Squid attraction to LED

tonmo

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#1
I received this real interesting email from TONMO.com visitor Manny. With his permission I am posting it here. Please reply with any input!

Hello Tony,

I had an interesting experience with our local California Market Squid and a very low power (6 watt) floating green-blue LED light array that I would like to share with you. The small floating LED array was originally designed and constructed, using standard off-the-shelf components, as a fish bait attraction device to be used to “make bait” such as sardines for the next days fishing. It works well for that purpose however the device appears to be a most effective squid fishing light, so effective in fact that after several sea trials I can say for a fact that it attracts our local inshore loligo opalescens squid better than our San Pedro commercial squid boats with their many full spectrum light arrays using as much as 30,000 watts per squid fishing vessel, Current California Fish & Game law limits each vessel to a max of 30,000 watts. Talk about wasting energy!

As you know the little squid is the prey of choice for most Southern California predator fish large and small, from rockfish to tuna, and it is the most important commercial fishery in California. It also happens to be rather easy inshore fishing compared to other commercial fisheries, if the squid are there they are usually readily attracted to the surface by bright lights. Typically three or four small boats with maybe 10KW light arrays scoot around the area “rounding up” the spawning squid, then lead then over to a mother boat, which in turn, using a small net boat, circles the now massive shoal with a net and hauls them in. It is only about a three or four hour job. When they are finished and have a surplus they go on the radio and offer squid for sale to the sport fishing boats in the area wanting live squid for bait. They charge US$60 a scoop, don’t know just how much a scoop weighs but it usually is enough squid for maybe three guys to fish all day with some left over to freeze for next time. Due to the cost many sport fisherman use glowing squid lures to try to snag their own squid at night for bait but if you ever tried it you know it is usually a waste of time and effort.

Early last year a few of us were anchored on backside of Catalina Island spending the evening waiting to do a bit of white seabass fishing the following morning. About dusk a large squid mother boat and four small lightboats anchored about a hundred yards away, as darkness fell they lit up and the small boats started cruising the area, very soon the surface waters around the small lightboats were alive with squid, they started leading the squid over to the mother boat. We had one 500 watt light pointed at the surface with a scoop net ready to grab a few squid, several squid moving very fast shot past us toward the lightboats with their thousand watt arrays, none even bothered to tarry around our 500 watter. We then launched our little LED array to see what if anything would happen, within five minutes it seemed that th e entire shoal of squid now close to the mother boat, came over to our little green-blue array, even the seabirds that had gathered around the mother boat waiting their chance to grab a bite, all came over squawking and diving around our boat. It was an amazing sight, in about a minute we scooped up enough squid to fill our small bait tank and quickly departed the area amid curses and threats from the furious commercial guys. They were so incensed that they did not even think to ask us what kind of a light we were using.

I understand that inshore waters are “green” and that many sea animals eyes peak in the that wavelength, and that “green light” has good penetration in those waters. If we were out there alone and squid were attracted to our light I would not think it much of a mystery, but in this instance we are one on one against many thousands of watts and yet we actually drew the squid away from those sources? I know that the full spectrum “white lights” they are using emit a goodly portion of green, but it is very hard to believe that our 6 watts of pure green-blue light produces more usable green lumens that of a 10,000 watts white array, even taking into consideration that most of that high wattage energy is wasted in heat, distance to the surface, reflection, refraction, scatter, etc. I now have to assume that it was not the specific color or wavelength that attracted them, but what was it?

If you have any thoughts or comments as to why these squid left the bright lights to gather around our low power green-blue LED array they would be most appreciated.

Thank you, Manny
 

skydivemcbain

Pygmy Octopus
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Oct 3, 2006
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#2
WOW!!! Very impressive, Was this light something purchased for bait collection, or a home-made light? I wonder if this was just a situation given the circumstances or if you found something very sacred.
Congrats on that.This experiance would have made my day, even if I didn't fish the next day. Cheers
 

monty

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#3
I've noticed that there are sometimes phosphorescent things (algae? bacteria?) in the water off California that leave blue-green "trails" around larger items; scuba diving, you get a "St. Elmo's Fire" effect when night diving if you turn off your dive lights (I saw this in Laguna Beach), and I've been on the beach near Watsonville when you could walk along the waterline at night and leave glowing footprints. Anyway, I wonder if the blue-green LEDs look like the this effect around a prey animal the squids like, so they're more attracted to it as a potential food source than they are to the super-bright boat lights. This is a completely unfounded guess, of course, but it seems kinda plausible...

edit: This says they're dinoflagellates, and suggests that they may deliberately glow to attract predators to eat crustaceans that are feeding on them, which would fit with the squid attraction theory.
 

fluffysquid

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Jul 3, 2003
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#4
When we go out collecting shrimp and fish (or sometimes squid) at night, we can see bright little dinoflagellate flashes in front of us as we walk and disturb the water. These particular ones are blue. Once your eyes are adjusted, though, they look pretty bright! Amazing sight to see the water lighting up in front of you.
 

chrono_war01

Colossal Squid
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Oct 7, 2004
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2,580
#5
In HK, fisherfolks use the same large wattage lights to attract squid, but recently, there's been a quiet discussion going on about towing a much smaller Blue/green LED and even a glow-in-the-dark object underwater seems to be much more cost effective at catching said squid.

The idea behind white lights seems to be that:
1) Lights attract fish, fish attracts squid.
2) Lure in water reflects light like fish scales, squid gets confused (bad eyesight?), takes lure, gets hooked/netted by the bunch.

Using the smaller lights seems to skip step 1, maybe the object looks more like prey? I don't know, I'm no squid (maybe a scuba diver underwater in test conditions to tell us.)

According to my few night diving experiences in HK, there doesn't seem to be a abundant amount of dinoflaggellates around. But just enough that waving your hands around in the water would produce 3-8 blue glowing dots.

Hope the information will be helpful...
 

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