Physiology of Finfish and Shellfish (2+1)

3.1.23. Hormonal control of reproduction

Hormones of pituitary gland play a major role in reproduction. Pituitary release gonadotropin hormones which control growth of testes and ovary in fishes. Pituitary also show many effect on behavior indirectly by their participation in the development of secondary sexual characters in fishes.

But the hormones of the gonads and adenohypophysis of pituitary (anterior pituitary) play a major role in controlling reproductive processes. Some evidence proves that neurohypophysial and thyroid hormones are also involved in the regulation of certain components of reproductive behavior in fishes. Other hormones also affect reproductive behavior indirectly by their effects on metabolism and growth.

(The primary hormones that regulate sex and reproduction are the sex steroids such as androgens, estrogens and progesterone which have masculinizing, feminizing and gestational effects, respectively. These hormones are secreted from the gonads called target glands which are in turn under the pituitary control. The pituitary gland manufactures many hormones and their mechanism of action varies considerably. The gonadotropins are secreted from the anterior pituitary (adenohypophysis) and affect their target glands- the gonads).