Histological Characteristic of the Gonads of Sardine Sardina Pilchardus (Walb, 1792) in the Coast East of Algeria (Gulf of Annaba)
Abstract
To illustrate the different kinetics of oogenesis and spawning strategies, reproduction in
the Sardine (Sardina pilchardus, Walbaum 1792) was discussed. The histological samples,
realized over the 3 periods of sexual cycle: oogenesis, egg and rest, were analyzed for
2217 specimens caught in the period from November 2015 to October 2016 using a
microscopic scale of oocyte development with 6 stages. The histological results allowed
us to determine the size of first sexual maturity is 12 cm, acquired during the third year
of life of the sardine. Monthly monitoring of the evolution of macroscopic and
microscopic stages of sexual maturity, allowed us to suggest that the waters of the
coastal eastern Algeria, sardines spawn from December to March. Sexual rest is
observed in the 2 sexes in May, during the summer and part of fall. Spawning and sperm
emission ending in April. Microscopic observations show six stages of maturity in
females and four males. Earlier maturation, oocytes come together in one lot, come into
vitellogenesis and evolve synchronously to mature simultaneously. Separated from each
other by the gap, they are issued in a fractional short laying. Ongoing recruitment of
pre-vitellogenic oocytes determined new ways of oogenesis and lying, there are as many
as egg laying lots placed in vitellogenesis. This type of distribution allows multimodal
oocyte laying series with lots of small eggs released during a long period of time, postspawn
is difficult to identify. These results illustrate the complexity of multiple clutches.