Fishery, stock assessment and management of the barracuda resource in India

The annual landings of barracuda increased from 1996 t in 1969 to 14679 t in 1995. During 1985-93 on an average 8332 I was landed and it constituted 0.44% oj the total marine fish catch, in India. The statewise contribution was Tamilnadu 3925 t (47.7%), Kerala 2471 t (30.0%), Andhra Pradesh 457 t (5.6%), Gujarat 420 t (5.1%). Maharashtra 416 t (5.0%), Karnataka 340 t (4.1%,), Pondicherry 98 i (1.2%), Orissa 71 t (0.9%) and Goa 29 t (0.4%>j. Four species Sphyraena obtusata, S.Jello, S. picuda and S.Jorsieri sustained the barracuda fishery in India. The growth paralmeters like Loa K, to: length weight relationships and natural mortality of S. obtusata S.Jello and S. picuda have been calculated The total mortality rate, fishing mortality rate generated by the trawl and drift gillnets and stock have been estimated for these three species. At present S. obtusata is under exploited by trawlnet and S.Jello and S. picuda are exposed to high fishing pressure by drift gillnets. The production may be increased by intensifying the exploitation in the deeper waters beyond 100 m depth. Suggestions and recommendations for proper management of the fishery have been propose

केंद्रीय समुद्री मात्स्यिकी अनुसंधान संस्थान का काकीनाडा अनुसंधान केंद्र

केंद्रीय समुद्री मात्स्यिकी अनुसंधान संस्थान का काकीनाडा अनुसंधान केंद्

Fishery, growth, yield per recruit and stock assessment of Sphyraena obtusata Cuvier off Tuticorin, Gulf of Mannar

Annual average catch of 612.2 t of barracudas were landed at the catch rate of 17.1 kg/unit which constituted 3.9% in the total catch landed by trawlers during 1987 - '89 at Tuticorin. Higher effort input during certain months did not coincide with better abundance of barracudas. Sphyraena obtusata Cuvier constituted on an average 69.6% of the total catch of barracudas. Based on the length-frequency data, the growth {^ameters have been estimated to be L 470.0 mm, K 1.0364/year and t^ -0.0098 ye. The natural mortality coefficient (M) is 1.591, the average annual total mortality coefficient (Z) is 2.8317 and the average exploitation rate (U) is 0.4123. The average standing stock is estimated to be 343.2 t and average annual stock 1,032.71. Yield per recruit studies indicate that S. obtusata is not exposed to higher fishing pressure as the average fishing mortality coefficient (F), 1.2407, for the prevailing age at first capture, 0.4709 ye is lower than the respective F,^which can yield the Y,^ in both the M/K ratios 1.0 and 1.535. There is scope for increasing the effort of trawl net with a view to increase the catch of this species at the prevailing conditions

Population dynamics of the cuttlefish Sepia elliptica Hoyle in Saurashtra waters

Tiie cephalopod fishery in Veraval is sustained mostly by five important species which are the squid Loligo duvaucelii, the cuttlefishes Sepia elliptica, S. pharaonis, S. aculeata and Sepiella inermis. On an average 1582.3 t of cephalopods were landed in a year during 1979-84 which constituted 5% of total catch by trawlers in Veraval. The annual average catch composition of the cuttlefish Sepia elliptica was 435.3 t forming 27.5% of cephalopod landings. Age and growth, instantaneous total mDrtality coefficient (Z) and instantaneous natural mortality coefficient (M) were estimated for S. elliptica. The natural mortality coefficient is estimated to be 1.59 by regressing the Z obtained for 5 years as per the method of Alagaraja (1984) against the annual effort. The Z varied from 3.33 in 1979-80 to 5.17 in 1983-84 with an average of 3.93. Yield per recruit at constant age at first capture and varying fishing mortality coefficient for different M/K ratios are inversely proportionate. For the prevailing M/K ratio and cod end mesh size (20 mm) the F mtx which can produce the yield max of 33 g is 2.0. This study indicates that further increase in effort may not result in proportionate increase in production. The exploitation ratio E is higher than the E opt during the period of this study indicating that the stock is exposed to higher fishing pressure. An increase in the cod end mesh size from 20 imn to 30 mm may favour increased production in commensuration with the effort increase. This suggestion is valid only when the fishery is aimed at exploitation of S. elliptica subjected to modifications with reference to other commercially important fisheries like prawn fishery

Salinity tolerance of certain freshwater fishes

To Rhinomiigil corsula (Hamilton) salinities below 12.25 %. (S) are not lethal at any temperature within the tolerance limit, in acute exposure from freshwater. The optimum temperatures from 26 to 30°C favour salinity tolerance. Low temperature is more detrimental than high, though this species has higher resistance times at low temperature. Sarotherodon mossambica Peters resists salinity better than common carp and freshwater mullet, Among carps, the common carp is highly tolerant to salinity, mrigal is the least tolerant and fringelipped carp is intermediate. Salinity acclimation in the fringelipped carp has enhanced only the resistance to salinity and there is no change in the tolerance level

Effect of temperature on respiration of Labeo fimbriatus (Bloch)

Labeo fimbriatus (Bloch) was tested at non-lethal temperatures to measure its oxygen uptake both in oxygen dependant and independant zones. The metabolic rate was almost uniform in oxygen independant zone, in oxygen dependant zone reduced drastically and then oxygen level becomes lethal. This species regulated the oxygen consumption at lower rate at extreme high and low temperatures than at intermediary optimum temperatures. The lethal oxygen level was much higher at low temperatures, whereas it was the lowest at optimum temperature. The highest lethal oxygen level at low temperature is attributed to the inhibition in oxygen uptake. Cold-acclimated fish consumed more oxygen than the warm-acclimated fish. The time to death was the highest at low temperature

Note on the subsistence fishery of Periasamipuram in Gulf of Mannar

The survey of Periasamipuram, one of the fishing villages has revealed that there are about 250 families in the village, among which 41 are actively engaged in the fishing activity. Three types of nets, a) Nachchuvalai, b) Viduvalai and c) Sippivalai are being employed for fishing. Some action has been initiated to establish a co- operative society at Periasamipuram

Carangids

Carangids occupy 9th position with a production of 1.11 lakh tonnes, constituting 4.1% of 2.7 million t of marine fish production in India during 2000. Among the pelagic fishery resources, carangids constitute the fourth important resource and rank next to oil sardine, ribbonfishes and mackerel. This resource is comprised mainly of horse mackerels, round scads, queenfishes, trevallies, leatherjackets and pompanos and has emerged as one of the important resources especially in the mechanised sector. As many as 35 and odd species belonging to 21 genera have been observed to support the carangid fishery along the Indian coast and other species occur in stray catches. Small growing species like Selaroides leptolepis attain a maximum of 185 mm where as queenfishes and jacks grow to 1-2 m. The smaller species usually occur in large schools in shallow waters. Owing to the recent approach of value addition the economic importance of small sized carangids have also increased considerably. Considering the economic and commercial importance of this resource, a detailed account on the fishery, biology and stock assessment of 11 species have been reviewed

Growth, mortality rates and stock assessment of the cuttlefish Sepiella inermis (Ferussac and D'orbigny) in Saurashtra waters

Age and growth of the cuttle fish Sepiella inermis was estimated from the length frequency data collected from trawl net operations in Veraval during 1979-83. Natural mortality coefficient (M) is estimated to be 2.1 and the total mortality coefficient (Z) estimated asper catch curve method are given. Stock assessment has been made. The exploitation rate, total mortality, instantaneous mortality, average annual stock have been estimated by cohort analysis. The continuous decline in the annual landings and average annual stock during 1979-83 is attributed to high fishing pressure in the shallow near shore waters off Veraval. Further observation on this fishery is felt essential to formulate suitable regulatory measures with due consideration on other major fisheries of the area

Effect of salinity, temperature and oxygen partial pressure on the respiratory metabolism of Panulirus polyphagus (Herbst)

The lethal oxygen levels, time to death, total oxygen consumed and the metabolic rates of Panulirus polyphagus (Herbst) are estimated at different salinities, temperatures and oxygen partial pressures after acclimating the lobsters to 17, 32, 39 and 50 ppt at ambient temperatures 22.5, 22.1, 28.1 and 20.1°C, respectively. The incipient lethal salinities are obtained graphically from lethal oxygen levels and time to death at different salinities. The metabolic rate is uniformly high within oxygen independent zone of higher pOj and, in oxygen dependent zone, it is curtailed drastically. Subsequently, the low oxygen partial pressure becomes lethal. As a means of compensation, the metabolic rate in this species decreases at extreme salinities and tends to increase at intermediary salinities. The influence of salinity acclimation and temperature on the metabolic rate is evident. It is suggested that factors other than salinity gradient may also be sought in order to explain the metabolic pattern of this species