Reproductive adaptation in fish: A case study on female Eurasian perch, Perca fluviatilis

Eurasian perch (Perca fluviatilis) is a promising new candidate species for inland aquaculture. However, the development of its reproductive system is largely influenced by water temperature in certain periods. The present study aimed to elucidate the annual reproductive cycle of Eurasian perch, at different water temperature profiles, more than one century since its introduction from a colder environment in Europe to a warmer place, in Western Australia. Female fish (mean body weight of 133±43 g and total length of 175±9 mm) were caught monthly from colder temperatures in Manjimup (34°11′08.97″ S, 116°04′18.09″ E), and compared every two-months with samples from a warmer temperature in Gingin (31°20″05.53″ S, 115°46′20.51″ E) and in the Curtin Aquatic laboratory, Bentley (31°59′38.26″ S, 115°53′18.09″ E) for a period of one year. From the sampled fish, the gonadosomatic index (GSI) was calculated and oocyte diameters (OD) were measured. The results showed that the gonad development of the colder temperature population commenced in May and spawning lasted until October. However, no gonadal development and spawning were observed in warmer temperatures either in ponds or in tank populations. Even if redfin perch has been adapted to Western Australia′s environment for a long time, it could not breed naturally in warmer temperatures.