An overview of the biology and status of undulate ray Raja undulata in the north‐east Atlantic Ocean

Abstract

The undulate ray Raja undulata is one of the lesser-known skates occurring on the continental shelf of the north-east Atlantic Ocean. It is patchily distributed throughout its range, with sites of local abundance in the central English Channel and off the coasts of Ireland, France, Spain and Portugal. Raja undulata is most abundant in coastal waters (<50 m deep) and is often found in proximity to large estuaries, rias and bays. It is a relatively large-bodied species, attaining a maximum total length (L(T) ) of at least 114 cm, with females maturing at an L(T) of c. 84 cm in Portuguese waters. Although infrequently taken in existing trawl surveys, it can be locally abundant in certain areas, where it can be the dominant skate species. Given its large size, patchy distribution and concern over the possibilities of localized depletions, the IUCN listed R. undulata as an endangered species and, since 2009, the European Union has established regulations to prohibit commercial fisheries landing the species. Given the increased interest in the species, a synopsis of current knowledge is provided, and available data from internationally co-ordinated trawl surveys presented.

Spatial Heterogeneity in Fishing Creates de facto Refugia for Endangered Celtic Sea Elasmobranchs

“…Many elasmobranch species also respond to local habitat characteristics such as substratum type [47], [48] and depth [49], [50]. In this context, it might be suggested that remaining (relatively) high biomass patches just reflect areas where high quality habitat supported greatest elasmobranch biomass prior to fishing.…”

DNA barcoding unveils skate (Chondrichthyes: Rajidae) species diversity in ‘ray’ products sold across Ireland and the UK

“…Therefore, the complete absence of species of critical conservation concern may also reflect effective controls by the EU and efforts of fishermen and stakeholders to reduce landings of these groups. Perhaps a more stringent test of such action could be made in regions where threatened species are more locally abundant: e.g., R. undulata remains relatively common around the Channel Isles (Ellis, McCully & Brown, 2012), and analyses focused on this area could form a more rigorous test of effective landing controls. Interestingly, the largest growing species identified ( R. brachyura ) also occurred most frequently in the study.…”

Using biological variables and reproductive strategy of the undulate ray Raja undulata to evaluate productivity and susceptibility to exploitation

“…The distribution of R. undulata in the north and central regions of mainland Portugal is in accordance with the other published data for south‐western Portugal (Baeta et al ., ), southern Portugal (Coelho et al ., ; Coelho & Erzini, ), Galicia (Bañon et al ., ), the U.K. (Ellis et al ., , ) and the Irish Sea (Minchin & Molloy, ). The occurrence of newborn and juveniles and egg‐laying females in estuarine habitats was also documented, proving their importance for the life cycle of the species.…”

“…According to Portuguese fishing records, R. undulata is relatively frequent off Setúbal and along the inshore waters off the Algarve coast (Coelho et al ., ; Baeta et al ., ). Inshore areas, namely estuaries and coastal lagoons, were identified as being associated with egg laying and as nursery sites (Prista et al ., ; Moura et al ., ; Ellis et al ., ).…”

“…Ellis et al . () compiled an overview of the current knowledge on the biology and status of R. undulata , and since this time, various European laboratories have conducted investigations, largely due to the controversy surrounding its listing on the prohibited species l. Whilst there are insufficient data to evaluate the stock structure and population status of the species or to assess abundance trends in each stock area, available data indicate that it is a locally abundant species, which may not justify its prohibited status. This measure has been very controversial for E.U.…”