704 



Abstract— Larval growth rates of the 

 anchoveta Engraulis ringens were de- 

 termined for two periods during the 

 winter spawning season off Talcahuano, 

 central Chile. Because winter is the 

 season of minimum plankton produc- 

 tion during the year, we hypothesized 

 that larval growth rates during winter 

 should be constantly low because of 

 decreased larval fish food availability. 

 Our results, however, indicate that 

 1) mean larval growth rates deter- 

 mined from three gi-owth models in 

 winter (mid-July through mid-Septem- 

 ber) were as high as in other periods 

 of the year (linear, Gompertz, and von 

 Bertalanffy; 0.47 mm/d, 0.50 mm/d, 

 and 0.48 mm/d, repectively); 2 1 differ- 

 ences in larval growth rates occurred 

 in two groups of cohorts spawned in 

 the two periods during the spawning 

 season (0.40 mm/d vs. 0.57 mm/d I; and, 

 3) larval food (dinoflagellates, copepod 

 eggs, and copepod nauplii) concentra- 

 tions in the field were relatively high 

 and not very variable during the study. 

 Hydrogi'aphy of the water column, how- 

 ever, varied throughout the season. 

 During the last weeks of the study sea- 

 water temperature was higher, indicat- 

 ing intrusion of offshore warmer waters 

 into the coastal zone. The presence 

 of these warmer waters suggests that 

 differences in growth rates between 

 groups of cohorts may have resulted 

 from larval development in water with 

 different characteristics. Consequently, 

 for a coastal upwelling species such as 

 the anchoveta, increased growth rates 

 in some cohorts may be advantageous 

 considering that its main spawning 

 season occurs in winter when the envi- 

 ronmental conditions fluctuate mark- 

 edlv in short time scales. 



Larval growth of the anchoveta 

 Engraulis ringens during the winter 

 spawning season off central Chile 



Eduardo H. Hernandez 



Leonardo R. Castro* 



Departamento de Oceanografia 



Universidad de Concepcion 



Casilla 160-C. Concepcion. Chile 



E-mail address (for t R Cas(ro, con[ac( au[hor): lecastro@udec-Cl 



Manuscript accepted 1 1 .April 2000 

 Fish. Bull. 98:704-710 120001, 



The anchoveta Engraulis ringens (also 

 known as "Peruvian anchoveta," FAO, 

 19881 has traditionally been one of the 

 most important pelagic resources in the 

 world in terms of landings (Pauly and 

 Palomares, 1989). After strong fluctu- 

 ations in abundance during the last 

 three decades, especially marked during 

 the anchoveta collapse in the early 

 seventies, the stocks have rebounded. 

 Catches in recent years have reached 

 over 12 million tons and constitute one 

 of the largest fisheries of the world. 



Within its long latitudinal distribu- 

 tion range from 4°S to 40°S, several 

 major spawning areas have been re- 

 ported. The most important spawning 

 areas have been traditionally located off 

 Northern Peru, from off Southern Peru to 

 off Northern Chile, and off Central Chile 

 ( Bernal et al. 1983 ). Despite its wide lat- 

 itudinal range and paramount economic 

 importance for the world fish markets, 

 other than distribution and abundance, 

 little information exists on basic biologi- 

 cal parameters during the lai-val phase. 

 For the larval stage, reseachers have 

 documented information on the age of 

 onset of feeding, feeding habits, and val- 

 idation of daily deposition of ring incre- 

 ments in the otoliths (Rojas de Mendiola 

 and Gomez, 1980, 1981; Ware et al, 

 1981; Muck et al., 1989; Morales-Nin, 

 1989; Villavicencio, 1989; Llanos, 1990). 

 Information on larval growth rates in 

 the wild, however, have been reported 

 only for the southern stock and, unfor- 

 tunately, only for seasons other than the 

 major winter spawning seasons (Her- 

 rera et al., 1985). 



There is a marked seasonality in the 

 southern spawning area of the ancho- 

 veta. During spring, summer, and early 



fall, southerly winds predominate and 

 lead to very intense upwelling events. 

 During winter, intense northerly winds 

 dominate, and upwelling events develop 

 only occasionally. This marked season- 

 ality in the oceanography also leads 

 to changes in environmental condi- 

 tions that may affect larval growth. 

 During winter, due to the low frequency 

 of upwelling events, the general pro- 

 duction of the area is lower than in 

 summer. Similarly, the very intense 

 north winds may produce high levels 

 of turbulence in the water column, 

 thus dispersing the potential larval 

 food patches (Lasker 1975, 1978). On 

 the basis of these harsh environmental 

 conditions, it has been proposed that 

 food for larval anchoveta off Talcahu- 

 ano might be limited during winter 

 (Herrera et al., 1985; Bernal et al., 

 1990). However, because the anchoveta 

 has been historically an important fish- 

 ery of central Chile ( 1996 landings in 

 the area reached ca. 300,000 metric 

 tons, SERNAPESCA, 1996), there must 

 be some mechanisms by which rela- 

 tively high levels of larval sun'ival can 

 be achieved: either feeding conditions 

 are not permanently harsh or factors 

 other than food enhance larval sur- 

 vival, at least for some periods within 

 the winter spawning season. 



The objectives of our study were 1 ) to 

 determine whether intraseasonal dif- 

 ferences in growth rates occur between 

 groups of cohorts of larval anchoveta 

 spawned throughout the winter spawn- 

 ing season, and 2) to assess the role of 

 two environmental factors (larval food 

 and temperature) as potential factors 

 affecting larval growth rates. Because 

 some basic information for the deter- 



