Chondrichthyan occurrence and abundance trends in False Bay, South Africa, spanning a century of catch and survey records

Baited remote underwater video system (BRUVs) survey of chondrichthyan diversity in False Bay, South Africa

“…Six fisheries are recognised as targeting sharks, rays, skates and chimaeras. These are the demersal and pelagic longline fisheries, linefishery (commercial and recreational), gillnet fishery, beach-seine net fishery and the KwaZulu-Natal bather protection programme (DAFF 2012;Best et al 2013;da Silva et al 2015). The greatest proportion of chondrichthyans, however, is caught as bycatch in other fisheries, e.g.…”

“…in the commercial trawl sector (da Silva et al 2015). This fact, compounded by inadequate and inaccurate reporting of catches, means that proper understanding of which species are most affected -and how -is limited (Best et al 2013). The commercial beach-seine fishery, commercial line fishery and recreational fishery in False Bay overlap spatially and temporally (Penney 1991), but the distribution of these fisheries along the South African coastline is often disparate, further complicating adequate monitoring and comparison of chondrichthyan assemblages (Sauer et al 2003;DAFF 2012).…”

“…The range of fishing methods utilised in the bay, and their relative impacts on the chondrichthyan population, are detailed in a study by Best et al (2013). That study recorded 37 species in the bay and showed the surf zone to be most affected by human activities, with populations of Mustelus mustelus and Carcharhinus brachyurus increasing and populations of Galeorhinus galeus and Raja species declining (Best et al 2013).…”

“…The range of fishing methods utilised in the bay, and their relative impacts on the chondrichthyan population, are detailed in a study by Best et al (2013). That study recorded 37 species in the bay and showed the surf zone to be most affected by human activities, with populations of Mustelus mustelus and Carcharhinus brachyurus increasing and populations of Galeorhinus galeus and Raja species declining (Best et al 2013). Whilst the relative abundance of each species has been documented according to selected information from fisheries catch data (Best et al 2013), basic ecological data such as the distribution of species across the bay, the effects of environmental factors on community composition, and species' seasonal habitat and depth preferences, remain lacking for False Bay.…”

“…Whilst the relative abundance of each species has been documented according to selected information from fisheries catch data (Best et al 2013), basic ecological data such as the distribution of species across the bay, the effects of environmental factors on community composition, and species' seasonal habitat and depth preferences, remain lacking for False Bay. Hence, the study by Best et al (2013) provides a baseline against which to test other methods to improve the overall quality of data.…”