The Case of the Disappearing Dolphin

  • A false killer whale, which is actually a type of tropical dolphin, with calf (Photo by Deron Verbeck, courtesy of iamaquatic.com)

Commercial fishing in the oceans of the US has done a lot to reduce
accidentally catching marine mammals such as dolphins. But there are
still problems. Ari Daniel Shapiro reports on concerns about one kind
of tropical dolphin called the false killer whale:

Transcript

Commercial fishing in the oceans of the US has done a lot to reduce
accidentally catching marine mammals such as dolphins. But there are
still problems. Ari Daniel Shapiro reports on concerns about one kind
of tropical dolphin called the false killer whale:

Jim Cook has been a fisherman in Hawaii for 18 years.

“You know, it used to be real simple: catch a fish, sell it, and go
back out and try and catch another one.”

Now he owns a company that operates six fishing vessels. Cook’s
ships catch deep swimming sashimi-grade tuna that ends up in sushi
restaurants across the US. They use a technique called longline fishing.

“We have around 45 miles of mainline to which we attach floaters
and 2200 to 2500 baited hooks.”

“The regulations imposed on the Hawaii longline fishery are
probably the most restrictive regulations on any longline fishery in the
world.”

That’s Bill Robinson. He’s an administrator with the National
Marine Fisheries Service. And these regulations he’s talking about are
meant to reduce bycatch. That means catching marine animals other than
the tuna. As a result of these policies, sea turtle bycatch has dropped
by more than 90-percent and seabird bycatch by 95-percent.

Things are looking up, but now there’s another problem. The numbers of
another kind of animal – the false killer whale – are declining. No one
knows why they’re disappearing. It might be related to longline
fishing, but it’s just not clear.

Robin Baird’s a biologist with Cascadia Research.

“There’s a whole variety of lines of evidence that imply the false
killer whale population around the main Hawaiian islands has declined
dramatically over the last 20 years. And I think it’s clearly the most
serious conservation or management issue for whales and dolphins in
Hawaiian waters today.”

Baird thinks the decline is partly related to fewer numbers of tuna
and other species false killer whales eat. He also suspects that the
false killer whales might be moving farther offshore, where they could
get hooked when trying to eat the tuna caught by the longline fishery.

So the question is: should the National Marine Fisheries Service come up
with even more regulations for the longline fishery in case more false
killer whales move offshore looking for tuna.

Bill Robinson with the Fisheries Service isn’t so sure that they
actually go that far offshore.

“That’s speculation, and it may or may not be true. What we
don’t really know is what the range of each population is.”

So, really, at this point, it’s anyone’s guess why the false killer whale numbers are declining.

The biologist, Robin Baird, is concerned that nothing’s being done.

“Unless something is done to change the factors that are
influencing the population, it probably will continue to decline.”

The environmental group Earthjustice and a coalition of
conservation groups have sued the National Marine Fisheries Service over
failing to develop a plan to protect the false killer whales.

The agency has not responded officially to the lawsuit yet. But Bill
Robinson says an action plan is in the works.

“Hopefully by the fall, we’ll be able to not only appoint the
team, but have the team begin work on a take recovery plan that will
make recommendations to the agency to reduce the incidental take of
false killer whales in the fishery.”

Such a plan might end up costing the commercial fishers money. But
Jim Cook says he’s willing to pay. That’s because false killer whales
pick fish off his lines. They eat the caught tuna before the fishers
can haul them in. That can mean a lot of lost income.

“We would very much welcome any methodology almost
irrespective of cost because we’re suffering quite a bit economically as
it is.”

But the National Marine Fisheries Service first has to find that
methodology.

For The Environment Report, I’m Ari Daniel Shapiro.

Related Links

Bugs Getting Confused by Asphalt

  • Dragonflies are one of the insects tricked by false light (Photo courtesy of the EPA)

Bugs are getting confused by the
reflections from manmade structures.
Rebecca Williams reports on a new study:

Transcript

Bugs are getting confused by the
reflections from manmade structures.
Rebecca Williams reports on a new study:

If you’ve ever noticed swarms of insects hovering over your car, there’s a
good chance they’re mistaking it for water.


Smooth, dark surfaces like cars and asphalt reflect polarized light. That’s
what bugs see – and that tricks insects such as dragonflies.


Bruce Robertson is an author of the study in the journal Frontiers in Ecology
and the Environment.


“Asphalt actually reflects polarized light more strongly than water and so it
looks more like water than water! And so these organisms are thinking
they’re finding a place to breed and hunt and lay eggs and mate when in fact
they’re finding a place that’s very dangerous.”


Robertson says these bugs swarm over buildings and roads in huge numbers,
and can die of exhaustion.


But he says it might be possible to stop tricking the bugs. Things like
adding white curtains to dark windows or adding a little bit of gravel to
asphalt to make the surfaces reflect less polarized light.


For The Environment Report, I’m Rebecca Williams.

Related Links