Shellfish landings — particularly brown crab and whelk — saw a significant boom in 2016 compared to previous years, with a value of €56 million to the economy.
But species such as lobster and periwinkle saw “unexpected changes in volumes” compared to 2004 levels, according to the Marine Institute’s Shellfish Stocks and Fisheries Review for 2016-2017.
“Although landings can obviously increase or decline due to changes in fishing effort or catch rates, the scale of change in some species, in fisheries that are known to have stable or increasing effort and where catch rate indicators are stable, is contradictory,” the report warns.
“Other sources of information from industry questionnaires also indicate significant differences between official landings and landings derived from estimates of catch rates, annual individual vessel landings, days at sea and individual vessel fishing effort.”
The review concentrates on cockles, oysters, scallops, lobsters and razor clams, of which the North Irish Sea fishery for the latter saw significant expansion between 2011 and 2017, in tandem with a decline in stock.
Earlier this year, consultations were held on proposals for new conservation measures to protect razor clams in the North Irish Sea and brown crab in Irish waters, as previously reported on Afloat.ie.
As for cockles, the main fishery in Dundalk Bay experiences variable rates of overwinter survival, resulting in a biomass that in some years “is insufficient to support a fishery”. The situation is even more serious in the Waterford Estuary.
“Continuing commercial fisheries for cockles in Natura 2000 sites [like Dundalk Bay] will depend on favourable conservation status of designated environmental features that may be affected by this fishing activity or a clear demonstration that changes to designated features are not due to cockle fishing,” the review states.
Oyster stocks, meanwhile, are “generally low in all areas, except Fenit”, prompting a need for “management measures to restore recruitment and re-build spawning stocks”.