A new study by a Swansea University academic suggests that European lobsters in highly protected marine protected areas (MPAs) are larger and have higher population densities, but these positive effects have resulted in some unintended consequences.
Research by Dr Charlotte Eve Davies from the University’s College of Science, published in the ICES Journal of Marine Science compared a fished area to an eight year old, unfished, no-take zone (NTZ) in the Lundy Island MPA, and found that although lobsters were more abundant, and larger in the NTZ, they were also more likely to be injured.
It was found that lobsters caught in the unfished area were 71% more likely to be injured than lobsters in the fished area, which could be a result of overcrowding resulting in competition and fighting in these highly territorial animals. In conjunction, if a lobster was found to be injured, it was 76% more likely to have shell disease than an uninjured animal, regardless of where it was caught.
Dr Davies said: “It has always been assumed that MPAs are the solution for conservation, with increased catch, and overspill into adjacent fisheries helping to replenish overfished stocks and enhance recruitment. Our study is interesting in that it introduces the idea that un-fished populations in marine reserves may eventually reach a threshold at which conditions become unhealthy. This may even introduce the possibility of controlled fishing in long-standing no take zones.”
Lundy Island was the first Marine Nature Reserve, NTZ and Marine Conservation Zone in UK waters and was implemented with no baseline monitoring in terms of disease and population health.
Dr Davies said: “This may be a controversial move but studies have shown that high abundance in marine reserves may render animals vulnerable to disease particularly because infections can no longer be “fished out”. Our study highlights both positive and negative effects of MPAs and has implications for ecologists, fisheries managers and fishermen. A total ban on fishing is certainly positive in allowing recovery of populations back to unexploited densities, but they may have a finite time span of success.
The study can be found here
- Tuesday 24 February 2015 12.23 GMT
- Wednesday 7 January 2015 15.38 GMT
- Swansea University