. Commercial fisheries review. Fisheries; Fish trade. REARING LARVAL TUNAS IN THE LABORATORY Edward D. Houde and William J. Richards the laboratory and an attempt was made to sort the eggs by type. Then eggs were incu- bated and the larvae were reared. Examina- tion of larvae that hatched from eggs collected in May 1969 showed that we had successfully hatched, and reared to 12 days past hatching, larvae that we identified later as those of the little tuna, Euthynnus alletteratus (Fig. 2). This was the first time tuna were reared past the yolk sac stage under laboratory condi- tions. Despite th
. Commercial fisheries review. Fisheries; Fish trade. REARING LARVAL TUNAS IN THE LABORATORY Edward D. Houde and William J. Richards the laboratory and an attempt was made to sort the eggs by type. Then eggs were incu- bated and the larvae were reared. Examina- tion of larvae that hatched from eggs collected in May 1969 showed that we had successfully hatched, and reared to 12 days past hatching, larvae that we identified later as those of the little tuna, Euthynnus alletteratus (Fig. 2). This was the first time tuna were reared past the yolk sac stage under laboratory condi- tions. Despite the extensive high-seas fisheries for the several species of tunas, little is known about the early life of these fishes. Oneof the objectives of the Life History Stud- ies Program at BCF's Tropical Atlantic Biological Laboratory (TABL) is to solve problems that biologists encounter in working with eggs and larvae of tunas. We hope to rear successfully tuna larvae from fertilized eggs--and to describe the egg and the de- velopment of the species from hatching to the juvenile stage. At present, tuna larvae caught at sea are difficult to identify with certainty because of the similarity in appearance among tuna species. We hope also to deter- mine growth rates and mortality rates of tuna larvae reared in the laboratory and to inves- tigate factors that may have an important influence on survival. If the effects on larval survival of physical and biological factors can be evaluated, then useful predictions of future recruitment to tuna stocks in the open sea may be possible--through the use of indices of larval abundance, and measure- ments of such environmental variables as temperature, salinity, and availability of potential food for tuna larvae. Obtaining Eggs and Embryos Tunas are seldom caught when they are ready to spawn. Attempts made by TABL biologists to artificially fertilize tuna eggs on research cruises have been unsuccessful. Kume (1962) has reported the only known succ
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