Atlantic cod

The stock is assessed annually via an analytical age-based assessment model (TSA) using commercial catch data and sampling and a survey index that also provides maturity indices (ICES, 2014a). A benchmark assessment was last conducted in February 2012 (ICES 2012b). Until then, it was not possible to accurately assess unaccounted-for mortality. Discards are estimated based on sampling by Marine Scotland Science (ICES, 2014a). Due to changes to the Scotland survey design and gear after 2010, later surveys have to be considered as a new abundance series. No fisheries-independent abundance series were available for 2012.

Since the early 1990s the most significant problem with assessment of this stock is with commercial data. Predicted catch is divided into landings and discards. Discard information is imprecise compared to landings data because of lower sampling coverage. However, discards reported to ICES (all fleets combined) are 3.6 times greater than landings. Scottish landings and discards (from 2006) are adjusted by estimates of misreporting. The misreporting estimates have uncertainty associated with them (ICES, 2013a,b), which is thought to be high (ICES, 2014b). Implementing surveys giving estimates of consumption by seals would give greater confidence in natural mortality estimates (ICES, 2012a).

The International Council for the Exploration of the Sea (ICES) assesses the stock and provides advice on catch limits. For 2015, on the basis of a Maximum Sustainable Yield (MSY) and precautionary approach, ICES advises as it has for the past 13 years, that the directed fishery should remain closed and that fishing mortality from bycatch and discards should be minimized. It also advised that further technical measures to reduce catches are required. The MSY approach would imply a total F of 0.02 in 2015, via 8 tons of landings and a predicted 30 tons of discards, much lower than the projected 2014 values of 300 tons and 1,229 tons respectively. The MSY approach is predicted to lead to a 91% increase in SSB in 2016 relative to 2015, to an estimated 3,852 tons. No non-zero 2015 catch rates would be compatible with both the MSY and precautionary approaches. Following the precautionary approach would imply zero catches in 2015, through either landings or discards.

Following the existing management plan would imply total catches of 1,186 tons in 2015, under a total F of 0.73, and leading to a 2016 SSB of 2,200 tons (ICES, 2014a).

Last updated on 07 Aug 2014

ICES proposes a precautionary SSB level (B_pa) of 22,000 tons, and the MSY B_trigger has been set at the same value. This is considered to be the minimum SSB required to ensure a high probability of maintaining SSB above B_lim, while considering assessment uncertainty. This is in accord with the lowest range of SSB during the early 1980s when the stock was in a more productive period. A lower limit reference point, B_lim, of 14,000 tons, is proposed, below which recruitment is impaired. The precautionary fishing mortality (F_pa) is determined to be 0.6. This F is considered to have a high probability of avoiding F_lim (= 0.8) (ICES, 2014a) but is well above F_MSY=0.19. Values in the range of 0.17-0.33 are thought to be consistent with F_MSY, but both the point estimate and the interval are provisional and based on analogy with North Sea cod. The 2008 management plan adopted a target F (F_trp) of 0.4, which was below the F_pa but is above the more recent estimates of F_MSY (ICES, 2014a).

According to ICES, fishing pressure on the stock is unsustainable and the depleted stock size implies reduced reproductive capacity (ICES, 2014a).The spawning-stock biomass has been below B_lim since 1997 and has remained very low, below 3,000 tons, since 2005. Recent recruitment at age 1 has been low but the 2005 and 2008 year classes appear to be the strongest since 2001 (ICES, 2014b). Fishing mortality remains too high, above either precautionary or MSY levels, and most likely above F_lim, the level that led to stock declines in the past. Predation by grey seals may also be a factor impairing the stock’s recovery (ICES, 2014a). Landings have been very low since 2005 but discards have increased and the resulting catch rates are too high.

Last updated on 07 Aug 2014

SSB was already on a decreasing trend in 1981, the first year for which an estimate is available. It has been below the precautionary reference point B_pa, equal to the current MSY B_trigger, since 1990, and below B_lim since 1997 and no signs of recovery are apparent. Recruitment is impaired by the current stock size and has been low since 2001, the culmination of a long-term decreasing trend (ICES, 2014b). Fishing mortality has been above the precautionary reference point, F_pa, for the entire time series, and also above F_lim 1987. It is well above the more recent F_MSY reference point. ICES-estimated catches decreased in line with TAC reductions from the late 1980s to 2005, and although landings have remained low, discards are significantly contributing to catches, keeping total catch at around 3.5 times higher than landings (ICES, 2014a).

Since 2009, cod in Division VIa is subject to the EU cod long-term management plan (EC 1342/2008). This regulation has the objective of ensuring the sustainable exploitation of the cod stocks on the basis of maximum sustainable yield, while maintaining a target fishing mortality of 0.4 on specified age groups. F_MSY has more recently been estimated in the range of 0.17-0.33. The fishery is managed by a combination of TAC, area closures, technical measures, and effort restrictions. A cod recovery zone is defined for depths of less than 200 m, where effort restrictions apply, and EC 53/2010 introduced new gear technical measures (ICES, 2014a). The TAC has been set at zero since 2003 but a bycatch allowance of 1.5% of live weight of total catch is permitted. These restrictions have not recovered the stock nor sufficiently reduced catches (ICES, 2014a). Fishing effort in Division VIa has reportedly increased in spite of the measures introduced to reduce it (STECF, 2013). The bycatch limit does not constrain discards and may have increased discard rates in some fleets (ICES, 2014a).

Until the 2012 assessment benchmark, unaccounted-for mortality was not accurately assessed. As a consequence ICES has not yet evaluated if the management plan is in accordance with the precautionary approach (ICES, 2014a).

Last updated on 07 Aug 2014

Since no recovery has been observed in this stock, ICES has continued to advise for a zero catch of cod since 2004. The management measures taken so far have not constrained catches and no increase in stock biomass has occurred (ICES, 2014a).

In 2009 the EU adopted a long-term plan for cod stocks and the fisheries exploiting those stocks (Council Regulation (EC) 1342/2008, Annex 5.4.21). This regulation had the objective of ensuring the sustainable exploitation of the cod stocks on the basis of maximum sustainable yield, while maintaining a target fishing mortality of 0.4 on specified age groups. Given ICES’s later estimates of F_MSY as lower than this value, the management objective of maximum sustainable yield is not expected to bereached under the plan (ICES, 2012a). The plan is based on a year-on-year reduction in F until the target F is reached, constrained by a limit to annual changes to TACs. Effort was similarly to be reduced for certain fleets. In additional, if recovery is failing, further reductions in TAC and effort may be employed (ICES, 2013b). In 2009 ICES evaluated this revised long-term plan for cod in relation to the precautionary approach. This evaluation concluded that assuming TAC and effort constraints would lead to rapid declines in fishing mortality, the stock would recover by 2015. However, given changes in discarding in response to moderate year classes, ICES could not conclude the plan was precautionary (ICES, 2012a), and although estimates of unaccounted mortality have since improved, ICES has not yet evaluated the plan as to its precaution (ICES, 2014a).

Catches (landings + discards) are around 3.6 times greater than reported landings. Bycatch of cod in the area covered by the TAC may be landed provided that it does not comprise more than 1.5% of the live weight of the total catch retained on board per fishing trip. However, ICES notes that this applies to the retained part of the catches and therefore does not constrain discards (ICES, 2014a). No reports as to compliance with the bycatch regulations could be located.

Cod is taken in mixed demersal fisheries, and in Division VIa is now regarded as a bycatch species. To reduce cod catch would likely imply having to greatly reduce harvesting of other stocks such as haddock, whiting and anglerfish. It is also bycatch, but to a lesser degree, in the Nephrops fishery (ICES, 2012b).

In 2008, Scotland introduced a voluntary program known as “Conservation Credits”, which includes measures such as seasonal closures, real-time closures (RTCs), and various selective gear options (ICES, 2014a).

Over recent decades, grey seal abundance has decreased in west of Scotland from 32 to 40 thousand. Seals are seen to be predators of cod, amongst other species. The increase in cod mortality in recent years seems to be directly correlated with seal predation and it is expected to be significant (Pope and Holmes, 2008 in ICES, 2008, 2009), which could impair the recovery of the stock of cod (ICES, 2014a). The latest estimates of grey seal abundance over time show the population in the area to have remained stable since the mid-1990s (Thomas, 2011 in ICES 2012a). The contribution of seal predation to total cod mortality is likely to be significant and this may impair the ability of the cod stock to recover, but data is limited (ICES, 2012a).

In the Celtic Seas ecoregion, skates are among vulnerable species, as is blackspot (red) seabream, red lobster and several deep water fish. Bycatch of cetaceans, particularly small cetaceans, has been identified as a problem in the ecoregion (ICES, 2008), although this fishery was not identified as problematic (Ross & Isaacs, 2004) and an action plan is in force to reduce bycatch numbers to below 1.7% of population abundance.

Cod taken in Division VIa is currently being taken as bycatch in the >100 mm otter trawl finfish fishery and to a lesser extent by the Nephrops fleet (ICES, 2014a). The advice for zero catch of cod will likely result in reducing significantly harvesting of other stocks such as haddock, whiting and anglerfish. Bycatches, including discards of cod in all fisheries in Division VIa, should be reduced to the lowest possible level. Bycatch of cod in the area may be landed provided that it does not comprise more than 1.5% of the live weight of the total catch retained on board per fishing trip (ICES, 2012a).

Habitats are well mapped in the fishing region and steps are underway to protect a representative network of priority habitats. The directed cod fishery is currently closed and bycatch of cod is due mainly to the demersal otter trawl fleet targeting other finfish (TR1) and the Nephrops fleet (TR2) (ICES, 2014a). Otter trawl is known to directly impact the sediment and benthic biota and thus the community structure (e.g. Jones, 1992; McIntyre et al., 2012).

Last updated on 07 Aug 2014

Scotland has since 2008 operated a voluntary program called “Conservation Credits”, which includes seasonal closures and real-time closures, to reduce catches of cod. Real-time closures are used based on LPUE data, and the number of these closures has varied between four and 19 per year in the area west of Scotland up to 2012 (ICES, 2014a).

There are three main area closures that intended to protect cod in ICES Division VIa. A closure in the Clyde Sea is likely to benefit a portion of the stock that spawns in this area. A closure in the “Windsock” area, first introduced as an emergency measure but maintained and made year-round, is thought to be of insufficient size to produce noticeable benefits to the stock, and its boundaries should be revised (STECF, 2007). A seasonal closure is enforced from November to April in statistical rectangle 39E3 in the Irish EEZ, which had historically contributed to over 40% of Irish cod landings. The closure is thought to have contributed to a reduction of over 50% in mortality due to the Irish fleet (STECF, 2012 in ICES, 2014a).

In addition, an area closed to bottom trawling is defined on the Darwin mounds to protect deepwater coral (Lophelia pertusa) aggregations (EC 602/2004) and is classified as a Special Area of Conservation. The Anton Dohrn seamount, East Rockall bank, North West Hatton bank, Hatton bank, Solan bank reef, Stanton banks and Wyville Thomson ridge are other SACs in Division VIa, also declared due to their benthic biota. Several Nature Conservation Marine Protected Areas are also declared in the region, intended to conserve a selection of marine biodiversity, both species and habitats, and a network of OSPAR MPAs, with the additional aim of protecting threatened species and habitats, are to be established in a network by 2016.