NMFS Concentrates on Sea Lion Pup Mortality


Anne Hillman/KUCB

The 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)

With crisp 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.

The NMFS 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)

Fritz says 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 harder.

(Sea lions – 3 "…competition with fishing." 14 s)

Fritz and 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 s)

In addition 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.


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