Latin American & Caribbean Aquaculture 2019

November 19 - 22, 2019

San Jose, Costa Rica

REPRODUCTION, NURSERY AND GROWTH UP IN CAPTIVITY OF DRUMS OR CROAKERS FROM AMERICAN PACIFIC: WEAKFISH Cynoscion squamipinnis AND WHITEFIN QUEEN Cynoscion albus: A REVIEW

Jorge Boza-Abarca1,*, Marvin Ramírez-Alvarado1, Juan Barquero-Chanto2, Emilia Calvo-Vargas1, Karen Berrocal-Artavia1
1Estación de Biología Marina Juan Bertoglia Richards, ECB, Universidad Nacional, Puntarenas, Costa Rica jorge.boza.abarca@una.cr
2Dirección de Acuicultura, Universidad Técnica Nacional. Puntarenas, Costa Rica.

Drums or croakers are distributed along the Pacific coast from California gulf in Mexico to Peru. In Costa Rica, these fish represent 50% of commercial fisheries in the Nicoya Gulf. Because they are overfished, weakfish (Cynoscion squamipinnis) and queen (Cynoscion albus) were included in a Scianid Reproduction Program that began on 2009 at the Culture and Reproduction of Marine Fish Laboratory, Marine Biology Station Juan Bertoglia Richards, Puntarenas, Costa Rica. The aim of the Program was to control the reproduction and nursery of drums in captivity to impulse restocking and mariculture projects. Wild weakfish (C. squamipinnis) were captured and maintained (3 ♀ and 3 ♂) in a 18 t external tank for maturation. After two years, spontaneously spawning period started producing 162000 eggs with 50-60% of fertilization, 60-85% survival. Specific description of ontogeny was done, which included embryonary and larvae development. After 45 days, hatchery-produced juveniles were grown up for a period of 355 days.  One hundred fifty two fish were stocked in 4 t tank, and feeding with a diet of 50% protein, 17.5% carbohydrates, 11.8% lipids, 16% ash and 5% humidity. Water conditions and growth perfomance were described. Initial mean weight was 3.77±1.15 g, and final mean weight was 132.60±32.95, with a minimun weight of 78.5 g and maximum weight of 219.3 g. Growth perfomance values were: Total growth of 128.83 g., growth rate of 0.36 g d-1, Specific growth rate of 1.00% BW d-1, Relative Growth rate of 0.0053 g g-1 d-1, and feed conversion of 1.8±0.4. These results were compare with growth parameters of other croakers species, and other characteristics were highligths like: calm behavior, accepted peletized diet, and easy to handle. The weakfish first generation were restocking in a 18 t tank with constant water exchange, 26.73±1.15°C, 32.60±2.69 PSU, and 6.20±0.61 mg L-1 dissolved oxygen. After two years, maturity of females were confirmed by ovarian biopsy, and males released semen by gentle abdominal massage. These fish producing a serial spawning of 34 spawns from march to october 2011, with a mean eggs production of 85996 eggs per spawn, maximum of 461000 eggs and minimum of 4500 eggs. Fertilization percentage was variable between 10-80%, with a mean of 53.09±26.97%. Most of the spawns ocurred in correlation between high tides, moon phases, rainfall period, but not significant correlations were detected.  Wild females and males of queen drum (C. albus, n = 12) were captured, transported, and stocked in a 18 t external tank for maturation. The spawning conditions were the same used in weakfish, because these species share the same wild ambiental conditions. After 2.5 years in captivity, females (11.7±1.0 Kg BW) and males 12.5±1.0 Kg BW) were completly mature, with an oocyte diameter of 500±20 µm, and fluid males. However, after a prudential period waiting spontaneous spawn like weakfish C. squaminipinnis, queen drums were anesthetized with eugenol clover oil (0.1 ml L-1), and females (n = 3) injected with 300 IU Kg BW, and males with 50 IU Kg BW, using hCG. After 49 hours spawn was detected in the eggs collector. Two continuous spawn were observed acounting 522467 eggs and 116375 eggs with 80% of fertilization both. The juveniles produced in these spawns were used in a growth perfomance experiment to compare the growth parameters obtained with weakfish. Also a growth perfomance at different densities was done. The whitefin queen drum first generation (C. albus), after three years spawn spontaneously in captivity without any hormonal induction treatment, evidencing adaptation to laboratory conditions.