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Animal tracking chips.

  1. Mar 19, 2007 #1
    Well I've been thinking for a long time about how to track fish in canals here in England. Reason being they move around a tremendous amount and are generally very hard to find, although they are often present in large numbers when discovered. This makes the fishing very exciting for about 1% of the time.

    No way am I smart enough to invent or build anything which could do this, but I was wondering where I could obtain a suitable device from. It doesn't have to be mega hi-tech, nor does it have to transmit over big distances as I know the length of canal I'm looking at between locks and I'm prepared to walk the entire length of the stretch to find the fish. This means it only needs to transmit say 20 feet or so, maybe a bit more (say 50ft).

    It also needs to be very small so as not to hinder the fish in any way and ideally not require it's own power source. I really need one of those things which only transmits back when hit with a signal itself but if I had to put a small battery in so be it.

    I know these things are out there and are publically available so anyone know where I could start looking to get one?

    I know it's a weird question, but variety is of course the spice of life.
     
  2. jcsd
  3. Mar 19, 2007 #2

    Danger

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    If you're referring to active sonar, as opposed to some tagging system, just about any fishing supply place should be able to get you a unit. At least, that's who sells them here. I don't know if they're legal everywhere, though.
     
  4. Mar 19, 2007 #3
    I was thinking of a tagging system which could track an individual fish to give very detailed accounts of their whereabouts.

    The sonar stuff is only really just coming out over here compared to how well used it is in the States, but you can get hold of it.

    Thanks for the reply.

    Anyone got any more ideas where I could get an active tag from?
     
  5. Mar 19, 2007 #4

    berkeman

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    The reason Danger is suggesting sonar, is that RF/radio waves are attenuated significantly by water (although seawater is worse than the fresh water in your canals). I don't think it would be realistic to use any kind of RFID tagging of the fish, but I could be wrong if others have different information.

    I think the closest you could come to having a sonar-based ID tag system, would be to make some kind of passive sonar cube corner reflector something-something, so that when you swept your sonar emitter/receiver thing around under water in the canal, you'd get a strong point reflection from the tagged fish.

    But to be small enough to not hinder the fish much, that would mean that the wavelength of the ultrasonic sonar would be around 1mm-3mm or so, it would seem. I don't know how that frequency of ultrasound propagates in water, but you could experiment or research it to find out more.

    Maybe one other thought would be if you could always confine your fish surveys to night time, you could use flourescent tags, and sweep the canals with a powerful spotlight a few times, then go to low light vision goggles. Bond, James Bond!
     
  6. Mar 20, 2007 #5

    Ivan Seeking

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    It looks like they already have a workable radio system.

    http://www.dpc.vic.gov.au/domino/We...16729e2077c3f8f1ca256fa30005d356!OpenDocument
     
  7. Mar 20, 2007 #6
    Ah I see. Thanks again for some great replies chaps. I think the technology those scientist type guys are using would be way too expensive for me although they do sound amazingly clever. It seems old pal Danger was ahead of me a bit :wink:

    As for the sonar stuff it certainly sounds feasible to me. Where could I get a suitable transmitter from, and would I need a device which was tuned to recieve a specific frequency?

    The fish I'm thinking of attaching it to are 7kg+ in weight and are amazingly strong so it doesn't have to be that small.

    Sorry for so many questions but this is a very new area to me.
     
  8. Mar 20, 2007 #7

    Danger

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    You guys are giving me credit that I don't deserve. The sonar device that I was thinking of, before we established that the goal was individual tracking, is the 'fish finder' unit made for fishermen to locate schools.
    To address your real needs, I don't know if what you want exists commercially. IIRC, radio propogation in water requires quite long wavelengths. I seem to remember that being mentioned when they were first able to outfit submarines with radio communications. They always used to have to surface to make contact.
    Sonar should work, but you might have to make it yourself. Along Berkeman's line of thought, you could also use ultra-bright LED's. Blue-green has the best underwater visibility. Using either that or ultrasonic transducers, I would consider using a single fixed frequency for every unit, but with a code modulation for individual identification (sort of the way a TV remote works). The parts might turn out to be fairly cheap if you buy them in bulk.
    Attachment might offer some challenges, but my first thought would be to staple the unit to the dorsal fin.
    In any event, you might have to do an environmental impact study and/or get governmental permission to carry out your experiment. I doubt that anything in your waterway system communicates by light, although lots of deep-sea creatures do, but the sound might have a negative effect upon some species.
     
    Last edited: Mar 20, 2007
  9. Mar 20, 2007 #8
    Sounds promising. Roughly speaking how would you power one, and do they come with a factory defined frequency?

    The canals in question are small in width and are used only for leisure activities these days although in the past they were very busy and often extremely violent and dangerous industrial supply veins.

    There is no comms equipment nearby and I intend only to attach the device to one fish and then track him and remove it after 12 months.

    Some say I'm too soft and over worry about fish given how tough they are but I do genuinely care about them and would not want one towing anything round (even something tiny like this) for anything longer than a year.

    Again range only needs to be a maximum of 50ft or so, thus very expensive signal producers operating at really high/low frequencies/wavelengths are not needed.

    Would I have to design my own little circuit board to power this thing?

    Thanks again:wink:
     
  10. Mar 20, 2007 #9

    turbo

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    It sounds as if you are describing fish that school, like our white perch. If they will surface-feed, you don't need electronics. Just broadcast some floating fish food over the water, and when you get rising fish, start angling for one and when you catch it, attach a small light bobber to the line and clip the line so the fish has to tow the bobber around. That way, wherever the school goes, you'll know where it is. When you're done fishing, pull in "Benedict Arnold" remove the hook and let him go. WARNING! This may not be legal in your location, so don't do this without checking game laws.
     
  11. Mar 20, 2007 #10
    It is indeed a great idea but I'm planning to leave the fish unattended for most of the day. This means there is a risk of them being tethered to snags and therefore dying given how congested with natural plant life the canals here often are.

    The method is also illegal here in England and could land me in trouble. I do like the straight-forwardness of the approach though :wink:

    I do still plan to go down the electronics route however, but I need a little guidance on the points mentioned in my post above.
     
  12. Mar 20, 2007 #11
    Found a site which sells emitters which go down to 3mm in 'element size'. Does element size mean that the transducer itself is 3mm or is it encased in something larger? I'm going to e-mail the company and ask.

    http://www.olympusndt.com/en/panametrics-ndt-ultrasonic/contact-transducers/

    Also it operates at 15-20MHz so highly unlikely I'll pick-up any naturally occuring frequencies at that level so nuisance readings are I suppose/hope fairly ruled out.

    I'm going to mail the company later today. Anyone got a ball park figure as to how much one of these will cost? And would I need to spend alot to get something that could receive the signal?

    Sorry again for so many questions but this is really getting quite interesting.
     
  13. Mar 23, 2007 #12
    Found some on RS.com which have a range of 4m which is maybe a little low but would perhaps be okay seeing as it's through water most of the way (maybe would be a bit more than 4m).

    Price wise it's very economical. Operates at up to 20Volts I presume DC? Small too at only 10mm across, easily small enough to tag to a 15lb fish. Has a transimt frequency of 40kHz.

    Only question is I'm not sure how it's powered. I'll also have to check that
    40kHz won't disturb aquatic life too much also but I doubt that will be an issue. What I could do with though is a very simple electronic circuit which would cause the transducer to pulse momentarily so the sound was not emitting all the time and draining the obviously small battery I'll have to use.

    Could I simply connect a small capacitor in parallel with the transducer? Would this work, like by building up the cap and then discharging every few seconds?

    I'm going to give the supplier a ring now but I really could use a little more help, sorry to be a pain :wink:

    Just checked it needs 20Volts with a rectangular wave input. I'm currently learning C++ and I'm deep into some reading about the Torque game engine so just don't have the time to research this one. Does anyone know of a simple way I could get a periodic roughly rectangular wave into one of these things electronically? It don't have to be perfect, it just has to be about right.

    Would something like a capacitor and a Zener diode work?
     
    Last edited: Mar 23, 2007
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