Natural spawning of greater amberjack (Seriola dumerili) kept in captivity in the Canary Islands

Abstract The histological process of gonadal differentiation together with the endocrine changes of glucocorticoids and sex steroids was studied in hatchery produced greater amberjack (Seriola dumerili) from 101 until 408 days post-hatching. In the samplings, which were conducted every 50 days, no size dimorphism was observed between the sexes and sex ratio was 1:1, suggesting that there was no influence of early rearing in captivity on sex differentiation. Plasma concentrations of cortisol, cortisone, adrenosterone (Ad), androstenedione (Δ4), 11-ketotestosterone (11ΚΤ), testosterone (Τ), estradiol (Ε2), progesterone (P4) and 17,20β-dihydroxyprogesterone (DHP) were measured in males and females with the use of liquid chromatography tandem mass spectrometry (LC-MS/MS) to examine their role in the sex differentiation process. From the nine hormones, the only one that exhibited differences between the sexes was 11-KT. However, variations were observed in the mean values of cortisol, Ad, Δ4, 11-KT, T, P4 and DHP over time in one or both sexes, indicating their involvement in the sex differentiation process. Moreover, the 11-KT/E2 ratio was found to be a useful diagnostic biomarker for greater amberjack sex, from as early as 150 dph.

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Spawning Induction of First-Generation (F1) Greater Amberjack Seriola dumerili in the Canary Islands, Spain Using GnRHa Delivery Systems

Fishes ◽

10.3390/fishes3030035 ◽

2018 ◽

Vol 3 (3) ◽

pp. 35 ◽

Cited By ~ 9

Author(s):

Salvador Jerez ◽

Ioannis Fakriadis ◽

Maria Papadaki ◽

M. Martín ◽

Juana Cejas ◽

...

Keyword(s):

Canary Islands ◽

Egg Production ◽

Delivery Systems ◽

Commercial Production ◽

Management Control ◽

Larval Rearing ◽

Spawning Period ◽

Seriola Dumerili ◽

Greater Amberjack ◽

Breeding Selection

The development of a sustainable aquaculture industry requires the closing of the life-cycle of a potential species in captivity, and the establishment of breeding selection programs using hatchery-produced breeding stocks. The greater amberjack Seriola dumerili is a cosmopolitan pelagic species that has been considered as a good candidate for the species diversification of aquaculture production in the Mediterranean region. However, commercial production is still very limited due to bottlenecks in reproduction, larval rearing and management control during grow out. The aim of the present study was to examine the reproductive development of hatchery-produced greater amberjack and to develop a spawning induction protocol based on the use of gonadotropin releasing hormone agonist (GnRHa) in a controlled-release delivery system. The results showed that hatchery-produced greater amberjack undergo normal gametogenesis and can be induced to undergo maturation, ovulation and spawning after multiple administrations of GnRHa implants, over an extended spawning period lasting from May to September in the Canary Islands, Spain. The use of GnRHa-delivery systems resulted in multiple spawns of fertilized and viable eggs. Egg production was high and egg quality adequate for the implementation of larval rearing for commercial purposes. The handling required to administer the GnRHa implants during the prolonged spawning season did not result in any negative effect on the welfare and reproductive performance of the fish based on evaluation of several biochemical parameters. The developed reproduction control method shows great potential to advance the commercial production of greater amberjack, by enabling the use of hatchery-produced broodstocks for further breeding selection.

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