Aggregations and reproductive events of the narrownose smooth hound shark, Mustelus schmitti, in relation to temperature and depth in coastal waters of the southwestern Atlantic Ocean.
Elisio, M., Colonello, J., Cortés, F., Jaureguizar, A.J., Somoza, G.M. and Macchi, G.J.
Instituto Nacional de Investigación y Desarrollo Pesquero, Mar del Plata, Argentina.
Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina.
Comisión de Investigaciones Científicas de la Provincia de Buenos Aires, La Plata, Argentina.
Laboratorio de Ictiofisiología y Acuicultura, Instituto de Investigaciones Biotecnológicas – Instituto Tecnológico de Chascomús (CONICET-UNSAM), Chascomús, Argentina.
Corresponding author. Email: melisio@inidep.edu.ar
Knowledge of environmental influence on reproductive dynamics in chondrichthyans is critical for effective management. This study assessed the potential influences of temperature and depth on aggregations and reproductive events of the narrownose smooth-hound shark (Mustelus schmitti), using an analysis criterion based on the co-occurrence of different reproductive stages. Data were collected from 363 sample sites during six research surveys, covering an area of approximately 13,920 nm2 along the coast (38–42º S and depths < 50 m). M. schmitti adult aggregations were mostly associated with the warmer springs surveys, being the aggregation sites significantly warmer than those of non aggregation. Pupping and ovulation evidences were observed, almost simultaneously, during all spring surveys. However, the occurrence of these reproductive events showed a clear interannual variability pattern significantly explained by water temperature. Particularly, the ovulation occurrence was associated with temperatures above 16-17 °C. These results suggest that M. schmitti adults may follow the warming gradient along the environment and thus they aggregate in shallow and productive waters during the course of spring. Their reproductive events could be induced by temperature increase. This scenario suggests that changes in bottom temperature patterns may be important drivers of the reproductive dynamics of M. schmitti.
Marine and Freshwater Research 68: 732-742 (2017)