Broodstock Management And The Method To Find The Spawning Temperatures Of Peruvian Rock Seabass Paralabrax Humeralis (Teleostei: Serranidae) Under Captive Condition

Abstract

Masatoshi Futagawa, German Bueno, Juan Pablo Díaz and Jessica Pizarro

Paralabrax humeralis known as the Peruvian rock seabass, is a serranid regularly found in the southeast Pacific Ocean [1,2]. As a consequence of fishing pressure, its numbers have been declining since the 1980s. The objective of this study is to provide information about the spawning habit of P. humeralis, describing the relation between water temperatures and spawning habits. The study is one of the initiatives of the FONDEF-CONICYT ID-16I10437 project is the repopulation of these species.

From November 2018 to the end of July 2021, 18 female broodstock weighing 14.4 kg laid 76.8 million eggs in 532 days and spawned at temperatures between 15.2 and 21.8 ° C. The floating egg rate and hatch-out rate were 71.4% and 75.1% respectively. The fish gonad matured correctly almost double speed in 2020 compared to 2018 and 2019. The relation between average water temperature and eggs quantity per g of female in 30 days suggests the spawning and the temperature have positive relationships, that abundant between 17 to 19 °C with 200 to 500 eggs per g of body weight in 30 days. The relation of 2018 and 2019 was Y=7.3739x2-176.58x+930.85 and 2020 was Y=2.7855x2+238.51x-3042.1; Y=Spawned eggs per female body weight (g) per 30 days, X=Compensated average water temperature (°C). The possible reasons for the improvement of 2020 are suitable water temperature and nutritional advantage as a fed homemade pellet that contains high protein fishmeal (32 %), fish oil (5 %), and vitamins (5 %), instead of silverside in 2018 and 2019. Additionally the project completed life-cycle of the fish, the F1 are spawning several eggs, from December 18, 2021.

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