Subject: questions (saving whales, sharks & dolphins, dolphin-safe)

Robert Kenney (
Wed, 16 Dec 1998 16:51:11 -0500

At 20:28 12/12/98 -0600, you wrote:
>Hello again Dr.
>I have a couple more questions. I hope you can answer them and I also hope
that I'm not abusing this service. These questions were emailed to me and
I'm at a loss as to how to answer them.
>1. Hi i'm a High school student doing a research paper on whether whales 
>should stop being killed. I believe they shouldn't be klled and I'm have a
>hard time finding info on why they should be saved. It would be very
>helpful if you could possible help me and send some info.  I would really

One of the problems here is that this is not really a scientific question,
it's an ethical question.  The function of science is to understand and
explain how the natural world works - questions of right and wrong are
beyond its scope.

>2. I was wondering if it was possible for a dolphin to kill a shark with
>it's bottlenose? me and my boyfriend have been arguing about this and I was 
>telling him that it wasn't possible. is this true? please reply to my
>email. I would really like to know this! Thank You

This is most likely one of those common beliefs which is perpetuated by
continual repetition, but for which there is little evidence.  The U.S. Navy
has had a long interest in methods of protecting people in the water from
sharks.  They conducted a research program 25 or 20 years ago in which they
tried to train a bottlenose dolphin to attack a shark.  A good friend of
mine was part of the project - his version of the research is much longer
and funnier than mine.  The short version is that after many hours of
training, they got the dolphin to ram a dead baby shark and a very slow
nurse shark, but it went into a total panic when anything more fearsome was
in the same tank.

>3. Can you tell us about consumer boycotts on specific seafoods, brands,
>countries of origin (We get tuna from the Ivory coast, crab from thailand
>and don't seem to find information anywhere) ? Is there such a thing as
>dolphin-safe tuna on the market ?

The entire issue of "dolphin-safe" tuna is extremely controversial.  The
label means that the tuna in the can were caught by some method other than
circling a giant net (called a purse-seine) around a group of dolphins and
catching the tuna that swim below the dolphins.  Even if every dolphin is
released unharmed from the net, the tuna can't be called dolphin-safe (there
are concerns about the long-term effects of stress on dolphins which are
netted and released alive).  But dolphin-safe doesn't mean that no dolphins
died in catching the tuna.  There are other ways to catch tuna - driftnets
and long-lines are two examples.  Dolphins are accidentally caught and
killed in both types of fisheries.  There are even more complex issues.
Yellowfin tuna schools swim underneath dolphins, but they also can be found
swimming underneath floating logs or just swimming by themselves.  Fisherman
who set their purse seines around tuna schools or around floating logs catch
fewer dolphins, but they catch more sharks, turtles, and other fish that
they throw away.  They also catch more little tuna, which may not have
gotten old enough to reproduce yet, which can seriously impact the health of
the tuna stocks (and tuna fishery).  It turns out in most cases not to be a
good idea to try to manage entire fisheries or entire marine ecosystems
based on one narrow objective (like saving dolphins) without looking at the
big picture.

Dr. Bob

 | Robert D. Kenney, Ph.D.              |
 | University of Rhode Island                                        |
 | Graduate School of Oceanography                                   |
 | Bay Campus - Box 41                          TEL:  (401) 874-6664 |
 | Narragansett, RI 02882-1197, U.S.A.          FAX:  (401) 874-6497 |