Individual identification of flapper skate Dipturus intermedius using a baited camera lander

Abstract

The ability of baited remote underwater video (BRUV) landers to attract and identify individual flapper skates Dipturus intermedius based on their spot patterns was tested within the Loch Sunart to Sound of Jura Marine Protected Area (MPA). Two BRUV lander designs, baited with a mix of mackerel, herring, squid and octopus, were deployed in 9 different locations at depths between 105 and 133 m for approx. 2 h per deployment. The BRUV successfully obtained video footage and still images of flapper skates during 4 deployments. On 6 occasions, skates remained at the bait long enough for us to obtain high-quality video of their dorsal spot patterns. Five individuals, one of which was observed at 2 adjacent landers in quick succession, were all uniquely distinguishable; one female was matched to existing records in a photo-identification catalogue based on images collected by recreational sea anglers within the MPA. BRUVs offer significant potential for studying individual presence, distribution patterns and abundance of flapper skates, independent of fishing/angling efforts. BRUV landers can therefore support monitoring efforts for evaluating long-term conservation management measures for this species.