The WorldFish Center Quarterly
Vol. 26, No. 2 (April – June 2003)

Age- or length-based methods of grwoth estimation. What drives the choice?
G.M. Pilling and A.S. Halls

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Pawpaw seed as fertility control agent on Nile tilapia
S.B. Ekanem and T.E. Okoronkwo

To fi nd out if pawpaw (Carica papaya) seeds can induce sterility in male Nile tilapia (Oreochromis niloticus) and to determine if sterility so induced is reversible or otherwise, mature male tilapia of mean weight 40 g were treated for 30 days with a low dose (4.9 g/kg/day) and a high dose (9.8 g/kg/day) of ground pawpaw seeds incorporated into their feed. Fish of similar sizes in the control experiment were fed with feed that did not contain pawpaw seed. The pawpaw seeds induced permanent sterility in the fi sh that received the high dose, while sterility in the low dose treatment was reversible. Fish in the control experiment spawned two weeks into the experiment and again in the fifth week. Fish in the low dose treatment spawned three weeks after the treatment had been discontinued. Histological sections of the testes showed that pawpaw seeds produced swollen nuclei in the low dose treatment and disintegrated cells in the high dose treatment. The study showed that pawpaw seeds, which are easy to obtain, can be incorporated into fi sh feeds and used by farmers to control prolific breeding of Nile tilapia.

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Fisheries production in Asia: Its role in food security and nutrition
P.S. Choo and M.J. Williams

Prediction of the worsening condition of fi sheries stocks worldwide and of aquatic ecosystems in crisis, together with the uncertainty on whether the emphasis given to intensive aquaculture production (which is still heavily reliant on fish meal and fish oil) is sustainable and is able to contribute to net growth in fisheries production, have been vigorously discussed and well documented in recent years. These challenges were recognized by the World Summit on Sustainable Development in 2002. The future of fi sheries and their sustainability will have great consequences in Asia, where large populations live in riparian and coastal states and are heavily dependent on fisheries and its products for food and for livelihoods. Asian countries produce almost 50 per cent of the world’s total capture fi sheries production and about 90 per cent of the world’s aquaculture production. Coastal and riparian states in Asia rely heavily on fi sh as a source of food, and statistics from FAO indicated that per caput consumption of fish from the East and Southeast Asian countries (24.0 kg), and China (24.7 kg) surpassed the global average of 15.8 kg. Some Asian countries are also important seafood exporting countries, with Thailand, China, China-Taiwan, Indonesia and the Republic of Korea ranking among the top ten world exporters of seafood.

Fish and other living aquatic animals have often been classifi ed as a good source of protein, vitamins and minerals. In recent years, fi sh has been acknowledged as a functional food and has important roles in the prevention and management of heart disorders, neurological diseases and mood swings. Important products such as fish leather, squalene, chitosan, eicosapantaenoic acid (EPA), and docosahexaenoic acid (DHA) are also obtained from fish and fisheries products.

This paper reviews the status and some management issues of fisheries production in Asia, as well as the supply and demand situation. Its food security and nutritional roles and opportunities for value addition are also discussed.

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Length-weight relationship of some deep sea fishes inhabiting the continental slope beyond 250m depth along the west coast of India
J. Thomas, S. Venu and B.M. Kurup

The length–weight relationships of 22 species of deep-sea fi shes inhabiting the continental slopes beyond 250 m depth along the West Coast of India are presented. The parameters a and b of the equation W=a Lb were estimated. The fish samples were collected from trawl surveys during 1999 to 2001 on board the FORV Sagar Sampada at a depth range of 250 to 600 m in the area between 7°N and 20°N latitude. The value of b ranged from 1.94 to 3.36.

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Incidence of human pathogenic bacteria in shrimp feeds - A study from India
R.P. Raghavan

The incidence of various human pathogenic bacteria in commercially available and home-made shrimp feeds used on some farms in India was analyzed. The Total Heterotrophic Bacteria in the commercial feed samples ranged between 103–105 cfu g-1 and those in the farm-made feeds between 106-107 cfu g-1. No bacteria of significance to human health were found to be associated with any of the commercial feed samples analyzed, while farm-made feeds analyzed during the study showed a high incidence of various human pathogens such as Vibrio parahaemolyticus, V. cholerae, Escherichia coli and Staphylococcus aureus. Possible modes of contamination in feeds and ways to prevent them are discussed.

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The cost of action: CRM investmentin the Phillipines
A.M. Salamanca

Knowing the cost of investment in coastal resources management (CRM) is important especially in understanding the cost of undertaking one and ascertaining whether the outcomes are worth the money spent. In the Philippines, various CRM projects have already been initiated and no studies have tried to account for the total level of investment. This paper provides an estimate of money spent or invested on CRM in the Philippines and examines the investment per km2 of coral reefs.

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INGA Article
Stock evaluation and development of a breeding program for common carp (Cyprinus carpio) in Karnataka, India: progress of a research project

Y. Basavaraju, D.J. Penman and G.C. Mair

Common carp (Cyprinus carpio) is the single most important species for aquaculture in the state of Karnataka, India, where it is generally grown in polyculture with Indian major carps. Precocious maturation and unwanted reproduction in the species have been identifi ed as constraints to increase production in aquaculture and culture-based fi sheries in Karnataka state. Stocks of C. carpio obtained from Hungary (Amur and P3), Indonesia (Rajdanu) and Vietnam (SV) are being assessed alongside two local stocks (L-BRP and L-FRS) in a series of culture performance trials with the objective of setting up a base population for selective breeding. The paper presents progress of research being undertaken at the Fisheries Research Station, University of Agricultural Sciences, Bangalore, India.

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