भारत के दक्षिण पूर्व तट पर कवाकवा मछली (यूथिन्नस) एकिनिस का विदोहन और इसका जीवविज्ञान

कृपया पूरा लेखा पढ

Spawning, intracapsular development and production potential of viable juveniles of a murex Chicoreus virgineus var. ponderosa Sowerby under laboratory conditions

Muricids are commercially important gastropods and are exploited primarily for shell craft industries. They also occupy a niche in ornamental keeping. Studies on the larval development of muricids in Indian waters are few. Hence, an attempt was made to study with a focus on the optimum requirements for captive brood maintenance; regional variation in egg laying, intracapsular development and to estimate production potential of individual brooder (the length/ weight ranged from 80 - 110 mm/49 - 169 g (average 94.875 ± 3.980 mm/111.625 ± 14.870 g) of Chicoreus virgineus var. ponderosa collected off Tuticorin coast, Gulf of Mannar. Experimental airlift water circulation system fitted in 1 t FRP tanks having an overturn of 300% water is found suitable for long term maintenance and maturation of brooders with near cent percent survival over a year. Spontaneous breeding commenced from June ’09. Eggs cases were ‘vase’ shaped and measured 1.2 - 1.5 cm in height. Egg case numbers varied between 110 and 140 and got reduced to 10 - 40 during October and increased in Nov & December. Number of eggs within the egg case was highly variable ranging from 100 - 380. Eggs were spherical, embedded in jelly mass within the egg case and measured 510 - 608 μ (578 μ). Intra capsular development is detailed and compared with the earlier report on this species from other areas of Indian coast. Development took nearly 20 days and only few free living juveniles measuring between 1.7 - 1.9 mm emerged and the rest of the eggs have functioned as “Nurse eggs”. Average net production potential of a single viable egg case was estimated to be 6.7 nos for Chicoreus virgineus var. ponderosa of Tuticorin coast of Gulf of Mannar

First record of Parapercis clathrata (Perciformes: Pinguipedidae) from Indian waters

A single specimen of latticed sandperch, Parapercis clathrata measuring 163 mm total lenth was caught in a trawler off Tuticorin, south-east coast of India in February 2010. Morphometric and meristic characters of the recorded specimen are described. This record constitutes the first occurrence of the species in Indian waters and a substantial westward extension of its known geographical distribution

Holding and spawning of the edible oyster Crassostrea madrasensis during off season

Production of seed from the hatchery throughout the year would help to undertake stocking in the grow out systems at appropriate time which may vary in different areas. Ripe oysters with a size range of 70-120 mm were collected from Korampallam creek near Tuticorin. Thus holding the ripe oysters is a promising line of work for getting spawn in the hatchery outside the spawning period, leading to seed production throughout the year

Experience paper on the operation of pilot project on oyster culture at Tuticorin

The technology of oyster culture was developed in India at the Central Marine Fisheries Research Institute. An experimental farm was established at Tuticorin bay in an area of 0.25 hectares. Different growout methods have been tried and it has been assessed that the shell string method could be practised with relatively low cost inputs with a production rate comparable to highly efficient systems such as rack and tray method or raft culture

Occurrence of deep sea prawns in the stomach of Yellowfin tuna

The earlier studies on yellowfin tunas (Thunnus albacares) from Indian waters have shown that the fish is an opportunistic feeder, consuming fishes, cephalopods and crustaceans. The main crustacean component is the deep sea pelagic crab, Charybdis smithii. The food and feeding studies of yellowfin tuna from Thoothukudi during the period 2011-2014 were also in conformity with the results of earlier studies

Restoration and natural revival of clam populations at Tuticorin Bay, Tamil Nadu after a mass mortality incident

Bivalves play key role in ecosystem stabilisation due to inherent filter feeding capability and clams are important components of soft bottom benthic communities. In the Tuticorin Bay, mass mortality of fishes and shellfishes was observed in Februay 2008. The probable cause for the large scale mortality has been indicated as increased levels of ammonia (Asha et al., 2009). A rapid survey was conducted in the bay to assess the impact on the bivalve fauna

Occurrence of Parascolopsis eriomma (Jordan and Richardson, 1909) and P. aspinosa (Rao & Rao 1981) from Tuticorin coast

The family Nemipteridae has five genera and 69 valid species. The dwarf monocle bream belonging to the genus Parascolopsis has 12 species. They are small, bottom-living fishes usually occurring in moderately deep water on outer shelf and continental slope waters throughout tropical and sub-tropical waters of Indo-West Pacific, ranging from Western Indian Ocean to North East Australia, South Japan and Delaga Bay on the coast of East Africa. The present report on Rosy dwarf monocle bream, Parascolopsis eriomma from Tuticorin coast is evidently a range extension from the known distribution areas

Assessment of impact of fishing on Indian mackerel Rastrelliger kanagurta (Cuvier, 1816) in Tuticorin, south-east coast of India

Fishery of the Indian mackerel Rastrelliger kanagurta (Cuvier, 1816) from Tuticorin was studied for the period 2011-2014. Indian mackerel formed fishery round the year in Tuticorin with peak during June to November in trawl and October to December in gillnet. The annual catch varied from 1650 to 5101 t (average 2968 t) in gillnet and from 815 to 1716 t (average 1231 t) in trawl. Total length (TL) of the fishes ranged from 10 to 30.5 cm. Length-weight relationship estimated was W = 0.0038777*L3.3 (r2 = 0.99, n = 535, L=TL in cm, W in g). The fishes were found to be continuous spawners with peak spawning during January to August and November. The von Bertalanffy growth equation derived was Lt = 31.2 [1-e -1.3(t+t0)]. The species attained TL of 22.7 cm in 12 months and 28.9 cm by the end of second year. Longevity estimated was 2.3 years, Phi-prime index (ᴓ) was 7.143, while Z and M were 4.36 and 2.132 respectively. Thompson and Bell model showed continuous increase of yield even after considerable rise in F-factor. Spawning stock biomass (SSB) was 79% at an f-factor of 3.5. F0.1 using Beverton and Holt Y/R model was 3.4 whereas the present F was 2.23 indicating that the current level of fishing is not affecting the stock adversely

Unprecedented landing of spine tail devil ray Mobula japanica (Muller & Henle, 1841) at Tharuvaikulam, Tuticorin

The spine tail devil ray Mobula japanica (Muller & Henle, 1841) is a large zooplanktivorous ray circumglobally distributed within tropical to warm temperate waters. This species belong to the family Mobulidae. In the genus Mobula, the mouth is located ventrally and is currently represented by nine recognised species