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Algal Bloom Killing Fish, Shellfish Off West Coast

29th July 2012
Algal Bloom Killing Fish, Shellfish Off West Coast

#MARINE WILDLIFE - An algal bloom off the west coast of Ireland is responsible for significant fish and shellfish kills from Galway to Donegal, according to the Marine Institute.

As The Irish Times reports, as much as 80% of stocks have been affected on Donegal oyster farms, and the bloom is also impacting negatively on angling tourism in the west and northwest.

The algae responsible, karenia mikimotai, occurs naturally in Ireland's coastal waters during the summer months and his harmless to humans, but contains a "toxic irritant" that damages the gills of fish, shellfish and other marine species.

Low-level samples were first detected in May but in the last two weeks it has grown into a dense bloom from Donegal to Mayo, with high levels now being recorded in Galway Bay, according to the Marine Institute's Joe Silke.

"In Donegal the bloom was so dense that there were many reports of discoloured red or brown water in some areas and several areas have reported dead marine life washing up on the shoreline, requiring local authorities to close certain beaches,” he said.

"The bloom affects species that live on or near the sea bed so we are seeing flatfish, lugworms and some shellfish getting washed up on the beaches."

The image evokes memories of the notorious 'red tide' that killed wild fish and shellfish along the west coast in 2005.

Meanwhile, the Marine Insitute said there are "some indications" that the bloom may be moving back out to sea, as observed in the latest satellite images and modelling data.

"However, cell counts of samples analysed in the Marine Institute... show that the bloom is still of the same density in the Donegal and Sligo regions as it was last week."

Published in Marine Wildlife
MacDara Conroy

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MacDara Conroy

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MacDara Conroy is a contributor covering all things on the water, from boating and wildlife to science and business

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Marine Wildlife Around Ireland One of the greatest memories of any day spent boating around the Irish coast is an encounter with marine wildlife.  It's a thrill for young and old to witness seabirds, seals, dolphins and whales right there in their own habitat. As boaters fortunate enough to have experienced it will testify even spotting a distant dorsal fin can be the highlight of any day afloat.  Was that a porpoise? Was it a whale? No matter how brief the glimpse it's a privilege to share the seas with Irish marine wildlife.

Thanks to the location of our beautiful little island, perched in the North Atlantic Ocean there appears to be no shortage of marine life to observe.

From whales to dolphins, seals, sharks and other ocean animals this page documents the most interesting accounts of marine wildlife around our shores. We're keen to receive your observations, your photos, links and youtube clips.

Boaters have a unique perspective and all those who go afloat, from inshore kayaking to offshore yacht racing that what they encounter can be of real value to specialist organisations such as the Irish Whale and Dolphin Group (IWDG) who compile a list of sightings and strandings. The IWDG knowledge base has increased over the past 21 years thanks in part at least to the observations of sailors, anglers, kayakers and boaters.

Thanks to the IWDG work we now know we share the seas with dozens of species who also call Ireland home. Here's the current list: Atlantic white-sided dolphin, beluga whale, blue whale, bottlenose dolphin, common dolphin, Cuvier's beaked whale, false killer whale, fin whale, Gervais' beaked whale, harbour porpoise, humpback whale, killer whale, minke whale, northern bottlenose whale, northern right whale, pilot whale, pygmy sperm whale, Risso's dolphin, sei whale, Sowerby's beaked whale, sperm whale, striped dolphin, True's beaked whale and white-beaked dolphin.

But as impressive as the species list is the IWDG believe there are still gaps in our knowledge. Next time you are out on the ocean waves keep a sharp look out!