Endocrinology and fish culture

Abstract

In the current practice of fish culture the use of hormones is mainly limited to the field of reproduction, and more precisely to induce or synchronize ovulation and stimulate spermiation. The practice of pituitary homogenates injection (called hypophysation) which started in the early 1930's has allowed spectacular developments in the culture of some cyprinid species, especially in China, India and Europe. HCG has been used successfully in a limited number of species and LHRH-A, often associated with antidopaminergic compounds, started to be used in some species, especially cyprinids, on a commercial scale. Sex steroids are now commonly used to reverse the sex of some species in salmonids, cyprinids, tilapias. Due to legal restriction and consumer opposition, the tendency is to limit the use of steroids, especially in fish which are later offered to consumption. GH, which significantly stimulates growth and reduces the food conversion rate in laboratory experiments, will possibly be used on a large scale in fish farms. Endocrinology has considerably increased the knowledge of the mechanisms controlling some physiological functions; this has allowed the identification of sensitive phases in fish in captivity, and helps in the management and the process of domestication (most of the cultured fish species have been taken form the wild recently).

Dose-dependent effect of a single GnRHa injection on the spawning of meagre (Argyrosomus regius) broodstock reared in captivity

“…Therefore, meagre of both wild (Duncan et al, 2012) and reared (Mylonas et al, 2013a,b) origin held in captivity appear to exhibit what was described as the most common reproductive dysfunction where oocyte development was arrested in late vitellogenesis and females did not complete oocyte maturation and ovulation (Zohar, 1988(Zohar, , 1989aPeter et al, 1993;). This dysfunction is often associated with reduced milt volumes and decreased sperm quality in males (Billard, 1986(Billard, , 1989. Hormonal treatment has been described as a therapy to overcome these types of reproductive dysfunctions and ensure spawning in captivity ).…”

Changes in Plasma Gonadotropin II and Sex Steroid Hormones, and Sperm Production of Striped Bass after Treatment with Controlled-Release Gonadotropin-Releasing Hormone Agonist-Delivery Systems1

“…Due to the various forms of reproductive dysfunction exhibited by captive female broodstocks, a large part of the research has focused on female reproductive biology and the development of ovulation-and spawning-induction therapies [12]. Much less work has focused on the male, although the low volume of expressible milt often produced in captivity has been recognized as a major concern regarding many fishes [13,14]. Due to economic considerations, it is of great value to understand the endocrine factors controlling spermiation in fish and to devise methods for enhancing the quantity and quality of the produced milt.…”

The mechanism of reproduction and hormonal function in finfish species: A review

“…Essays maturity in aquaculture conditions and gonadal growth occurs normally ). However, some of female species often fail final oocyte maturation stage (FOM) and do not spawn (Zohar, 1989;Peter et al, 1993), while males exhibit diminished production or low quality of milt (Billard, 1986(Billard, , 1989Mylonas and Zohar, 2001).…”