STUDIES ON THE BIOLOGY OF THE WEDGE CLAM DONAX INCARNATUS (GMELIN) FROM THE MALIPPURAM BEACH OF KERALA

The present investigations have considerably enhanced the existing knowledge on the biology and distribution/availability pattern of D.incarnatus in the Malippuram region. The species occurs in good concentration during October - March/April, and disappears from the area during late premonsoon and monsoon months. Recolonising the area in September, it grows fast in the subsequent months. The life span of the species is estimated to be about an year. Studies on the reproductive biology of the species have revealed that there are two spawning peaks, the major peak in February - March and minor peak, in December. The salinity regime of the area influences the reproductive activity. These observations form the original contribution in the thesis. The information on variation in water content, protein,glycogen and lipid levels in relation to reproductive cycle has helped to a better understanding of the gametogenic activity and spawning of the species. Similarly, the findings on salinity tolerance and filtration rate have shown that small sized clams exhibit greater tolerance range than larger clams, and grow at a faster rate with active metabolism. It is hoped that these information would considerably add to the present knowledge of the basic facts which are relevant to the improvement and management of the clam fishery of this region.

Larval biology of the spiny lobsters of the genus panulirus

Lobsters are renowned the world over as tasty delicacies and are in great demand for Epicurian gourests. As a result these animals found in different parts of the world from countries like India they are mostly frozen and exported thus earning considerable foreign exchange for the country. Importance of this crustacean is thus well known and whatever harvested from nature are utilized to the maximum extent. The demand being much more than what is being produced the need for artificial culture becomes evident. In this context a complete knowledge of the lifecycle ,larval biology and their culture is very essential. Thus with the object of studying the life history of the commercially important lobsters fished from Indian waters the larval biology of panulirus homarus has been taken up as the project for the present study

“Studies on the Biology, Morphometrics and Biochemical composition of the Ommastrephid squid, Sthenoteuthis oualaniensis (Lesson,1830) of the south west coast of India”

With the stabilization of world finfish catches in general, and the depletion of a number of fish stocks that used to support industrial-scale fisheries, increasing attention is now being paid, to the so-called unconventional marine resources, which include many species of cephalopods. One of such important cephalopod resource is the tropical Indo-Pacific pelagic oceanic squid Sthenoteuthis oualaniensis. It is the most abundant large sized squid in the Indo- Pacific region with an estimated biomass of 8-11 metric tons. However, its distribution, biology, life cycle and nutrient value in the south west coast of India are still poorly known. So any new information of this species in the waters off the south west coast of India has important scientific significance for effective and rational utilization of this Oceanic fishery resources, especially during the time of depletion of shallow water resources. In view of that this study investigated different aspects of the Sthenoteuthis oualaniensis, such as morphometry, growth, mortality, maturation, spawning, food, feeding and biochemical composition in the south west coast of India to understand its possible prospective importance for commercial fishing and management of its fishery

Studies on the effect of Polycyclic Aromatic Hydrocarbons in the life and activity of Perna spp

In the present study an endeavour has been made to analyse the acute toxicity of WAFs of Bombay High crude and Light Diesel oil on commercially important bivalve species Perna viridis and Perna indica by static bioassay methods. The toxic effects of chemicals in the WAF on the organisms ; their tissues and eventually on rate functions have been elucidated. Marine oil pollution not only affects productivity and quality of marine organisms but also eventually affects the health of human population due to a possible health risk by way of consumption of oil contaminated seafood

Fishery and biology of deep-sea chondrichthyans off the southwest coast of india

Elasmobranchs comprising sharks, skates and rays have traditionally formed an important fishery along the Indian coast. Since 2000, Indian shark fishermen are shifting their fishing operations to deeper/oceanic waters by conducting multi-day fishing trips, which has resulted in considerable changes in the species composition of the landings vis- a-vis those reported during the 1980’s and 1990’s. A case study at Cochin Fisheries Harbour (CFH), southwest coast of India during 2008-09 indicated that besides the existing gillnet–cum- hooks & line and longline fishery for sharks, a targeted fishery at depths >300-1000 m for gulper sharks (Centrophorus spp.) has emerged. In 2008, the chondrichthyan landings (excluding batoids) were mainly constituted by offshore and deep-sea species such as Alopias superciliosus (24.2%), Carcharhinus limbatus (21.1%), Echinorhinus brucus (8.2%), Galeocerdo cuvier (5.4%), Centrophorus spp. (7.3%) and Neoharriotta pinnata (4.2%) while the contribution by the coastal species such as Sphyrna lewini (14.8%), Carcharhinus sorrah (1.4%) and other Carcharhinus spp. has reduced. Several deep-sea sharks previously not recorded in the landings at Cochin were also observed during 2008-09. It includes Hexanchus griseus, Deania profundorum, Zameus squamulosus and Pygmy false catshark (undescribed) which have been reported for the first time from Indian waters. Life history characteristics of the major fished species are discussed in relation to the fishery and its possible impacts on the resource