Otago Harbour is an important area for undefined aggregation of one shark species.

Broadnose Sevengill Sharks aggregate in Otago Harbour during the austral summer months (Housiaux et al. 2019; Lewis & Carson 2020). Shore-based surveys (n = 71) using chum were conducted every three weeks from July 2013 to May 2015 to confirm anecdotal reports of aggregations of Broadnose Sevengill Sharks in this small bay. Animals measuring between 150–250 cm total length (TL) were found to aggregate in the area (Housiaux 2016; Housiaux et al. 2019). Broadnose Sevengill Sharks were recorded on 86% of trips during summer months (mean = 2.1 sharks per trip) and were detected in smaller numbers (mean = 0.7 sharks per trip) during autumn (Housiaux et al. 2019). The study was conducted in adjacent bays where records of Broadnose Sevengill Sharks were not detected. Despite similar effort across seasons, no Broadnose Sevengill Sharks were detected in winter or spring. Additionally, Broadnose Sevengill Shark was the most commonly reported species from baited remote underwater video station (BRUVS) surveys in 2020 and 2021 and were almost exclusively recorded in summer confirming their regular occurrence in the area (Lewis & Carson 2020). Otago Harbour is one of the few locations around New Zealand where this species regularly aggregates in a specific season. Broadnose Sevengill Sharks have been found to seasonally aggregate during summer in bays in other parts of the globe for feeding or reproductive process (Ebert 1989; Lucifora et al. 2005; Barnett et al. 2010; Abrantes & Barnett 2011; Williams et al. 2012; Stehfest et al. 2014; Hammerschlag et al. 2019). The nature and function of Broadnose Sevengill Shark aggregations in this area could be for feeding purposes. This is because their presence may be driven by a high abundance of potential demersal prey in the area during summer (Housiaux et al. 2019). Further information is required to determine the nature and function of these aggregations.