Baited camera lander attracts flapper skates (Dipturus cf. intermedia) for photo-identification

Description

Flapper skates (Dipturus cf. intermedia, formerly combined with Blue skate D.cf.flossada as Common skate D. batis) are currently classified as Critically Endangered throughout their habitat range due to historic and ongoing fishery-related overexploitation (Brander 1981; Dulvy et al. 2006). In the UK, small relict populations survive in inshore Scottish waters (Neat et al. 2015). Flapper skates can be individually identified using dorsal pigmentation patterns, allowing development of a photo-identification catalogue for assessment of presence, distribution, survival and other biological parameters (Benjamins et al., submitted). Images of individual skates have, however, typically been collected from sea angling records which can introduce inadvertent biases (e.g. non-random geographical sampling distribution, inadvertent selection of particular size/age classes).

To determine whether current efforts at building a skate photo-ID catalogue on the basis of sea angler photos are biased, we deployed a baited camera lander within the Loch Sunart to Sound of Jura Marine Protected Area (MPA) set up for flapper skates in western Scotland, UK. The aim was to test whether flapper skates could be attracted for long enough to collect high-quality images allowing individual identifica-tion and comparison of free-swimming skate to the existing photo-ID catalogue (Whitmarsh et al. 2017).

Flapper skates were successfully attracted to the baited camera lander on at least seven occasions during 5 deployments (totalling approx. 10.5 hours). At least four different individuals could be visually identified by comparing dorsal pigmentation patterns, none of which matched existing records in the photo-ID catalogue based on angling images from nearby areas. These initial data suggest that spatially restricted recreational angler-based sampling efforts might indeed underestimate skate presence across the whole MPA.
Baited camera landers can provide novel insight into flapper skate presence and distribution in situ, independent of fishing and angling efforts. This approach offers significant potential in clarifying flapper skates’ individual movement and residency patterns and should provide a valuable tool for monitoring the success of the MPA.

Period	4 Oct 2017 → 6 Oct 2017
Event title	MASTS ASM
Event type	Conference
Location	Glasgow, United Kingdom
Degree of Recognition	National