“…Methods for hypophysectomy (surgical removal of the pituitary) exist for a wide range of fish species: rainbow trout, Komourdjian and Idler, (1977); sterlet (Acipenser ruthenus L), Kuzik and Polenov (1985); winter flounder (Pseudopleuronectes ameticanus), Campbell and Idler (1976); tilapia (Sarotherodon mossambicus), Nishioka (1980); and coho salmon (Oncorhynchus kisutch), . However, this experimental approach, while successfully eliminating the ability of the fish to elevate cortisol levels during stress (Bjornsson et aL, 1987), has a severe drawback.…”