Virtually all squid jigs [fishing lures] have luminescent sections, but now available in the South West are jigs made by Japanese companies like Yo-Zuri, where intense luminescence covers the entire upper half of the jig. It may be bad news for squid . . .Why exactly would it be bad news for the squid? Well, lights are used around the world to summon squid to their death, from glow-in-the-dark jigs to high-wattage surface lights.
Squid fishing lights are so bright and so abundant that the fleets can be tracked from space.
But the crazy thing is that no one actually knows why squid are so predictably and suicidally drawn to light sources. You'd think some teuthologist would have tackled this question, but as far as I know, no one has.
A 1979 paper by well-known cephalopod biologist Roger Hanlon sums up the state of knowledge (or lack thereof) and I don't know of any real progress in the ensuing 32 years:
It is well known that many cephalopods [squids and octopuses] can be attracted to lights at night but the attraction mechanisms are not understood. Woodhead (1966) and Bearse and Saila (1975) reviewed and summarized most of the current theories of light attraction among marine organisms: 1) positive phototaxis 2) intensity preference (brightness) 3) wavelength preference (color response) 4) conditioned or unconditioned response where light is associated with food 5) curiosity 6) photic disorientation and 7) hypnosis. No one has reliably determined which factors are responsible in any particular species.
The first three possibilities are all built-in biological features. True or not, none of them are very satisfying. In fact, they're almost tautological: "Squid are attracted to light because squid are attracted to light."
Numbers 4 and 5 are much better: squid swim toward light because they either think it's food or just want to check it out. We humans are quite familiar with the powerful motivations of hunger and curiosity.
Numbers 6 and 7 are a little disturbing, but who knows? Perhaps one day an enterprising scientist will discover just the right pattern of lights to hypnotize squid into jumping on the boat and saving fishers the trouble of catching them.*
There's just so much yet to learn about squid, and so few teuthologists to do the learning!
There's just so much yet to learn about squid, and so few teuthologists to do the learning!
* That was a joke.
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