Rapid increase in fish numbers follows creation of world’s largest marine reserve network

So the results on the Great Barrier Reef Marine Park zoning are in, and according to new research published in Current Biology, the evidence strongly suggests a rapid increase in fish numbers in no-take areas. Not that this in itself should be so surprising (a decrease in fishing = increase in fish numbers!), but to date previous studies have shown varying results as to the effectiveness of no-take reserves. The rezoning of the GBR back in 2004 resulted in 33.4% of the reef being declared as a no-take marine reserve, essentially closing these areas from all fisheries (recreational and commercial). At the time this created considerable controversy from the community (leading some misguided ‘scientists’ to claim "the over-fishing thing doesn’t have a shred of credibility, as an overall thing"), and numerous critics over the years have highlighted the lack of direct monitoring to show the effectiveness of these reserves.

In short, the work by Garry Russ and team shows that after only two years following the zoning, fish density of a primary target species (the coral trout) increased by 60-70% when compared to unprotected areas. Even more interesting is the finding that the 2006 coral bleaching event in the Keppel Islands caused a decline in the density of fish in the region. With the government debating stronger protection for the GBR, the evidence that these no-take reserves are boosting populations of target species across huge scales (>1000km) is encouraging not only for the GBR but for fledgling marine parks across the globe.

Here is the abstract from Current Biology:

No-take marine reserves (NTMRs) are much advocated as a solution to managing marine ecosystems, protecting exploited species and restoring natural states of biodiversity [1, 2]. Increasingly, it is becoming clear that effective marine conservation and management at ecosystem and regional scales requires extensive networks of NTMRs [1, 2]. The world’s largest network of such reserves was established on Australia’s Great Barrier Reef (GBR) in 2004. Closing such a large area to all fishing has been socially and politically controversial, making it imperative that the effectiveness of this new reserve network be assessed. Here we report evidence, first, that the densities of the major target species of the GBR reef line fisheries were significantly higher in the new NTMRs, compared with fished sites, in just two years; and second, that the positive differences were consistent for multiple marine reserves over an unprecedented spatial scale (>1,000 km).

1 thought on “Rapid increase in fish numbers follows creation of world’s largest marine reserve network

  1. “At the time this created considerable controversy from the community (leading some misguided ‘scientists’ to claim “the over-fishing thing doesn’t have a shred of credibility, as an overall thing”), and numerous critics over the years have highlighted the lack of direct monitoring to show the effectiveness of these reserves”.

    Actually they are Scientists – not ‘scientists’. For example Prof Colin Buxton and Assoc Prof Caleb Gardener and Prof Bob Kearney wrote in to Current Biology regarding the Harrison et al paper (which refers to the Russ et al paper you describe) and which like you claims a fishery wide benefit from the marine reserves on the GBR.
    They point out that any quantification of fishery benefits must include catch data – this work wasn’t carried out. Also there were declines in fished areas which is consistent with displaced catch. As well they didn’t consider that biomass is heterogeneous and the areas closed to fishing may have always been more productive (this is actually in the literature including work done by the same authors). In response the authors seemed to back away from claims of any fishery wide benefits.

Leave a Reply to Phillip Brown Cancel reply

Your email address will not be published.