Trout/Salmon growth and climate change

[sarce]

Found this article interesting.

https://news.wisc.edu/tiny-trout-st...species-are-bucking-one-climate-change-trend/

"Jensen says this development may have a lot to do with how climate change is reshaping our winters. Typically, winter months are a period of very slow growth for fish. Now, however, ice cover durations are shrinking as water temperatures stay warmer longer into the fall and warm up sooner in spring. The end result could be longer growing seasons for fish, and increased growth rates in aquatic ecosystems throughout the northern hemisphere, Jensen says."

I've wondered about this recently. If most warming compared to average is occuring in winter, it makes sense that the trout growing season is longer. I should note they say that in Wisconsin, warming temperature is benefitting browns and harming brook trout.

There are a lot of projections out there for where air temperature will be in 100 years. Let's say you have on average, an 8F increase in air temps compared to today in the year 2120. That could mean a +12 increase the coldest 6 months of the year and only a +4 increase the warmest 6 months. Then you have to filter those increases down to what the impact on water temp will be, it's not a 1:1 relationship. Especially if riparian cover increases along a given stream. Might be wishful thinking, but it's something I think about often. Seems like up to a certain point of warming, there may be benefits to trout in the areas that are currently coldest (but likely also a loss of populations currently on the fringe). It could create a false sense that everything's fine in the short term.

 

[pcray1231]

Not to diminish climate change. I'm not a denier. But as far as stream temps go, flow means more.

We have de-watering, the springs flow less because humans take the water. And we have development, with decreasing forest, and increasing the amount of pavement and even just grass, which leads to more runoff and less groundwater recharge, and this is to include freestoners as well as limestoners. This leads to lower summertime flows, which is increasing stream temperatures. This isn't a new thing. Before western settlement, big waters like Pine flowed more steady and stayed cold. Just a continuation of the same ole decline.

As far as climate change, I am EXTREMELY interested in the changes of precipitation, moreso than the temperature. I think the jury is still out which way it will go in PA, I've seen estimates that we will have increased precipitation, and ones where we'll have decreased. As was mentioned, the seasonality of those changes matter too. I'm not saying this will happen, but increased and more steady summertime rain may more than offset a slight increase in air temperature. Just something to think about. For coldwater fisheries, more attention needs to be paid to the expected changes in precipitation, and not just on air temperature.

If you fish and take temperatures during our summers. The water is colder on a 95 degree day with good flows than it is on a 85 degree day with low flow.

 

[Fish Sticks]

Dr. Mark Kirk is going to be publishing projections in the future for brook trout in PA headwaters with climate change and in densely forested areas with thick canopy there will be some what of a buffering effect on stream temperature is the quick and dirty I believe. For brook trout its not always that the water is too hot and that means only brown trout can live there, although sometimes it is. However, its more about are the brown trout hogging all the thermal refuge in a lot of cases.

7 day lethal temp difference less than 1deg Celsius of separation in a michigan study. Temperature just increases competition in a-lot of cases


Heres your land mark paper adapted into science communication format for public

USGS Study Reveals Interactive Effects of Climate Change, Invasive Species on Native Fish | U.S. Geological Survey

A new USGS study shows non-native Brown Trout can place a burden on native Brook Trout under the increased water temperatures climate change can cause.

www.usgs.gov

Here are two proofs of concept

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/rec.12925

https://files.dnr.state.mn.us/areas/fisheries/lanesboro/research/677report.pdf

 

[sarce]

Not to diminish climate change. I'm not a denier. But as far as stream temps go, flow means more.

We have de-watering, the springs flow less because humans take the water. And we have development, with decreasing forest, and increasing the amount of pavement and even just grass, which leads to more runoff and less groundwater recharge, and this is to include freestoners as well as limestoners. This leads to lower summertime flows, which is increasing stream temperatures. This isn't a new thing. Before western settlement, big waters like Pine flowed more steady and stayed cold. Just a continuation of the same ole decline.

As far as climate change, I am EXTREMELY interested in the changes of precipitation, moreso than the temperature. I think the jury is still out which way it will go in PA, I've seen estimates that we will have increased precipitation, and ones where we'll have decreased. As was mentioned, the seasonality of those changes matter too. I'm not saying this will happen, but increased and more steady summertime rain may more than offset a slight increase in air temperature. Just something to think about. For coldwater fisheries, more attention needs to be paid to the expected changes in precipitation, and not just on air temperature.

If you fish and take temperatures during our summers. The water is colder on a 95 degree day with good flows than it is on a 85 degree day with low flow.

I completely agree that precip is a major factor. And what worries me is that while we could see an increase in the total amount of rainfall each year, it will come in the form of quick intense downpours, which results in erosion and channel widening anywhere you have any amount of development.

In my Catoctin Mountain water temp study, I traced the warmest temps at a few sites to runoff from a very intense (3" rainfall) afternoon thunderstorm on a 90-degree day. These are generally completely forested areas with gravel roads, if any. Data showed that water temps converged on 68F pretty much everywhere. In some sites, that was a cooldown compared to before the rain started. But in the coldest sites, which were running 65 degrees prior to the storm, this runoff appeared as a warm spike in water temps. The following summer, there was never a comparable storm, and those cold sites maxed out at 66F. All this to say that it's really complex and temperature alone isn't going to determine what happens to our trout.

 

[sarce]

Dr. Mark Kirk is going to be publishing projections in the future for brook trout in PA headwaters with climate change and in densely forested areas with thick canopy there will be some what of a buffering effect on stream temperature is the quick and dirty I believe. For brook trout its not always that the water is too hot and that means only brown trout can live there, although sometimes it is. However, its more about are the brown trout hogging all the thermal refuge in a lot of cases.

7 day lethal temp difference less than 1deg Celsius of separation in a michigan study. Temperature just increases competition in a-lot of cases


Heres your land mark paper adapted into science communication format for public

USGS Study Reveals Interactive Effects of Climate Change, Invasive Species on Native Fish | U.S. Geological Survey

A new USGS study shows non-native Brown Trout can place a burden on native Brook Trout under the increased water temperatures climate change can cause.

www.usgs.gov

Here are two proofs of concept

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/rec.12925

https://files.dnr.state.mn.us/areas/fisheries/lanesboro/research/677report.pdf

I was talking to MD DNR about water temps recently and they told me that based on studies they've reviewed, they believe brook and brown trout have almost identical thermal limits. Development and degradation from stormwater runoff has been the biggest contributor in MD to brown trout displacing brook trout. Brook trout are still found in some very warm locations where browns never took hold. (I know you know this from your podcast, just another point supporting it)

 

[Fish Sticks]

The precipitation you speak of is in the area of whats called “environmental resistance” and the timing of precipitation on a background of different life history events such as spawning or thermal refuge. You should google scholar Dr. yochiro Kanno and read his works. He and Dr. Kurt Fausch have looked at how hydrology patterns influence species composition l, success, and invasion. You would have a lot of interest in his articles


He also happens to be giving the next EBTJV Lunch’n Learn lecture so tune in to that too!!!

 

[Fish Sticks]

I think the original post is essentially describing reverse environmental resistance(good for the species) and very relevant to that discussion.

 

[JeffK]

Over in NJ, acid rain was an issue in having wild rainbow trout. The work was done in the 1970's when acid rain was worse (and we had snowpack), but the science is still interesting. Snow is basically frozen acid rain. When the snow melted in the spring it caused a sudden drop in pH that killed newly hatched rainbow fry, but brown and brook trout fry from the fall were further developed and could survive. The streams with wild rainbows, like Van Campens BK, usually had a lake in the headwaters that buffered the pH.

 

[Fish Sticks]

Over in NJ, acid rain was an issue in having wild rainbow trout. The work was done in the 1970's when acid rain was worse (and we had snowpack), but the science is still interesting. Snow is basically frozen acid rain. When the snow melted in the spring it caused a sudden drop in pH that killed newly hatched rainbow fry, but brown and brook trout fry from the fall were further developed and could survive. The streams with wild rainbows, like Van Campens BK, usually had a lake in the headwaters that buffered the pH.

Yea i have wondered if decreased acid rain
Has allowed invasion as well. The spectrum seems to be in increasing acid tolerance bow-> brown->brook