
Courtesy ODFW
The controversial program to trap and remove sea lions at Bonneville Dam just might be doing what it’s supposed to do, getting rid of troublesome sea lions and reducing the numbers of salmon they eat.
After two years, it’s still too early to draw firm conclusions. But after looking at the latest report by the Army Corps of Engineers, here’s what they found.
There are fewer sea lions at the dam.
In 2009, wildlife officials counted 80 sea lions at Bonneville. This is one of the lowest numbers on record and down about 20% from last year. California sea lion numbers are down dramatically, but Steller sea lions numbers are up some.
They’re still eating lots of salmon.
A record amount in fact. The sea lions ate nearly 4,500 salmon from January through May. That may be due to one of the largest salmon runs in decades. Percentage wise, the sea lions ate 2.4% of the salmon trying to get over the dam, that’s slightly down from last year.
Hazing them doesn’t appear to work.
There are two main methods of hazing, scaring them with noisemakers and spraying them with hoses. The report says the noisemakers are pretty much worthless (although it said so in much nicer language) and the hose hazing only works temporarily. When the hazing stops, the sea lions return.
They’re targeting the worst of the bunch.
Wildlife officials have what you might call a “hit list” of sea lions, ones that spend the longest amount of time at the dam and eat the most salmon. This targeted approach appears to be working. The 25 sea lions that were captured and removed in 2008 and 2009 were indeed among the group that stayed the longest and ate the most. The report estimates removing them spared about 1,000 salmon.
Things should improve next year.
The Corps recommends continuing the program. It predicts another sharp drop in California sea lions in 2010 and as a result, fewer salmon will be eaten.
The trapping program is controversial with some parts of the environmental community because, quite often, the sea lions are killed. In 2009 for example, 20 sea lions were captured. While six were tagged and released, and four went to zoos or aquariums, ten of the sea lions were euthanized by wildlife officials. Medical tests on the animals determined they had health conditions that didn’t allow them to be placed in captive programs.
While sea lions haven’t exactly been strangers to Bonneville Dam, it wasn’t until 2001 and 2002 that they began to show up in large numbers. The dam acts as a bottleneck for endangered salmon, creating a large pool of fish for hungry sea lions.