Information

Fish and Shellfish Stocks: 2013

Information on the state of fish and shellfish stocks of commercial importance to the Scottish fleet, inclduing Total Allowable Catches (TACs) for each stock.


Cod Stocks - West of Scotland (VIa)

West of Scotland cod ( Gadus morhua) is mainly taken in a mixed demersal fishery by bottom trawl gears with mesh size 100 mm and greater and is now regarded as a by-catch species. Discarding remained high for this species, approximately 83% caught in 2010 was discarded.

2013 position : UK share zero tonnes
Last Year : zero tonnes
Landed into
Scotland in 2011 : 933 tonnes
Value for 2011 : £235,203

Biology
Cod are distributed throughout the west coast but occur mainly in the northern area. Tagging experiments have shown that cod from this region inter-mix with those in IVa, west of Shetland. In contrast, further south in areas such as the Clyde, cod appear to be largely resident all year round.

Many cod reach maturity by two years old and by the time they reach four years, all cod are mature. An average three year old female can produce around four million eggs in a season. Spawning on the west coast takes place between January and April with a peak in March and occurs in most offshore areas. The major spawning area extends offshore from the Outer Hebrides although there are other important areas such as the Clyde. During the spawning season, there is a continuous distribution of cod eggs and larvae around the west and north coasts of Scotland. It is possible that these drifting eggs and larvae could contribute in some small way to the North Sea stocks. Although cod can live for many years, they are big enough to be caught as early as age one. By the time they reach two years old, young cod are fully exploited by the commercial fishery. Many fish are therefore caught before they have the chance to spawn and less than one twentieth of fish aged one will survive to the age of four. This means the stock is particularly vulnerable to an on-going reduction of the spawning component.

Young cod produced in springtime live in the upper water layers until about July before adopting the demersal way of life. They grow quickly and can reach 20cm after one year, 50cm after two years and 80cm by the time they are four years old. On the west coast, juvenile cod during the first year of life are often found close inshore or around the entrances to sea lochs. As they grow older they move offshore, although they appear to recruit to nearby adult areas.

Cod are active feeders and around three quarters of the food of all cod consists of fish and crustaceans. Unusual food items are sometimes eaten: small birds, stones, coal and the occasional salmon smolt.

Left: Spawning Grounds. Right: 2010 Distribution of Landings by Scottish Vessels (Tonnes).

ICES Advice on Management

Information Source: ICES advice 2012 ( http://www.ices.dk/sites/pub/Publication%20Reports/Advice/2012/2012/cod-scow.pdf). Quoted text in italics.

Catches, Recruitment (age 1), Estimated Fish mortality and Spawning Stock Biomass

MSY and precautionary approach reference points

Type Value
MSY Approach MSY B trigger 22,000 t
F MSY 0.19
Precautionary Approach B lim 14,000 t
B pa 22,000 t
F lim 0.8
F pa 0.6

State of stock and advice

  • Total mortality in 2011 was estimated to be high
  • Spawning stock biomass for 2012 was estimated to be just over 3,700 tonnes.
  • Fishing mortality is currently higher than any of the reference points. The stock biomass is well below both the Precautionary approach reference limit (B lim) and the level set for achieving maximum sustainable yield ( MSY B trigger).
  • Due to the decline of the spawning stock biomass to very low levels only a zero catch of cod would be compatible with the precautionary approach.
  • Fishing advice following the MSY approach calls for catches (mainly discards, but also bycatches) to be reduced to the lowest possible level in 2013 and 2014.

The stock is suffering impaired recruitment. SSB is very low. It is necessary to reduce all sources of fishing mortality to recover the stock above B pa as quickly as possible. Management measures taken thus far have not recovered the stock. The 2008 year class is estimated to be more abundant and consequently additional measures (such as real-time closures - RTCs) to protect it are essential to ensure that it contributes to the rebuilding of the stock. The number of RTCs west of Scotland were four in 2008, twenty in 2009, nineteen in 2010, and four in 2011, representing 27%, 14%, 12%, and 2% of the total RTCs in each year. RTCs are determined by lpue, based on fine-scale VMS data and daily logbook records, and also by on-board inspections. The low number of RTCs west of Scotland result from few instances of high lpue in the area. Estimates of continuing high discard rates in Division VIa indicate the scheme has not been effective west of Scotland.

The stock is managed under the cod long-term management plan ( EC 1342/2008). Until the 2012 assessment benchmark ICES considered it not possible to assess unaccounted mortality accurately. As a consequence ICES has not yet evaluated if the management plan is in accordance with the precautionary approach.

Considering the low SSB and low recruitment over the last decade, it is not possible to identify any non-zero catch which would be compatible with the MSY approach. Also, bycatches including discards of cod in all fisheries in Division VIa should be reduced to the lowest possible level and further technical measures to reduce catches should be implemented.

Management outcomes for 2013
The fishery is managed by a combination of TAC, area closures, technical measures, and effort restrictions. TAC restrictions on landings and effort and spatial management of fisheries catching cod in Division VIa have not controlled mortality levels. Catch (landings + discards) is 12 times the reported landings.

At the December 2012 meeting in Brussels, the Council of Ministers decided that the international Total Allowable Catch for west of Scotland cod should be zero tonnes with a consequent UK quota for 2013 of zero tonnes. A 1.5% bycatch allowance has however been introduced for EU fleets fishing this stock. This 1.5% rule applies to the retained part of the catches and therefore does not constrain discards.

This quota decision was reached in response to the recommendation that only catches reduced to the lowest possible levels are compatible with the MSY and precautionary approaches.

West of Scotland, the UK also committed to evaluation of its 2012 demersal fish selectivity measures, to exploring further selectivity developments in the light of findings and to conducting additional surveys in 2013.

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