An unusual need for a detector

[madsalts]

Hi,

I am designing a research project involving crayfish (miniature freshwater lobsters, essentially). I need to be able to set up a scenario where crayfish can be captured, tagged, releases, and found again in freshwater to depths not exceeding ten feet. I'm thinking that if a piece of metal were attached to the crayfish as a harmless tag, a metal detector would be able to locate it in the future. The deepest that I'd need the detector to work under the substrate (dirt at the bottom of the water) is six inches. The project will probably take place in New England, United States. I don't know if there is magnetic soil in this region. If there is not magnetic soil, I'm thinking that small (about a gram) stainless steel tags will be used. If this would be inappropriate, perhaps some other metal could be used (probably not something copper based, as it MIGHT harm the crayfish).

So,

Do you think that stainless steel would be appropriate? If not, what might be? What type of detector do you think would be appropriate, PI or VLF (I suppose this depends on the type of metal used for the tag). Would a "good" detector be needed? I see that Garrett makes an AT pro that can be had used for less than $500. They also make the Sea Hunter Mark II, which seems more expensive. Could I get away with a cheap $100 detector, or would this be too unreliable?

Thanks.

 

[Grilled Scallops]

I dunno, I'd maybe first consider an alternative method of retrieving them, like getting them to come out with a chopped up hotdog or something. I think you'll get a lot of signals from other junk metals lying around and it could be frustrating finding the crayfish.

 

[goodmore]

You will never find them with a detector.

 

[bootyhoundpa]

My experience is that stainless steel does not give a good signal..ideally if it were practical to attach a zinc penny to each of them your problem would be solved as you would get a target id and decent depth..i dont know what you could use that would be small enough as to not effect the animals mobility...

 

[dewcon4414]

Arent craw dads fresh water? My first thought was earth magnet or something like they use to pick up nails around new construction if you taged the cridders with tin tags. In fresh water you are asking a lot to find them just because trash dont desolve very fast out there. Apparently the method you are using to catch them in the first place isnt workiing or is to slow. Yes you can reduce the sensitivity thus the depth and on some machines LEARN a taget and disc out everything else....... but i still think its not going to be a faster method than say traps.

Dew

 

[madsalts]

Thanks a lot. I appreciate the replies. I need to start rethinking things. Out of curiosity though, even though it's a probably a moot point, are the PI or VLF detectors better for freshwater?

 

[Grilled Scallops]

A PI, which is a monotone rig, you wont be able to tell a bobby pin from the hood of a Ford Ranger, although the metal content is basically the same...

LOL

 

[dewcon4414]

Pulse machines are way to deep and have NO way of telling one metal from another. The only thing they would be good for was to use as a stick to chase the dads into a sane. Like was mentioned aluminum and a disc waterproof VLF is your best bet. Like was said thou they aint going to stand still. A large weighted Sane may be your best bet with a couple of guys and a chaser........worked for us as kids catching them for bate. Maybe a flourescent paint on the tail...... or radioactive. With a detector you are attempting to catch ONE at a time..... it would be like chasing a cock roach you tagged.

Dew

 

[BEEPITYBOP]

just about anything you attatch to one will kill it.they get in tight spaces and any protrushions will get it snagged.or stuck in the muck.
if im not mistaken they have developed quick set agents that you can glue stuff underwater thats frendly?(er)to the specimen.you might evenmix a copper powder in it to get hits on a detector that will falloff after a short while.