dolphin echolocation and entanglements

From: Phil Clapham (
Date: Tue Oct 16 2001 - 08:06:54 EDT

Hi Marisa:

Thanks for the question. You have some good ideas! Scientists have
thought about two things to try to stop dolphins and porpoises from
swimming into fishing nets. One is what we call "pingers", which are
little sound transmitters that are fixed to the net to warn the animals
that it's there (in case they can't see it). The other thing is that
scientists have been experimenting with different kinds of material in
the netting itself to see if they can make it more "reflective" - that
is, more visible to a dolphin's echlocation. This usually involves
making the netting material hollow so that it becomes a better "target"
for the sonar. Pingers seem to work quite well in some cases; the
hollow net material idea is still rather experimental.


> karin anderson wrote:
> Dear phil,
> My name is Marisa and I am from Cold Spring Harbor high school. Our
> class is doing a project on dolphins echolocation.
> All these fishermen want to catch fish, but dolphins usually get stuck
> in the net, and it is against the law to catch a dolphin.
> My question to you is... what type of object can we put on the net, so
> that the dolphins will swim away from the net and don't get caught.
> please e-mail me information on echolocation and respond to my
> question.
> Thank
> you so much
> Student,
> Marisa

The Society for Marine Mammalogy will be holding its 14th Biennial
Conference from 28 November to 3 December 2001, in Vancouver, BC.  Visit
the conference Web site at for full details of
this important meeting.

Phillip J. Clapham, Ph.D. Large Whale Biology Program Protected Species Branch Northeast Fisheries Science Center 166 Water Street Woods Hole, MA 02543, U.S.A.

tel. 508 495-2316 fax 508 495-2066 email:

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