Lobsters grow larger in protected Scottish bay

The first and only protected marine reserve in Scotland shows promise for marine conservation, say researchers. Adult lobsters there more than doubled in number and increased in size.

Conducting potting surveys over four years in Lamlash Bay, Firth of Clyde, Scotland, scientists monitored populations of European lobster (Homarus gammarus), brown crab (Cancer pagurus), and velvet swimming crabs (Necora puber).

They found that protection in the marine reserve was beneficial for lobsters, with their density, length, and weight all being greater than that found at other sites. Catches of egg-bearing female lobsters were also twice as high in the reserve, and these females carried an average of 22 percent more eggs—increasing breeding potential.

Tagging studies also showed that lobsters are spreading out from the marine reserve as numbers grow, thereby boosting local fisheries.

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However, although adult lobsters are thriving, juvenile lobsters and brown and velvet crab numbers are declining, which may be evidence of competitive displacement or predation. This could be due to the relatively small size of the Lamlash Bay reserve, showing that larger reserves are needed to allow marine ecosystems to recover more naturally.

“Our findings provide evidence that temperate marine reserves can deliver fisheries and conservation benefits, but they also highlight the importance of investigating multi-species interactions, as the recovery of some species can have knock-on effects on others,” says Bryce Beukers-Stewart, a lecturer in the University of York’s environment department and supervisor of the study.

Leigh Howarth, who led the study during his PhD at the University of York, now with Bangor University’s School of Ocean Sciences, adds: “Studies into the effects of marine reserves remain scarce in temperate and cold waters and are particularly limited in Europe and the UK. However, our research within Lamlash Bay has shown that a wide range of species and habitats can benefit from protection.

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“Marine reserves are only one part in creating sustainable fisheries. It is widely agreed that a combination of managing fishing effort, fishing gears, and establishing protected areas, all of which have received mutual consent from managers, fishers, and other stakeholders, is by far the most effective way to restore stocks and marine ecosystems.”

The Lamlash Bay marine reserve was created off the Isle of Arran in 2008 following a decade-long campaign by the local Community of Arran Seabed Trust (COAST). The group has assisted with research and encouraged the community to keep an eye on activities in the area.

The research appears in the ICES Journal of Marine Science. Funding came from Fauna and Flora International, the Kilfinan Trust, and the COAST.

Source: University of York

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Source: Futurity