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[Morty]

A 48lb White was caught this week in the Strait near the mouth of the Fraser.  There's been some debate about whether the angler should have killed it or not. 

That got me to wondering...
   - What's the largest Chinook that actually makes it up the creek to the Chilliwack hatchery?
   - Would / does the hatchery use fish that large for brood stock?
   - What is the largest Chinook that the hatchery would use for brood?
   - Does the hatchery collect any large Chinook from the river and take up to the hatchery for brood?

Hoping someone has answers please.

[RalphH]

The white springs in the Chilliwack are sourced from the Harrison. That stock of fish generally max out at about 50 to 60lbs. I saw one in the Allco Hatchery (same stock) that was 50lbs or more.

[Old Blue]

The fish was hooked deep and would have died anyways.  Within the regs too so a legal fish.....end of story.

[Morty]

The fish was hooked deep and would have died anyways.  Within the regs too so a legal fish.....end of story.

What story are you imagining.  I asked some straight forward question aiming at learning about White Chinook.  The reply quoted here is way off target.

[wildmanyeah]

What story are you imagining.  I asked some straight forward question aiming at learning about White Chinook.  The reply quoted here is way off target.

Guess you weren't around when people would string up 40 pound black boot chinook from the harrison bridge.

[Morty]

Guess you weren't around when people would string up 40 pound black boot chinook from the harrison bridge.

I was.  And have also see huge chocolate Springs being carried out of the Vedder Canal. but, that still doesn't answer any of my questions.

[RalphH]

these sound like questions that require a call to the hatchery to see if they are able to provide an answer.

[Old Blue]

What story are you imagining.  I asked some straight forward question aiming at learning about White Chinook.  The reply quoted here is way off target.

What story are you imagining? 

Your statement regarding weather or not it should have been retained is what I was responding to.

Don't add a statement to your question without getting responses.  On target...or did you experience it differently?

[Morty]

One of the "debates" referred to was between a relative and myself about whether it should have been returned to the gene pool.  I had read other argumentary comments on another fishing thread.  That got me to wondering about the questions I posed.  My thoughts around it were:
  * after fighting a fish that large long enough to get it in front of a camera, it likely wouldn't survive the remaining struggles to get to spawn.
  * do hatchery fish that large actually ever make it back to the hatchery channel anyway?
and all the other questions I posed.

(my relative's opinion was that the trophy fish should be allowed to spawn and produce more like them)

[Rodney]

So when it comes to "fitness", big or strong does not always translate into "fit" if we are talking about genetic or adaptation. A population is not fit if there are only large fish, or only small fish, or medium sized fish. Fitness of a population can be measured by diversity. The more diverse a population is, the stronger it is when it comes to a change in environment, diseases, predation etc.

Killing that one big fish does not alter the fitness of the population, you're not taking away all the big fish immediately. If it was a female, then yes you're losing a lot of offsprings so that has an impact on the population.

If we are selectively harvesting only big fish (like we have unconsciously been doing) - directional selection, then that's bad for the population in the long run. You're shifting the bell curve of the population spectrum. Over time, fish become smaller because you're slowly taking out the genes that yield larger fish.

Selectively spawning only large fish at the hatchery is no good either, again, directional selection. This time, the bell curve of the population spectrum shifts right instead of left.

[RalphH]

Morty some of these arguments are specifically about genetic fitness of a large fish that gets to the hatchery. There's evidence that hatchery production reduces the genetic fitness of the salmon as there is no natural genetic selection within a hatchery.

There is also no proof this fish was produced in the hatchery or that it is headed to the Chilliwack. It could very likely be a fish naturally produced in a river like the Harrison which is by far the largest natural stock of white springs in the Fraser system though there are others.

The question, would such a fish survive to spawn or even spawn successfully if released, is pertinent. There is no doubt that being caught and released reduces the probability of either but in most the chances of survival and successful spawning are good. Where the fish is hooked, was there significant bleeding, how long it takes to land it, the amount of time it is removed from the water (if at all) are all important factors that influence the probability of survival. However no one can say a fish that is alive when released will not survive.

[wildmanyeah]

We selectively catch fish that more aggressively go after our lures. I have seen some underwater footage, A gopro attached  to a downrigger cable and there will be like 3 to 4 chinook following it around and one fish will come out of frame and push its way though and smash the lure.  IT's not always the big fish doing this.

So one does wonder what effect this is having on the population. Removing this type of fish?

[BladeKid]

Great information and response Rodney.

We selectively catch fish that more aggressively go after our lures. I have seen some underwater footage, A gopro attached  to a downrigger cable and there will be like 3 to 4 chinook following it around and one fish will come out of frame and push its way though and smash the lure.  IT's not always the big fish doing this.

So one does wonder what effect this is having on the population. Removing this type of fish?

I have thought about this a few times over the years, and I think it is a legitimate question for sure. A few thoughts:
--I've never thought of aggression being linked to big fish, if anything, I believe it is the opposite. I'm sure many fisherman can attest to just how aggressive jacks are for example. Although anecdotal, I bet if you standardized the number of jack and adult Chinook, returning to Vedder for example, jacks would be found to bite at a higher rate than adults.

--Young, sub-adult salmon at sea (i.e., those one or more years away from spawning) are ultimately trying to put on as much weight/size as fast as possible so as reduce their chances of size-selective predation (e.g., by larger fish, birds). In other words, when fish are young, survival is key, and so since survival is linked to eating and growing (quickly), this would likely lead to younger (smaller) fish being very aggressive, and as such, perhaps being more likely to bite. Fitness, as Rodney mentioned, is determined by one's ability to survive AND reproduce. So feeding aggressively to grow to be a big adult is also a good thing (e.g., larger fish are generally more fecund (large females make more eggs) and large adult males often have a competitive advantage over smaller adult males when it comes to winning over a female). However, it may be possible that when fish make it to that crucial size that eliminates them from being eaten by the majority of predators that they are able to be more “choosy” as to whether they want to grow very fast by being aggressive (which we presume to be riskier) or slower (which we presume to be safer, for example by not exposing themselves to predators as much) – these “choices” or behaviors of course likely being under genetic control.

--Using juvenile coho as an example (which rear in freshwater for 1 or more years), we see a variety of "behavior" types/strategies, displayed among individuals. Some individuals display extreme aggression against conspecifics/other fish for the most productive rearing locations, some choose feeding lanes that provide a lot of food but have less cover for protection against predators, and some are more timid (getting kicked to the back of the school or choosing slower moving areas with less food but high cover), etc. Ultimately, all of these strategies/behaviors have trade offs, and it is this variety of behavior types that make a stock/population of fish resilient against all that we and nature can throw at them.

----So, while I don't have an answer to your question, I think that if we think about some of the considerations I've listed above, and the myriad of other natural selective forces going on prior to the point in time at which a salmon is typically caught, that there will always continue to be some component of very "bitey" fish in a population, even if we are inadvertently counteracting those natural selective forces by catching and killing the more aggressive/bitey individuals.

[Morty]

Another aspect of survivability I've wondered about is time of day that the salmon move once they're back in the river.  I wonder if some are predisposed to mostly swim during the day and some predisposed to move at night.

I've noticed that there seems to be a good number of Coho reach the hatchery over night, and that there seem to be more difficult to catch during the day.
If we're continuing to harvest day-swimmers in the river, and a higher percentage of night-swimmers are getting to spawn, we are likely interfering with that aspect mix in the local Coho populations.

Somewhat along the lines of what the hatchery concluded about Steelhead and time of year they return.

[BladeKid]

Another aspect of survivability I've wondered about is time of day that the salmon move once they're back in the river.  I wonder if some are predisposed to mostly swim during the day and some predisposed to move at night.

I can confirm this 100%, but every stock is a bit different. Some are primarily day-time travelers and some are night. Some stocks more or less travels at all times of the day, with only small bumps of migration at a particular time of day, and then everything in between. I don't think we have a complete handle on what drives stock-specific diel (24h) migration patterns, but I suspect environmental conditions (turbidity, tides, temperature, available cover, etc.) and predation risks are big drivers. On a tangent, bear predation on small, sockeye spawning creeks has had such strong selection that sockeye in these streams have evolved to come back at a younger age (i.e., smaller) - small size meaning that they are harder to catch and are less exposed while migration through, or spawning in riffles.   

I've noticed that there seems to be a good number of Coho reach the hatchery over night, and that there seem to be more difficult to catch during the day.
If we're continuing to harvest day-swimmers in the river, and a higher percentage of night-swimmers are getting to spawn, we are likely interfering with that aspect mix in the local Coho populations.
Again, in theory this is possible, however I'm not sure the directional selection we are exerting (and length of time we've been doing it) would make a difference. And again, there are likely strong enviornmental drivers for the diel migration patterns a stock exhibits.

Somewhat along the lines of what the hatchery concluded about Steelhead and time of year they return.

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