Dredgers devastate precious reef

A rare reef in a Scottish loch has been devastated by a commercial dredger and could take decades to recover, say conservation experts. 

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A Scottish scallop dredger has caused extensive damage to a flame shell reef in Loch Carron, north-east Scotland claims the National Trust for Scotland. Scallop dredging involves the raking of heavy metal teeth through the sea-bed that, while catching shellfish, causes disturbance and damage to the seabed – including in this case reefs of flame shells.

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Conservationists from the National Trust for Scotland have compared the dredging to “dropping a bunker-busting bomb on a nursery school

The Scottish Fishermen’s Federation explains that local jobs rely on mechanical scallop dredging and that diving for scallops does not meet the markets high demand for shellfish. Scallop harvesting is the third most lucrative sector of the UK fishing industry and as it is currently not a Marine Protected Area (MPA), Loch Carron can be legally dredged.

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The dredger nets are hauled out of the water, displaying the destructive metal “teeth” which rake the shell bed. © Getty 

There are increasing calls for a ban on inshore fishing after studies indicate that not only were dredgers were highly destructive but also that the profits were disproportionate to the damage caused. Calum Duncan, Head of Scottish Conservation at the Marine Conservation Society (MCS) believes “it is economic madness to damage these habitats which are critical habitat for juvenile scallops and other commercial species. They are ‘spat factories’ for fish and shellfish and should be protected”.

Flame Shells (Limaria hians) are bivalve molluscs with bright orange tentacles, which construct nests by intertwining threads to create a living carpet on the sea floor. They bury into the sand, stabilising it and providing habitat for thousands of marine species including fish and chip favourite; the Atlantic cod. The beds are therefore vital to the North Atlantic food chain.       

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A “hidden gem”, Loch Carron’s shell beds could take decades to recover to their original state. © Getty 

The Scottish Government’s promised Inshore Fisheries Bill to help deliver sustainable fisheries management is urgent,stated Calum Duncan of the MCS “Our inshore waters are those most in need of sustainable stewardship. Spatial management of all types of fishing is the way forward, proactively identifying areas of ground that are suitable for the use of relevant gear and no-take areas.

A peer-reviewed paper by Trigg and Moore, 2009, gave evidence for the negative impact of dredging activity in these rare habitats; shell beds were seen to recover less than 25% of their original nest cover with poor nest thickness in a one year period. Therefore the flame shell reefs of Loch Carron could take decades to fully recover to their full size and quality.

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To read more about the damage and regrowth of Flame shell beds, read; Recovery Of The Biogenic Nest Habitat Of Limaria Hians (Mollusca: Limacea) Following Anthropogenic Disturbance – Colin Trigg and Colin G. Moore.