Sharks and Skates of Scotland Report: Small spotted catshark (Scyliorhinus canicula)

An extract from the Sharks and Skates of Scotland Report.

Small spotted catshark - Scyliorhinus canicula (Linnaeus, 1758) 

Note on data quality: Landings of ‘catsharks’ were traditionally reported in category groups (e.g. dogfishes and hounds), though since 2005, more species-specific landings have become available (ICES, 2019a). Misidentification between S. canicula and S. stellaris is also problematic in fisheries data, especially in areas where both species occur, such as the Celtic Sea (ICES, 2018). The lack of historical landings data and the uncertainty associated with recent species-specific information suggest fisheries-dependent data should be viewed with caution. However, scientific groundfish surveys provide valuable information on the abundance and distribution of this species (ICES, 2018).  

Population status

Scotland and Northeast Atlantic: Increasing biomass in the North Sea Ecoregion between 2004 and 2022 (ICES, 2024). Increasing biomass in the Celtic Seas Ecoregion between 2008 and 2018, and stable to increasing between 2018 and 2022 (ICES, 2024). Increasing in the rest of the Northeast Atlantic (Finucci et al., 2021, Serena et al., 2015). 

Global: Stable (Finucci et al., 2021)

Conservation listings

Range and distribution 

Small spotted catshark (Scyliorhinus canicula) is one of the most abundant and wide-ranging elasmobranch species in the Northeast Atlantic and the Mediterranean (Serena et al., 2015) and can also be found in the central Atlantic. In the Northeast Atlantic its range extends from waters around Shetland and Norway in the north, all the way southwards to the waters off West Africa (Serena et al., 2015). It is relatively abundant throughout Scottish waters (Baxter et al., 2011), and around much of the British Isles (Ellis et al., 2005). Small spotted catshark are thought to have localised movement patterns with limited migration, and ICES assumes that “immigration and emigration from adjacent populations are either insignificant or on a par” (ICES, 2018). ICES currently consider 4 stock units for this species: (i) North Sea ecoregion (Subarea 4 and Divisions 3.a and 7.d), (ii) Celtic Seas and west of Scotland (Subarea 6 and Divisions 7.a–c and 7.e–j), (iii) northern Bay of Biscay (Divisions 8.a–b and 8.d), and (iv) Atlantic Iberian waters (Divisions 8.c and 9.a) (ICES, 2018). 

Habitat 

This species inhabits inshore waters from the shallow coast out to the edge of the continental shelf, at depths ranging from about 6 – 300 m (Ellis et al., 2005), although it is most common in water <110 m deep (Ebert and Stehmann, 2013). Small spotted catsharks are a bottom-dwelling species that can be found over a variety of substrates, including sand, coralline algal, gravel and mud (Ebert and Stehmann, 2013). Juveniles and hatchlings are often found in shallower water than the adults (Ebert and Stehmann, 2013). 

Biology and Ecology

Small spotted catshark are a medium sized elasmobranch that can grow to a maximum length of about 80 - 85 cm around the British Isles and in the North Sea. In the Northeast Atlantic males mature at 49 – 55 cm, and females mature at 52 – 65 cm (Ellis and Shackley, 1997). Females are oviparous (egg laying), and eggs are deposited on macroalgae or sessile invertebrates (e.g. hydroids, sponges, bryozoans) and take 5 – 11 months to hatch (Ellis and Shackley, 1997; Ebert and Stehmann, 2013). Females lay eggs year-round; however most are deposited between November and July (Ellis and Shackley, 1997; Ebert and Stehmann, 2013). Fecundity of females is proportional to their length, and they produce around 29 - 62 eggs per year in the Northeast Atlantic, with size at birth ranging from 7-11 cm TL (Ellis and Shackley, 1997). Small spotted catsharks are known to aggregate according to sex and size, with females tending to return to or remain in a particular area, while males are more wide-ranging (Sims, 2003). Studies suggest they generally exhibit site fidelity (Labourgade et al., 2024) and have a small home range, which was estimated at 0.2 – 38.5 km in the Balearic islands (Ferragut-Perello et al., 2024). Small spotted catsharks feed on a variety of bottom-dwelling invertebrates, such as hermit, swimming and various other crab species, shrimps, whelks and other gastropods, small cephalopods and polychaetes (Martinho et al., 2012; Ebert and Stehmann, 2013). They may also prey on teleost fish, and both adults and juveniles consume relatively more fish in the spring and summer than in other seasons (Martinho et al., 2012).   

Human interactions 

Small spotted catshark are a bycatch of demersal trawl, gillnet and longline fisheries over much of their range in Northeast Atlantic waters. They are usually of low commercial value and, except for some seasonal, small-scale fisheries in some coastal areas, are not subject to target fisheries, discarding can be high (ICES, 2024). Some Small spotted catshark may occasionally be landed as bait by creel and pot fishers in the UK, specifically by whelk and brown crab fisheries. They are also commonly caught by recreational anglers around the UK. 

Scyliorhinids are considered to be a relatively productive species in comparison to other demersal elasmobranchs (ICES, 2024), so may be resilient to fishing pressures. In addition, the survival rates of discarded Small spotted catsharks are estimated to be high (Barragán-Méndez et al., 2019). For example, in the Western English Channel beam trawl fishery, discard survival was estimated that more than 90% in a 48-hour aquarium trial (Revill et al., 2005), and similar high survival rates were observed for this species in otter trawl fisheries (Serena et al., 2015).  

ICES has provided species-specific advice on landings since 2012. ICES advice on landings for 2024 and 2025 (using the maximum sustainable yield approach) were 2680 tonnes for the North Sea ecoregion (Subarea 4 and in divisions 3.a and 7.d; ICES 2023a) and 3984 tonnes for the Celtic Seas and west of Scotland (Subarea 6 and divisions 7.a–c and 7.e–j) (ICES 2023b).