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Bosch-Soler, A., F., Galván-Magaña, C.A., Awruch, R., González-Armas & M.V., Fuerte (2020). Morphological and endocrine correlates of reproduction in the Pacific sharpnose shark (Rhizoprionodon longurio) in Bahia de La Paz, Baja California Sur, Mexico. Northeast Pacific Shark Symposium IV. La Pa, Baja California Sur, México, marzo 5 - 7, 2020, 1.

Morphological and endocrine correlates of reproduction in the Pacific sharpnose shark (Rhizoprionodon longurio) in Bahia de La Paz, Baja California Sur, Mexico

Adriá Bosch-Soler, Felipe Galván-Magaña, Cynthia A. Awruch, Rogelio González-Armas y Marcial V. Fuerte

A better understanding of commercially captured shark’s life history is essential for their management, and reproduction is the biological most important process for species to propagate over time. Microscopical and macroscopical examination of the gonads have been the most used methodology to carry out reproduction studies,but using this methodology the organism needs to be killed. This study will use both non-lethal and gonadal examination to determine the shark reproductive status during a year. Sexual hormones 17ß-estradiol, Testosterone and Progesterone were measured using radioimmunoassay (RIA). Additionally, gonadosomatic (GSI) and hepatosomatic (HSI) indexes were calculated as well as sexual maturity (L50%). A total of 39 blood samples (25 females and 14 males) and 89 gonads were obtained from Bahía de La Paz occidental shore from November 2018 to October 2019. Sexual proportion was 1.52M:1F (p < 0.05) with sizes between 46 and 123 cm total length (TL). In both sexes, GSI reached the maximum during late spring and early summer with 1.7% and 0.43% for males and females respectively, and the minimum was found in august with 0.2% and 0.05%. Similarly, maximum follicle diameter raised from December (6.5 mm Æ), to May (16 mm Æ). Thus, mating season seems to be during August as mating scars in the body as well as presence of vitellogenic sac in uterus were seen in females. Moreover, terminal embryos and distended cloaca were found during April and May, suggesting that gestation period takes 9 to 10 months. HSI had no statistical differences between months (ANOVA, p > 0.05) but, in females, it was found to be lower during the highest GSI values. L50% results showed 89 cm for males, with a linear correlation between TL and clasper length (R2 = 0.901; p-valor < 0.05), and 92 cm for females. Hormone results are being processed.

Palabras clave: Rhizoprionodon longurio; Bahía de La Paz; Reproduction

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