveniles were in the size range of 88-140mm (mean size = 1 IOmm) with the modes at 106-1 10mm and at 116-120mm. They fed on crabs (C11arybdi.v sp.), mysids, Acetes sp., and alima larvae of Squilla. Length-weight relationship of these small fishes was worked out as LogW = - 5.421865 +3.26 Log L (r =0.9193). It is estimated that the juveniles with an average calculated weight of 17.2g, if allowed to grow would have yielded a biomass of 76t with each individual attaining a total weight of 504g at the end of first year. Necessary management measures such as establishing Marine Protected Areas (MPAs) are necessary for protecting their nursery spawning grounds