What 160 Years of Walrus Haul Out Data Can Tell Us

By: Eva Gruber

Sea ice in the Arctic is melting faster than any climate models predicted.

The first ice-free summer may happen as early as 2025. The Pacific Walrus Haulout Database, based on 160 years (1852-2016) of data collected by American and Russian scientists, is now available publicly.

The United States Geological Survey hopes that by releasing the database, it will help fishermen, wildlife managers, mariners, industry, and others with increasing operations in the Arctic minimize their impacts on walrus populations.

Image Source: http://alaska.usgs.gov/science/biology/walrus/images/walrus_haulout_fade.png

Walruses are one of the largest pinnipeds on the planet and reside in a discontinuous range (three subspecies) in shallow waters around the Arctic ocean and subarctic islands of the Northern Hemisphere.

Due to extensive hunting during the 19^th and 29^th centuries, walrus populations declined severely. Once they were protected by the Marine Mammal Protection Act in 1972, their populations have been able to rebound somewhat.

Image Source: https://www.facebook.com/USGeologicalSurvey/photos/a.1113724448673537.1073741879.102635589782433/1113724695340179/?type=3&theater

The database also serves as a record of places that walrus traditionally haul out versus where they begin to haul out following climate change. Normally, walruses prefer to haul out on sea ice in between foraging trips to the sea floor.

However, in the past several years, summer sea ice has been retreating further and further north in the Chuckchi Sea and Russian waters, as temperatures are trending upwards. This is simply a condition that did not exist even a decade ago.

According to National Wildlife Service and the USGS Walrus scientists, walrus prefer to haul out and rest on remnant sea ice over shallow feeding areas about 100 miles off Alaska in the Chukchi Sea, but that ice has disappeared in 8 of the past 9 years, forcing the animals and their young to swim toward the beaches of NW Alaska to haul out.
Image Source: http://www.worldviewofglobalwarming.org/images15/AKPointLayKasagelukBarrierPacificWalrusHaulOutDetail%209326BraaschWeb.jpg

Since there is less sea ice around them when they forage, they have to travel farther to shore to be able to rest on land – this can have serious implications in how much energy they are expending, and in turn how much fat they are able to store to protect themselves from the extreme cold.

These behaviors are mirrored in the walrus haulout reports, as more mass haulouts are observed when walrus become concentrated on the few shores closest to rich feeding grounds. With more walrus hauling out in one location, the dangers of a stampede rise, and as a consequence more young walrus are trampled to death at these mass haulout locations.

With warmer temperatures and less sea ice, there is a longer open water season in the North Pacific – which can be beneficial to businesses exploiting open water, such as the shipping, oil, and tourism industries. However, this is not good news for walrus, polar bear, and other animals endemic to this threatened region.

Data from studies such as the walrus haulout database will provide resource management with significant information on ecologically important areas, such as human activities in the Arctic increase.

Featured Image Credit: http://alaska.usgs.gov/science/biology/biometrics/images/walrus_on_ice.jpg