Sharks and Skates of Scotland Report: Nursehound (Scyliorhinus stellaris)

Habitat 

Nursehounds inhabit both inshore and offshore waters, between depths of 1- 380 m, but are most commonly found in water <60 m deep (Weigmann 2016). In the Northeast Atlantic they are thought to prefer rocky or cobble seabed (Ebert and Stehmann, 2013).

Biology and Ecology

Nursehounds are Europe’s largest catshark species growing to a maximum size of 162 cm TL and commonly measuring about 125 cm TL (Ebert and Stehmann, 2013). Data on sexual maturity is lacking for the Northeast Atlantic, but in the Mediterranean males and females become sexually mature at 77 cm TL and 79 cm TL, respectively (Ellis et al., 2015). They are oviparous like other catsharks and produce large thick-walled egg cases 10-13 cm minimum length, which are deposited on macroalgae in the lower intertidal and subtidal zones in spring and summer (Ebert and Stehmann, 2013). Eggs are laid all year round except for December and January and take 9 – 12 months to hatch. Newly hatched sharks are around 105 -110 mm TL (Capapé et al., 2006, Soares and Carvalho 2019). Nursehound diet is mainly made up of crustaceans and cephalopods, with smaller amounts of shellfish and fish. The most important prey reported are lesser octopus, squat lobsters, and both brown crabs and hermit crabs. The species occasionally eats thornback rays (Ellis et al., 1996). A tagging study found that Nursehounds go on foraging excursions during the night, and refuge in narrow-entrance holes in rocks during the day (Sims et al., 2005). Several Nursehounds may find refuge in the same rocky locations or “home refuges” at the same time, and the species displays philopatric behaviour whereby tending to return to or remain near a particular site (Sims et al., 2005).

Human interactions 

NNursehounds are of limited importance to fisheries, but may be taken as bycatch in bottom trawls, gillnets, longlines and fixed bottom nets. They are also targeted by recreational fisheries (Ebert and Stehmann, 2013, Finucci et al., 2021). Data from the Cefas observer programme (2002 -2016) in the Celtic Seas and North Seas ecoregions indicated that 68 -98% of bycatch of this species from net and beam trawl fisheries, respectively, were discarded (Silva and Ellis 2019). However, the species' preference for rocky inshore habitats (Cook et al., 2024) may offer it some protection from demersal fisheries that cannot operate over such grounds (Ellis et al., 2015). In addition, the survival of catsharks after discarding is believed to be relatively high, although this has not been studied for Nursehounds (ICES, 2018). In the Northeast Atlantic, France and Portugal report the highest landings of this species, where they may be sold fresh or dried and salted for human consumption. In the Mediterranean, overfishing is considered the primary cause of the species' decline. Species misidentification (confusion with S. canicula) is common and is likely to lead to inaccuracies in fisheries reporting data (Silva and Ellis, 2019; ICES, 2024). The stock status is currently only assessed by ICES for Subareas 6 and 7 (Celtic Seas Ecoregion, including west Scotland). ICES advised that when the MSY approach is applied, landings should be no more than 682 tonnes in 2025 (ICES, 2024).