Community science datasets identify the spatial occurrence and hotspots of flapper skate (Dipturus intermedius)

The flapper skate, Dipturus intermedius (Parnell, 1837), is a large-bodied, slow-growing and late-maturing, Critically Endangered elasmobranch with a constrained population distribution. Here, we use two longitudinal community science datasets to investigate the occurrence of flapper skates in Irish waters. The two datasets are as follows: the Inland Fisheries Ireland mark-recapture tagging programme (1972-2021; n records = 1188) and Irish Specimen Fish Committee records (1958-2022, n records = 489). Of the 1677 records, 767 were identified as mature based on size-based thresholds (n males = 418, n females = 349). Hotspots of immature and mature individuals were identified across the south, southwest, north and northwest coasts of Ireland. Flapper skates were predominantly caught within 12 NM of the coast in the summer to early autumn (June-October). Time at liberty ranged from 0 to 11.5 years [mean years ± standard deviation (SD) = 1.5 ± 1.6]. Recapture events were typically <50 km from their initial capture location (93% of individuals), with dispersal distances of up to 171 km recorded. This study demonstrates that mature female and male flapper skate, and immature female flapper skate exhibit interannual site fidelity with short dispersal distances and move within existing ICES stock management areas.