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Fish Tagged For Research Become Lunch For Gray Seals
sciencehabit writes: When scientists slap an acoustic tag on a fish, they may be inadvertently helping seals find their next meal. The tags — rods a few centimeters long that give off a ping that can be detected from up to a kilometer away — are often used to follow fish for studies on their migration, hunting, or survival rates. Researchers working with 10 gray seals (Halichoerus grypus) who were captive for a year have now reported that the animals can learn to associate the pings with food. If the findings hold true in the wild, the authors warn, they could skew the results of studies trying to analyze fish survival rates or predation.
Radio waves don't travel well underwater. You need stupidly low frequencies like those used for submarine communication, and you won't be able to generate those frequencies from an object that's a few cm long which means you're stuck with acoustic methods. The tags in question operate at 69KHz, which as far as I know is outside the hearing range of seals - this article makes me wonder though, I've got it bookmarked and I'll give the underlying paper a good read when I've got the time.
I'm actually an engineer at the company that makes the tags in question. We're hardly a huge corporation (100 people) and we don't have the financial clout or even any obvious reason to bankroll corrupt science - we just make scientific gear that helps scientists do their science. I wouldn't consider us to be much different from a company that makes lab coats or glassware.