Variation in the spawning periods of Engraulis ringens and Strangomera bentincki off the coasts of Chile: A quantitative analysis

In Chile, anchovy (Engraulis ringens) and common sardine (Strangomera bentincki) are two commercially important small pelagic fish. In southern Chile (32–41° S), both species coexist and inhabit the coastal zone. In northern Chile (18–25° S), only anchovy is present in the coastal zone. The determine onset, peak, end, and duration of the spawning periods in these small pelagic fish are key factors in population studies and of great interest for fisheries management. The objective of this study is to determine the temporal trends of spawning in these two species. A quantitative method was developed to obtain objective indicators of the spawning periods and the method is a useful tool for comparative studies between populations as well as to study the relationship of spawning periods with other demographic variables affected by fishing or environmental variability. Peak spawning in the three populations was consistent through time but showed changes in the duration of the maximum reproductive period. Anchovy and common sardine of the southern zone show synchrony and a shortening of the duration of spawning periods, probably in response to environmental fluctuations. Anchovy in northern Chile have shown an increase in duration from 1986 that is coincidental with the regime shift reported for the Humboldt Current Ecosystem in the mid-1980s.