Warming seas due to climate change bringing anchovies to Irish waters

That may be the only positive outcome of climate change’s effect on Ireland’s marine environment, however.

A new report from the Marine Institute sets out the consequences of the changing climate, warning that its effect is already being observed.

“Irish waters are warming and have become more acidic; the distribution and abundance of key plankton, fish and seabird species are shifting, and sea levels are rising in most coastal waters,” it says.

Higher sea temperatures drive away other fish that are the mainstay of the fishing industry. Increasing acidification of the water, an associated impact, inhibits shell development in shellfish and also stymies skeleton and coral growth.

Harmful algal blooms, which are becoming a year-round feature, pose an additional threat.

The Irish Ocean Climate and Ecosystem report says sea temperature has risen most significantly on the north coast where it has increased by about half a degree in the last 10 years.

It says the south-west is also on track to become notably warmer and less saltier in the next decade.

Sea level has risen by 2-3 mm every year since the 1990s, with larger increases in Dublin and Cork. That has implications for coastal areas where sea and freshwater mix, and for the marine life those regions support.

Important plant life in salt marshes, already under threat, could further decline and growth of phytoplankton, essential food for marine creatures, could suffer.

Abnormal growth of sea lettuce has already been observed.

Paul Connolly, the Marine Institute’s chief executive, warned that changes in the ocean not only brought changes to seafood and biodiversity but weakened the ocean’s ability to absorb carbon, moderate weather and keep the climate in balance.

“The oceans provide 50pc of the oxygen we breathe,” he said. “They are a critical element of the global climate system in their role to regulate atmospheric processes and for distributing heat, salt, and organisms.

“This research shows the impact of climate change is already evident in Irish marine waters.”

The arrival of “high densities” of anchovies off the southeast coast is significant because they are more normally found in the Bay of Biscay and the Mediterranean.

“Anchovy can respond quickly to changes in climate and can often be used as an indicator of ecosystem change,” the report says.

While they could become a potential new catch, there is a tough trade-off in the reduction of herring and cod, which need colder waters.

The report warns, however, that there can be multiple factors at play and that further research is needed.

“One of the biggest challenges to determining climate-change impact on fish species is disentangling the simultaneous pressure of fishing,” it says.

“An over-exploited stock may be more sensitive to environmental changes.”​

The report is a collaboration between the Marine Institute, Met Éireann, several universities, the Environmental Protection Agency and other scientific bodies.