Ocean Conditions & Sea Lions

I’m back from the most recent ODFW Restoration & Enhancement Board meeting.  A discussion of interest to Central Oregon anglers who pursue steelhead and salmon was around current ocean conditions and predation on these anadromous fish by pinnipeds, primarily sea lions.

For a few years now, “ocean conditions” have been blamed for the poor returns of salmon and steelhead in many Pacific Northwest river systems.  I have asked many biologists to explain this to me in more detail as not all rivers appear to be equally impacted nor are all species in the same drainage.  The past return season on the Deschutes is a good example of this.  The most recent steelhead and chinook returns on the Deschutes were very low while sockeye returns were the highest in some time.

Simply put, the biologists don’t know what is going on.  The ocean is “just off”.  Conditions are poor, but not uniformly so.  Along with often reported higher than normal water temperatures, there have been toxic algae blooms, acidification, and oxygen depletion.  These conditions are not uniform and change in various regions at different times. There is little to no understanding of what is likely to occur going forward and it was described as a “black box”.

Outmigrating anadromous fish enter the ocean at different times, encountering different conditions, and the fish move in different directions.  Some species and runs disperse over the entire northern Pacific, while some school up and move as a group to different areas up and down the coast or far out to sea.

A better understood issue is predation on outmigrating smolts and returning adults.  Since 1972 marine mammals have been protected by the Marine Mammal Protection Act which has allowed species like sea lions to recover from their former threatened status.  Today sea lion populations are very healthy and appear to be at their ecological carrying capacity.  As a result, they are expanding past their traditional habitat and into rivers in search of prey.

In particular, these highly intelligent animals have learned to inhabit “choke points” at dams, fish ladders, and natural obstructions like waterfalls where anadromous fish gather.  Recently, sea lions have eaten enough returning Willamette drainage steelhead to drive this entire run to the edge of extinction.  The damage is not limited to Willamette fish as sea lions have learned to inhabit the Columbia and other river systems as well.  Pinniped predation on anadromous fish is also thought to be a factor in Orca recovery efforts.

A commercial salmon fisherman on the R&E board related that when he was learning his trade on his father’s boat they would routinely shoot near sea lions to scare them out of the Columbia.  He stated that the sea lions are very smart and they did not need to hit the sea lion, only harass them, although I assume some were killed as well.  Harassing as well as killing has been banned now for decades.

This is an tough issue.  Clearly, sea lions have a right to live, but the threat of extinction has now been shifted from marine mammals to anadromous fish.  This is a federal issue and I hope that something can be done soon to avoid catastrophe.