ABSTRACT
The reproduction of Blackfin tuna Thunnus atlanticus has been described for coastal regions, and for a long time, this species was considered to be a strictly continental spawner. Recently, this species was observed around a seamount habitat 500 nautical miles Northeast of Brazil, located between South America and Africa. In this study we describe the reproductive biology of Blackfin tuna at Saint Peter and Saint Paul Archipelago (SPSPA). Male and female gonads were sampled from December 2008 to July 2010, and analyzed macro and microscopically. A total of 361 fish were sampled (247 males and 114 females). Males were more common than females, with a sex ratio of 2.2 ♂:1♀. The fork length (FL) of all sampled specimens ranged from 38 to 98cm, and larger length classes were more frequent in males. It was possible to distinguish six maturity phases for females: immature, developing, spawning capable, actively spawning, regressing and recovering. Five phases were identified for males: immature, developing, spawning capable, actively spawning and recovering. The gonad index (GI) mean monthly values ranged from 6.6 (SD=4.1) to 58.4 (SD=34.7) for females, and from 2.6 (SD=1.3) to 66.2 (SD=30.4) for males. For both sexes, the largest GI values were observed at the beginning of the first semester of the year. Size at first maturity was estimated at 48cm FL and 55cm FL for females and males respectively. Approximately 80% of the specimens were adults and considered to be in reproductive conditions. Histological analysis of the ovaries and testes showed that most of the specimens were sexually mature and were reproductively active during all months of the year. However, females with mature ovaries, with large amounts of hydrated oocytes and post-ovulatory follicles, were mainly found from December to March, thus these months may constitute the main spawning season in SPSPA. Batch fecundity varied between 272 025 and 1 140 584 oocytes for 56 and 68cm FL females respectively. Oocyte development and spawning patterns suggest a multiple spawning behavior. The results revealed that Blackfin tuna is using the SPSPA as a spawning ground, similar to other species commonly observed in the same area during the same reproductive season.
A pesar de la importancia de las capturas del atún de aleta negra Thunnus atlanticus en el noreste de Brasil y en las cercanías del Archipiélago San Pedro y San Pablo (ASPSP), hay una escasez de información sobre su reproducción, especialmente en las islas. La reproducción del atún de aleta negra en este archipiélago se estudió de diciembre 2008 a julio 2010. Con este fin, se recolectaron 361 gónadas de hembras y machos, los machos fueron predominantemente más frecuentes en la muestra total, con una proporción sexual de 1♀:2.2 ♂. La longitud furcal todos los ejemplares muestreados varió entre 38 y 98 cm, y los machos fueron más abundantes en las clases de mayor longitud. Los valores medios mensuales del índice gonadal (IG) variaron de 6.6 (SD=4.1) a 58.4 (SD=34.7) y de 2.6 (SD=1.3) a 66.2 (SD=30.4) para hembras y machos, respectivamente. Los mayores valores de IG para ambos sexos fueron observados el inicio del primer semestre. Los análisis histológicos mostraron que la mayoría de los ovarios y testículos correspondieron a especímenes aptos para reproducirse. Sin embargo, hembras con ovarios maduros, con gran cantidad de oócitos hidratados y folículos post ovulatorios, se encontraron principalmente de diciembre a marzo, que se considera es la época de reproducción del atún de aleta negra alrededor del ASPSP.
Subject(s)
Animals , Female , Male , Gonads/growth & development , Reproduction/physiology , Sexual Maturation/physiology , Tuna/physiology , Brazil , Seasons , Sex Ratio , Tuna/classificationABSTRACT
The mutton snapper Lutjanus analis is an overexploited species of economic importance for the Northeast region of Brazil. To determine the reproductive aspects of the mutton snapper, biological data were sampled from Bahia, Pernambuco, Paraíba, Rio Grande do Norte and Ceará States, between 7 and 200m depth, from February 1997 to December 1999, performed in the Brazilian Economic Exclusive Zone Study Program (REVIZEE-NE Program). Data on total length (TL), fork length (FL), standard length (SL), total weight (TW) and gutted weight (GW) were measured. The gonads were collected and fixed in FAACC for histological analysis on maturational stage and calculation of the gonadosomatic index (GSI). A total of 135 fishes were collected; from these, 74 were females and 61 were males. Females were between 28.0 and 69.0cm (TL) and the males between 35.0 and 75.0cm (TL). Mutton snapper are gonochorists, and the spawning season, determined by the maturity stages frequency and the GSI, occurred between November and April, with peak spawning in March. The mature females minimum length was 28.0cm fork length, smaller than the minimum maturation length previously reported for the species in Cuba. The exploitation status of the species and the biological traits enhances the importance of establishing spatial and seasonal protection measures such as protected areas both in nursery and spawning sites. Rev. Biol. Trop. 58 (3): 791-800. Epub 2010 September 01.
El pargo criollo Lutjanus analis es una especie de importancia económica para la región noreste de Brasil, que esta siendo sobreexplotada. Para determinar sus aspectos reproductivos, se tomaron datos biológicos en los Estados de Bahía, Pernambuco, Paraíba, Rio Grande do Norte y Ceará, entre 7 y 200m de profundidad, de febrero 1997 a diciembre 1999, en el Programa de REVIZEE-NE en la Zona Económica Exclusiva de Brasil. Se midieron la longitud total (LT), longitud de horquilla (FL), longitud estándar (SL), el peso total (TW) y peso evicerado (GW). Las gónadas se recolectaron y fijaron en FAACC para el análisis histológico de las etapas de maduración y el cálculo del índice gonadosomático (IGS). Se recolectaron un total de 135 hembras y 61 machos. Las hembras midieron 28.0-69.0cm (TL) y los machos entre 35.0-75.0cm (TL). Lutjanus analis es gonocorista, y la época de desove, determinada por la frecuencia de las etapas de maduración y el GSI, ocurre entre noviembre y abril, con con un pico de desove en marzo. La longitud mínima (FL) de las hembras maduras fue 28.0cm, menor que la reportada para la especie en Cuba. El estado de explotación de las especies y los indicadores biológicos observados justifican el establecimiento de medidas de protección espacial y temporal, como las áreas protegidas, tanto en sitios de crianza como en zonas de desove.