Role of environmental variables on spawning and recruitment of small pegalics in an upwelling system

The marine ecosystem is dynamic and the variations several abiotic and biotic factors directly and indirectly affect the fish stocks and their population structure. Spawning and recruitment success is to a large extent linked to these environmental variations. It is well known that resources occupy a particular habitat because of their preference to the environmental variables prevalent there and also due the availability of food. We have large shoal forming small pelagic fishes like the sardines and anchovies and the deep water large pelagic and demersals occupying the marine ecosystem from the upper pelagic zone to the benthic realms. Fishing is one of the major activities directly impacting the fish stocks and fishery records show several cases of overfishing leading to stock collapses. Definitely, fishery management tools have supported revival of several of these stocks but have failed to do so in few others. Almost equally important in inducing the biological changes that control maturation, spawning and recruitment are the some ocean atmospheric processes which change inter-annually in the tropics

Biodiversity of bivalves (Invertebrata: Mollusca)

Bivalves constitute an important component of many benthic ecological habitats. They are adapted to withstand the frequ e nt physical and chemical changes characteristic of the marine aquatic ecosystems and as a resul they form an integral part of the benthic community structure. In estuaries, intertidal zones and near shore coastal areas of Kerala, they are well distributed. Geological history records of Kerala havc indicated several transgressions and reg ressions of the sea along the coast resu lting in many standstills during the Pleistocene and Holocene periods

Edible oyster seed production and remote setting- Winter School on Recent Advances in Breeding and Larviculture of Marine Finfish and Shellfish

Throughout the world natural spat collection forms the basis of most oyster culture industries. Along the Pacific Northwest USA coast, hatchery produced seed are used in the cultivation of the Pacific oyster Crassostrea gigas. Natural seed collection is cheaper when compared to the cost of seed produced in the hatchery but is unpredictable. However, in the recent years, more efficient methods of setting the oyster seed in remote areas have been developed and this method is widely practiced no

Book Review: Marine Mammal Species of India

The charismatic marine mammals of Indian waters which include the majestic whales, intelligent dolphins and endearing sea cows are among the least known of the marine living resources. Lack of appropriate literature on identification, nature of their habitat and restrictions on their capture under Wild Life protection Act are some of the constraints faced by researchers studying these spectacular endangered animals. The recent publication of the Central Marine Fisheries Research Institute, “Marine Mammal species of India” is packed with vital information on all the 26 species recorded in the Indian Seas. The Institute has been studying marine mammals since 1947 and particularly from 2003 to 2012 as a programme funded by Ministry of Earth Sciences

Environmental Impact Assessment of Suspended Bivalve culture

Bivalves are sedentary organisms that require substrate for spat settlement and subsequent growth during which lime they filter feed on phytoplankton, detritus, protozoans and bacteria. It is well known that large scale aquaculture can pose complex ecological socio-economic and management problems. As commented by Hastings and Helnte in the introduction to the dedicated issue on “Effects of Aquaculture in the Estuarine Environment

भारत में शंबु पालन

भारत में शंबु पाल

Edible oyster farming- Winter School on Recent Advances in Breeding and Larviculture of Marine Finfish and Shellfish

Oysters are one of the most valued seafood and are farmed extensively. Nearly eleven species of oysters are commercially popular and of these Crassostrea gigas is the most important. In Asia during the year 2003, 4.2 million tonnes of oysters were produced of which 3.6 million tonnes was from China contributing to 87% of the continents oyster production . Korea and Malaysia also produce significant quantities of oyster. Concerted efforts to develop the oyster farming technology have been made since 1970 ‘s at the Tuticorin Research Centre of CMFRI. Initially natural seed were used. The development of hatchery technology for large-scale oyster seed production in 1982 at the Shellfish Hatchery of CMFRI, Tuticorin gave further impetus for oyster culture. Several location testing programs for oyster culture have been taken up at many centres along the Indian coast, using both the natural and hatchery seed

Impacts of marine litter on coastal and marine benthic ecosystems

Marine litter has been identified as one of the greatest threats to sustainability of aquatic ecosystems. The litter in the coastal and marine habitat can be those transported from the intertidal zone, terrestrial region through tidal waters, storm-water, wind, sewage and rivers, or it can be those directly deposited on the beaches or dumped into the aquatic systems by human interactions. About 50% of plastic marine litter is composed of low-density polymers like polyethene - PE and polypropylene – PP which readily sinks and reaches the benthic ecosystem where it can be trapped in hard rocky structures. Different items like plastic, rubber, glass, metal and other non-biodegradable items contribute to marine debris and UNEP has provided a code for categorizing each of these items. The dominant litter in each area differs, but in most areas, plastic has been found to be the major litter. The tiny micro-plastics have spread into different benthic realms of the coastal and marine eco-systems and in some locations even very high concentrations are observed. The impacts of marine litter on the benthic ecology and on the marine fauna are discussed briefly

Edible Oyster

Oysters come under the Class Bivalvia which encompasses aquatic molluscs that show a fundamental bilateral symmetry. Oysters inhabit the littoral and shallow subtidal areas and their distribution extends to a wide range of ecosystems including the coral reefs, mangroves and rocky shores. Unlike the mussels and scallops which attach by byssus threads, the oysters are cemented by the left valve to the substrate

Trade-offs in Environment and Trade : Need for sustainable development

In economics the term ‘trade-off’ is expressed as opportunity cost, referring to the most preferred alternative given up. A trade-off, then, involves a sacrifice that must be made to obtain a certain product, rather than other products that can be made using the same required resources. For a person going to a basketball game, its opportunity cost is the money and time expended, say that would have been spent watching a particular television program (Wikipedia). Another key word is ‘sustainable development’. Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs (World Commission on Environment and Development). Sustainable development was added as one of the general objectives of the World Trade Organization when it was established in 1994