solving the mystery of ocean conditions and disappearing salmon

The other day I posted a story about how the U.S. Commerce Secretary announced a “fishery disaster” for the lower portion of the Yukon River in Alaska. This past season there was no commercial fishery, last season (2008) there was a fishery at 90% less than the five-year average – only 4600 Chinook were caught whereas the year previous 33,600 Chinook were caught.

From approximately 1960 – 1997 the average commercially caught Chinook on the Alaskan portion of the Yukon River was 100,000 Chinook per year. The subsistence catch averaged approximately 35,000 – 40,000 Chinook. As mentioned in an earlier post, and in an article I wrote for the Yukon News in 2002, salmon conservation concerns became a major concern around 1997 and some big changes were made — especially when it became clear that approximately 80% of the salmon on the Yukon River spawned in Canada — yet less than a quarter of that (less than 20%) was generally caught in Canada.

It has been a much different picture over the last few years. Similar to Canada, subsistence harvests are given a higher priority than commercial harvests. From 2004 – 2008 the average subsistence harvest has been 51,000 the commercial harvest has been 34,000.

In 2007 the commercial harvest was near the average of 34,000. In 2008 it was just over 4,600 and this past year it was 131. Subsistence numbers from this past season are not in yet.

In less than fifteen years the commercial harvest of Yukon River Chinook has gone from well over 100,000 Chinook caught in Alaska to less than 200.

Curiously, as mentioned in a post the other day. The Marine Stewardship Council has “ecocertified” and “ecolabelled” all Alaskan salmon fisheries – including the Yukon River.

What are some of factors suggested for the Chinook collapse?

Everyone’s most recent favorite is certainly right there – changing ocean conditions. However, I find this one a little difficult to believe in that there are several other fisheries in the neighborhood that are thrumming along like a CN train – for example the entire US #1 fishery.

Seattle Times July 2008

Just out front of the Yukon River in the Bering Sea is the pollock fishery. The Bering Sea-Aleutian Islands pollock fishery is also “ecocertified” by the Marine Stewardship Council as as a “sustainable” “well-managed” fishery. The Bering Sea-Aleutian Islands pollock fishery is also the biggest fishery in the entire United States – generating over $1 billion in processed fish.

How big? The annual quota is 900,000 metric tonnes. If my math is right that’s 900,000,000 kg. These are all caught by trawlers.

If you’re not familiar with trawlers – these areĀ  boats approximately 100 to 150 feet long dragging huge nets. This particular trawl fishery is approximately mid-water, as opposed to bottom trawling where a huge bar drags along the bottom scooping everything into the net and ruining bottom habitat.

Unfortunately, when you drag a huge net through the Bering Sea a heck of a lot of other species hanging out with the pollock – for example Yukon River Chinook salmon – get scooped up as well. When other species are pulled up in these massive nets they are thrown overboard as they are considered “prohibited species”. This is bycatch. The onshore fish processors or mothership processors want pollock only – not salmon or halibut or crab or anything else caught in the nets.

Mothership factory trawler Arctic Storm

However, not to worry – On their website the Marine Stewardship Council, regarding the pollock fishery “environmental impact”, states:

Proportions of bycatch are very low (below 1%). All significant bycatch species (nonpollock groundfish, primarily) are subject to annual scientific assessment. There is extensive regulation to limit bycatch in U.S. North Pacific fisheries. The threatened and endangered Steller sea lion is found in the area of the fishery. Fishery regulations are in place to minimize fishing impacts on sea lions and other protected species.

Salmon bycatch? Chinook tend to swim with pollock and are often caught.

This graph is from the Anchorage Daily News – click it and it will take you to a March 2009 article. This graph shows that the National Marine Fisheries Service reported the pollock trawl fishery caught a high of 121,638 Chinook in 2007, a little under 90,000 in 2006, approximately 65,000 in 2006.

In 2008, the trawl fleet apparently caught significantly less at approximately 27,000. However, that’s five times what the actual Yukon River commercial fishery caught in the same year. The difference being that the 27,000 that the pollock fishery caught were thrown overboard dead…

The five year average for Chinook caught in the trawl fleet is just under 60,000. Other salmon species – a bit more troubling – the record in 2005 was 706,000 other salmon species. This is almost the same number as the entire Fraser River sockeye return this year.

Could you imagine the uproar if it was discovered that 800,000 salmon were caught in a fishery just off the west coast of Vancouver Island – and tossed overboard?

Keep in mind as well that this graph is showing reported bycatch. There are fishery observers on board the trawl fleet reporting bycatch… on board less than 30% of the fleet. Thus, often times the Fisheries Service extrapolates the numbers out from the actual observed numbers. Plus, a massive fishery facing potential closures or severe limitations due to salmon bycatch – would you be accurately reporting salmon bycatch?

“Disappearing” salmon due to ocean conditions?

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