National Marine Fisheries Service is continuing their research on Stellar Sea
Lions this summer. This time they are using high-resolution aerial photography
to count the number of pups at rookeries and haul outs from Sitka
to the western Aleutians. Biologist Lowell
Fritz says they need to take the photos now, before the pups start swimming
with their mothers. This year's survey is aided by new technology.
-- (Sea lions - 1 "...using a tripod." 34 s)
images they can more distinctly see the animals. Fritz says in older surveys it
was sometimes hard to distinguish between pups and rocks. The survey started on
June 24th and it took only five days to go from Sitka to Unalaska. Then the crew was stuck in
Adak for over a week because of bad weather.
They were also unable to survey the far western Aleutians
where sea lion populations are having the worst problems. Unlike in other parts
of western Alaska,
their numbers never rebounded in the early 2000s.
sea lion research focuses on juveniles and adults some years, but those age
groups seem to be healthy with high survival levels.
-- (Sea lions - 2 "...is going down." 33 s)
they need to study adult females to find out why they aren't reproducing and
next year's research will focus on that. Currently scientists have three
different theories on why birth rates are low. The first two - disease out
breaks and environmental contaminants and pollutants - don't have much evidence
supporting them, but Fritz says they need to look into the contaminants theory
-- (Sea lions - 3 "...competition with
fishing." 14 s)
others are looking into this theory. Researchers are also looking at sea lion
scat to learn what different populations of sea lions are eating and how that's
changing. They want to know if diet diversity effects survival or health. Fritz
says they need to understand the physiology of females as well because the overall
population survival depends on their reproductive success.
-- (Sea lions - 4 "...had in the past." 16
to doing aerial surveys of sea lions, Fritz's team is also taking photos of the
fur seal rookeries in the Pribilof Islands. Aerial surveys of the fur seals
started 80 years ago and have continued on 20 year cycles.