Reproductive biology and seed production of the tropical abalone Haliotis varia Linnaeus (Gastropoda)

• Main Author: Najmudeen, T M
• Format: Thesis
• Language: English
• Published: 2000
• Subjects: Molluscan Fisheries; Theses; Gastropods; Arctic; Pacific
• Online Access: http://eprints.cmfri.org.in/7123/; http://eprints.cmfri.org.in/7123/1/TH-90_Naj.pdf

The vast expanse of ocean has often been seen as a limitless source of animal protein for mankind. As this source is depleting in recent years due to more intense fishing pressure, maritime countries have given priority to aquaculture development with the objective of preserving and increasing their natural resources. The expansion of culture industry of any species chiefly relies on an improved understanding of the biology of the species, particularly on spawning characters. Dependence on the natural seed resources for culture is risky because it is extremely variable in quality and quantity and off-season availability. So artificial seed production is the only alternative for the expansion of aquaculture especially when the distribution of the species is limited. Diligent work by fishery scientists in many parts of the world is bringing the reproductive process and seed production of more organisms under control. Molluscs are one of the most compact groups of animals with more species known from marine environments than of any other animal phylum. In number of species, the mollusca are the second phylum to the Arthropoda, comprising about 80000 species. A major part of the world marine aquaculture production is made up of molluscs including clams, cockles, oysters, mussels, scallops and abalones. In aquaculture production, molluscs are the third largest commodity in the Asia-Pacific region providing about 16% of the total. Three quarters of molluscs are gastropods with about 1650 genera. Gastropods are among the most conspicuous sea animals, and species of limpets, snails and slugs are found in all the marine habitats. Members of this class have one shell, as opposed to clams and oysters with two. The most valuable gastropod from an epicurean point of view is certainly the abalone. Abalones, commonly kno':Vn as ear shell, are economically important marine gastropods belonging to the genus Haliotis. There are about 100 species of abalones in the world. They are found in both the hemispheres, but the larger varieties exist in the temperate regions, while the smaller ones live in tropical and arctic regions. Because these animals have been of commercial value since ancient times much has been written about their natural history beginning with Aristotle (Croits, 1929). The first fisheries of abalone were in China and Japan over 1500 years ago, but it is only in the last 30 years that the fisheries for abalone have burgeoned worldwide and become economically important in many countries.