. Commercial fisheries review. Fisheries; Fish trade. 34 Potential for Rearing Tunas probably can be reared beyond the larval stage in sufficient quantity for experi- mental purposes. Techniques still need to be improved. But the major obstacle in culturing pelagic larvae of marine fishes--failure of larvae to initiate feeding--does not seem as great a problem for tuna larvae (at least for the little tuna) as it is for larvae of many other fishes that we have attempted to rear. Experimental rearing of tunas offers an ex- citing opportunity to study many critical problems associated with life d
. Commercial fisheries review. Fisheries; Fish trade. 34 Potential for Rearing Tunas probably can be reared beyond the larval stage in sufficient quantity for experi- mental purposes. Techniques still need to be improved. But the major obstacle in culturing pelagic larvae of marine fishes--failure of larvae to initiate feeding--does not seem as great a problem for tuna larvae (at least for the little tuna) as it is for larvae of many other fishes that we have attempted to rear. Experimental rearing of tunas offers an ex- citing opportunity to study many critical problems associated with life during the lar- val stage. Studies of growth^ nutritional re- quirements, behavior, and survival can be carried out in the laboratory under a variety of conditions. The potentialfor culturing tunas commer- cially remains unclear. One problem is the lack of a reliable and continuous source of tuna eggs. Collecting fertilized eggs in a plankton net is an undependable method of obtaining large numbers. Catches at sea of adult tunas ready to spawn are rare. This precludes the possibility of artificially fer- tilizing their eggs. Recent successes in maintaining adult tunas in captivity (Naka- mura, 1962; Inoue et al, 1967) suggest that hormone injections might be used to stimu- late these captive fish to spawn. Because adult tunas are among the most difficult of fishes to handle without causing mortality, however, the repeated handling now neces- sary when using hormone injections may be impossible for successful spawning of tunas and tunalike fishes. Other problems to be solved include pro- viding large quantities of animal food, and the large volume of good water required by fast- growing and active tunas. Some of our labora - tory-rearing experiments may help to determine whether these problems can be overcome and, if so, whether tunas can be reared on a commercial scale. UTERATURE CITED INOUE, M., R. AMONA, Y. IWASAKI, and M, AOKI 1967. Ecology of various tunas under captivity -
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