A report on shark diving tours operating in Oahu, Hawaii suggests that the tours do not result in an increase of risk of shark attacks on humans according to an AP article that appeared at MiamiHerald.com. The report is based on a “snap-shot” study over the course of 4 years, which relied primarily on the logbooks of tour operators and reports from boat operators, which I would expect would draw some criticism from those opposed to shark diving (and likely anybody with some knowledge of research design). The article also mentions that federal fisheries are investigating shark tours in Hawaii on the grounds that they are illegally feeding sharks. Based on the results of the study Galapagos sharks and sandbar sharks were the most prevalent sharks encountered by the shark tours involved in the study. The study also concluded that shark tours “do not increase the potential of shark attacks near the shoreline because the boats operate three miles from the coastline and because the chumming they do to attract sharks to cages mimics the decades-old operations of crab fishing vessels in the same area that discard bait from their traps.”
Having been through multiple courses in grad school on research design, it’s hard for me to take this study seriously, based on the methodology described in the article. While my personal opinion leans toward the theory that cage diving (particularly when it occurs several miles from recreational shorelines) does not increase the risk of shark attacks on humans, I don’t really put much stock into the results of this particular study from a scientific point-of-view. It just seems to be filled with “soft” research to me. The article mentions that the researchers “determined that humans are not threatened by shark cage tours in Hawaii because Galapagos and sandbar sharks rarely bite people.” The fact of the matter is that you could say that about any and every species of shark. Great white sharks, tiger sharks, and bull sharks rarely bite people either, but it probably wouldn’t be a good idea to chum at a crowded beach for them. Fortunately, the shark tours in Oahu are 3 miles from shore. One person did mention in the comments section that there is empirical evidence that sharks follow the boats back into port. However, there is no reference to this evidence, so I haven’t been able to check it out.
The only statement quoted from the study in this article that seems worth mentioning, to me, is, “there is no evidence that the rate of shark attacks along the adjacent coast has increased significantly since the advent of shark cage diving operations in 2001.” If there is no statistically significant difference in the shark attack trends in the area since the advent of cage diving operations compared to the long-term trend of attacks prior to the cage diving, I can buy into that, from a scientific standpoint.