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 - North Sea (IV, VIId and IIIa)

Cod ( Gadus morhua), by weight, is the third most important demersal species landed from the North Sea by Scottish fishermen. Like many North Sea stocks, cod is overfished with a high percentage of removals from the stock unaccounted for.
2013 position : UK share 10,311 tonnes
Last Year : 10,331 tonnes
Landed into
Scotland in 2011 : 9,222 tonnes
Value for 2011 : £21,89 million

Biology
Cod occur mainly in the northern and central areas. New born cod are distributed over a large part of this area, with high concentrations off the Jutland coast. One and two year old cod tend to overwinter in shallow coastal areas, but eventually disperse into deeper water. Whilst some cod tend to reside all year around in coastal areas, the larger offshore congregations of cod tend to be migratory.

Many cod now reach maturity at two years old, with 50% mature by three years old. By the time they reach five years, all cod are mature. An adult female of around 80 cm can produce around four million eggs in a season. Most spawning takes place between February and March with the largest spawning areas in the northern North Sea and around Dogger bank. Young cod live in the upper water layers for a period before moving to the seabed in July and August. They grow quickly and can reach 20cm after one year, 50cm after two years and 80cm by the time they are four years old. By the time they reach two years old, young cod are fully exploited by the commercial fishery as the minimum landing size for cod is 35cm. Many fish are caught long before they have the chance to spawn, and less than one twentieth of one year olds will survive to the age of four.

Cod do not usually browse for food on the bottom but are active feeders. By weight, around three quarters of the food of all sizes of cod consists of fish and crustaceans. The rest is made up of small quantities of molluscs and worms. As they grow, cod eat an increasing amount of fish. Sandeel, Norway pout, whiting, herring, dab and cod themselves are the main fish species eaten.

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-347.pdf). Quoted text in italics.

Total removals, Recruitment (age 1), Average Fish mortality and Spawning Stock Biomass

MSY and precautionary approach reference points

Type Value
Management Plan SSB MP 150,000 t
F MP 0.4
MSY Approach MSY B trigger 150,000 t
F MSY 0.19
Precautionary Approach B lim 70,000 t
B pa 150,000 t
F lim 0.86
F pa 0.65

State of stock and advice

  • Fishing mortality in 2011 was estimated to be 0.572: this means that approximately 44%, by number, of all fish between 2 and 4 years of age were caught.
  • Spawning stock biomass has increased since its historical low in 2006, but is estimated still to be below B lim in 2012 at 65,300 tonnes.
  • Fishing mortality and biomass are between and below, respectively, the precautionary approach limits. However fishing mortality is well above the level which is consistent with achieving maximum sustainable yield ( F 2010> F MSY).
  • The advice is in accordance with the long-term management plan and recommends a TAC in 2013 of 25,441 tonnes for areas IIa, IIIa Skagerrak, IV and VIId combined.

In February 2008 Scotland implemented a national scheme known as the 'Conservation Credits Scheme'. The principle of this two-part scheme involves additional time at sea in return for the adoption of measures which aim to reduce mortality on cod and lead to a reduction in discard numbers. ICES notes that from the initial year of operation (2008) cod discarding rates in Scotland have decreased from 62% to 24% in 2011. In 2010 there were 185 closures, and from July 2010 the area of each closure increased (from 50 square nautical miles to 225 square nautical miles). Recent work tracking Scottish vessels in 2009 has concluded that vessels did indeed move from areas of higher to lower cod concentration following real-time closures during the first and third quarters (there was no significant effect during the second and fourth quarters).

In previous years, comparison between the fishers' North Sea stock survey and the IBTS survey data has shown that the time-series are broadly in agreement in recording a stable overall stock abundance until 2003-2005, followed by a more recent increase. Because of the inherent spatial variation, the IBTS surveys have more variability, but exhibit similar trends in the same areas as the fishers' survey, showing significant increases in stock abundance in the north and west, and less in the south, with a leveling off in these southern areas in 2011.

Management outcomes for 2013
At the December 2012 meeting in Brussels, the Council of Ministers decided that the EU Total Allowable Catch for cod in Subarea IV and Division IIa should be 26,475 tonnes. The UK quota for 2013 was set at 10,311 tonnes.

This quota decision is consistent with the existing cod long term management plan. This plan (affecting a number of cod stocks) includes an effort management scheme which limits the effort available to the main cod catching gears. The Council Regulation covering the plan also includes provision for applying management measures to reduce cod mortality without reducing effort. The UK interpretation of permissible effort 'buy back' under the Conservation Credits Scheme (effort levels can be reinstated up to the level of the baseline established at the start of the scheme) was upheld. In accordance with the cod LTMP a further 10% cut in effort (before buy back) from the baseline applied in 2012. To justify existing and future effort buy back the UK was committed to the introduction of highly selective gears and several gears were developed, tested and introduced.

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