Sunday, 1 February 2015

Q and As – January 2

Salmon East and West: In putting together a piece for the Pacific Salmon Foundation, it crossed my mind that one indication of the importance of the BC salmon fishery to Canada would be to compare the number of wild Pacific salmon with the wild Atlantic salmon.

I was stunned to find out that in 2012 the entire Atlantic salmon numbers for all of North America was only 170,000 adults. That is the entire number from six provinces (half the country) and the State of Maine. The entire number has not exceeded the minimum conservation limit of 213,000 adults (termed 2SW for spending winters in saltwater, i.e. no grilse) for 23 years. And even in the early ‘70s, before the precipitous decline, the entire run was typically below 900,000.

Here is the report with graph. Do look:

In BC, I have not found a good source document from DFO for wild Pacific salmon. I settled in one snowy winter day – okay it wasn’t snowing, but those deer eating my tulips had gotten me steamed – and went through all the rivers and areas in BC and came up with, in an average year, 86 million wild Pacific Salmon in BC, only one province in Canada. In a good year, I would say 100 million is in the ball park.

So the east coast ‘fishery’ for Atlantic Salmon is, at .18%, far less than one percent of the BC fishery. By comparison, the Campbell River pink run, since the Quinsam spawning barrier was removed, is about one million fish. The sockeye run in Port Alberni has exceeded one million fish for several years. In fact, many chum runs on the island far exceed all the Atlantic salmon on the east coast.

I have fished in a year that the Nitinat was 1.8 million (1.2 million taken in aboriginal nets) and with 650,000 chum we got soaked to the skin just floating through schools that bolted as only chum can bolt. And the artificial spawning channel in the Big Qualicum regularly returns 100,000 chum to that river. The Cowichan terminally returned, before a mop up commercial fishery two years ago, 400,000 chum. These are regular events.

In other words, there really is no comparison between the two coasts of Canada, and little wonder that carbon 14 dating of west coast cedar a millennium old (BC and Alaska) shows that 14% of the carbon in them originates from salmon carcasses taken up into the forest by bears, wolves and other animals.

Oh, and in BC, DFO et al put out about 600 million fry per year. In Atlantic Canada, there has been no Salmon Enhancement Program. Atlantic numbers are more comparable to our steelhead numbers. Our steelhead had their origin in the Atlantic and are more like Atlantics in behaviour. They began migrating west in warm weather periods more than a million years ago, and then came to be only on the west coast because of cold weather cycles.

For 2015, DFO, for the first time, has put $4 million toward enhancement in the east.

Ocean Survival: Bruce Morrison queried me on the meaning of the term ocean survival of salmon. It is a term that has more than one meaning. In loose terms, it doesn’t mean much, other than estimating the fish in the river this year, and comparing the number with past numbers, particularly the brood year. If numbers are high, this is taken as meaning good ocean survival because more fish survived to come back.

But the problem is that science has suggested that salmon migrate out into the ocean in as precise a pattern as they do coming back to spawn within 100 metres of where they were hatched. In other words, without doing the science to measure the ocean in a systematic grid, some rivers can return high numbers and some low, indicating both low and high ocean survival at the same time, and thus not be useful.

The other meaning of ocean survival is stricter and it does indicate that science has been done to monitor the ocean and correlate it with salmon numbers. If you look at the sources of the Salmon Outlook and the Integrated Fishery Management Plans you can find the references to follow up.

Good survival typically indicates higher ocean wind patterns, the Aleutian decadal weather cycle, for instance, and colder water temperature. High wind pushes surface waters aside and brings up nutrients resulting in vastly higher phytoplankton numbers that are the base of the food chain, producing chlorophyll. Photos of the ocean can show the vastly increased numbers, typically where plumes of freshwater from rivers carries iron oxide, a rate determining metal, and where weather has been bad.

The second problem is that we tend to use both the loose and strict definitions at the same time, and so it is often debatable whether ocean survival has actually been good or bad. And, of course, a La Nina is a cold water event, but an El Nino is a warmer water event, associated with lower salmon numbers.

Another wrinkle is that we assume higher ocean survival based on the relative presence or absence of jacks, and for chinook, 3-year old fish that come back with the run. The Cowichan, for instance, returned 4,000 chinook jacks in 2013, indicating a higher run of mature fish in 2014.

SFAB Minutes Port Renfrew: Probable ocean survival for 2015 is discussed in a PDF by Ian Perry, and Marc Trudel, You can get it from them.

Their presentation showed that 2014 temperatures were as much as 4 degrees centigrade higher than records from 1981 – 2013, which they note is: HUGE. (PDF page 5). Warm surface water of low density (low salinity) prevented nutrients being brought to the surface and, hence, low chlorophyll production.

This water moved east and clearly shows warm water pushed up against Alaska, BC and the lower Pacific States (P7). But growth rates for coho show conflicting predictions (P15). The references will give you the science behind ocean survival, i.e., in the strict sense of the expression.

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