[ music and rushing water ]
[ energetic music ]
Narrator: Keeping track of Steller sea lion populations is no easy task,
but it's critical to ensuring their survival.
This animal is one of the largest pinnipeds in the world
with adult males weighing over 2,000 pounds.
In the United States, the Steller sea lion is endangered
under the Endangered Species Act in the western part of its range,
and numbers are continuing to decline in the western half of the Aleutian Islands.
Even though this area is remote,
it's also home to one of the most productive fisheries in this country.
For both to flourish,
scientists search for answers as to why this population hasn't recovered.
Both the Western and Eastern populations were once considered threatened,
but the Eastern population has continually increased,
and as of 2013, has fully recovered.
During this same time period,
the Western population declined and then stabilized as a whole,
but in the Western Aleutians the decline continues,
and scientists are trying to figure out why.
Tom Gelatt: One of the challenges we have with Steller sea lions is that,
unlike most large mammals,
we still are trying to understand basic life history information.
So by marking these animals as pups and then following them through their lives
we're able to collect that type of information.
Narrator: From the U.S. Fish and Wildlife Research Vessel Tiglax,
one team of researchers deploys,
often several times a day to different rookeries and haulouts.
These are the re-sighters searching for previously marked animals,
and depending on the conditions and site,
survey from land or from a small boat.
Different prefixes correspond to where these animals were born,
and year after year, valuable data starts to illustrate trends,
like what percentage of pups survive to adulthood,
and how old a female is when it has its first pup.
But covering dozens of sites over hundreds of miles in two weeks
leaves lots of gaps in the data.
Tom Gelatt: A few years ago we started putting remote cameras
on some of our Steller sea lions haulouts and rookeries.
The cameras are put into water-tight housings,
we sometimes have to build temporary structures to hold the cameras,
and they're set to take a photograph every 10 minutes or 15 minutes,
whatever interval we need during daylight hours, in perpetuity.
So those images hopefully will provide us a couple things.
One is that they can give us counts,
daily counts of some of these areas.
We're also using the cameras to look for marked sea lions.
And some of these animals roam quite a distance
and so we're able to identify those animals
including some from the Commander Islands in Russia.
Narrator: To gain another perspective,
one of NOAA's Twin Otter aircrafts is dedicated to conducting aerial surveys
of the rookeries and haulouts every summer.
But most years this dataset is incomplete,
because summertime in the Aleutians usually means fog.
Tom Gelatt: So one of the new pieces of equipment that we have this year
is an unmanned aircraft, a hexacopter,
which allows us to be ready to deploy when the fog or the ceiling lifts,
something that a Twin Otter would never be able to do.
It also allows us to look at sites that
even with researchers in the field with binoculars we can't see.
Some of these sites are very flat, low islands
and there's just no elevation for a person to get an accurate count.
And it also allows us to do a lot of the work without disturbing the animals.
Narrator: Some of the sites surveyed with the hexacopter in 2014
had not been photographed from the air since 2008.
Together with the remote cameras and continued re-sight efforts,
NOAA Fisheries is working to build long-term populations trends,
which will aid in developing recovery strategies for this endangered population.
Tom and his crew are also partnering with killer whale biologists at NOAA
to investigate predation and competition for food.
And new tools are continually being designed and implemented,
like satellite tracking,
which is beginning to paint a picture of foraging habits and ranges.
Tom Gelatt: And the reason that Steller sea lion research
or any kind of marine mammal research out here is important
is that there's a lot going on out here.
Even though it's a rather remote area,
Dutch Harbor has the largest number of landings in the United States for fisheries.
And Steller sea lions,
some of their primary prey is also the primary target of large fisheries in Alaska,
things like pollock and even Atka mackerel in the western Aleutian Islands.
So understanding what Steller sea lions do
can help our managers to make wise decisions in regard to fisheries management
as well as knowing where Steller sea lions go, what their habits are,
is baseline information that we can use to identify differences over time
that might indicate some sort of threat that's affecting the population.