Shellfish dredging wiping out key carbon-catching seagrass meadows, Coastwatch warns

Irish Times

09-05-2025

Dredging for shellfish in some of Ireland's most sensitive marine areas is wiping out seagrass meadows that play a critical role in capturing vast amounts of carbon and in enriching
biodiversity
, according to
Coastwatch
.
Following the environmental group's discovery this week of the latest evidence of seagrass destruction, at Elly Bay in Co Mayo, it has called on the Government to ensure 'no more bottom dredging in
protected sites
with sensitive features'.
This was necessary 'so seagrass can do its carbon-capture job' and ensure biodiversity-rich areas are preserved in places under the umbrella of marine protected areas (MPAs), said Coastwatch director Karin Dubsky. This was needed 'to address both biodiversity and
climate change
crises'.
Decline of seagrass underlined the need to switch to 'managed, licensed shellfish diving and gathering, with licences reserved for traditional scallop and native oyster fishermen', she said. The fishers' local knowledge and stock-protection traditions, combined with the right diving skills and scientific knowledge was the way effective MPA management could work.
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Last Sunday, Coastwatch regional co-ordinator Sam Moran assessed seagrass (
Zostera marina
) meadows in Elly Bay, part of a special area of conservation (SAC) known as the Mullet/Blacksod Bay Complex.
He free dived with a simple underwater camera and recorded healthy but thin seagrass with spiny crabs and other sea life, Ms Dubsky said, but also 'the odd reef hump teeming with life, interrupted by large areas of recently ripped up sea floor with empty shells. He even found a lost dredge with the damaged seabed running up to it'.
This was the latest evidence of extensive damage by dredging in important marine ecosystems around the Irish coast, she added.
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'This is in one of our prime, internationally protected sites, which also hosts seagrass, the most valuable carbon store and fish nursery area. Yet we see boats licensed to dredge here. Licensed damage has to stop. We call on Government to halt dredging in and around seagrass, foster site restoration and management with local, traditional knowledge,' she said.
Mr Moran said he believed the area could recover if dredging were halted.
'Looking at the ground and shelter here, there is huge potential for seagrass meadows to expand. This would provide a return in more shellfish, fish and other sea life which needs healthy seagrass meadows to flourish,' Mr Moran added.
He said he was shocked this practice was going on in such an important ecological area, and by the dredge abandoned on the seabed.
Spider crab in a depleted seagrass meadow in Elly Bay off Belmullet in Co Mayo. Photograph: Sam Moran Coastwatch
Ms Dubsky said a Government decision to stop dredging in MPAs would be an apt 99th birthday present for environmentalist and film-maker David Attenborough, coinciding with the release of his new documentary Ocean.
Separate to the film displaying 'the awe of the beauty and complexity of our underwater world', she said it conveyed 'sadness and frustration as more and more of our seas are being damaged by ever-growing variety and intensity of human activities'.
While it brought some hope of turning things around before it's too late, she said the same pressures were evident on Irish seas. 'You can see both beauty and damage yourself right here in Ireland,' she added.
The dredges used in Elly Bay 'aren't huge like those shown in David Attenborough's Ocean film, but we see how they can still do the seagrass damage – think of sensitive parts of your body where a poke can do real damage, while others might just get bruised and be grand'.
'Adequate monitoring and enforcement, as well as a publicity campaign to highlight this transformative change, would bring more ecotourism and a top price for shellfish selected for size right there at the seafloor,' she added.
Inland Fisheries Ireland is responsible for issuing oyster dredge licences, while enforcement comes under the National Parks & Wildlife Service (NPWS). The NPWS was asked to comment on concerns raised by Coastwtch.