Latin American & Caribbean Aquaculture 2019

November 19 - 22, 2019

San Jose, Costa Rica

FIRST SPONTANEOUS SPAWNING OF F1 GENERATION QUEEN DRUM (WHITEFIN WEAKFISH) Cynoscion albus IN CAPTIVITY

Jorge Boza-Abarca*, Marvin Ramírez-Alvarado
 
Estación de Biología Marina Juan Bertoglia Richards, ECB, Universidad Nacional, Puntarenas, Costa Rica
jorge.boza.abarca@una.cr
 

Whitefin weakfish, Cynoscion albus (corvina reina), is distribute along the pacific coast of the Americas and overexploited in the Gulf of Nicoya, Costa Rica. Wild males and females were captured  and transported to the Laboratory of Culture and Reproduction of Marine Fish, in the Marine Biology Station Juan Bertoglia Richards, Puntarenas to start a Reproduction Program. Like years before, fish were exposes to captivity reproduction strategies which were successful with another scianid species, Cynoscion squamipinnis. However, wild queen drum not spawned spontaneously, even though ovaries biopsy indicated a complete maturity stage of the gonads. After hCG hormonal induction of wild females, their spawn a high quality eggs which it were fertilisated by males naturally, without  manipulation. First generation of queen drum (C. albus), grown up and reached gonadal development after two years. The same captivity reproduction strategies were applied to these F1 generation, which consist in: keep females (n = 6) and males (n = 6) (2-3 kg. body weight) in an 18 t external cylindrical fiberglass tank with open flow through water supply, Saran cover (80% shade), aeration (20 PSI), daily water exchange (80 %), fed with fresh caballa fish at 2% of body weight. In the third year of captivity, queen drum F1 generation spawning spontaneously for the first time. Ambiental conditions during 31 may 2018 spawning event were: water temperature of 28.8°C; salinity of 32 PSU; oxygen dissolved of 4.6 mg/L; high tide at 16:08, 2.47 m; full moon phase. Spawns occurred two days, first day being a premonitory spawn and few eggs were obtained (7000 ± 150 eggs) with a low percentage of fertilization (10%). Second day spawn was 500000 ± 1545 eggs with high percentage of fertilization (95%). Eggs were pooled in several 1 t external cylindrical fiberglass tanks, which it were preparate with microalgae, and enrichment rotifers. Larval feeding period was similar to their wild generations (35-45 days), but few juveniles were obtained. These juveniles will be grown up to obtain a F2 progeny. In conclusion, F1 generation of  queen drum demostrate advantage over their wild parents like: small total size to reach maturity (45 cm total length), and less bodyweight (2-3 Kg.). Ocurrence of spontaneous spawning in a F1 generation also represent an advantage for the species, because demostrate that these fish can to complete the gonadal development and the final maturation and ovulation, without extra stimulus. These results confirm C. albus as strong candidate in possible restocking programs and mariculture.