Ovary development and annual egg production of hake, M. merluccius: a promising aquaculture species

Abstract

The full range of stages in ovarian development and fecundity of hake in the North Sea and the west coast of Scotland are described from histological examination of ovaries. Male hake from the North Sea had a gonadosomatic index of 0.88 in February compared with 3.30 in fish from west Scotland and 0.61 compared with 8.17 in females from respective locations, suggesting that the fish had still to mature in the North Sea. The maturation cycle of hake ovaries was described by a 7-point developmental scale after Rinchard and Kestemont (J Fish Biol 49:883–894, 1996). All developmental stages were present in hake from the North Sea and the west coast in February and stages 2 to 6 from the start of vitellogenesis to maturity in fish in west Scotland in May. This suggests that peak hake spawning occurred from February to May. The mean diameter of oocytes in previtellogenesis (developmental stage 1), the beginning (stage 2) and end (3) of endogenous vitelloegenesis, and exogenous vitellogenesis (4) was 34, 56, 105 and 249 μm, respectively, in histological material. Annual egg production was in the range 0.41 to 2.95 million for females of 962 to 3710 g, and the relationship to fish weight was described by y = 3985750.0005x , r 2 = 0.916.