Asynchronous Oocytes of all stages of develop- ment are present without dominant populations The ovary appears to be a random mixture of oocytes, at every conceivable stage Only when hydration occurs is there a clearly separate stock of oocytes with regard to diameter (a clear separation appears between advanced yolked oocytes and hydrated oocytes), as shown in Fig 2c Such ovaries may be found in iteroparous species, with protracted spawning seasons and where yolk accumulation, and hence oocyte development, relies mostly on the food available in the environment at that moment (Hunter and Leong, 1981), and occurs in European hake (Merluccius merluccius), Atlantic mackerel (Scomber scombrus), anchovies (Engraulis sp ) and in general in small pelagic species in temperate waters