249 



Abstract — In this study we describe 

 the courtship and spawning behaviors 

 of captive yellowfin tuna iThiiniiiig 

 alhacares). their spawning periodicity, 

 the influence of physical and biologi- 

 cal factors on spawning and hatching, 

 and egg and early-larval development 

 of this species at the Achotines Labo- 

 ratory, Republic of Panama, during 

 October 1996 through March 2000. 

 Spawning occurred almost daily 

 over extended periods and at water 

 temperatures from 23.3' to 29.7°C. 

 Water temperature appeared to be the 

 main exogenous factor controlling the 

 occurrence and timing of spawning. 

 Courtship and spawning behaviors 

 were ritualized and consistent among 

 three groups of broodstock over 3.5 

 years. For any date, the time of day 

 of spawning (range: 1330 to 2130 h) 

 was predictable from mean daily 

 water temperature, and 95'> of hatch- 

 ing occurred the next day between 

 1500 and 1900 h. We estimated that 

 females at first spawning averaged 

 1.6-2.0 years of age. Over short time 

 periods (<1 month), spawning females 

 increased their egg production from 

 SO^r to 234^4- in response to short- 

 term increases in daily food ration of 

 9''f to 33'~'f . Egg diameter, notochord 

 length (NL) at hatching, NL at first 

 feeding, and dry weights of these 

 stages were estimated. Water tem- 

 perature was significantly, inversely 

 related to egg size, egg-stage duration, 

 larval size at hatching, and yolksac 

 larval duration. 



Spawning and early development of 

 captive yellowfin tuna iThunnus albacares) 



Daniel Margulies (contact author)' 



Jenny M. Suter' 



Sharon L. Hunt' 



Robert J. Olson' 



Vernon P. Scholey^ 



Jeanne B. Wexler' 



Akio Nakazawa^ 



Email address for D Margulies: dmarguliesfffiattcorg 



' Inter-Amencan Tropical Tuna Commission 

 8604 La Jolla Shores Drive 

 La Jolla, California 92037-1508 



^ Inter-Amencan Tropical Tuna Commission 

 Achotines Laboratory, Las Tablas 

 Los Santos Province, Republic of Panama 



^ Overseas Fishery Cooperation Foundation 

 Sankaido Building, 9-13 Akasaka 1, Minato-ku 

 Tokyo 107-0052, Japan 



Manuscript submitted 15 July 2005 

 to the Scientific Editor's Office. 



Manuscript approved for publication 

 10 October 2006 by the Scientific Editor 



Fish. Bull. 105:249-265 (2007). 



The yellowfin tuna iThu?})ius alba- 

 cares > is found worldwide in tropical 

 and subtropical oceans. Yellowfin 

 tuna reproduction is characterized 

 by serial batch spawning and asyn- 

 chronous oocyte development that is 

 typical of tunas (Schaefer, 2001a). Yel- 

 lowfin tuna are broadcast spawners 

 and exhibit extremely high batch and 

 annual fecundities over protracted 

 spawning seasons (McPherson, 1991; 

 Schaefer 1996, 1998). 



Tuna reproduction has been studied 

 predominantly through histological 

 analyses of the gonads of fish sampled 

 at sea. Estimates have been made of 

 either spawning seasons, spawning 

 intervals, fecundities, or energetic 

 costs of spawning for yellowfin tu- 

 na (Joseph, 1963; McPherson, 1991; 

 Schaefer, 1996), skipjack tuna, Kat- 

 suwonus pelamis (Goldberg and Au, 

 1986; Hunter et al.. 1986; Schaefer, 

 2001b), bigeye tuna, Thunnus obe- 

 sus (Nikaido et al., 1991), albacore, 

 Thunnus alalunga (Ramon and Bai- 

 ley, 1996), and southern bluefin tuna, 

 Thunnus maccoyii (Farley and Davis, 

 1998). Egg and early larval develop- 

 ment of tunas has been described 

 in a number of identification guides 



or descriptive reviews (Nishikawa 

 and Rimmer, 1987; Ambrose, 1996; 

 Richards, 2006). Most descriptions of 

 early life stages of tunas are based on 

 examinations of specimens collected 

 at sea. 



Our knowledge of the spawning dy- 

 namics and early development of tu- 

 nas remains incomplete, and most of 

 our understanding comes from stud- 

 ies of cultured tunas. Before 1980, 

 there were several small-scale efforts 

 in Japan to artificially spawn tunas 

 and to rear the larvae and juveniles 

 (HaradaM. In the past decade sev- 

 eral programs have been developed 

 worldwide to induce spawning and to 

 rear tunas in captivity. Maturation 

 and spawning of tuna broodstock in 

 sea pens in Japan has been described 



1 Harada, T. 1980. Progress and future 

 prospects in tuna culturing studies. In 

 Proceedings of the 1979 Japan Tuna 

 Research Conference, Shimizu, Japan, p. 

 50-58. [Engl. Transl. no. 50 by T. Otsu, 

 1980, 8 p., avail. Pacific Islands Fisheries 

 Science Center, National Marine Fisher- 

 ies Service. 2570 Dole Street, Honolulu. 

 HI 96822.1 



