Egg trait variation in anchoveta Engraulis ringens: a maternal response to changing environmental conditions in contrasting spawning habitats

The Engraulis ringens distribution (4 to 42° S) covers a wide variety of environmental conditions. We assessed the coping mechanisms used by this anchoveta in different spawning habi- tats, reporting differences in egg traits between populations off northern (Iquique, 20° S) and south- ern Chile (Talcahuano, 36° S) and throughout the spawning season. Eggs were smaller off Iquique, declined in size during the reproductive season (both populations), and inter-population differences persisted throughout the spawning season. Batch fecundity (eggs per batch per female) and relative fecundity (eggs per female weight) were lower off Talcahuano during the peak spawning months. Thus, larger eggs spawned in the southern population seem to be produced at the cost of a reduction in fecundity. The eggs also differed biochemically between the 2 populations; total lipids and triacyl- glycerides were much higher off Talcahuano. The biochemical composition (both populations) also changed throughout the spawning season, with higher lipids early in the spawning season (July to August) off Talcahuano. Hatching success decreased during the spawning season, and correlated positively with egg size and lipid contents. Environmental conditions differed markedly between spawning areas and from mid-winter to late spring. Off Talcahuano, the temperature and winter-time water column productivity are lower and turbulence is higher, while eggs are larger, lipid contents higher, and batch fecundity lower. This mechanism seems to facilitate survival of young offspring in the more adverse winter conditions off Talcahuano. These egg characteristics are determined by the adult female reproductive system, representing a maternal influence on the early life-history traits of anchoveta that might enable rapid changes in population densities in some years of improved habitat conditions.