Squid, West of Scotland, demersal trawl
Squid, West of Scotland, demersal trawl
Content last updated
28th Mar 2017
Stock:
Stock in Subarea VIa, VIb
Management:
None
Overview
Squids taken commercially by demersal otter trawl in the ICES Subarea VIa and VIb represent a mixture of species belonging to families:
Loliginidae (‘long finned squid’) which includes species such as Loligo forbesii, Alloteuthis subulata, and A. media, and Ommastrephidae
(‘short finned squid’) which includes Todarodes sagittatus, Illex coindetii and Todaropsis eblanae (ICES, 2016, Oesterwind et al, 2010). Long
finned squids occur in relatively shallow water and are mostly caught by demersal gear. They are amongst the most valued squid species.
Short-finned squids are occasionally very abundant and important in catches and are more prone to extreme variations in abundance
than long-finned squids. They are mostly pelagic and are mainly taken by trawling and by using gill and trammel nets (Pierce et al, 2010).
Recently, squid fishing has attracted considerable attention in Scotland and in 2005 small-scale directed squid fisheries were
reported in several localities, including off the islands of Skye and Lewis (Hastie et al., 2009).
All these species have short and flexible life cycles (averaging one year, but up to 2 years in T.sagittatus), with very fast growth rates, nonspecialised predatory behaviour (preying on any food within their prey size range) and round the year spawning. However, there are
species-specific seasonal spawning peaks. Long finned squids lay eggs on the bottom in inshore waters, whereas short finned squid
produce pelagic egg masses of neutral buoyancy. Because of the short annual life cycle the squid stocks depend heavily on recruitment
success and fluctuate significantly between years. Squids are taken predominantly as a bycatch species by demersal trawling (Arkhipkin et
al., 2015). Official fishery landings data do not normally identify squid to the species level (ICES, 2014).
References
Arkhipkin , A., Rodhouse, P., Pierce, G., et al. (2015) World Squid Fisheries, Reviews in Fisheries Science & Aquaculture, 23:2, 92-252
ICES. 2014. Report of the Working Group on Cephalopod Fisheries and Life History (WGCEPH), 16-19 June 2014, Lisbon, Portugal. ICES CM
2014/SSGEF:02. 355 pp.
ICES. 2016. Interim Report of the Working Group on Cephalopod Fisheries and Life History (WGCEPH), 8–11 June 2015, Tenerife, Spain.
ICES CM 2015/SSGEPD:02. 127 pp.
Oesterwind, D., ter Hofstede, M., Harley, B., Brendelberger, H. and Piatkowski, U. 2010. Biology and meso-scale distribution patterns of
North Sea cephalopods. Fisheries Research 106: 141-150.
Pierce, G. J., Allcock, L., Bruno, I., Bustamante, P., González, Á., Guerra, Á., Jereb, P., et al. 2010. Cephalopod biology and fisheries in Europe.
ICES Cooperative Research Report No. 303. 175 pp.
Stock Status
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more risk
The status of squid in Subarea VIa, VIb (West of Scotland) has been scored as high risk. This is because vulnerability of these squids
as assessed by SealifeBase can be high in some species and because mixed abundance trends are reported for different squid species.
Management
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The management of squid in Subarea VIa, VIb (West of Scotland) has been scored as high risk. This is because data from active
fisheries and research surveys are collected regularly, but are not adequate for the stock assessment that would be required to inform
management of these populations. There are no management measures in place to restrict catch of any particular species involved into
the multi-species fishery because there is no species-specific reporting, though surveillance of boats (and landing)s in the fisheries is at the
highest level.
Bycatch
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more risk
The bycatch risk of this fishery has been scored as moderate risk. This is because squids represent a bycatch of larger demersal otter
trawl fisheries targeting finfish in which discarded undesirable bycatch can represent over a quarter of the total catch. Squid discards are
highly variable between fleets. In directed fisheries for squids discards occur occasionally in larger amounts (25% of total catches by
weight).
Habitat
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more risk
The habitat risk of this fishery has been scored high-moderate risk. Although demersal trawls are considered to have potential to
cause significant habitat damage, damage to vulnerable and sensitive marine habitats is likely to be reduced given that main footprint of
the fishery lies within areas of historically fished ground. In addition future MPA networks will provide further protection to squid habitat.
Outlook
Type
Current Risk Status
Outlook
Reason
Stock
High
Stable
Reporting at a family level is likely to continue which will preclude proper
evaluation of stock status.
Management
High
Stable
There are no management measures in place to monitor or restrict catch
of any particular species involved into this multi-species fishery because
there is no species-specific reporting.
Bycatch
Moderate
Improving
Bycatch in this fishery is relatively high, but it is envisioned that with the
landings obligation squid might benefit indirectly from improved gear
selectivity.
Habitat
High
Stable /
Improving
As planned networks of Marine Protected Areas become established
larger areas of sensitive habitat will become protected from trawling.
Stock Status Details
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Time-trends
Landings (tonnes live weight for long-finned and short-finned squid species combined) from the North West of Scotland and North Ireland
(VIa) and Rockall (VIb) between 1980-2014 show a peak in the mid 1980s to 1990s and a decline thereafter. Since the late 2000s there has
been an increase in annual landings but they have not reached the levels observed in mid-1980s. In ICES Subarea VI, long-finned squid
landings were more important in terms of total landing weight than short finned squids (Fig. 2).
Fig. 1. Squid landed in ICES Subarea VI. Official landings (in tonnes) from 1980-2014. Source: ICES Historical Nominal catches 1950-2010
and Official Nominal Catches 2006-1014.
Fig. 2. Long finned-squid (black line) and short finned-squid (red line) landings (tonnes) from ICES Subarea VI (Western Scotland, North
Ireland and Rockall). Source: ICES, 2014.
Survey hauls conducted by Marine Scotland Science from 1980-2012 revealed high biomass values for long finned squids combined in the
west of Scotland in the mid-2000s. Among the factors explaining this variation in biomass were haul duration, depth, and spatial variation,
with the remaining year to year variation showing a clear peak around 1990 and a general upward trend since the mid-1990s (ICES, 2016).
The pattern between the years is partly explained by previous abundance (a positive effect of the previous year’s landings (and related
recruitment likelihood) and also shows significant but weak relationships with annual and winter NAO indices (ICES, 2016).
Stock structure and recruitment
European cephalopod stocks have not been formally defined. However, genetic studies suggest that for all the squid species, single
populations exist in shelf waters around the UK (although an offshore form of Loligo forbesii has been tentatively identified). Traditional
stock-recruitment relationships have generally been thought to be unsuitable for assessing cephalopods. These relationships are strongly
impacted by environmental factors and show wide interannual fluctuations in abundance (Pierce et al., 2010).
Data gaps and research priorities
The most crucial gap in the data is an absence of reporting of landing at species level, making it impossible to manage fisheries at an
appropriate level. Additionally some aspects of basic squid biology are poorly understood, the planktonic (paralarval) stage is poorly
known, notably in relation to how long these animals spend in the plankton. Studies are needed, using appropriate nets, to determine
their seasonal, annual, and bathymetric and latitudinal distribution.
The lack of long‐term data series, even of basic fishery parameters like CPUE for individual species, is one of the major constraints on
improving our understanding of cephalopod population trends. Long‐term data series will be imperative to the success of any
management strategy to cope with climate variability. It will also be critical to consider interactions between different stressors, such as
overfishing, habitat destruction, and climate change (Pierce et al., 2010).
References
ICES. 2014. Report of the Working Group on Cephalopod Fisheries and Life History (WGCEPH), 16–19 June 2014, Lisbon, Portugal. ICES CM
2014/SSGEF:02. 353 pp.
ICES. 2016. Interim Report of the Working Group on Cephalopod Fisheries and Life History (WGCEPH), 8–11 June 2015, Tenerife, Spain.
ICES CM 2015/SSGEPD:02. 127 pp.
Pierce, G. J., Allcock, L., Bruno, I., Bustamante, P., González, Á., Guerra, Á., Jereb, P., et al. 2010. Cephalopod biology and fisheries in Europe.
ICES Cooperative Research Report No. 303. 175 pp.
Management Details
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Advised and Agreed Catches
Currently squid are not regulated under the Total Allowable Catch (TAC) system. In 2014, the total reports landings of all squids combined
from the West of Scotland was 939 t.
Stock Harvesting Strategy
Limited species specific information and several aspects of the population biology of squids (e.g. fast growth, difficulty in estimating age,
lack of synchronization of lifecycle events), restrict the variety of methods that can be used to assess squid stocks. Causes for concern
about the suitability of the data for stock assessment is that it includes different levels of species identification and it is not clear whether
A. subulata and juveniles of other Loliginidae have been accurately distinguished (ICES, 2016).
In UK waters, directed squid fishing is unregulated, apart from a minimum mesh size allowed in trawls for squid fishing (32 mm), with the
provision that at least 60% of the catch retained on board is squid (Young et al., 2006). There is no effort restrictions and no spatial or
seasonal closures around Scotland.
Surveillance and Enforcement
The requirements for surveillance and sanctions for infringements are laid down in the EU Control Regulation (EC) No 1224/2009.
Surveillance activities on fisheries that take witch sole include the use of vessel monitoring systems (VMS) on board vessels over 12 m
overall length; direct observation by patrol vessels and aerial patrols; inspection 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.
References
ICES. 2016. Interim Report of the Working Group on Cephalopod Fisheries and Life History (WGCEPH), 8–11 June 2015, Tenerife, Spain.
ICES CM 2015/SSGEPD:02. 127 pp.
Pierce, G.P., Bailey, N., Stratoudakis, Y. & Newton, A., 1998. Distribution and abundance of the fished population of Loligo forbesi in
Scottish waters: analysis of research cruise data. ICES Journal of Marine Science 55: 14–33.
Young, I.A.G., Pierce, G.J., Stowasser, G., Santos, M.B., Wang, J., Boyle, P.R., Shaw, P.W., Tuck, I. & Collins, M.A., 2006. The Moray Firth
directed squid fishery. Fisheries Research 78: 39–43.
Bycatch Details
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Targeting and behaviour
A demersal otter trawl is a cone-shaped net consisting of a body and with lateral wings extending forward from the opening. Demersal
otter trawls operating in the North Sea are 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. The functions of the ground gear are to ensure close contact with the bottom and to enable fishing on rough bottoms without
damage to the trawl net. The trawl doors keep the trawl mouth spread open laterally and create the sand clouds that herd fish into the
opening of the net (FAO 2014; Løkkeborg, 2005). Various modifications of demersal trawling gears have been tried, aiming to keep the net
just off the seabed by using several 30cm chains hung at equal distances from the groundrope and enough floats on the headline to give
the net neutral buoyancy (Pierce et al., 2010).
Evidence of bycatch risk
The bycatch in squid fisheries might be addressed as a) bycatch of demersal otter trawl fisheries targeting finfish, and b) bycatch and
respective discard of undesirable squids from directed commercial squid catch.
Demersal fisheries operating in the North Sea targeting finfish discarded on average 40% of the catch in weight between 2010-2012, with
78% of the discards consisting of plaice and dab. The average discard ratio for the years 2010-2012 in the Skagerrak was 23% and for the
Eastern Channel between 10 – 40% of catches were discarded during the same time period (Quirijns et al, 2014). Catches of short-finned
squid are routinely discarded in Scotland due to its low abundance or low market demand (Pierce et al., 2010).
Few studies have assessed the amount of bycatch of the directed commercial squid catch. A rough estimation, consisting of four samples
of fish bycatch was undertaken from August to November 2005 in Aberdeen. Discard rates (in terms of weight) were reported for
whitefish (gadoid) species, including cod (<1%), haddock and whiting (0.5-8.4%), however, these results are only considered to be
indicative (Campbell and McLay, 2007). Another study recorded discard rates during 2007 – 2008 in the Firth of Forth and the Moray Firth.
This study found that the main fish species bycaught (in terms of overall weight per day) were whiting (17-56%), haddock (1-8%), cod
(<1%), mackerel (5%), dab and flounder and the main shellfish species was velvet crab. All the non-squid species were discarded (Hastie et
al., 2009)
Mitigation measures
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 2016 – 2019 in this fishery. This obligation will ultimately apply to all species managed by TAC; it will not apply to non-TAC
species (e.g. squids), however many of these may benefit from improved selectivity. It is envisioned that the landing obligation will create
incentives for fishermen to reduce current levels of discards, for example, recent surveys of the trawling fleet operating in the Celtic Sea
shows that fishers retain and land other species, including squids. This would be a consequence of reduced income from high value quota
species (due to quota restrictions and landing obligation), promoting better utilization of other resources caught (ICES, 2016).
References
Campbell, R. & McLay, A., 2007. The Moray Firth Squid Fishery 2006. Fisheries Research Services Internal Report No. 15/07, Aberdeen.
Crown Copyright.
FAO 2014. Fisheries and Aquaculture topics. Fisheries technology. Topics Fact Sheets. In: FAO Fisheries and Aquaculture Department
[online]. Rome. Updated 31 October 2001. [http://www.fao.org/fishery/geartype/306/en] [Date accessed: 27-Dec-16]
Hastie, L., Pierce, G., Pita, C., Viana, M. Smith, J., Wangvoralak, S. 2009. Squid Fishing in UK Waters. SEAFISH Industry Authority. 84 pp.
ICES. 2016. Interim Report of the Working Group on Cephalopod Fisheries and Life History (WGCEPH), 8–11 June 2015, Tenerife, Spain.
ICES CM 2015/SSGEPD:02. 127 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
Pierce, G. J., Allcock, L., Bruno, I., Bustamante, P., González, Á., Guerra, Á., Jereb, P., et al. 2010. Cephalopod biology and fisheries in Europe.
ICES Cooperative Research Report No. 303. 175 pp.
Quirijns FJ, Pastoors MA, Uhlmann SS, Verkempynck R. 2014. Discard Atlas of North Sea fisheries. IJmuiden: IMARES, prepared by the
Scheveningen group. 84 pp.
Young, I.A.G., Pierce, G., Stowasser, G., Santos, M.B., Wang, J., Boyle, P., Shaw, P., et al. 2006. The Moray Firth directed squid fishery.
Fisheries Research, 78: 39 – 43.
Habitat Details
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Gear effects, targeting and behaviours
Demersal otter trawls are designed to catch fish and shrimps that stay above the sea bed, from close to the bottom to several metres
from the bottom (Løkkeborg, 2005). 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 environmental conditions in which they can operate. Most otter trawling
therefore occurs within ‘core’ areas where yields are high and it is safe to trawl, typically historically fished grounds (Jennings and Lee,
2011).
Evidence of habitat risk
The physical disturbance of spawning grounds due to localised displacement of bottom sediments could have a serious potential impact
on benthic spawning cephalopod species in UK waters, such as Loligo forbesii and Loligo vulgaris (Stowasser et al., 2005). Demersal
trawling causes physical disturbances on the sea bed, the extent of which will depend on the door weight and the sediment structure
(Løkkeborg, 2005). Decreased habitat complexity has been suggested through the destruction of biogenic structures such as tubes and
burrows (Schwinghamer et al, 1996). Otter trawls also remove, damage and kill seabed biota, can cause reductions in biomass, production
and species richness (Jennings and Kaiser, 1998; Hinz et al, 2009), and ultimately can lead to substantial changes in benthic community
structure (Kaiser et al., 2000). The severity of impacts are habitat and gear specific, the most severe impact occur when fishing on biogenic
reefs composed of sessile epifauna trawled with heavy fishing gears. 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).
Cephalopods in generally are largely ignored by the Habitats Directive. They are mentioned in the Financing Natura 2000 Guidance
Handbook in relation to activities related for harbour porpoise conservation (ICES, 2016).
Mitigation measures
Under the Marine Strategy Framework Directive (MSFD) from the European Union (Council Directive 56/2008), the European nations have
committed to aim for ‘good environmental status’ (GES) for the seabed habitats by 2020. 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 Special Areas of Conservation under the European Habitats Directive (Council Directive 43/1992) contributes to this
process as does the UK Marine 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) is
engaging in a programme designed to assess the effects of fisheries and implement management measures where sites are considered at
risk. Similar initiatives are taking place in other European countries.
References
Hiddink, J.G., Jennings, S., Kaiser, M.J., Queirós, A.M., Duplisea, D.E, and Piet, G.J. 2006. Cumulative impacts of seabed trawl disturbance on
benthic biomass, production, and species richness in different habitats. Canadian Journal of Fisheries and Aquatic Sciences 63: 721–736.
Hinz, H., Prieto, V. & Kaiser, M.J. (2009). Trawl disturbance on benthic communities: chronic e ects and experimental predictions. Ecological
Applications, 19, 761–773.
ICES. 2016. Interim Report of the Working Group on Cephalopod Fisheries and Life History (WGCEPH), 8–11 June 2015, Tenerife, Spain.
ICES CM 2015/SSGEPD:02. 127 pp.
Jennings, S. & Kaiser, M.J. (1998). The e ects of fishing on marine ecosystems. Advances in Marine Biology, 34, 201–352.
Jennings, S., Lee, J and Hiddink, J.G. (2012). 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: 1053-1063.
Kaiser, M. J., K. Ramsay, C. A. Richardson, F. E. Spence, and A. R. Brand. 2000. Chronic fishing disturbance has changed shelf sea benthic
community structure. Journal of Animal Ecology 69:494–503.
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
Schwinghamer, P., Guigné, J.Y. & Siu, W.C. 1996. Quantifying the impact of trawling on benthic habitat structure using high resolution
acoustics and chaos theory. Canadian Journal of Fisheries and Aquatic Science, 53: 288-296.
Stowasser, G., Bustamante, P., MacLeod, C.D., Wang, J. and Pierce, G.J., 2005. Spawning areas and toxic element levels in squid (Loligo
forbesi) in UK waters, with notes on toxic element levels in other squid species. Report to Geotek Ltd and Hartley-Anderson Ltd.
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