Sharks and Skates of Scotland Report: Starry smoothhound (Mustelus asterias)
An extract from the Sharks and Skates of Scotland Report.
Starry smoothhound - Mustelus asterias (Cloquet, 1819)
Occurrence in Scotland: Shelf. Regular summer visitor. Very high number of records
Synonym(s): None; Order: Carcharhiniformes; Family: Triakidae
Common name: Starry smoothhound;
AlphaID: 105821 TSN Code: 160240
Note: Mustelus asterias (Starry smoothhound) has historically been confused with Mustelus mustelus (Common smoothhound), whose range partially overlaps with M. asterias (Farrell et al., 2010b). However, ICES notes that M. asterias is the predominant, and possibly only, species of Mustelus to occur around the British Isles (ICES, 2018). There are no reliably confirmed records of M. mustelus occurring north of Portuguese waters (Farrell et al., 2015b). Mustelus asterias is the dominant smoothhound species in northern European waters and is found in both the Northeast Atlantic and the Mediterranean Seas. Species-specific landings for the various Mustelus species are not considered accurate, and data are collated at the genus level (ICES, 2018).
Population status
Scotland and Northeast Atlantic: Increasing abundance in the North Sea and west Scotland (ICES 2024). Increasing abundance in the rest of the Northeast Atlantic (ICES 2024, Jabado et al., 2021).
Global: Decreasing. This species has undergone a population reduction of 20–29% over the past three generation lengths (39 years) due to actual levels of exploitation, primarily in the Mediterranean and Black Seas (Jabado et al., 2021).
Conservation listings
- IUCN Red List Europe: Near Threatened (assessment 16 December 2014)
- IUCN Red List Mediterranean: Vulnerable (assessment 25 March 2016)
- IUCN Red List Global: Near threatened (assessment 04 August 2020)
- CITES: Not listed
- CMS: Not listed
- OSPAR: Not listed
- EU Regulation 2019/1241
Range and distribution
In the Northeast Atlantic, the range of Starry smoothhound extends from Scottish and southern Norwegian waters southwards to Sweden, Denmark, Germany, the Netherlands, Belgium, France, the United Kingdom, Ireland, Spain and Portugal. ICES consider there to be a single biological stock in Northeast Atlantic waters (ICES subareas 4 and 6-8) (ICES, 2024). The species is also found along the coast of NW Africa, as well as in the Mediterranean and Black Sea (Farrell et al., 2015a).
ICES DATRAS records for Starry smoothhound (Mustelus asterias and Mustelus mustelus (assumed to be M. asterias)) 1970-2019.
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Five maps of the economic exclusion zone (EEZ) of Scotland showing ICES (International Council for the Exploration of the Sea) DATRAS (database of trawl surveys hosted by ICES) records for Starry smoothhound (Mustelus asterias and Mustelus mustelus (assumed to be M. asterias)). Red points represent trawl shoot positions in which Starry smoothhound were captured. For 1970 to 1979 2 records are illustrated, one east of Orkney and one east of Wick. For 1980 to 1989 there is one record to the northeast of Orkney. For 1990 to 1999 there are many more records distributed across the whole of the continental shelf within the economic exclusion zone (EEZ) of Scotland, records are highest in density in the North Sea. For 2000 to 2009 records occur in similar positions but at slightly higher density and for 2010 to 2019 records again occur in similar positions but again at higher density. A change in the number or distribution of records over time does not reflect a change in occurrence or abundance since data have not been corrected for effort.
Landings data from commercial fishing vessels in ICES rectangles for Starry smoothound (Mustelus asterias and Mustelus mustelus (assumed to be M. asterias)) 2011 - 2019.
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Map of the economic exclusion zone (EEZ) of Scotland showing landings data for Starry smoothound (Mustelus asterias and Mustelus mustelus (assumed to be M. asterias)) recorded on commercial fishing vessels from 2011 to 2019. The EEZ of Scotland is covered by a grid dividing it into the International Council for the Exploration of the Sea (ICES) rectangles. Data is filtered to exclude information in rectangles where three vessels or less operate. Values are presented as individuals per trip and represented as a heat map, colouring each ICES rectangle from 1 (blue) to 81 (red). Small numbers of landings, illustrated by one blue rectangle representing 1 to 10 individuals, were reported around the north east coast of Scotland, on the south shore of the Moray Firth.
Discard data from commercial fishing vessels in ICES rectangles for Starry smoothhound (Mustelus asterias and Mustelus mustelus (assumed to be M. asterias)) 2014-2018.
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Map of the economic exclusion zone (EEZ) of Scotland showing discard data for Starry smoothhound (Mustelus asterias and Mustelus mustelus (assumed to be M. asterias)) recorded on commercial fishing vessels from 2014 to 2018. The EEZ of Scotland is covered by a grid dividing it into the International Council for the Exploration of the Sea (ICES) rectangles. Data is filtered to exclude information in rectangles where 3 vessels or fewer fish. Values are presented as individuals per trip and represented as a heat map colouring each ICES rectangle from 1 (blue) to 160 (red). Discards are low represented by blue rectangles (0 to 40 individuals) north west of Orkney, east of Orkney and in the North Sea at the eastern edge of Scotland’s EEZ.
Tag – recapture records for Starry smoothhound (Mustelus asterias) from the Scottish Shark Tagging Programme, the Glasgow Museums tagging programme and the UK Shark Tagging Programme data from 1970 to 2025.
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Map of the economic exclusion zone of Scotland showing records for Starry smoothhound (Mustelus asterias) from the Scottish Shark Tagging Programme, Glasgow Museums tagging programme and the UK Shark Tagging Programme data from 1970 to 2025. Data are presented as blue dots for each individual Starry smoothhound (M. asterias) tagged or recaptured. These tag – recapture records provided by anglers and occasionally supplemented by reports of tagged animals subsequently captured on commercial fishing vessels show tight clusters in places where angling and tagging have occurred, in this case, the south east of Scotland (Solway Firth, Wigtown Bay, Luce Bay and east of Portpatrick).
Habitat
Starry smoothhound inhabit waters on the inner continental shelf down to a depth of 200m, with a preference for large bays, sandy beaches, outer parts of large estuaries and coastal areas in UK waters (Ellis et al., 2005b, Weigmann 2016). Tag-and-release studies in the Dutch Delta found that Starry smoothhound undergo a yearly migration, with fish spending the summer in the southern North Sea and overwintering in the English Channel and Bay of Biscay. The studies suggest they habitually return to a particular area (philopatry), and that there are sex-based differences in dispersal, with females travelling further than males, with more males in the Northern North Sea, and more females in the Bay of Biscay during the winter months (Brevé et al., 2016, 2020, Griffiths et al., 2020).
Biology and Ecology
Starry smoothhound are a relatively small demersal shark species, with a maximum recorded size of 140 cm (TL) in UK waters (Ellis et al., 2005). The size of males and females caught in both commercial fisheries and research‐vessel surveys ranges from 24-99 cm (TL) and 28 – 124 cm (TL), respectively (McCully-Phillips and Ellis, 2015). In British waters, size at 50% maturity was estimated to be 70.4 cm and 81.9 cm (Tl) for males and females, respectively (McCully-Phillips and Ellis, 2015), and age at 50% maturity for males and females was estimated to be 4-5 years and 6 years respectively (Farrell et al., 2010; McCully et al., 2012). Growth studies for the Northeast Atlantic population estimated that males can live for 7.3 – 13 years, and females for 9.9 – 20.2 years. However, the maximum observed ages for both males and females caught in the wild was 13 years (Farrell et al., 2010). Starry smoothhound have been found to aggregate according to sex and size (ICES, 2018). They are an aplacental viviparous species, with fertilised eggs developing in the oviducts until they are ready to ‘hatch’. Along the coast of Britain, ovarian fecundity ranged from 1 to 28 oocytes, with 4 to 20 embryos present in the uterus at any one time (McCully-Phillips and Ellis, 2015). The gestation period is 12 months, followed by a resting period such that the reproductive cycle is thought to extend beyond 1 year (Farrell et al., 2010; McCully-Phillips and Ellis, 2015). It is thought Starry smoothhound may enter estuaries to reproduce and/or forage for food (Quigley, 2016), and new-borns are seasonally abundant in the English Channel, southern North Sea/Thames Estuary and Bristol Channel (Ellis et al., 2005) and in shallow waters off sandy beaches on the southeast coast of Ireland (Farrell et al., 2010b). The number, mass and size (TL) of pups is positively correlated with the size of their mothers (TL), and in British waters full‐term pups ranged from 20.5 to 32.9 cm LT (McCully-Phillips & Ellis, 2015). Females give birth in February in the western English Channel and during June to July in the eastern English Channel and southern North Sea, indicating that spawning either lasts several months or varies regionally (McCully-Phillips and Ellis, 2015). Sperm storage in females, and multiple paternity (where more than one male sires a single litter of pups) has been demonstrated in this species (Farrell et al., 2013).
The diet is largely made up of crustaceans, with hermit crab (Pagurus bernhardus) and flying crab (Liocarcinus holsatus) being the dominant prey species in Starry smoothhound from the north-east Atlantic (McCully-Phillips et al., 2020). Other crustaceans include the commercially important velvet swimming crab (Necora puber) and small edible crab (Cancer pagurus), as well asstomatopods, brachyuran crabs, squat lobsters and shrimps have been identified as prey items (Ellis et al., 1996). The diet of Starry smoothhound sampled in the North Sea ecoregion was found to have a lower diversity of prey types than that of Starry smoothhound in the Celtic Seas ecoregion (McCully-Phillips et al., 2020). In this study, no teleost fish were found in the diet; however, previous studies have documented the occasional consumption of teleosts by larger individuals (Ford, 1921; Ellis et al., 1996).
Human interactions
Smoothhounds as a ‘group’ are caught seasonally in trawl, gillnet and longline fisheries, and Starry smoothhound is becoming increasingly important as a non-quota species to some inshore fisheries (ICES, 2018 and 2024; Silva and Ellis, 2019). The species may be either landed or discarded depending on market demands for ‘dogfish’, and they may also be used as bait if caught in pot and creel fisheries, for example, by vessels targeting whelk (ICES, 2018). The majority of Starry smoothhound caught in beam trawls and Nephrops trawls are juveniles (<70 cm TL), while a wider size range is typically caught in gillnets and otter trawls. The majority of juvenile Starry smoothhound (<60 cm TL) are discarded by these fisheries (Silva & Ellis, 2019). Data suggest that discard mortality for Starry smoothhound varies but may be high, depending on the fishing method. In a study investigating discard mortality, at-vessel mortality was highest for Starry smoothhound caught in gillnets (56%). In comparison, 91% of longline-caught individuals were in good condition at capture. Longline-caught Starry smoothhound were generally larger individuals, while smaller sharks caught in beam trawls were generally found in poor condition. (McCully Phillips et al., 2019, ICES, 2024) In the UK, the number of Starry smoothhound retained (rather than discarded) has increased in recent years, which may be a result of restrictions on Spurdog landings (Silva & Ellis, 2019, ICES, 2024). Starry smoothhound are also an important species for recreational anglers around the coast of the UK (Biton-Porsmoguer and Lloret 2023, ICES 2024). Catch and release protocols are often in place however there is insufficient data on the degree of mortality associated with catch and release angling in this species. There are no management or conservation measures currently in place for Starry smoothhound, and no restrictions are in place on catch in the UK. UK fisheries management plans for elasmobranchs (sharks, skates, and rays) are currently under development, plans will focus on specific regions. ICES advised that when the maximum sustainable yield approach is applied, landings should be no more than 5329 tonnes in each of the years 2024 and 2025 (ICES, 2024).
References
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