Maturity classification and growth of capelin, Mallotus villosus villosus (M), oocytes

Ovaries of female capelin, Mallotus villosus villosus (M), from the Barents Sea were sampled at various times of the year and material conserved for morphological examination. The maturity of female capelin, was assessed using low power microscopy for examination of whole oocytes. The diameters of oocytes were measured to give additional information regarding development, and to study the growth rate of the ripening oocytes. A maturity scale for use in the field is described based on the result of low power microscopy. A comparison is made between the‘old’and‘new’maturity scales, and the ease of use of the new scale has been tested.