219 



Tagging studies on the jumbo squid 



(Dosidicus gigas) in the Gulf of California, Mexico 



Unai Markaida 



Deparlamento de Ecologia, Centra de Investigacion Cientifica y 



de Educacion Superior de Ensenada (CICESE) 



Ctra. Ti|uana-Ensenada km 107 



Ensenada. Ba|a California, Mexico 



Present address: Departamento de Aprovechamiento y Maneio de Recursos Acuaticos 



El Colegio de la Frontera Sur 



Calle 10x61 No 264 



Colonia Centra. 24000 Campeche, Mexico 



Joshua J. C. Rosenthal 



Institute of Neurobiology 

 University of Puerto Rico 

 201 Blvd del Valle 

 San Juan. Puerto Rico 00901 



William F. Gilly 



Hopkins Marine Station 



Stanford University 



Pacific Grove, California 93950 



Email address (for W F Gilly. contact author): lign|eia'stan(ord edu 



Dosidicus gigas, the only species in 

 the genus Dosidicus, is commonly 

 known as the jumbo squid, jumbo 

 flying squid (FAO, see Roper et al., 

 1984), or Humboldt squid. It is the 

 largest ommastrephid squid and 

 is endemic to the Eastern Pacific, 

 ranging from northern California 

 to southern Chile and to 140°W at 

 the equator (Nesis, 1983; Nigmatul- 

 lin, et al., 2001). During the last two 

 decades it has become an extremely 

 important fisheries resource in the 

 Gulf of California (Ehrhardt et al., 

 1983; Morales-Bojorquez et al., 2001), 

 around the Costa Rica Dome (Ichii 

 et al., 2002) and off Peru (Taipe et 

 al., 2001). It is also an active preda- 

 tor that undoubtedly has an impor- 

 tant impact on local ecology in areas 

 where it is abundant (Ehrhardt et al., 

 1983; Nesis, 1983; Nigmatullin et al., 

 2001; Markaida and Sosa-Nishizaki, 

 2003). 



Ommastrephid squid, including the 

 jumbo squid, are largely pelagic and 

 may migrate long distances as part 

 of their life cycle (Mangold, 1976). A 



general pattern of long-distance mi- 

 gration for the jumbo squid over its 

 entire range was proposed by Nesis 

 (1983) and smaller-scale migrations 

 within the Gulf of California have 

 also been proposed according to the 

 distribution of the fishery during 

 1979-80 (Klett, 1982; Ehrhardt et 

 al., 1983). During this period squid 

 were reported to enter the Gulf from 

 the Pacific in January, to reach their 

 northernmost limit (29°N) by April, 

 and to remain in the central Gulf 

 from May through August; the high- 

 est concentrations were found along 

 the western (Baja California) coast. 

 From September onward these squid 

 appear to migrate eastward to the 

 Mexican mainland coast and then 

 southwards, to the mouth of the Gulf 

 and back into the Pacific (Klett, 1982; 

 Ehrhardt et al., 1983). 



Since 1994 a seasonal pattern in 

 the jumbo squid fishery has emerged 

 in which large squid are abundant in 

 the central Gulf essentially all year. 

 During November to May, the fishery 

 is centered in the area of Guaymas. 



In Sta. Rosalia the fishery oper- 

 ates from May to November, which 

 is also the period of peak landings 

 (see Fig. 1; SEMARNAP, 1996, 1997, 

 1998, 1999, 2000; SAGARPA, 2001; 

 SAGARPA 1 ) (see also Markaida and 

 Sosa-Nishizaki, 2001). These gener- 

 ally reciprocal landing patterns are 

 consistent with the abundance pat- 

 terns described by Klett (1982), al- 

 though the exact migrations proposed 

 by Ehrhardt et al. (1983) have never 

 been directly observed (Morales-Bo- 

 jorquez et al., 2001). 



All these studies concerning jumbo 

 squid migrations have relied on anal- 

 yses of landing statistics and catch 

 data acquired by fishing stations on 

 commercial squid-jigging vessels. Al- 

 though migratory patterns of several 

 other ommastrephid species of com- 

 mercial importance have been directly 

 demonstrated with conventional tag- 

 and-recapture methods (Nagasawa et 

 al., 1993), to our knowledge jumbo 

 squid has not been studied in this 

 manner. Given the commercial and 

 ecological importance of this spe- 

 cies, such studies would be valuable. 



This paper describes conventional 

 tag-and-recapture experiments on 

 jumbo squid in the central Gulf of 

 California. Tag-return rates were 

 higher than in most previous stud- 

 ies of other ommastrephid species, 

 and seasonal migrations between 

 the Sta. Rosalia and Guaymas areas 

 were directly demonstrated. Growth 

 rates were also directly determined 

 for the first time. 



SAGARPA (Secretaria de agricultura, 

 ganaderia, desarrollo rural, pesca y 

 alimentacidn). Anuario Estadistico 

 de Pesca, http://www.sagarpa.gob.mx/ 

 conapesca/planeacion /anuario /a nu- 

 ario2001.zip and http://www.sagarpa. 

 gob.mx/conapesca/planeacion/anuario 

 2002. [Accessed 26 July 2004.] 



Manuscript submitted 21 March 2003 

 to the Scientific Editor's Office. 



Manuscript approved for publication 



8 September 2004 by the Scientific Editor. 



Fish. Bull. 103:219-226(2005). 



