Size-specific seasonal trends in spawning of pilchardSardinops ocellatusin the northern Benguela system, 1973/74

Is the spawning frequency dependent on female size? Empirical evidence in Sardinops sagax and Engraulis ringens off northern Chile

“…Batch fecundity is clearly a size dependent relationship as a consequence of proportional growth of ovary with fish size. Also, the duration of spawning season have been shown to be size-dependent for Engraulis mordax (Parrish et al, 1986), Sardinops ocellatus (Le Clus, 1989), Seriphus pollitus (DeMartini and Fountain, 1981), Clupea harengus (Lambert, 1987), Gadus morhua (Marteinsdottir and Thorarinsson, 1998), Engraulis encrasicolus (Millan, 1999) and Sardinops sagax , among others. However, the effect of female size on the spawning intensity, that is spawning fraction or spawning number in a breeding season has been ignored.…”

The selection of spawning location of sardine (Sardinops sagax) in the northern Benguela after changes in stock structure and environmental conditions

“…In the past, larger sardine were mainly females (Matthews, 1964). The decrease in length in comparison with the 1950s leads to a lower fecundity of the sardine stock, as large sardine spawn more and larger eggs, which have a better chance of survival (le Clus, 1989). In later years, the sardine stock was largely composed of zero and 1‐yr‐old fish with some 2‐yr‐olds; the mean length of the population being about 21 cm (Fig.…”

Basis of an alternative method of utilizing low-resolution ovary-weight data for the assessment of seasonal spawning trends of the batch-spawning pilchardSardinops ocellatusin the northern Benguela system

“…Use of a stage considered to be close to spawning may also provide some insight into the length of the interval between spawnings and the average number ofspawnings per month (Le Clus 1989). In this study, the oocyte volume beyond which dry weight remains constant was selected as the criterion for calling the ovaries advanced, being close to that at the onset of the final maturation stages prior to spawning.…”

“…With the method, it is possible to show not only that larger pilchard have a greater reproductive potential than do smaller ones (Le Clus 1989), but also that the spawning intensity of the species has changed considerably over the years in conjunction with changes in stock biomass and fish condition (Le Clus 1987).…”

“…Other uses of the method permit comparison of the seasonal spawning pattern of different length classes (Le Clus 1989) and evaluation of changes in longterm trends of spawning over decades (Le Clus 1987). With the method, it is possible to show not only that larger pilchard have a greater reproductive potential than do smaller ones (Le Clus 1989), but also that the spawning intensity of the species has changed considerably over the years in conjunction with changes in stock biomass and fish condition (Le Clus 1987).…”