This post is a bit behind the times, but I wanted to take the time to do the research before I wrote about it. Journalist Kate Newton published an interesting article on the future extinction of New Zealand (Hooker’s) sea lions on 11 January, 2012. In the article, Newton states the Ministry of Agriculture and Fisheries (MAF) has produced a paper stating that the New Zealand sea lion populations in the Auckland islands are unaffected by the squid fishery that is located in their hunting and breeding territory. The paper goes on to say that there should be no limit to the number of NZ sea lions caught in squid trawling nets, because the number of NZ sea lions caught as bycatch is “minimal” and therefore, the direct effects of fishing are not the cause of NZ sea lion population decline.
While this may be true, the paper’s data is based largely on a mechanical behaviour modelling analysis of the sea lion exclusion devices (SLEDs) installed in the trawl nets, which were implemented and improved upon over the last ten years. The paper does not, however, examine the possibility of indirect effects of squid fishing in their hunting and breeding grounds.
Bruce Robertson of the University of Otago states in Newton’s article that research done suggests that the opposite is true. Research papers by WD Bowen and the Department of Conservation (DoC) suggest that the squid fisheries in the territory are a possible cause of the decline in NZ sea lion numbers, though more research needs to be done to investigate just how much influence, both direct (by trawling) and indirect (by resource competition and disturbance). While there is little research that has been done about the foraging distribution of nursing females and juveniles and there is only limited knowledge of their diet, it is also uncertain whether or not population decline may also be related to their sensitivity to disturbance, weather, or any other unknown pressures untested. Bowen states that it would be more effective to evaluate the possibility of multiple factors in population decline, of which one may be the presence of the squid fisheries in the hunting and foraging areas in which the sea lions live.
So how can we ascertain what is accurate, and what is embellishment or incomplete? Well, one needs to consider the costs and benefits of each conclusion, and who stands to gain, and who stands to lose, with respect to the conclusions reached in each paper. In addition to that, who is funding the research and may or may not have a vested interest in the outcome of the results is also relevant, as is for whom the paper is being produced. In this case, MAF’s economic interest in the squid fisheries would suffer if the research they produced pointed to a correlation between declining NZ sea lion populations and the squid fisheries, since the NZ sea lion is nationally critical and therefore protected under the Endangered Species Act. The initial position paper published at the end of last year has undergone a series of revisions, most of which are available on MAF’s website. It is important to note that the MAF paper’s argument states that there shouldn’t be any restrictions on the NZ sea lion bycatch, because it isn’t common. If the bycatch number is as minimal as their research states, what then is the harm in having a limitation? By their calculations, their bycatch is minimal and would therefore not be an issue, so their argument against a bycatch limitation is moot.
For all the information that is given in the MAF paper about population modelling, SLED escape modelling, survival modelling in relation to the strike rate, the monetary value of the squid fishing industry, and many other theoretical models, what it doesn’t say can be illuminating as well. The picture is incomplete; fisheries can have a negative impact on non-target species’ populations even if their bycatch rates are minimal, and the MAF paper reflects this hole in their investigations. The scope of the MAF paper is purely limited to direct interactions with the NZ sea lions, and ignores indirect factors mentioned in Bowen and DoC that could be relevant. If one only reads the MAF paper, one gets the impression that the SQU6T fishery has no impact whatsoever on the sea lion population, and their decline in numbers, although the fishery and the sea lions are fishing for the same resource in the same area, is purely coincidental.
The interests of DoC and other conservation researchers are in the protection of the environment and the species that exist in that environment; in this instance, the NZ Sea Lion is a protected species, and therefore its welfare is of paramount importance to DoC. Therefore, it is within DoC’s best interest to examine all the possible phenomena that could be affecting the species, hence the research indicating that indirect effects of the fisheries could potentially be a correlating factor in the decline of the sea lion population. The limitation of this research is, naturally, budget. Unfortunately the costs of undertaking a multi-pronged research project can be much more than the limitations of a small government department.
The most important thing we can do is continue to examine the studies that come out, and read them with a critical eye; it is up to the public to demand transparency and ethical research from all our government departments, and we can do that by objecting to insincere science, and supporting honest research.
Crossposted at Diverkat
