Subject: Re: speed boats impact on cetaceans

Rui Prieto (
Fri, 18 Sep 1998 17:15:59 -0000

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Your question was:

>I have a concern about high powered commercial dolphin watching vessels and
>their methods and require any information that would support my concerns.
>First, some vessels have twin two stroke outboards of over 200hp each, they
>travel at 30 knots and locate pods by a high speed grid search system.
>Often they work in a team, i.e. one boat locates and stays with the pod
>until another arrives, where by the first returns to pick up more
>Our Department of conservation is of the opinion that such vessels are fine
>and see no reason to restrict the numbers of these vessels issued with
>permits to harass dolphins.  Have you any comments.
>Are the pods disturbed by this.
>Are dolphins endangered around such vessels.
>Is there any info about collisions and dolphin injuries or death.
>Is it detrimental to dolphins to have people leap into their path in order
>to have an encounter.
>Any information that can help support refusal of this practice would be
>greatly appreciated.  This is the common method of dolphin watching in New
>Graeme Butler

We are working on the same kind of problems here in the Azores, and let me
say that there are no definitive answers.

Any human activity causes disturbance in the surrounding environment, and I
have no doubt that dome disturbance is involved when approaching cetaceans
with boats, either by the noise as by the physical presence of the boats
there. The question is: "is that disturbance endangering the animals?" There
is no simple formula to answer that question. There are several problems

# the presence of the boats can disrupt social bonds, lower the hunting
efficiency, interfere with rest, social behaviors (like play or sexual
activity), cause actual physical injuries (like collisions or deafness
caused for long term exposition to sound ), etc.?
# in the case one or more of these are proven, does it actually can have
long term effects, like lower reproductive rates, higher mortality,
avoidance of the area, that could threaten the local populations
# do the animals get habituated in a medium to long term basis?
# can we extrapolate experiences from other areas and species to our case?

Our answer here has been trying to implement regulations with precautionary
principles, but giving the space to the companies to develop their activity,
because there are economic and social aspects that cannot be forgotten. On
the other hand, we are implementing research programs to try to uncover some
of the answers to those questions.

Try to ask for the proceedings of the Workshops on whale watching held in
Montecastello de Vibio (Italy) and in Martinica, to IFAW (V. Papastavrou; 17
Hartington Prk; Bristol BS6 7ES; UK) They are very educational.
Good luck and good work

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