Researchers Revealed – In search of Salmon

Researchers Revealed – In search of Salmon

Southern resident killer whales are endangered,
and we’re trying to find out if it’s because they can’t get enough salmon to eat. Our study uses hydro-acoustic technologies
to look beneath the surface of the ocean, trying to figure out how many fish there are,
what kind of fish they are, and where they are. Southern resident killer whales are very picky
with what they feed on. There are five different species of salmon
in British Columbia, and they feed on mostly Chinook salmon – that’s
the most energy rich and the largest among all the species. So what we are trying to do is figure out
whether there is enough Chinook salmon for southern resident killer whales to feed. Part of our study is trying to compare the
declining southern resident population with the increasing northern residents. When we look at their body condition, the
southern residents are thinner on average, compared to the northern residents,
and that’s our strongest clue to suggest that the problem is food availability –
they’re simply not getting enough to eat. So our typical day starts at 4:00 in the morning. We wake up and quickly eat breakfast
and pack up the van with the gear and then drive
to the marina. Once we get to the marina,
we load all our gear into the small vessel and then leave the marina by 6am. Once we get to the site
we deploy the CTD, which measures conductivity depth and pressure. Providing us some environmental parameters
where the chinook salmon are staying. Then we use the multifrequency echo-sounder,
which has 4 frequencies, from 38 to 200 kilohertz. By having multiple frequencies, we can separate
fish from zooplankton, or perhaps the different species of the fish. So we’re using technology to find fish. In fact, we’re using the same technology
that killer whales have used forever. They too send out sound, and it bounces off
the prey back to them, and they get it in their melon, and from that
they can visualize whats there and they’re finely tuned to identify chinook
salmon in particular and go for them. Killer whales can like sweep [sweep], across
the frequencies, so I’m pretty sure they’re getting way more information than we have
so that’s why probably they can detect the chinook from other salmon. We are using a similar technology but not
quite yet as sophisticated as the killer whale is using And also we need a small vessel to deploy
it, and we need to validate with more sport fishing techniques. We you look at the surface, it almost looks
like a desert, it’s hard for us to imagine how rich these waters are. And yet if you look at the surface, you see
the sea birds that are feeding, you see the seals, the seal lions, the white
sided dolphins, the humpback whales. This is such a rich ocean, and it’s therefor
so puzzling when we look at the southern residents because everybody else is doing so well. The southern residents are an outlier: why
can’t they make it, when all the other species that are feasting on all this prey that are
in the ocean, are doing so well? Why can’t the southern resident killer whales
do it as well? And that’s been so puzzling to us, we hope
to get to the bottom of it . We’re looking at a problem as why are southern
killer whales declining, you think well maybe a killer whale specialist can answer that
question themselves. When in fact, we need more than just a killer
whale biologist. We need people who understand acoustics. Who understand how to look for fish in the
water. We need to work with nutritionists. We need to work with laboratories that can
analyze the fish. It takes a whole team to come together to
solve this problem.

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