Lyme Bay Experimental Potting Project

The Lyme Bay Experimental Potting project was set up by Plymouth University and funded by the Blue Marine Foundation in order to assess the impact of static potting on benthic reef habitats as well as commercially targeted species within the Lyme Bay MPA. The project was set up partly in response to concerns raised by local fishermen about the potential for an increase in static potting in response to mobile fishing being banned from inside the Lyme Bay MPA.

Started in 2013, this project manipulated potting densities across 4 experimental treatment areas to create a gradient of potting effort from no potting through to low, medium and high levels of potting effort. Inside these areas towed and baited video data are collected in order to assess changes in benthic and mobile assemblages in response to increasing potting pressures. Additional quantitative catch data is collected to monitor the commercial catch composition of mainly brown crab and lobster, the species primarily targeted by potting in Lyme Bay.

The results have been published in Scientific Reports, a journal published by the Nature group, We found that in areas of higher pot density, fishermen caught 19% less brown crab and 35% less European lobster, and their catches of brown crab were on average 35 grams per individual (7%) lighter. The effect on marine species was also significant with two ecologically important reef species, Ross coral (Pentapora foliacea) and Neptune’s Heart sea squirt (Phallusia mammillata), 83% and 74% less abundant respectively where pot density was higher.

The study provides evidence of a pot fishing intensity ‘threshold’ and highlights that commercial pot fisheries are likely to be compatible with marine conservation when managed correctly at low, sustainable levels.

“The effects of bottom-towed fishing have been clearly shown as part of the University’s long-term monitoring project in Lyme Bay. But before we started this research, very little was known about the precise impacts of pot fishing over a prolonged period. We have shown that – if left unchecked – it can pose threats but that changing ways of working can have benefits for species on the seabed and the quality and quantity of catches.” – Dr Adam Rees

Return to the Projects page for details of other projects.

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