On Mon, 13 Aug 2012 15:33:47 -0700, Paul Kanner <[log in to unmask]>
wrote:

>Does anyone have a design for a trap that would work for shells? �Nothing
too big. �I am aware of a lot of specimens that show up as by catch in
deep water shrimp traps. �Might be an interesting experiment to try at one
of my dive spots.
Thanks,
Paul

Dear Paul,

I think there is a fundamental dihotomy in this mollusk-baiting initiative.

In shallow water, carrion-feeding snails are often abundant and eminently
responsive (in both alacrity and recruitmnent radius) to bait with
sufficient olfactory appeal. In my experience sufficient to overwhelming
numbers of Melongena, Nassarius (s.l.), Oliva, Olivella, Prunum, etc. can
be gathered in minutes to a very few hours. In this context, the need for
containment of bait is not so compelling. I recall using plastic
windowscreen material to bundle up fish and pink conch entrails.
Maintaining the baits in easily-retrievable array varies with the depth
(just subtidal to 2 m in my experience).

In deeper water these taxa are generally not so dominant, and a more
desultory pattern of recruitment can be expected. In such a time frame,
fish and other large, fast-moving predators can be expected to interfere
with the accumulation of shells as the interlopers are inclined to carry
off the attractant(s) rather promptly. Here enclosure and limitation of
access to the bait is advisable. Depending on the target quarry, this
situation is the germ behind the design of crab, lobster, and eel traps.
Jack Lightbourn, our COA colleague from Bermuda, has a long and fruitful
experience using "lobster pots" to collect mollusk shells from depths in
the 100-300 m range. Since Jack is not a Conch-L'er, I'll try to recount
some of his observations below.

Firstly, he and Arthur Guest, his first mate and collecting companion for
decades, soon recognized that securing the traps was paramount. Loss of
hardware and line was frequent and painful in the first weeks of the
enterprise. Bulky ballast (anchorage) and marking (LORAN/buoy) proved
essential for efficient retrieval. Secondly, unlike the nearshore scenario
above, virtually all the shells they collected were inhabited by hermit
crabs. It was the crabs who drove the process. Any number of baits were
tried, and most succeeded. One of the most favorable attributes proved to
be the physical integrity of the animal flesh over one to four weeks, In
that regard, the best of the best was a dead neighborhood cat, which
lasted over a month - about eight cycles of immersion and retrieval. Dead
fish, especially their heads, were a more customary fare. Ideal immersion
time, determined by labor and shells collected, seemed to be one to two
cycles per week.

If you're operating in 30 m I suspect you'll have a mix of the snail
carnivore/hermit crab participation, but your greater numbers and
diversity will likely be delivered by the latter animals.

My advice is to securely fix your lobster pot (or generic equivalent) to a
familiar and easily-telocated bottom feature and try fish-heads,
perforated cat-food cans, etc. together for your first run. If your
pleased with the results (1) delete one or more of the bait types as you
continue, and (2) move the trap a few dozen meters.

Keep Conch-L'dom in the loop, my man,
Harry

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