Mullet, Grey, Thicklip

Chelon labrosus

Method of production — Caught at sea
Capture method — Gill or fixed net
Capture area — North East Atlantic (FAO 27)
Stock area — UK
Stock detail — English Channel, North Sea
Picture of Mullet, Grey, Thicklip

Sustainability rating five info

Sustainability overview

There are three distinct species (Thick Lipped Grey Mullet (Chelon labrosus), Thin Lipped Grey Mullet (Liza ramada) Golden Grey Mullet (Liza aurata)) of grey mullet within the Eastern IFCA district. The species are often considered together: landings data are combined. Grey mullet are a commercial species, mainly caught in the English Channel: most of the landings in IFCA districts occur in the Southern, followed by Devon and Severn, Cornwall, Sussex and Kent & Essex.

The status of the grey mullet stocks are unknown and there is a lack of data collected for the species. However, the National Mullet Club (NMC) catch statistics suggest declines in their populations. Data for mullets species in general, in the North Sea, show slight population increases over time.


Grey mullet belong to a large family, which comprises some 80 species of marine fish, known as Muglidae, and is a common inhabitant of marine coastal waters in Europe. The thick-lipped grey mullet is the commonest of three species which occur in northern European waters. They are slow-growing, long-lived and late-maturing fish, which makes them susceptible to overfishing. They live to around 25 years old and mature around 9 years old (42 cm) for males and 11 years (47 cm) for females. Thicklipped mullet are thought to spawn on alternate years. Grey Mullet spawn in the English Channel and Irish Sea and potentially in estuaries in Eastern England. They spawn in open water and after around two to six weeks, the then juvenile fish move into inshore waters, especially estuaries. Their occurrence is impacted by temperature and they are often observed near the surface (0-10 m depth). Because of this, their large size, and east to capture, they can be popular with anglers.

Grey Mullet are catadromous (which means that they migrate from freshwater to seawater to spawn) and can be found in brackish lagoons and at the heads of estuaries because they can tolerate very low salinity levels. Grey Mullet are grazers, the scrape the surface off mudflats to eat diatoms and other algae off surfaces.

Stock information

Criterion score: 1 info

Stock Area


Stock information

The stock status is unknown. There are a lack of data and conflicting biomass trends. Project Inshore show that The stock is considered stable or increasing but this conclusions is 5 years old. The National Mullet Club (NMC) catch statistics suggest that mullet stocks have declined. Biomass of general mullets in the North Sea has is estimated to have experienced slightly positive biomass trends, but there is considerable uncertainty in these estimates. Fishing mortality of mullets (mullet species in general) in the North Sea has declined since 2008 and recently increased, whilst discard rates have spiked at high levels. Grey mullets landings have increased in several IFCA districts in recent years. Therefore, there is conflicting biomass trends.

There is no formal stock assessment of Grey Mullet stocks and the status of the stock is unknown relative to reference points. There is little information available on the mullet speciesa abundance in UK waters as there are a lack of data collected on the species.

There is conflicting evidence in biomass trends: Project Inshore suggest that The stock is considered stable or increasing and current catch levels are considered precautionary, compared to previous exploitation levels. However, this conclusion was published in 2013 and the National Mullet Club (NMC) suggest that mullet stocks have declined in recent years and that NMC catch statistics suggest mullet stocks are in gradual long-term decline.

Mullets in the North Sea are estimated to have fluctuated over time with slight increases. A sharp decrease has been estimated to occur around 2012 but populations have since been estimated to increase. Mullets have generally been experiencing slightly positive biomass trends, but there is considerable uncertainty in these estimates. Fishing mortality levels have been generally declining since 2008 but have subsequently increased since around 2012. Discards of mullets in the North Sea have spiked in the recent few years and the uncertainty for discard rates is very high.

In a 2014 report by Eastern Inshore Fisheries Conservation Authority (EIFCA), mullet landings were shown to have largely increased, albeit from a low base. The EIFCA reported that mullet species cannot support high levels of fishing mortality, due to their slow growth and late maturation. Increased landings may have been attributed to their bycatch in the bass fishery. Grey mullet landings in this area have increased appreciably in recent years.

FishBase considers mullets to have a medium resilience score.


Criterion score: 0.75 info

There is a general lack of management for grey mullet considering their vulnerable life history attributes. Southern IFCA mandate a 30cm MCRS but other IFCAs have no MCRS or it is set at a level lower than the size-at-maturity. Eastern IFCA have implemented some spatial protection which protects the juvenile Grey Mullet. There are measures in place for bass which may inadvertently protect the Grey Mullet but there is also a lack of monitoring and catch reporting for the species, which limits the efficacy of management.

Management of grey mullet is more associated with managing the nursery areas, rather than the stock. For example, in the EIFCA district, most of the estuaries, and a high proportion of the shallow near shore areas, are covered by some form of Marine Protected Area designation. However, these designations do not necessarily account for the food habits of the species, particularly in its juvenile phase. There is currently no minimum landing size for grey mullet within the EIFCA district, however, there is a minimum conservation reference size (MCRS) of 30cm in the Southern IFCA. The Cornwall IFCA have an MLS of 20cm. Therefore, gray mullet may be caught at a size smaller than the size that they mature and reproduce. There is some management in terms of technical measures, catch limits, closed areas and seasons, but catch limits may not be effective in this case because catches appear to be poorly recorded. There is some management (closed areas and seasons), but catch limits may be ineffective as catches are poorly recorded and adequate catch levels are unknown. An EIFCA report suggested that measures to protect bass may indirectly protect mullet. In Sussex IFCA, there is currently no MCRS for Mullet. Since mullet are often caught with bass, pressure on the species is likely to have increased with increasing restrictions for bass.

Gill nets which are often used to catch grey mullet reportedly are challenging to collect accurate landings data from. Most of the vessels targeting the species are fishing in inshore waters and are smaller (less than 12m in length), therefore, they are not monitored under the EU legislation 812/2004.

The species is not a quota species and there are not EU Minimum landing sizes to enforce. However, IFCAs generally enforce gear management and area and temporal closures using a variety of inspections and surveillance.

Capture Information

Criterion score: 0.5 info

Grey mullet tend not be a major commercial species but when fished commercially, they are a target or bycatch species which are mostly caught with gill nets, set close to the shore. They can also be fished with trawls. Gillnets in the English Channel are used to target demersal species including mullet and sea bass in inshore areas.

Data collected through the EU Habitats Directive show that harbour porpoises, small sharks (smooth-hound, lesser spotted dogfish for example) can become entangled in gillnets. Of concern, particularly in North Cornish waters, are the incidental entanglement of seabirds. The stock size of lesser spotted dogfish has been increasing in the north sea and English channel. Although bycatches of harbour porpoises occur in this fishery, their overall catch relative to the estimated populations, is not expected to be of concern. To mitigate the risk of entanglement, European vessels over >12 m in length are required to use pingersa on gillnets. However, this is not required on smaller vessels. Since 2013, the UK have reported to be fully-implementing the use of acoustic deterrent devices (ADDs). The Royal Navy and enforcement officers carry out at-sea inspections and have found no infringements were detected in 2013, but some in 2014. The Agreement on the Conservation of Small Cetaceans on the Baltic, Northeast Atlantic, Irish and North Seas (ASCOBANS) recommended monitoring and mitigation in the UK tangle and gillnet fisheries in the southwest of England in their 2017 report.

Bycatch can also include skates and rays: there is little management to protect the skate and ray species but their landings are monitored. There is also no endangered, threatened and protected (ETP) species management. European Commission regulations state that landed catches taken from bottom set nets must include at least 70% of specified target species, therefore, IFCAs ensure that gillnets commonly used in fisheries do not exceed bycatch requirements.

Cornwall IFCA have implemented new measures in 2018 to ban netting for sea fish in its rivers and estuaries which will protect juvenile bass and mullet.

The main impacts that gillnets may cause to the habitat are their anchoring to the sea floor and ghost fishing when gillnets are lost through bad weather. Gillnets can last up to a year before they deteriorate and therefore, can damage and kill sea life and habitats. However, the rate of permanent gillnet loss has been shown to be low (around one percent), due to positioning systems and efforts to recover lost and expensive gear, particularly among the under 10 m fishing fleet. VMS data are used to collect data on habitat interactions for vessels over 12m, along with surveillance data, however, this does not include data for the smaller vessels in inshore waters.


Based on method of production, fish type, and consumer rating: only fish rated 2 and below are included as an alternative in the list below. Click on a name to show the sustainable options available.

Basa, Tra, Catfish or Vietnamese River Cobbler
Bass, seabass (Farmed)
Bream, Gilthead (Farmed)
Cod, Atlantic Cod
Coley, Saithe
Hake, Cape
Hake, European
Monkfish, Anglerfish
Pollock, Alaska, Walleye
Sturgeon (Farmed)


"ASCOBANS. 2017. Cetacean Bycatch Monitoring and Mitigation Under EC Regulation 812/2004 in the Northeast Atlantic, North Sea and Baltic Sea - Interim Report Cetacean. 23rd ASCOBANS Advisory Committee Meeting: Le Conquet, 5 - 7 September 2017. Available at:

Armstrong, P. 2017. New bylaw bans netting sea fish in Cornish rivers and estuaries. The Packet. [online] Available at: [Accessed 11 Jul. 2018].

Save Our Seabass. 2018. Response to Sussex IFCA review of Nearshore Trawling and Netting Management. Available at:

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ICES. 2017. Lesser-spotted dogfish (Scyliorhinus canicula) in Subarea 4 and in divisions 3.a and 7.d (North Sea, Skagerrak and Kattegat, eastern English Channel). Version 2: 24 October 2017. Available at:

ICES. 2017. Lesser-spotted dogfish (Scyliorhinus canicula) in Subarea 6 and divisions 7.a-c and 7.e-j (Celtic Seas). Published 6 October 2017. DOI: 10.17895/ Available at:

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Cornwall IFCA. 1966. SEA FISHERIES REGULATION ACT 1966. Available at:

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Southern IFCA. 2018. Other Regulations. Available at: [accessed on 07.08.18]

The National Mullet Club. 2013. The Value of Recreational Angling For Grey Mullet and the Case for Recreational-Priority Status. Available at:

North Western IFCA. Mullet. Available at: [accessed 07.08.18]. Jessop, R.W., Strigner, R., Thompson, S., Welby, P.R. 2013. Research Report 2013. Report produced for Eastern IFCA. Available at:

ICES. 2018. DATASET COLLECTIONS: Catch statistics. Available at: . [Accessed 02.08.18]

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