Many studies have considered the temporal patterns of reproduction of Engraulis ringens,
but little attention has been given to the spatial patterns of
reproduction (spawning areas), which have shown great variability in
both location (geographical position) and extent (the area covered by
positive stations), without a satisfactory explanation. Along the
Chilean coast, the daily egg production method (DEPM) has been used for
several years to estimate spawning biomass in the northern Chile E. ringens population, with 24 surveys being carried out from 1992 to 2020. The
most fluctuating parameters estimated in the DEPM have been the location
and extent of the spawning area and the average female weight. In the
last few years the eggs were distributed near the coast, whereas in the
first few years they showed a more oceanic distribution. The average
female weight has fallen from 30 g in the 1990s to 11 g in the last few
years. In the present study, we analysed the relationship of the
location and extent of spawning areas with female size and abundancy in E. ringens from northern Chile. According to the results, periods of high
abundancy of eggs are positively correlated with larger females that
spawn in more oceanic zones and to the south, expanding the spatial egg
distribution and increasing the egg density. By contrast, in years with
low abundance of eggs, the spawning was located north and towards the
coast, with a smaller spawning area and smaller female size. |