Invasive/stocked trout likely function similar to culverts for Brookies

[Fish Sticks]

There are often additional benefits that are highly beneficial from an infrastructure, water quality, and in some cases public safety perspective. We are not at a point where many culverts are being replaced solely based upon the need to provide for aquatic organism passage. Most are replaced because they are at the end of their serviceable life, are greatly undersized and causing flooding issues etc. It would be foolish to construct a structure intended to last 100 years and not provide for aquatic organism passage outside of extreme biological reasons.

Shannon White's study that you continously cite amongst others documents the importance of providing connectivity. Mainstem movement is happening and genetics are linked throughout that watershed even though the Loyalsock is one of the more densely stocked creeks in the state. Another post discusses the frequency that several posters are seeing brook trout in Kettle, another densely stocked creek.

Many groups have put tremendous effort and time into bringing aquatic organism passage into the picture as an important piece of culvert construction. I would be cautious in saying this should not be a consideration as momentum could quickly turn the other direction.

I understand that culverts have more uses than AOP for one species. What i am talking about is when its (truly)allopatric upstream and sympatric downstream. These are rarer situations and when that does occur there are often not much else up there with them. Now I know that passage is for amphibians/herps as well. I am just saying that it needs to be considered and we cannot blindly act without considering the consequences in this situation. I don’t think we are going to lose momentum if in this specific case we just consult the appropriate people, we had to do this on hammer creek for walnut run and guess what, DEP permit apporval process killed the momentum, not responsibly checking with the appropriate folks, they said go for it there is already browns up walnut run and if their hadn’t been then they may have still said go for it.

The real problem is what we need are more fin clips/genotyping to see where unique genes exist on the landscape by state agencies as mentioned word for word in casey thomas weathers thesis above. Then we can actually protect rare genetics and make more educated culvert decisions in the tare situation there is a question of should we do it. Wer putting our money into stocking instead.

Mike and you both have both mentioned that there is movement in shannons study but what i keep mentioning is from a conservation genetics stand point there are two big problems with your guys stance that just because some movement is happening it means brook trout will survive longer than our grand kids in this state.


1. Invasive trout species often replace native brook trout: thats loss of genes on the landscape. If we loose the genes…..they cannot flow. So they don’t get factored into genetic adaptation to deal with stressors that could potentially cause us to lose these fish.

2. gene flow increases genetic diversity because when you have low levels genetic drift and inbreeding depression cause allelic fixing, loss of diversity, and decreased adaptability and fitness. However what you guys need to understand is simply avoiding inbreeding depression is just the low hanging fruit, its not the same as maximizing adaptive genetic capacity. There is such thing as a more rapid adaptive genetic capacity with fish but you need a high level of gene flow to achieve this result which could very likley be whats needed for brook trout to survive climate change and other stressors. The above dissertation provides evidence that these stocked fish are likely suppressing this gene flow to some extent. Hence recommendation of remove invasive species from mainstream migration corridor.

I just can’t believe we are at the point where managers wont recognize these invasive species being stocked in native brook trout watersheds. its not just me inventing this, i’m parroting it from the most qualified people in the brook trouts native range. We have seen a true death of experts in our society. The only place the Eastern Brook Trout Joint Venture, University academics, and federal fisheries science agencies have not communicated DONT STOCK OVER NATIVE BROOK
TROUT is a sign dragged behind a plane in the sky over the beach this memorial day weekend.



Casey Thomas Weathers Dissertation I posted says all of this almost word for word.

Movement is a spectrum, the brook trout in the sock and kettle would almost certainly have more genetic adaptive potential to deal with climate change/other stressors if stocking was discontinued. That increase in genetic adaptive potential may be what causes them to stay on the landscape long term.

 

[Fish Sticks]

The risk is not just from stocking brown trout. The risk is mostly from brown trout populations. Which exist in a great many places that have not been stocked for many decades.

Stocking browns and brown populations shouldn't be conflated. A stream could be stocked with browns and have a brown trout population. It could be stocked with browns and not have a brown trout population. And it could be not stocked with brown trout, and have a brown trout population.

Well actually stocking browns can increase propagule pressure that overwhelms biotic resistance so yes, stocking browns if wild browns are present causes more damage, furthers stage of invasion as propagule pressure has been documented to do and ultimately can create so many brown trout that brook trout to brown trout ratio that keeps them out is lost( this is called biotic resistance).

The truth is there are some waterways out there that if brown trout stocking was stopped the brook trout would have alot less browns to deal with and there are some acidic waterways brook trout would likely ultimately take over.