La pesquería de tiburones oceánicos-costeros en los litorales de Colima, Jalisco y Michoacán
Angélica Cruz, Sandra R. Soriano, Heriberto Santana, Cecilia E. Ramírez & Juan J. Valdez
ABSTRACT
Fishery of oceanic and coastal sharks in Colima, Jalisco and Michoacán. Shark fishery is one of the most important activities in the Mexican Pacific coast, nevertheless, there is few data available about the specific captures done by the fleet along the coast. This study describes fishery biology aspects of the shark species catched by the semi-industrial long-line fleet of Manzanillo. Monthly samplings were made on board of these vessels during an annual period from April 2006 to April 2007. Captured species composition (n=1 962 organisms) was represented by nine species. The one that sustains this fishery was Carcharhinus falciformis (88.12%), followed by Prionace glauca (8.21%). Low frequency species were represented by Sphyrna zygaena (1.78%), Alopias pelagicus (0.82%), Carcharhinus longimanus (0.45%). Furthermore, rare species were Alopias superciliosus (0.35%), Carcharhinus leucas (0.1%), Carcharhinus limbatus (0.1%) and Isurus oxyrinchus (0.05%). Fishery activity affected principally (60-92.70%) young males of C. falciformis, S. zygaena, C. longimanus and I. oxyrinchus; adult males (56-75%) of A. pelagicus, A. superciliosus, and C. limbatus; for P. glauca there were primarily female adults. For all the species found, females showed the bigger sizes when compared to males (with the exception of S. zygaena, that showed sexual dimorphism). Considering the lineal regressions made between precaudal length and total length, and, fork length and total length for C. falciformis, P. glauca, S. zygaena and A. pelagicus, the determination coefficients (r2) showed that both lengths can be useful to obtain the total length of fish with some damage or absence of its caudal fin. The estimated fecundity for C. falciformis was of 3-7 offspring/female of 30-45cm LT (average of 40.57+2.03cm LT); and for P. glauca 5-52offspring/female of 5-18.6cm LT (average of 11.61±0.21cm LT). In the case of C. longimanus only one female was captured with a total of eight embryos, with an average of 45cm LT each; for this reason we assumed that the fishery areas do not coincide with the nursery ones for this species. According to the information obtained, we concluded that C. falciformis has a concurrent cycle and P. glauca a consecutive biannual one.
RESUMEN
La pesquería de tiburón es una de las más importantes en el Pacífico mexicano, en la actualidad no se cuentan con los datos de la composición específica de las capturas de las diferentes flotas. En el presente trabajo se describen aspectos biológicos-pesqueros de las especies de tiburón, capturadas por la flota palangrera de mediana altura del puerto de Manzanillo, en un periodo anual de abril 2006- abril 2007, los muestreos se realizaron mensualmente a bordo de estas embarcaciones. La composición de las capturas estuvo representada por nueve especies (n=1 962), de las cuales Carcharhinus falciformis (Bibron, 1839) (88.12%) sostiene esta pesquería y en segundo lugar Prionace glauca (Linnaeus, 1758) (8.21%). Las especies poco frecuentes fueron Sphyrna zygaena (Linnaeus, 1758) con (1.78%), Alopias pelagicus (Nakamura, 1935) (0.82%), Carcharhinus longimanus (Poey, 1861) (0.45%), Alopias superciliosus (Lowe, 1839) (0.35%), Carcharhinus leucas (Valenciennes, 1839) (0.1%), Carcharhinus limbatus (Valenciennes, 1839) (0.1%) é Isurus oxyrinchus (Rafinesque, 1810) (0.05%). La fecundidad estimada para C. falciformis fue de 3-7 crías/hembra con tallas de 30-45cm LT; 40.57+2.03cm LT y P. glauca con 5-52 crías/hembra, con tallas de 5-18.6cm LT; 11.61±0.21cm LT. Por lo tanto se asume que C. falciformis presenta un ciclo concurrente y P. glauca probablemente un ciclo bianual consecutivo.