Atlantic cod in the Celtic Sea, Demersal otter trawl
The most recent assessment has resulted in a large downward revision of recruitment and stock size in several years and an increase in the estimates of fishing mortality. Recruitment of young fish in 2017 has been much lower than assumed in projections. Due to the reliance of this stock on recruitment this results in a diminished stock size. The trends in the assessment are evident in catch trends in recent years.
In the longer term perspective the stock has been on a downward trend since the 1990s, and outside safe biological limits in most years since 2004, with the exception of the period 2011-13 following good recruitment in 2010. Fishing mortality has fluctuated at high levels for most of this period.
Stock structure and recruitment
The stock structure has been examined in WKRound (ICES, 2009). Tagging work by Ireland and the United Kingdom supports the idea that there is a self-contained, resident cod stock in the Celtic sea and the western English Channel (7e-k). Although minimal population mixing occurs between cod stocks in the Irish Sea and the Celtic Sea, cod are migratory and undertake a limited degree of population mixing in other areas. Both conventional tagging and data storage tag (DST) information indicates that the distribution of the cod population in Division 7g (where the majority of landings are taken) remained spatially constrained within the division and the highest abundances were found in central areas between January and March. The cod population in the Northern Celtic Sea (Division 7g) was more widely dispersed throughout the division between April and June. Fish tagged in the Bristol Channel (Division 7f) tended to mix with offshore populations in Divisions 7g and 7h. In contrast, some of the fish tagged in the western English Channel (Division 7e) migrated into the Eastern Channel (Division 7d) for at least part of the year.
Juveniles found close to the southeast Irish Coast (south of Division 7a) are considered to be part of the Celtic Sea stock and the landings adjusted accordingly since 2004 (ICES, 2018a).
Data gaps and research priorities
A degree of uncertainty exists in the catch statistics for this stock. Misreporting, discard practices and high grading are a main cause of uncertainty in the catch data, especially when quotas have been particularly restrictive in the 2003–2008 period as well as 2011 (ICES, 2009).
ICES (2018b) advise that this stock should be benchmarked in 2019.
ICES. 2009. Report of the Benchmark and Data Compilation Workshop for Roundfish (WKROUND), 16–23 January 2009, Copenhagen, Denmark. ICES CM 2009/ACOM:32.
ICES. 2016. Report of the Working Group on Celtic Seas Ecoregion (WGCSE) 4–13 May 2016 Copenhagen, Denmark; stock annex
ICES. 2018a Cod (Gadus morhua) in divisions 7.e–k (Western English Channel and southern Celtic Seas). ICES Advice 2018
ICES. 2018b. DRAFT Report of the Working Group on Celtic Seas Ecoregion (WGCSE) 9-18 May 2018 Copenhagen, Denmark