Developments in world aquaculture , feed formulations , and role of carotenoids

Aquaculture is a rapidly growing global industry, comprising cultivation of various freshwater and marine species of finfish, shellfish, molluscs, and ornamental fish. By the year 2000, as much as 20% of the world production of fish will be based on aquaculture. Properly formulated feeds are a significant part of successful aquaculture. Carotenoids play a major role in culture of salmonids such as Atlantic salmon and rainbow trout. Various biological and nutritional roles for carotenoids in salmonids are documented along with the effect of biotic and abiotic factors on astaxanthin transport and retention and final flesh pigmentation. Relevant recent feeding results are presented. INTERNATIONAL DIMENSIONS OF AQUACULTURE Global moduct ion and growth Aquaculture, involving farming of a variety of freshwater and marine species of finfish, shellfish, molluscs, and ornamental fishes, is a rapidly growing global industry with a broad range of technological and managerial practices. In 1990 (ref. l), world aquaculture reached 15.3 million metric tons (MT), or 12.1 million MT, if aquatic plants were excluded. This is more than double that reported for the year 1975. Of this, approximately 50% was of freshwater origin, largely cyprinid species, while 6% was of marine origin. As much as 80% of aquaculture production is centered in Asia, particularly in China and Southeast Asia. During the 1984-89 period, capture fisheries expanded only about 14%, while aquaculture rose nearly 70%. Furthermore, the total value of world aquaculture production averaged an annual increase of 15% during the 1984-90 period. Market demand for quality product has stimulated much of the growth in aquaculture, especially for salmonids and marine shrimp species. The total world aquatic harvest in 1991, including aquaculture, was about 96 million MT of which aquaculture comprised about 16% (ref. 2). Harvest limitations in global fisheries suggest that further growth in aquatic production will depend upon aquaculture. Projections are for global aquaculture output to exceed 20 million MT by the year 2000, comprising about 25% of the world’s seafood. Of cultured finfish, 85% are nonsarnivorous species, mostly cyprinids of various Chinese and Indian carp species. Almost half of the carnivorous species are salmonids, a ratio of about 50:50 salmon and trout. In the period 1986 to 1989, increases of 100-180% occurred in production of farmed Atlantic and Pacific salmon, while increases of 20-70% were recorded for common carp, tilapias, channel catfish, rainbow trout, and various species of marine shrimp, the latter comprising nearly 88% of crustacean aquaculture production. Global shrimp production alone in 1989 was over 530,000 MT, varying in volume and particular species with specific country. Successful cultivation of other marine finfish includes that of yellowtail, sea bass, sea bream, flatfish, grouper, and snapper. Numerous other marine and freshwater finfish are in various stages of evaluation for commercial aquaculture purposes. Salmonid broductim In 1991, the worldwide annual harvest of salmon was approximately 720,000 MT, of which 2530% were produced in a variety of aquaculture facilities and encloske designs. This includes such salmonid species as rainbow trout, Atlantic salmon, chinook salmon, and coho, pink, and chum salmon. The most spectacular growth has been with Atlantic salmon, notably in Norway