Recently I posted about a paper on the global footprint of fisheries, based on AIS. Albeit an interesting read on the use of the technology, I was taken aback on some of the comparisons made in the website of origin. Yet I had not the time to elaborate much on them, but someone that is good at that is Ray Hilborn, so I quote some of his responses to the claims.
Study state that vessels are now fishing in 55% of the world’s oceans, which is an area four times larger than occupied by onshore agriculture. The immediate popular conclusion was that this shows immense overfishing, and Oceana was quoted saying “That means we’re putting more pressure on fish populations.”
Hilborn says “The comparison to agriculture fails to note that the 50 million square kilometers under agriculture have destroyed the natural ecosystem as the plow or new pasture eliminates the native plants. The areas fished, particularly for tunas, have changed very little.”
Furthermore, “Fishing does not impact the primary production (plants), and in very few cases does it impact the species that graze on the primary producers. So the 50 million square kilometers of the earths’ surface that is used for agriculture is totally transformed, most of the oceans that are being fished (high seas tuna) have some changes in top predators abundance.
“High seas fishing for tuna, which constitutes the majority of the “footprint” shown in the Science paper has been mapped for 40 years, and the widespread nature of high seas tuna fishing is well known. The footprint of bottom trawlers has been mapped in much finer scale already in many places, and the Science paper overestimates the proportion of the seabed impacted by trawls by 10 fold.”
The AIS data is interesting, and allows for specific types of research that was not possible before. However, the dataset does not give as accurate a picture of global fishing as does the comprehensive database on fish stock surveys and catch records.
Hilborn is a longtime collaborator with Dr. Boris Worm, one of the authors of the paper. Together they did a groundbreaking study of global fisheries databases, and helped create a standard dataset to measure fisheries catches and stock health. Neither Worm nor the other authors are claiming that the AIS study shows increased fishing pressure on stocks, they are simply reporting that the tracking data provides a new visualization tool for global fisheries.
Now in my opinion, while these comparisons have the advantages of (sometimes) putting things in perspective against each other, they feel a bit like a "my dick is bigger (or in this case smaller) than yours" and I'm never sure how conductive to change this is. By the fact of living we are impacting nature... nothing grows under our houses, roads, schools, etc... We all have to make constantly more compromises, and this is not going to change as long as we live.