Female Steller sea lions tend to breed near their birthplace

Familiarity with other females, geography may be crucial for reproduction

Date: June 7, 2017

Source: PLOS

Female Steller sea lions tend to breed at or near the rookery where they were born, according to a study published June 7, 2017 in the open-access journal PLOS ONE by Kelly Hastings from the Alaska Department of Fish and Game, USA, and colleagues.

Understanding the patterns of dispersal for an animal species is critical for measuring changes in the population, which helps with conservation efforts. Previous studies have shown that Steller sea lion (Eumetopias jubatus) males tend to disperse more frequently than the females, however, little is known about the movements of breeding females.

The authors of the present study monitored 369 Steller sea lion females that had been marked as pups in the rookeries where they were born in southeastern Alaska, gathering observation and recapture data between 2001 and 2015 to assess how frequently breeding females switched rookery.

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Autopsies from space: who killed the sea lions?

A decade ago, we set out to unravel deep ocean crime scenes we weren't even sure existed. The crime? Endangered Steller sea lions were rapidly disappearing in parts of Alaska. Their numbers dropped by 80% in three decades, yet only rarely did anyone see or sample dead sea lions. Live sea lions studied in the summer when they haul out to breed seemed healthy and had healthy pups.

We wanted to know when, where, and why sea lions die. To unravel the mystery, we needed information from those animals that we don't see, those that might not breed, those that might never come back ashore. So we developed a special monitoring tag that could send us data about the sea lions we can't directly observe.

This so-called Life History Transmitter or LHX tag is a small electronic monitor surgically implanted into the gut cavity of young sea lions under anesthesia. Don't worry, we checked that this does not alter the behavior or survival of the animals. After all, we don't want to influence the data we need!

Since 2005, we've placed tags in 45 young sea lions in the Prince William Sound area of the Gulf of Alaska. So far, 17 of these sea lions have died. That's actually about how many deaths we expected. Young sea lions have a tough life and most don't even reach the age of reproduction.

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Could sleeper sharks be preying on protected Steller sea lions?

Date:

October 15, 2014

Source:

Oregon State University

Summary:

Pacific sleeper sharks, a large, slow-moving species thought of as primarily a scavenger or predator of fish, may be preying on something a bit larger -- protected Steller sea lions in the Gulf of Alaska. A new study has found the first indirect evidence that this cold-blooded shark that can grow to a length of more than 20 feet -- longer than a great white shark -- and may be an opportunistic predator of juvenile Steller sea lions.

Continued ...

Sea lion test to probe declines

By Pallab GhoshScience correspondent, BBC News, Vancouver

Canadian researchers have trained sea lions to take part in an experiment designed to find out why the species is dying out.

The team strapped cameras and tracking equipment onto endangered Steller sea lions to see how they dived for food.

Early results from the project indicate that overfishing might not be the main factor in their decline as had previously been thought.

Male Steller sea lions measure 3m (10ft) and weigh more than 950kg.

This makes them the biggest of all sea lions.

These marine mammals once thrived on the shores of the North Pacific ocean. Now their numbers have dwindled to around 100,000. But no one knows why they are dying out.

Continued:  http://www.bbc.co.uk/news/science-environment-17051429