Hi Steve,
Welcome back from your trip! Wish you have better luck with the weather next time. Very interesting photos of the light traps. I am really interested in these traps. Could you tell me more about the design and construction of these traps and how they are deployed during day time collection and night time collection? please. Some more photos showing more detail would be a big help.
Oh, about the baby squid,
. I used to collect and keep common species of squids quite often (but I prefer octopii and cuttles because they are apparently more intelligent, :P ). Please refer to my earlier posts dated Mar 4 and Mar 5 in this same column. My squids were mostly baby and juvenile (mantle length 1.5cm to ~6cm) because they are easier to collect and, being smaller, more manageable. The largest one I have ever kept had a mantle length of ~15 cm, in a 6'L by 2'W by 2.5'H glass tank.
Obviously, being pelagic species, it is harder to keep squids in glass tanks compared to cuttles and octopus which are so much easier. Also, they are also much more sensitive to poor water quality. I have always kept them in glass tanks (rectagular) because I want to observe them from the side (offers much better observations) rather than from the top (if opaque circular tank was used instead, as in research facilities). To acomplish this, there are quite a few additional precautions to be taken (compared to keeping octopii and cuttles). I won't recommend other people to try keeping squid in rectangular glass tank unless they know exactly what they are doing.
Please also understand that the fish that you see in the photos were no ordinary fish. I guarantee you won't see photos of 'live-and-kicking baby spanish mackerels in fish tanks' anywhere else. The tank that you see in the photos was a bare rectagular glass tank with no rocks or inside filter. Apart from the mackerels(around 5) and the squids(around 8) which were schooling together against the water current, there were only a few baby batfish in the plastic crate (the black object floating to the top right hand corner of the photo). Both the mackerels and the squids were fed live baby mullets, ~1 to 2 cm TL because they are both pelagic piscivores. They were weaned onto frozen baby mullets later with difficulty. Should there be a significant size difference, I would not be able to keep them together (they seemed to enjoy each others company,
). If the baby mackerels (
Scombermorus Commersoni)had been baby dolphinfish instead (
Coryphaena spp.) , they may attack smaller individuals of the squids.
cause baby dolphinfish prey on baby squids.
Regretably, I must point out that the baby
S. commersoni (mackerels) were the focus of interest at that time because they were at least 100 hundred times more difficult to find, collect and keep alive than the squid. I am also a fishmaniac. I never plan to keep the baby squid for too long before I have to release them because they grow too fast and eat a lot. They compete with the mackerels for live fed. The supply of live fed (baby fish) was never reliable. Sometimes I didn't have time to collect them (at jetties or at the marina). Sometimes they are too big. Sometimes I couldn't find them at all.
I think the longest time I kept squids in tanks was about four months before I had to release them (with a mortality rate of ~50%, nearly all within the first 2 months). Again, food supply was my major problem. Sometimes I ran out of live fed for a while. Those refused to take frozen food are starved and some eventually die before I released them.
I have written too much again! Have to dash.....
cheers