Captive Tunas in a Tropical Marine 

 Research Laboratory: Growth of 

 Late-larval and Early-juvenile 

 Black Skipjack Euthynnus lineatus 



Robert J. Olson 



Inter-American Tropical Tuna Commission 



c/o Scripps Institution of Oceanography, La Jolla, California 92093 



Vernon P. Scholey 



Inter-Amencan Tropical Tuna Commission, Achotines Laboratory 

 Las Tablas. Los Santos Province, Republic of Panama 



Little is known about the biology of 

 tunas during larval and early-juve- 

 nile stages because they are rela- 

 tively inaccessible to scientists. In 

 the eastern Pacific Ocean fishermen 

 seldom catch juveniles of less than 

 about 30 cm in length. Concurrent 



laboratory and field studies of tuna 

 growth and mortality are important 

 to gain insight into the recruitment 

 process. These considerations moti- 

 vated the Inter-American Tropical 

 Tuna Commission (lATTC) to estab- 

 lish a research center at Achotines 



7»20 



Achotines Bay 

 Fraites del Norte 



Frailes del Sur, 



ecis' 



30' 



25' 



7»20' 



Figure 1 



Location of the 

 study site (cross- 

 hatched) south of 

 Achotines Bay, 

 Panama. The 

 lATTC's Achotines 

 Laboratory is situ- 

 ated on the east side 

 of the Bay. 



Bay in the Republic of Panama, a 

 site located near tuna spawning 

 grounds (Fig. 1). 



Black skipjack tuna Euthynnus 

 lineatus are not commercially im- 

 portant; however, their similarity to 

 other tunas makes them valuable 

 subjects of study. Their distribution 

 is limited to tropical and subtropical 

 regions of the eastern Pacific Ocean 

 (Collette and Nauen 1983), with 

 two stray specimens reported from 

 the Hawaiian Islands (Matsumoto 

 1976). For many years, E. lineatus 

 was thought to inhabit only coastal 

 waters and waters around islands 

 (Calkins and Klawe 1963, Yoshida 

 1979). However, recent fishing rec- 

 ords show that black skipjack also 

 occur in oceanic habitat (Schaefer 

 1987, fig. 1; Bayliff 1988a, fig. 62). 



Clemens (1956) reported the only 

 previous information on rearing 

 and growth rates of early-juvenile 

 black skipjack. Some information 

 was reported by Peterson (1983:54) 

 on the growth of 32-51 cm fork 

 length (FL) black skipjack in the 

 field, based on tagging studies and 

 length-frequency modal progression 

 analysis. Houde and Richards (1969) 

 described the growth of larval little 

 tunny E. alletteratus reared in the 

 laboratory from planktonic eggs. 

 The larvae were fed unspecified 

 quantities of mostly copepod nauplii 

 and copepodites, and grew from 

 less than 3.0 mm total length at 

 hatching to almost 8.5 mm in 18 

 days, a rate of about 0.3 mm/day. 

 No data are available on larval 

 growth of kawakawa E. affinis 

 (Yoshida 1979). 



The purpose of this note is to 

 report the establishment of the 

 Achotines Laboratory in Panama, 

 to describe sampling results and 

 rearing procedures of late-larval 

 and early-juvenile black skipjack 

 tuna, and to report growth experi- 

 ments on captive black skipjack. 



Manuscript accepted 23 May 1990. 

 Fishery Bulletin. U.S. 88:821-828. 



821 



