Food limitation linked to record California sea lion pup strandings

http://www.eurekalert.org/pub_releases/2016-03/nfwc-fll030216.php

Public Release: 2-Mar-2016
Food limitation linked to record California sea lion pup strandings
New research shows a decade-long decline of sardines and anchovy associated with poor condition of sea lion pups
NOAA Fisheries West Coast Region

Large numbers of California sea lion pups have flooded animal rescue centers in Southern California in the past few years. Now, as part of an ongoing investigation into the Unusual Mortality Event of California sea lions by a team of NOAA scientists and private partners, researchers may have an explanation.

Booming sea lion numbers combined with declines in the highest-calorie prey around the Channel Islands breeding rookeries have left nursing females struggling to support the nutritional needs of their pups, according to a new study published today in Royal Society Open Science.

The study by NOAA Fisheries scientists is the first to analyze changes in fish populations sea lions prey on for clues as to what is causing the record strandings. Scientists examined changes in the abundance of four of the main prey species: sardine, anchovy, rockfish and market squid over the 2004-2014 time period. They found that that high-calorie sardines and anchovies, both rich in fat that is vital to the growth of young sea lions, have declined since the mid-2000s in the areas around the Channel Islands where the females forage. That has forced the female sea lions to prey instead on market squid and rockfish, which contain far less fat and fewer calories.

•••••