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[Chum Slayer]

just a quick question what are the stats for coho in Region Two? From my understanding, they are an abundant species, but my question is for all of Region Two. How many are returning like a few 100k or a million plus? Also what percentage are hatchery vs wild? I know we are a few months from the season but with the amount of fry I have seen it has just got me curious. Also, what is the difference in the strains of coho? for example spring cap coho vs late January Harrison coho vs the mid-October Stave etc.

[RalphH]

That's a very good question for which any answer will be complicated and not at all clear.

You are asking about Region 2 that includes at least 8 major watersheds and dozens maybe hundreds of minor rivers and creeks?

A few have hatcheries. A few hatcheries produce a large number of fish, particularly the Capilano and Chilliwack hatcheries. Both can see returns in the river, not counting coho caught in the tide water in the 10s of thousands. Others will produce smaller numbers of hatchery fish in some cases less than 100. Other streams produce significant coho returns without a hatchery so all the fish are wild. Compare the Capilano to Chilliwack. The chilliwack produces more or less the same number of wild and hatchery fish as it has good habitat. I think it's more or less 50/50. The Cap with poor habitat likely has a much smaller % of hatchery fish. The Squamish a large system with pretty good habitat has a relatively small hatchery operation on the Cheakamus so most will be wild.

The final complication is actual numbers. Since for the most part on 90+% (this is a guess) of the rivers and streams, no one is counting how do we know how many there are? 

[canucksfan233]

blueback cap coho are a different strain, produced at cap hatchery. Fall hatch cap coho come from cap and chilliwack hatchery. Chilliwack hatch coho come from the wack hatchery.  Stave hatch coho come from inch creek hatchery and nicomen hatch coho are from inch creek hatchery. Chehalis coho come from chehalis hatchery. For the other smaller streams that operate with small hatcheries (such as the ones in Surrey and various other ones across the lower mainland), I'm not sure.

I'm guessing because of run timings of the fish, the coho produced at each hatchery are probably different strains from each other.

[clarki]

I don’t know that the early blueback coho are a different strain. I found a DFO report that said as early as the 1930’s, Fisheries Officers noted two runs of Capilano coho: a June run of smaller fish (1-2kg) and a run of larger fish in July-Aug. The smaller June fish spawned further upstream (before the dam was built) than the later run of larger fish. The spawning practices of the hatchery has ensured that these two runs of fish are perpetuated.

And it’s true that Stave River coho are reared at the Inch Creek hatchery, but the fry at the hatchery are from Stave River coho that were netted at the Stave and used as brood stock back at the hatchery. So yes, they are reared at Inch Creek but they are very much Stave fish.

[RalphH]

Prior to the Capilano hatchery that river did have a spring run of smaller coho as it does to day. As some fish are transported over the dam to the upper watershed by tanker truck some natural spawning & rearing does take place there.

To my knowledge FOC/DFO does not use the term 'strain' to refer to refer to any of the individual  stocks of fish enhanced and raised in their hatcheries. That term originates with the Provinces Fish management group primarily for rainbow trout.

Per the FOC Brood stock production plan and actual reports they use Species (ie Coho), Run (Spring, Summer or Fall) Stock (stream) and then there is a conservation unit number and name. For the Cap' there is no differentiation between the spring and fall runs. They are all classed as fall fish. Used to be (and still could be) that DFO hatchery would use a number of males and females to collect and fertilize eggs in one batch to enhance genetic diversity. The spring run may be a genetic factor common within the Cap and Seymour stocks that switches on or off among some individuals depending on unknown factors.

[clarki]

Also, what is the difference in the strains of coho? for example spring cap coho vs late January Harrison coho vs the mid-October Stave etc.

That’s a good question and reminds me that coho are a unique Pacific salmon species in that you can probably catch an adult coho in Region 2 in any month of the year . Personally, the latest I’ve caught one is January (seen them in February) and the earliest I’ve caught one is May.

This explains it better than I could “Coho salmon enter spawning streams from July to November, usually during periods of high runoff. Adult coho return timing reflects requirements of
specific stocks. For example, in some streams with barrier falls, adults arrive in July when the water is low and the falls are passable, however in some streams,
coho may wait until August or September when higher flows from fall rains allow passage into small streams not normally passable at low flows In large rivers, adults
must arrive early, as they need several weeks or months to reach headwater spawning grounds. Run timing is also regulated by water temperature at spawning
grounds: where temperatures are low and eggs develop slowly, spawners return early to compensate. Conversely, where temperatures are warm, adults are late
spawners.”

[RalphH]

There have been studies of Coho genetic diversity plus in  terms of life cycle they are less diverse than chinook and likely less than sockeye. They are no where close to rainbow trout or cutthroat in terms of diversity though it looks certain cutthroat will be revised to 3 separate species in the very near future. Like most salmon within their range there is a lot of influence from water temperature. Due to lower temperatures it takes longer for salmon to grow to smolt size in northern regions. Adults return earlier in northern latitudes as well. Returning in October could mean water temperatures too low for spawning.  Coho return as early as late August in some rivers in the Fraser Valley and as late as February or even March (historically). This may be a genetic imprint of previous adaptations. As far the Cap and Seymour "bluebacks" go remember both streams have summer run steelhead. These are barrier steelhead in that a early return gives them a better chance to pass through cataracts and or watefalls to upper river spawning areas. This may be the cause of the "blueback runs". There are other rivers in Southern BC where coho return early though the Cap and Seymour are the most well known.

[clarki]

This report is interesting https://publications.gc.ca/collections/collection_2014/mpo-dfo/Fs97-4-2118-eng.pdf

In the 1980’s, over two brood years, the Capilano hatchery experimented with spawning males and females from early run coho, and males and females from later run coho. They then measured return timing and ocean exploitation of the progeny of those two groups.

They found that the adult run timing of the progeny resembled that of the parent fish, thereby concluding that run timing can be controlled by selective breeding of parent stock.

After construction of the hatchery, the early run fish started to disappear and the midpoint of the overall coho run shifted from August to September. The deliberate propagation of the early run coho succeeded in re-establishing the early run component.

[RalphH]

Yes and this has been noted elsewhere. One example is the effect of the Stamp Falls fishway and the enhancement of the winter steelhead run. Much the same shifting occurred and what  was once a primarily summer run separated from winter fish above the falls became a fall winter run. Bob Hooton devotes a chapter on the impacts on the Stamp in his book Days of Rivers Past.