A recent exchange in one of the popular ecological journals illustrates the challenges of determining impact accountability in an ecosystem context. The first two authors (Wilcox and Donlan) suggested that an approach to mitigating for marine bycatch would be to have the responsible fishing industries pay for some restoration actions. In this case they used the example of flesh-footed albatrosses on Lord Howe Island, Australia, and said that instead of requiring increased monitoring and penalties for bycatch, that funding be rested from the fisherman to eradicate rats from the island (about 2 million US$). They employed a population model to support the claim that removing rats would sufficiently increase shearwater numbers to overcome losses from bycatch. This perhaps sounds reasonable, but this is where the story gets interesting.
In the next issue of the same journal, the respected ecologist Dan Doak and his colleagues completely refuted the Wilcox and Donlan model, and made other comments on the dangers of this kind of mitigation approach. Finally, this month, Priddel, who has studied this shearwater species and in fact published the data that Wilcox and Donlan used in their model, agreed with Doak et al. that the model was applied incorrectly, and even went so far as to say that in his publication he and his colleagues specifically dismissed rats as a threat to shearwaters. He makes clear that he strongly supports the removal of rats for other reasons, but says that the absence of rats will not increase shearwater populations, as Wilcox and Donlan claimed.
The relevance of this discussion to the Channel Islands is that the suggested effects of non-native species on native populations has been used repeatedly to support and justify eradication programs. Again, in some cases the programs are beneficial, but in others the claims of ecological damage made in the supporting documents are simply unsupportable. For example, the recent Montrose Settlements Restoration Program included an action that was titled ‘Restore Seabirds to San Miguel Island.’
Without going into details, even the people who wrote this knew that this was disingenuous if not outright misleading. There have never been large seabird colonies on San Miguel proper because island foxes would prey heavily on most of these ground-nesting birds and their eggs. The restoration program is simply a euphamism for rat eradication on the island. Again, not to go too far afield, but the impacts of this project would be enormous, not to mention the fact that no one knows how many rats there are on San Miguel, how they are distributed, or even what their impacts are. There is absolutely no documented evidence and certainly no published data that suggest that rats on San Miguel have ever preyed upon native seabirds.
If someone wants to make the case that rats have ecological impacts and should be removed, let them make the case. As with Dr. Priddel, there may be valid justifications for large, expensive eradication programs. But the people who make the decisions about how this money is spent do themselves and the entire conservation community a disservice when they don’t know, or don’t choose to know, the facts upon which they claim to make their decisions.
