Habitat use, seasonality and demography of the broadnose sevengill shark Notorynchus cepedianus in central Patagonia: Another piece of the puzzle ALEJO J. IRIGOYEN, 1 * NELSON BOVCON, 2 GAST  ON TROBBIANI, 1 AGUST  IN M. DE WYSIECKI, 1 FEDERICO ARGEMI 3 AND ANDR  ES J. JAUREGUIZAR 4,5 1 Centro para el Estudio de Sistemas Marinos (CESIMAR), Consejo Nacional de Investigaciones Cientıficas y Tecnicas (CCT CENPAT–CONICET), Puerto Madryn, U9120ACD (Email: alejo@cenpat-conicet.gob.ar); 2 Departamento de Pesca Deportiva, Secretarıa de Pesca de la Provincia del Chubut, Rawson; 3 Aquarium Fundacion Temaiken, Buenos Aires; 4 Comision de Investigaciones Cientıficas de la Provincia de Buenos Aires (CIC), La Plata; and 5 Instituto Argentino de Oceanografıa (IADO), Bahıa Blanca, Argentina Abstract The habitat use, seasonality and demography of the broadnose sevengill shark Notorynchus cepedianus were investigated in central Patagonia, where a data gap exists for the species. Catch and effort and video- derived indices indicated high relative abundance of sharks during warm months. Video stations revealed differ- ences in the spatial use by sharks, being more frequently observed in the inner section of the bay. Complemen- tary tagging efforts evidenced both a seasonal residence pattern and site fidelity between consecutive warm seasons. Juveniles outnumbered adults, which suggests that they may use the study area as a secondary nursing ground. Evidence from spontaneous regurgitation further suggests that prey abundance may be driving the sea- sonal occurrence of sharks in the region. This study allows for a more comprehensive understanding of the pop- ulation structure and dynamics of sevengill sharks in the Southwest Atlantic. Abstract in Spanish is available with online material. Key words: baited remote underwater video stations, Caleta Malaspina, catch-per-unit-effort, seasonal occurrence, Southwest Atlantic. INTRODUCTION Animal movement and its relation with the environ- ment represent crucial ecological knowledge for suc- cessful management and conservation strategies at multiple spatial scales (Humphries et al. 2010; Block et al. 2011; Avgar et al. 2013). In the case of large sharks, movement information is usually scarce and scattered due to our limitations to survey the marine environment, also exacerbated by their widespread long-scale migrations (Papastamatiou et al. 2013). Compared to other marine animal groups, in general large sharks occur in low densities, have elusive beha- viour and distribute over vast areas that are usually inaccessible by standard research methods (Heithaus et al. 2008; Heupel et al. 2015). Furthermore, their migratory patterns are known to be complex as a result of sexual- and/or life-history stage-specific inequities (Chapman et al. 2012; Papastamatiou et al. 2013). The broadnose sevengill shark Notorynchus cepedi- anus (Peron 1807) is a highly migratory species occur- ring in most temperate coastal and continental shelf marine environments (Compagno 2009; Last & Ste- vens 2009). This shark is an upper predator that exerts top-down effects by influencing the population of other predators (e.g. marine mammals), highlighting their important role in marine ecosystems (Barnett et al. 2012). Despite worldwide efforts have been made to increase knowledge on the species, available information remains limited to assess its conservation status (Compagno 2009). Furthermore, the species is highly vulnerable to overfishing in many parts of the world as a consequence of exposure to coastal fish- eries. In the Patagonian region of the Southwest Atlan- tic, for example, N. cepedianus is widely targeted by anglers (e.g. Cedrola et al. 2009) and incidentally caught in the prawn (Pleoticus muelleri) and argentine hake (Merluccius hubbsi) fisheries, with frequencies of occurrence decreasing from a maximum of 2.7% of hauls in the 1990s (Van Der Molen et al. 1998) to 0.4% in the period 2005–2014 (Ruibal N u~ nez et al. 2018). Such findings are in line with recent studies in *Corresponding author. Accepted for publication August 2019. © 2019 Ecological Society of Australia doi:10.1111/aec.12820 Austral Ecology (2019) , –