Habitat use, seasonality and demography of an apex predator in a marine temperate environment: the case of the sevengill shark Notorynchus cepedianus in northern Patagonia

JAUREGUIZAR, A. ; TROBBIANI, G. ; ARGEMI, F. ; IRIGOYEN, A.; AWRUCH C. A.; BOVCON, N.

Congreso; Sharks International 2018; 2018

Gaining insight on howspecies relate to the environment and other members of the trophic community iscritical for their management. This study investigates the habitat use,seasonal patterns of abundance and population structure of the broadnose sevengillshark, Notorynchus cepedianus, in a marine temperate environment of anorthern Patagonian bay (Argentina). A suit of baited remote underwater videostations (BRUVS) derived and catch-and-effort data indices were constructed toestimate the seasonal abundance of the species inside the bay. Reproductivehormone levels were used to determine reproductive status and maturity stagesof the population. Results indicated that N. cepedianus uses the bayyear-round, with a peak of abundance during spring when the species aggregates forfeeding and mating purposes. Male and female sizes at maturity occurred at 170and 190 cm of total length, respectively. Conversely to other studies in the SouthwestAtlantic, population composition remained similar throughout the seasons with adultindividuals dominating over juveniles and adult females prevailing in thepopulation at all times. Considering the historical abundance decline recentlyreported for the species, protection and enforcement within protected areasacross the Southwest Atlantic must remain of high priority in governmentinitiatives.