Striped red mullet in the North sea and Eastern English Channel, Demersal otter trawl

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1 Striped red mullet in the North sea and Eastern English Channel, Demersal otter trawl Content last updated 27th Jan 2016 Stock: Striped red mullet in Sub area IV and division VIId (North Sea and Eastern English Channel) Management: EU Striped red mullet in the North sea and Eastern English Channel, Demersal otter trawl Overview Striped red mullet (Mullus surmuletus) is a widely distributed, bottom-dwelling roundfish that inhabits muddy or sandy habitats up to depths of 100 metres. This species is located along European coastal waters from southern Norway and the Faroe Islands in the North to the Strait of Gibraltar in the South (Davis and Edward, 1988; Gibson and Robb, 1997). The distribution of striped red mullet also extends along the northern part of western Africa and in the Mediterranean and Black Seas (Quéro and Vayne, 1997). Dunn (1999) suggested the appearance of striped red mullet in the North Sea might be a newly established stock. They feed on bottom-dwelling organisms such as crustaceans, molluscs and other fish using their chin barbells to detect prey and search the mud. The population abundance of striped red mullet is highest in areas of elevated temperature (ICES, 2007). Juveniles are typically found in coastal waters with low salinity, while adults typically inhabit more offshore waters with higher salinities and sandy sediments. Some nursery areas have been located in the Bay of Saint-Brieuc and around the coastal areas of the Falklands (Morizur et al., 1996). Research surveys conducted in the English Channel have identified that the length of first sexual maturity is 16.2 cm for males and 16.7 cm for females (Mahé et al., 2005). Landings of striped red mullet have been observed in the Eastern English Channel since ICES collected official catch statistics, however, landings were largely recorded in the North Sea at the beginning of the 1990s corresponding with the increase in the economic importance of the stock (ICES, 2015). Historically, France has taken most of the landings in bottom trawlers using a mesh size of mm in the Eastern English Channel and the southern North Sea. The United Kingdom also caught red mullet in the same area using otter trawls. A Dutch fly-shooting (Scottish Seine) fishery that uses a mesh size of mm has been taking striped red mullet in Eastern English Channel since Striped red mullet landings are now shared between French otter trawlers and Dutch fly-shooters. All catches of striped red mullet are assumed to be landed and discards are considered to be negligible given the economic value of the species, the lack of a minimum landing size and the absence of catch limits for the stock. The three main countries landing striped red mullet in the region are France, the Netherlands and the United Kingdom. Davis, P.S. and Edward, A.J New records of fishes from the northeast coast of England, with notes on the rediscovery of part of the type collection of marine fishes from the Dove Marine Laboratory, Cullercoats. Transactions of the Natural History Society Northumbria 55: Dunn, M.R The exploitation of selected non-quota species in the English Channel PhD thesis. Lowestoft: 323pp. Gibson, R.N. and Robb, L Occurrence of juvenile red mullet (Mullus surmuletus) on the west coast of Scotland. Journal of the Marine Biological Association of the United Kingdom 77(3): ICES Report of the Working Group on Fish Ecology (WGFE), 5 9 March 2007, Nantes, France. ICES CM 2007/LRC: pp. ICES Report of the Benchmark Workshop on North Sea Stocks (WKNSEA), 2 6 February 2015, Copenhagen, Denmark. ICES CM 2015/ACOM: pp. Mahé K., Destombes A., Coppin F., Koubbi P., Vaz S., Leroy D. and Carpentier A Le rouget barbet de roche Mullus surmuletus (L. 1758) en Manche orientale et mer du Nord, 186pp. Morizur, Y., S. Pouvreau and A. Guénolé Les rejets dans la pêche artisanale française de Manche occidentale. Editions Ifremer, 127 pp. Stock Status less risk more risk The status of striped red mullet in Subarea IV (North Sea) and Division VIId (Eastern English Channel) has been scored a very high risk. Although this species has moderate resilience to fishing activities (FishBase, 2015), the spawning biomass of the stock is below the long-term average and fishing mortality has increased above the long-term average. Froese, R. and D. Pauly. Editors FishBase. World Wide Web electronic publication. version (10/2015).

2 Management less risk more risk The management of striped red mullet in Subarea IV (North Sea) and Division VIId (Eastern English Channel) has been scored a high risk. This is because data are too limited to develop any form of management controls to adjust fishing opportunities on the stock, but management measures have been established to control effort levels in the fishery. Management controls are advised by an ICES data-limited stock assessment, however, compliance can be patchy and is reliant on the enforcement of mixed fishery effort controls. Infringements happen only very occasionally and are unlikely to compromise harvest objectives. Bycatch less risk more risk The bycatch risk in this fishery has been scored a high risk. This is because otter trawls have the potential to take relatively high quantities of bycatch (> 40% of catch weight). However, the cod recovery plan has been implemented in this area and this is expected to have had an influence on the discarding levels in North Sea demersal fisheries and the incoming EU landings obligation is also intended to reduce discarding. There are also catches of demersal elasmobranchs and protected, endangered and threatened (e.g. sharks and rays) species in certain circumstances. Habitat less risk more risk The habitat risk of this fishery has been scored a high-moderate risk. This is because, although otter trawls are considered to have a potential to cause significant habitat damage, damage to vulnerable and sensitive marine habitats is likely to be minimised given that the footprint of the fishery is within core areas, typically historically fished ground. Spatial management to reduce potential interactions with vulnerable habitats are being developed, as there remains uncertainties about the location of some sensitive seabed habitats so these remain at risk. Outlook Current risk status Outlook Reason Stock Very high Unknown The status of the stock in the future is unknown due to a high level of uncertainty in the assessment outputs. Although the species has moderate resilience to fishing activities, spawning stock biomass remains below the long-term average and fishing mortality has increased above the long-term average. Consequently, stock status remains stable at lower than average levels. Management Very High Stable The management of the stock is likely to remain stable in the future. The EU Common Fisheries Policy is going through reform and there is some uncertainty on how this will impact fisheries management in this region. Bycatch High Improving Bycatch of non-target species in this fishery is relatively high with poor selectivity. However, with technical and spatial management measures continuously under development and the incoming EU landings obligation intended to reduce discarding of managed species, the bycatch risk is likely to reduce in the future.. Habitat Moderate Improving Otter trawls have the potential to affect seabed habitats, but spatial management measures are continuously being developed and will likely reduce the risk. As planned networks of Marine Protected Areas become established, larger areas of sensitive habitat will become protected from trawling. Type Current Risk Status Outlook Reason Stock Management Bycatch Habitat

3 Stock Status Details less risk more risk Time-trends Landings of striped red mullet ranged from 367 to 4744 tonnes between 2006 and 2014 (Figure 1). Most of the landings originated from the Eastern English Channel, and recent catches mainly consisted of juvenile fish (ages 0 and 1). Spawning stock biomass peaked at 6349 kilo tonnes in 2007 and then steadily decreased to a low level, averaging around 800 kilo tonnes thereafter. Since 2010, spawning stock biomass has been around 4 lower than the productive period observed a decade ago. The spawning stock biomass declined to the lowest levels on record (292 kilo tonnes) in 2012 and then subsequently increased between 2013 and Fishing mortality is highly uncertain but estimates indicate that the stock is exploited at very high fishing mortalities. Recruitment indices derived from the Eastern English Channel ground fish survey show an exceptionally large recruitment peak in 2014, the largest of the time-series and more than treble that of historic estimates (ICES, 2015ab). Figure 1. Striped red mullet in Subarea IV (North Sea) and Division VIId (Eastern English Channel). Summary of stock assessment: Landings and discards (in thousand tonnes). Spawning stock biomass estimates in thousand tonnes (the insert shows the last 6 years; the orange lines are the averages of the last 2 years and the 3 previous years, which are used in the catch advice calculation) (ICES, 2015a). Stock structure and recruitment For assessment and management purposes, ICES considers the striped red mullet population inhabiting Subarea IV (North Sea), Division VIId (Eastern English Channel) and Division IIIa (Skagerrak and Kattegat) to be a single unit stock. The striped red mullet stock in this region is known as the Northern Unit (ICES, 2015b). Dunn (1999) suggested that an independent striped red mullet stock could inhabit the Eastern English Channel due to the presence of catches all year round. Morphological differences between striped red mullet inhabiting the Eastern English Channel and the Bay of Biscay have been identified indicating the presence of two substocks (Mahé et al., 2005). Otolith shape analysis revealed that populations of striped red mullet in the Eastern English Channel and Western English Channel could represent separate sub-stocks. In the north, the striped red mullet population appears to be a continuum between the North Sea and Eastern English Channel. An additional continuum has been identified between the north and south of the Bay of Biscay (Benzinou et al., 2013). Currently, however, not enough information is available to separate striped red mullet populations in the Bay of Biscay from the Celtic Sea or Western English Channel. The spatial distribution of striped red mullet observed every year shows this species in the western part of the North Sea during the first quarter and in the Southern part of the North Sea and the Eastern English Channel during the third and fourth quarters. These migrations patterns coincide with the spawning period in the second quarter and the spawning areas located in the southern part of the North Sea and the Eastern English Channel (ICES, 2015b). Data gaps and research priorities Most of the uncertainty in the stock assessment stems from the absence of information from the North Sea (no landings age structure, no commercial tuning fleets) and the lack of information on age structure of the landings from the Dutch fleet. However, some length-based information is or might be made available for these areas and fleets. A more integrated approach would make it possible to use all the available fisheries information in the stock assessment (ICES, 2015b). Benzinou A., Carbini S., Nasreddine K., Elleboode R., Mahé, K Discriminating stocks of striped red mullet (Mullus surmuletus) in the Northwest European seas using three automatic shape classification methods. Fisheries Research 143: Dunn, M.R The exploitation of selected non-quota species in the English Channel PhD thesis. Lowestoft: 323pp. ICES. 2015a. Striped red mullet (Mullus surmuletus) in Subarea IV and Divisions VIId and IIIa (North Sea, Eastern English Channel, Skagerrak and Kattegat). ICES Advice on fishing opportunities, catch and effort. Greater North Sea Ecoregion. ICES Advice 2015, Book 6, Section ICES. 2015b. Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK), 28 April-7 May, ICES HQ, Copenhagen, Denmark. ICES CM 2015/ACOM: pp. Mahé K., Destombes A., Coppin F., Koubbi P., Vaz S., Leroy D. & Carpentier A Le rouget barbet de roche Mullus surmuletus (L. 1758) en Manche orientale et mer du Nord, 186pp.

4 Management Details less risk more risk TAC Information Catch 2015 (t) Advised Catch 2016 (t) Agreed TAC 2016 (t) Advised Catch 2017 (t) Advised and agreed catches Catch 2014 (t) Advised catch 2015 (t) Agreed TAC 2015 (t) Advised catch 2016 (t) None 552 ICES provides catch advice for this data-limited stock, but no Total Allowable Catch (TAC) has been agreed by the European Council. ICES advises that when precautionary approach is applied, catches should be no more than 552 tonnes in each of the years 2016 and All catch are assumed to be landed. Selectivity in the fishery should be improved to avoid fishing on juvenile recruits and to protect the strong 2014 year class (ICES, 2015a). Stock harvesting strategy Striped red mullet in Subarea IV (North Sea) and Division VIId (Eastern Englsih Channel) is assessed annually to estimate relative trends in recruitment, spawning stock biomass and fishing mortality. The stock assessment is based on a time-series of international fishery landings including age compositions from Division VIId (Eastern English Channel) and an index of abundance derived from the catch rates of one standardised research trawl survey. Landings are monitored exhaustively from EU log books and sales notes. Discard estimates are not included in the stock assessment given that they are considered to be negligible and all catches are assumed to be landed (ICES, 2015a). Striped red mullet is managed under the EU Common Fisheries Policy (CFP) but is not subject to EU TAC s and quotas. Harvesting of striped red mullet is controlled primarily through management of effort controls and technical measures imposed for the recovery of other stocks within a mixed fisheries context. Consequently, the likelihood of overexploiting this stock remains high (ICES, 2015b). No specific management objectives have been established for this data-limited stock. Fisheries in Subarea IV (North Sea) and Division VIId (Eastern English Channel) have, however, been subject to the long-term EU Management Plan for cod since 2008 (Council Regulation (EC) 1342/2008, amended by Regulation 1243/2012) which establishes annual effort limits for different fishing gears. Fishing effort regulations have not been restrictive for the fishery on this stock. No minimum landings size has been defined for this species in European waters (ICES, 2015b). Surveillance and enforcement Fisheries taking striped red mullet in Subarea IV (North Sea) and Division VIId (Eastern English Channel) are carried out by five countries (Belgium, Denmark, France, the Netherlands and the United Kingdom) and surveillance activities to record compliance with national and international fishery control measures are primarily the responsibility of the competent fishery inspection authorities in each country (ICES, 2015a). In addition, the European Fisheries Control Agency (EFCA), established in 2005, organises operational coordination of fisheries control and inspection activities by the Member States as well as cooperation with third countries and other Regional Fishery Management Organisations. The requirements for surveillance and sanctions for infringements are laid down in the EU Control Regulation (EC) No 1224/2009. Surveillance activities on fisheries for striped red mullet in Subarea IV and Division VIId include the use of vessel monitoring systems (VMS) on vessels over 12m overall length, an electronic reporting system (ERS) and a vessel detection system (VDS). Surveillance may also include direct observation by patrol vessels and/or aerial patrols, inspections of vessels, gear, catches at sea and on shore, and verification of EU logbook data against sales documents. The EU Control Regulation specifies that Member States should set up electronic databases containing the inspection and surveillance reports of their officials as well as records of infringements. EFCA. [ [Date accessed: 23-Dec-15] ICES. 2015a. Striped red mullet (Mullus surmuletus) in Subarea IV and Divisions VIId and IIIa (North Sea, Eastern English Channel, Skagerrak and Kattegat). ICES Advice on fishing opportunities, catch and effort. Greater North Sea Ecoregion. ICES Advice 2015, Book 6, Section ICES. 2015b. Report of the Working Group on the Assessment of Demersal Stocks in the North Sea and Skagerrak (WGNSSK), 28 April-7 May, ICES HQ, Copenhagen, Denmark. ICES CM 2015/ACOM: pp.

5 Bycatch Details less risk more risk Targeting and behaviour Demersal otter trawls operating in the North Sea (Sub-area IV) and eastern English Channel (Division VIId) can be towed by a single boat as a single or multiple rig. The trawl doors create sand clouds that herd the fish into the net. Otter trawls can be rigged with different types of ground gear depending on seabed topography and the species targeted (Løkkeborg, 2005). Demersal otter trawling is not a well targeted fishing activity given that a wide variety of non-target species can be caught. This fishery catches a wide variety of mixed demersal finfish, such as sole (solea solea), whiting (Merlangius merlangus), and plaice (pleuronectus platesa) and these mixed catches means that the minimum cod end mesh size of 80 mm and other aspects of the management regimes and markets are not optimal for all the species caught. Fish may be discarded because they are smaller than the Minimum Conservation Reference Size, or the size and/or species are not marketable. Discarding due to the vessel being short of quota for the managed species also occurs. Evidence of bycatch risk Discard rates have been estimated from surveys at around 30-40% of total catch weight in European demersal otter trawl fisheries (European Commission, 2011). According to the Discard Atlas for North Sea (Anon, 2014a) the main managed species discarded ( ) in the North Sea are species such as: dab (97%), plaice (77%), haddock (59%), cod (56%), and whiting (51%) by weight. There are high rates of discards for individual species, the total proportion of discards for the Greater North Sea in this fishery is around 41%. In addition, common skate (Dipturus batis) and spurdog (Squalus acanthias) can be taken as bycatch. Currently landings of these species is prohibited and fishermen are required to return them to the sea where they have a chance of survival. However, catch composition and discard rates vary according to regional variations in species composition, the design of the trawl, the cod-end mesh size and other selectivity devices used (see mitigation measures). Mitigation measures A wide variety of non-target species are caught in European mixed otter trawl fisheries. Optimising gear selectivity in mixed fisheries is challenging given that different species have different selectivity requirements. Many measures have been designed and tested over recent years, designed to increase selectivity in otter trawls. To actually be effective in controlling bycatch levels in fisheries, these measures have to be operationally viable, enforceable and used within an incentive scheme which encourages fishers to use them. The cod recovery plan (EU 1342/2008) which is in force in North Sea, Eastern English Channel, Irish Sea, West of Scotland and the Skagerrak, has encouraged a diversity of measures to incentivise the use of more selective gear by vessels targeting whitefish with demersal otter trawls. Effort per vessel is limited to a number of days at sea per year. Additional days at sea are available for vessels using certain specified gears and measures, tested for their efficacy at improving selectivity. The different European Nations have implemented different measures in their fisheries, described below are measures implemented in the UK fisheries. Fully documented fisheries scheme The fully documented fisheries scheme, which participating vessels (representing 27% of landings in 2012) use independent electronic monitoring devices (video recordings which monitor fishing activities) to ensure that all caught fish are recorded, and all caught cod are retained onboard, landed and count against quota (including undersized fish). In return, these vessels are allowed additional quota and days at sea, though they have to stop fishing when they use up their quota. By this means the total mortality on the cod stock is capped, wasteful discarding is reduced, and improved information on catches is available. Moreover, there is more flexibility for fishermen to use the additional days at sea up to the point when they run out of quota, and there is an incentive to use more selective gear in order to target more marketable fish. Since cod grow to a relatively large size compared with other species before they are marketable, the scheme benefits the selectivity of fishing on other fish in the catch thereby helping to reduce the overall discards. So far the scheme has not been in force long enough to fully evaluate the results, but it an illustration of the way in which measures to reduce discards can be incorporated into the overall management of the fishery thus increasing efficacy and incentives. Real time closures The cod avoidance plans also include real time closures of areas where concentrations of cod are found. Since 2007 UK administrations have operated these areas for UK vessels in the North Sea and English Channel in response to concentrations of juvenile cod; when a vessel catches more than threshold number of cod per hour agreed by a boarding officer and the skipper or concentrations of adult cod through analysis of landings and Vessel tracking data (VMS). The size and duration of the closure varies according to administrative body. This a similar scheme to designed operated under European legislation (EU 783/2011) which is designed to protect juvenile cod, saithe, haddock and whiting and there are also seasonal closures to protect spawning stocks (See Marine Scotland and Marine Management organisation websites). It has proved difficult to quantify the efficacy of each of these measures, however it seems likely that cod avoidance measures have contributed significantly to the reduction in the discard rate of cod in the North Sea fishery (Anon, 2014). Landings obligation The introduction of the landings obligation or discard ban under the EU Common fisheries policy (EU 1380/2013) is intended to take place over the period in

6 this fishery. This landings obligation will ultimately apply to all species managed by TAC; it will not apply to non-tac species, however many of these are likely to benefit from improved selectivity. Anon Prepared by Scheveningen group, Discard Atlas of the North Sea Fisheries, August 2014, 80 pp. Løkkeborg, S. (2005). Impacts of trawling and scallop dredging on benthic habitats and communities. FAO Fisheries Technical Paper 472. Food and Agriculture Organisation of the United Nations, Rome, 58 pp.

7 Habitat Details less risk more risk Gear effects, targeting and behaviour Fishermen use their knowledge of seasonal fish aggregations and seabed types together with information from the vessel s electronic mapping tools to make informed decisions on where to trawl. Gears are adapted to the substrate type and the species targeted, with a relatively narrow range of conditions in which they can operate. Most otter trawling occurs within core areas where yields are high and it is safe to trawl, typically historically fished grounds (Jennings and Lee, 2011). Risk of habitat impact Otter trawl impact risk on the seabed habitat can include modification of bottom topography and disturbing biogenic features. Biological communities can potentially be disturbed both directly and indirectly by changes in the physical attributes of the areas being fished. Trawl doors have the most pronounced impacts on seabed habitats by creating scouring marks and furrows up to 20 cm deep (Løkkeborg, 2005). The habitat risks are related to the types of seabed communities and other sources of seabed disturbance such as wave and tidal action. A number of theoretical and field studies have focused on the effects of towed gears, which show that areas outside core fished areas tend to be more sensitive to fishing (Grey et al., 2006; Jennings et al. 2012). Consequently, habitats that have not traditionally been disturbed by fishing activities are relatively more sensitive to the effects of otter trawling. However, TR2 gears predominate in shelf waters for plaice, sole and dab which occupy habitats subject to relatively high levels of natural disturbance (due wave and tidal action). The impacts of TR2 gears on habitats is therefore less significant than the potential impacts of TR1 gears which operate in deep water muddy habitat environments. Understanding the nature of these differences is important in the management of the effects of otter trawling. Communities that inhabit areas where there is more disturbance by wave and tidal action are less likely to be affected by trawling, whereas communities inhabiting deeper waters unaffected by disturbance from wave and tidal action or on harder more gravely substrate are relatively more sensitive to trawling (Bolam et al., 2014). However, there are some habitats such as ross worm (or sabellaria) which inhabit shallower areas which are considered relatively sensitive, but such areas are traditionally avoided by TR2 fisheries. In the North Sea, demersal otter trawlers have reduced the biomass and production of bottom-dwelling organisms (Hinz et al., 2008; Hiddink et al., 2006). Sustained fishing has resulted in a shift from communities dominated by relatively sessile, emergent and high biomass species to communities dominated by infaunal, smaller bodied organisms (Kaiser et al., 2000). Within the core area of this fishery where the substrate is mostly sandy or muddy sand the risks of further ecosystem change due to fishing are minimised because the area has been continually heavily fished so the sea bed ecosystem has adapted to the fishing pressure. However, outside the core area of fishing there is the potential for significant habitat impact.. The fishery generally targets relatively shallow areas which are expected to be subject to wave and tidal action and hence relatively resilient to the effects of fishing. Fishing which has occurred in a specific location over many years is likely to result in the seabed ecosystem adapting to the fishing activity. However, there are sensitive areas, mostly outside the core areas of the fishery which may be vulnerable and such areas have in recent years been identified and protected to some extent through the Natura 2000 network of MPAs Mitigation measures Under the Marine Strategy Framework Directive (MSFD) from the European Union (Council Directive 56/2008), Member States have committed to aim towards good environmental status (GES) for the seabed habitats by The Convention for the Protection of the Marine Environment of the North-East Atlantic (the OSPAR Convention ), which was signed up to by 15 nations plus the European Union, is developing a coherent network of Marine Protected Areas to protect vulnerable marine habitats in the North-East Atlantic. The development of offshore Special Areas of Conservation under the European Habitats Directive (Council Directive 43/1992) contributes to this process as does the UK Marine Act and Marine Scotland Act designating Marine Protected Areas in UK waters. These initiatives have resulted in improvements in habitat mapping and risk assessment of the effects of trawling on the seabed, and the UK Marine Management Organisation (MMO) and Marine Scotland are engaging in a programme designed to assess the effects of fisheries and implement management measures where sites are considered at risk. Bolam, S.G., Coggan, R.C., Eggleton, J., Diesing, M. and Stephens, D Sensitivity of macrobenthic secondary production to trawling in the English sector of the Greater North Sea: A biological trait approach. Journal of Sea Research 85: Gray, J.S., Dayton, P., Thrush, S. and Kaiser, M.J On effects of trawling, benthos and sampling design. Marine Pollution Bulletin 52: Hiddink, J.G., Jennings, S., Kaiser, M.J., Queirós, A.M., Duplisea, D.E, and Piet, G.J Cumulative impacts of seabed trawl disturbance on benthic biomass, production, and species richness in different habitats. Canadian Journal of Fisheries and Aquatic Sciences 63: Hinz, H., Hiddink, J.G., Forde, J., and Kaiser, M.J Large-scale responses of nematode communities to chronic otter-trawl disturbance. Canadian Journal of Fisheries and Aquatic Sciences 65: Jennings, S. and Lee, J Defining fishing grounds with vessel monitoring system data. ICES Journal of Marine Science 69: Jennings, S., Lee, J and Hiddink, J.G Assessing fishery footprints and the trade-offs between landings value, habitat sensitivity and fishing impacts to inform marine spatial planning and the ecosystem approach. ICES Journal of Marine Science 69:

8 Kaiser, M.J., Ramsay, K., Richardson, C.A., Spence, F.E., and Brand, A.R Chronic fishing disturbance has changed shelf sea benthic community structure. Journal of Animal Ecology 69: Løkkeborg, S. (2005). Impacts of trawling and scallop dredging on benthic habitats and communities. FAO Fisheries Technical Paper 472. Food and Agriculture Organisation of the United Nations, Rome, 58 pp. All content 2018 Seafish. Origin Way, Europarc, Grimsby, DN37 9TZ. This page created on 14th August 2018 at 05:29pm.