Climate change and hope for Pa’s wild trout

[Mike]

Climate Change and Hope for Pa Trout

While I have certainly been an observer of climate change for decades as it has related to my personal experiences with ice glacier recession and my on-the-scene exposure to rock glacier research/landslide occurrence in Switzerland, I have not been a “sky is falling” proponent when it comes to Pa wild trout populations. Note that I said Pa, not nationwide. Not every region of the US or elevation within the US has the rapid tree and shrub colonization and growth rate that we see in Pa and in some parts of the country snow melt, which could be lacking in the future, is a driving force behind trout stream conditions.

Within the warmest portion of the state I have seen too many cases of BT population expansion into formerly too warm waters for BT population survival over the course of as little as 8 yrs and as long as decades. While the climate is warming, land use is shifting, riparian vegetation is growing…growing faster and with greater density, and BT populations are expanding into stream reaches that were previously too warm, and in some cases not only expanding longitudinally but also achieving Class A biomass status. I have not seen any BT populations get worse or decline because of temperature changes. This is the opposite of what I think some biologists and anglers would think would be happening, especially in the warmest part of the state.

This should provide hope, but it should also provide opportunity for intervention in some cases because nature is telling us how to cool or better safeguard some streams for the future. This certainly indicates that there is time to have riparian tree and shrub plantings grow to shade enhancing heights and densities, and possibly time for Adelgid thinned hemlock forests, often in the case of ST, to respond with new growth of other tree species where conditions are suitable.

 

[Fish Sticks]

there is a paper I have yet to read thats on my list by mark kirk looking at projected temperature increases in streams with dense canopy and brook trout and what i heard is that in a lot of the streams warming will happen very slowly where there is dense canopy. So what i was told about this paper without seeing it yet pretty much supports what you said that no one should be throwing in the towel on native brook trout.

I would imagine there are all kinds of opportunities backing up out there without enough people to address where tree canopy or mountain laurel tunnels could cool down streams.

Hemlocks appear to provide more shade and have better root systems for holding in place it seems but they grow relatively slow. However, i have heard there are some stands that seem to be not effected by adelgids as much?

 

[troutbert]

There are many

there is a paper I have yet to read thats on my list by mark kirk looking at projected temperature increases in streams with dense canopy and brook trout and what i heard is that in a lot of the streams warming will happen very slowly where there is dense canopy. So what i was told about this paper without seeing it yet pretty much supports what you said that no one should be throwing in the towel on native brook trout.

I would imagine there are all kinds of opportunities backing up out there without enough people to address where tree canopy or mountain laurel tunnels could cool down streams.

Hemlocks appear to provide more shade and have better root systems for holding in place it seems but they grow relatively slow. However, i have heard there are some stands that seem to be not effected by adelgids as much?

In the colder parts of PA the hemlocks have less damage from wooly adelgids than in the warmer parts.

The colder areas correspond to further north and higher elevations.

 

[troutbert]

More riparian buffers would greatly benefit PA trout streams. Every stream needs good riparian/floodplain vegetation.

 

[wildtrout2]

There are many

In the colder parts of PA the hemlocks have less damage from wooly adelgids than in the warmer parts.

For sure. That's been my observation for a long time.

 

[Fish Sticks]

More riparian buffers would greatly benefit PA trout streams. Every stream needs good riparian/floodplain vegetation.

I knew about cold beating back the adelgids but I also though there were a few stands showing some intrinsic resistance instead of environmental?

 

[kbobb]

Pardon my ignorance - is BT brook trout or brown trout? and ST? Thanks

 

[wildtrout2]

BT is for brown trout, ST is for speckled/brook trout.

 

[Oregon_OwlII]

More riparian buffers would greatly benefit PA trout streams. Every stream needs good riparian/floodplain vegetation.

Agree. It is the single most important characteristic of a healthy stream from the standpoint of temperature, siltation, and food availability, the exception being streams with headwater AMD, where the pH overrides the riparian factors.