Restoring ecological links in no-take MPAs is a good thing

On 31 December 2014, Peter J.S. Jones published this important opinion on the Open Channels portal, a recommended reading not only for marine conservation ecologists but also for anyone interested in marine conservation issues. By re-establishing natural links amongst the components of marine ecosystems, habitat restoration will bring about consequences in animal populations, such as reverting to natural age structure, increased competition, decreased per capita production, etc., which opponents to conservation with vested interests are quick to denounce as a conservation failure. The exact opposite is true.   GNdS


Why the negative spin on a consequence which anybody with even a basic understanding of population ecology would accept and even welcome as inevitable?

Posted on Open Channels on December 31, 2014 – 8:24am, by PJSJones

In relation to the recent news item on the Hidden side effects of MPAs? based on the paper Effects of population density and body size on disease ecology of the European lobster in a temperate marine conservation zone.

Density dependence is a well recognised central tenet of population ecology, i.e. as the density of a population is restored back to unexploited levels, a number of ‘natural’ trends will increase, such as increased prevalence of disease amongst more crowded populations and older ‘senile’ individuals (as natural age structure is restored), along with increased competition for space, sexual partners, food, etc., leading to increased fighting related injuries. Per capita production will also decrease due to competition for food, cannibalism, etc. This is naturally what happens when you stop thinning a population through harvesting. It certainly is not hidden or unexpected, nor is it a threat to a successful marine conservation story. It is simply what should be expected to happen when a population is restored back to natural levels.

The negative spin related to findings such as this are eagerly seized upon by the fishing industry and some fisheries scientists [1]  as arguments against no-take MPAs, when they should be more positively presented as a natural consequence of the recovery of populations back to unexploited densities and age structures, along with related spill-over and export benefits. I have been presented with a partial understanding of such findings by several fishermen as yet another reason why no-take MPAs are a bad idea. It would be better if these findings could be presented in a more balanced way that recognises that they are merely a representation of basic population ecology associated with the recovery of marine populations back to natural unexploited levels, rather than as the negative ‘rarely broadcast’  threatening and hidden side effects of no-take MPAsWhy the negative spin on a consequence which anybody with even a basic understanding of population ecology would accept and even welcome as inevitable?

[1] Jones P.J.S. (2007) Point of View – Arguments for conventional fisheries management and against no-take marine protected areas: only half of the story? Reviews in Fish Biology and Fisheries17(1), 31-43. doi:10.1007/s11160-006-9016-8 – Copy of paper. See also pp.46-55 on Divergent views and the quest for common ground amongst fisheries scientists and marine ecologists in Jones P.J.S. (2014) Governing Marine Protected Areas: resilience through diversity (see previous MPA News interview on this book)



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