Brook trout age classes, tiny wstrn MA stream

[k-bob]

Stumbled across this data I saved... don't recall source... anyhow tiny wstrn ma brookie stream so harsh that few live to 4... and apparently prone to varying spawning season flows, and possible post-spawn floods, that lead to highly variable numbers of spawning survivors. The influence of a larger age class suggested in this unusual annual data over a number of consecutive years. Anyhow, probably better not to expect smooth numbers from year to year of the relatively large (of course they are all pretty small) brookies in the tough environment of a truly tiny brookie stream.

 

[silverfox]

Absolutely. Which further reinforces (to me anyway), the importance of protecting those "larger" 3/4 yo "legal harvest" size fish. In other words, theoretically, a handful of anglers harvesting fish legally might completely wipe out the upper age class fish. The ones that are typically more fecund and generally more mobile. i.e., the entire justification for Maryland's western region regulations.

 

[k-bob]

To me, that data seems driven by the high variability of age 0 fish. These age 0 ones are probably more difficult to count, but post-spawn winter floods in some years seems the explanation for such huge swings in age 0 year to year. So maybe the driver is the number of spawning survivors, and that number in turn maybe more result of variation in fall and winter flows and floods than the number of spawners in the first place.

 

[k-bob]

Btw I think brookies can spawn at a young age... see very low numbers 3 year old fish in first few years of data... might not be brookies here if they could not spawn at small age/ size.

 

[k-bob]

Looked it up.

 

[silverfox]

Looked it up.View attachment 1641225339

Right, but an age 4 fish is likely to result in more eggs than an age 1 fish. I.e. more fecund. I’d like to see research into the correlation (if there is any) between mobility and lifespan. Are these fish that travel long distances living longer? In MD, tagged fish exceeded 7 years in age where harvest isn’t a factor. I’d assume fecundity drops with age, but there’s probably a sweet spot in age/size that could increase egg production if we’re not removing them from the population .

My point was more about how rare the older/larger age class/size fish are, or can be. If you have a down year in YOY survival due to environmental factors, and then you remove a high percent of older fish simultaneously, wouldn’t that create a scenario where we’re adding significant additional reproduction stress to the population even though only a handful of adults are being harvested ? Reducing the most fecund fish while the next cohort is reduced due to floods etc. would create a population gap in 2 or 3 years.

 

[Mike]

With respect to egg contribution, that single age 4 fish is practically meaningless. And genetically, it has already contributed to the population up to three prior times. If it is a female, there are possibly half of 53 +7 fish, meaning 30 females if there is a 50/50 sex ratio in ages 2-3. If there are 20 females, then there are 2 males for every female within ages 2-3. Either way, the cumulative number of eggs produced by the younger females overwhelms the relatively small number produced by a single larger female. If it is a four yr old female, she has already done her part. You can also see that in terms of population size and yr class strength, four yr olds were not necessary.

As for movement, as I recall the Loyalsock basin study indicated that age/size was not a factor, meaning that movement was neither age or length specific.

Finally, age 1 is where you want to start looking at the numbers because age 0 fish are not being fully recruited to the sampling gear, as indicated by more age 1 fish than age 0 fish in all but one sample.

Finally, perhaps it is obvious so just a reminder that to follow a single age class you have to do so diagonally, not horizontally.

 

[k-bob]

Thanks mike... right, focus on age1 vs age0 numbers as 'age class anchors' because of measurement issues w/ age0s.

also, the worst year for age1 #s, 2007, had a larger pool of fish to spawn in the prior year than the best year of age1#s, 2002. post-spawn flood could account for that.

while such age class issues may be diluted in a somewhat bigger brookie stream (more age4 and some age5), still probably better not to expect smooth numbers of relatively old/large fish in a brookie stream across years.

 

[Mike]

That’s right. The numbers will bounce around considerably due to natural variations in year class strength for starters and then sometimes because of unusually large floods or anchor ice events that even take their toll on older fish than YOY. The good news is that small year classes are often followed by big year classes the next year or possibly better survival of the following year’s small to avg year class due to the lack of competition from yearlings.

 

[Mike]

Another exercise, a particularly good one for those who oppose fall fishing, is to look at the rows focusing on the abundances of age 2 and age 3 fish OR just age 3 fish since they are larger. Then drop down two rows and note how many age 1 fish were produced by fish in the row two rows up that was examined for age 2 and/or age 3 fish. As I have said numerous times in the past, the number of young produced, especially the number effectively produced when the year class is set by the time the YOY reach age 1, is seldom determined by the abundance of adults, or in my example, the number of adult size fish that anglers would typically catch.

 

[silverfox]

I'm just curious what the strong opposition is to any kind of ST angling regs? I'll be honest, I haven't paid much attention over the years, but have you opposed any C&R regs for other species with such gusto? Are you opposed to all the C&R regs for brown trout throughout the state? Is there anything PA should do differently that would be acceptable, or are we right and everyone else is wrong?

I think it's pretty obvious at this point my biggest bone of contention is comparing PA to other states in the range, especially our immediate neighbors. Are they all wrong in their approaches? Is NPS's entire mission wrongheaded? Are you suggesting we just let nature run its course at this point? Nothing I advocate for is unique, my own idea, or not already done elsewhere. I would "get it" if I was suggesting things that were off the wall or hair brained. All I'm doing is suggesting we do one, or any of the things our neighbors do. The amount of obstruction is mind-blowing and extremely discouraging.

4 days in the northern tier. Stocked rainbows, stocked brown trout, wild brown trout. All protected and unremovable from brook trout streams. I caught nonnatives (stocked or wild) in every single stream we fished. Such a shame.

Every one of those nonnatives represents one of these that doesn't exist.

 

[Fish Sticks]

Measuring all the age classes and sizes can be good metrics of a streams brook trout populations health. However, its just a snap shot in time. Density and size should not be our only goal or even or main goal in native brook trout expert’s opinion.

Have you ever met with your financial advisor or read the prospectus on a mutual fund? “ Past performance does not guarantee future results”.

The same concept applies here in native brook trout conservation. High density and large size are great, but it doesn’t tell you about adaptive capacity from a genetics standpoint. Adaptive potential is an enormous influence on effectively brook trout can persist on the landscape. The more diversity of genetics we preserve on the landscape the faster adaptive potential to climate change and human activity can create a brook trout equipped to deal with and persist through some of these these stressors in certain places.

If we loose genetic diversity (class B,C,D what ever), enjoy those super dense populations while you can because if they are not part of a large connected network that values genetics over fisheries rooted density metrics from a management perspective, get ready for the high likely hood to say goodbye to that population that has lost the ability to change with its environment.

This is Pa fish and boats greatest failure as a resource manager for native brook trout. The Inability to carve out a tiny slice for conservation of native brook trout somewhere in this state and sacrificing these unrealistic socially conditioned expectations of density, size and catch rate. Essentially trading fishing goals for conservation genetic goals in a tiny portion of our states waters to secure the long term existence of the species. They have also greatly mislead the angling public from a resource education standpoint by selectively omitting the brook trout stressors the agency exacerbates like biotic and connectivity issues with stocking of twonof the worlds top 100 most harmful invasive species. As they fall behind neighboring states and the mainstream fisheries science it gets harder and harder to defend an absolute turd. We have not begun to try to restore brook trout in this state and in fact we really likely just beed to get our of their way with stocking and invasive species in many places and managing for watersheds to see some significant degree of improvement in their adaptive genetic capacity.

We cannot have high genetic adaptive capacity in brook trout if our fish managers have a severe deficit in adaptive capacity with their management in regards to being informed by solid fisheries science neighboring states are using. Huntsman at the last EBTJV meeting available on line was quoted as saying “ if you need a reason to not stock any brown trout look at the study on the shavers fork” referencing the invasive species stealing the benefits of habitat restoration. This stuff is even making it into popular angling circles-Tom Rosenbauer recent podcast “ they should not be stocking rainbow trout over narove brook trout, its an invasive species, you can quote me on that”.

Why are the people having to drag the resource manager into this centuries fisheries management from a science standpoint when Pa fish and boat has a stated responsibility for angler education.
Pennsylvania has more protection for stocked and non native species than almost any other state in the east and the most primitive incoherent native brook trout management you will find. Its such a shame because what PAFB would need to do to give us healthier brook trout populations would actually be cost saving to free in a huge way yet this false notion that we need to get it back to how it was 600 years ago is perpetuated. They have all the volunteer conservationists chasing the undefined ever increasing mythical unicorn value of water quality and temperature while streams that are ice cold and clean flip brook trout to brown trout after restoration. While streams in potter county lined by hemlocks flip brook trout to brown trout. While they hide their incoherant managment’s effects kn critical factora like biotic interactions/invasive species and connectivity/ adaptive potential.

Take away who gives a flying you what if a stream is class a b c d. Protect it, connect it to others, don’t drop invasive competitors on it or at its doorastep. And yes restore it for temp/water quality, BUT NOT IN A VACCUM IGNORING ALL THE FORMER FACTORS.

 

[silverfox]

Back to the topic, some visualizations based on Mike and KBob's comments.

Obviously, age 0 fish are missed in sampling. The trendline by class should be a steady decline from left to right, not a low age 0 # followed by an increase in numbers of that same cohort the following year. Unless immigration plays a role.

It's worth noting the decrease in age 3 and 4 fish may be due to emigration too. As noted in the original post, the stream is characterized as "tiny". It may not be accurate to assume the lack of older fish is due to death from harsh conditions. Maybe this is a nursery stream and the older/larger fish leave for larger habitat? Without sampling downstream or radio tagging, it's impossible to know what's happening to the older fish. It would be interesting to see sampling done across multiple seasons as well to see the rate of movement and whether, again, this is a nursery stream, rather than year-round habitat for all age classes. As is typically the case, the temporal piece of the puzzle is missing.

Here the data is organized differently from the original. Cohort tracking is diagonal as Mike mentioned. So you're following a cohort from year to year diagonally down the chart, not horizontally.

Again, the low age 0 numbers relative to the higher numbers from that same cohort the following year show how many age 0 fish are missed when sampling. i.e., cohort 2 from the graph above and in orange starting in 2001 in the spreadsheet below should have a higher count than 212 to result in 399 age 1 fish the following year, again, unless a significant portion of the age 0 fish are upstream (or down) of the sampling area and then move into the sample area when older/larger.

I'm not necessarily seeing the correlation between high age 2 fish and higher age 0 fish the following year. i.e., in 2003, the highest number of age 2 fish didn't result in a high number of age 0 fish in 2004. In fact, there were fewer age 0 fish in 2004 than there were in 2003 when the age 2 numbers were lower the prior year (2002). There was a bump in age 0 fish in 2005 and 2006 following a relatively stable or higher population of age 2 and 3 fish in 2004, but that's not an obvious occurrence in other years. Again, environmental factors may negate spawning success.

On the movement issue, I think it's important to think about the range of movement. While the Loyalsock study indicated some 20% of the population "moved", a much larger percentage moved smaller distances. Those smaller distances might still be in and out of a sample area. The biggest thing to consider is that the study was only 6 months (June - November) of the year due to transponder life, and didn't capture what happened after November when the conditions would have gotten much harsher.

 

[silverfox]

Measuring all the age classes and sizes can be good metrics of a streams brook trout populations health. However, its just a snap shot in time. Density and size should not be our only goal or even or main goal in native brook trout expert’s opinion.

Have you ever met with your financial advisor or read the prospectus on a mutual fund? “ Past performance does not guarantee future results”.

The same concept applies here in native brook trout conservation. High density and large size are great, but it doesn’t tell you about adaptive capacity from a genetics standpoint. Adaptive potential is an enormous influence on effectively brook trout can persist on the landscape. The more diversity of genetics we preserve on the landscape the faster adaptive potential to climate change and human activity can create a brook trout equipped to deal with and persist through some of these these stressors in certain places.

If we loose genetic diversity (class B,C,D what ever), enjoy those super dense populations while you can because if they are not part of a large connected network that values genetics over fisheries rooted density metrics from a management perspective, get ready for the high likely hood to say goodbye to that population that has lost the ability to change with its environment.

This is Pa fish and boats greatest failure as a resource manager for native brook trout. The Inability to carve out a tiny slice for conservation of native brook trout somewhere in this state and sacrificing these unrealistic socially conditioned expectations of density, size and catch rate. Essentially trading fishing goals for conservation genetic goals in a tiny portion of our states waters to secure the long term existence of the species. They have also greatly mislead the angling public from a resource education standpoint by selectively omitting the brook trout stressors the agency exacerbates like biotic and connectivity issues with stocking of twonof the worlds top 100 most harmful invasive species. As they fall behind neighboring states and the mainstream fisheries science it gets harder and harder to defend an absolute turd. We have not begun to try to restore brook trout in this state and in fact we really likely just beed to get our of their way with stocking and invasive species in many places and managing for watersheds to see some significant degree of improvement in their adaptive genetic capacity.

We cannot have high genetic adaptive capacity in brook trout if our fish managers have a severe deficit in adaptive capacity with their management in regards to being informed by solid fisheries science neighboring states are using. Huntsman at the last EBTJV meeting available on line was quoted as saying “ if you need a reason to not stock any brown trout look at the study on the shavers fork” referencing the invasive species stealing the benefits of habitat restoration. This stuff is even making it into popular angling circles-Tom Rosenbauer recent podcast “ they should not be stocking rainbow trout over narove brook trout, its an invasive species, you can quote me on that”.

Why are the people having to drag the resource manager into this centuries fisheries management from a science standpoint when Pa fish and boat has a stated responsibility for angler education.
Pennsylvania has more protection for stocked and non native species than almost any other state in the east and the most primitive incoherent native brook trout management you will find. Its such a shame because what PAFB would need to do to give us healthier brook trout populations would actually be cost saving to free in a huge way yet this false notion that we need to get it back to how it was 600 years ago is perpetuated. They have all the volunteer conservationists chasing the undefined ever increasing mythical unicorn value of water quality and temperature while streams that are ice cold and clean flip brook trout to brown trout after restoration. While streams in potter county lined by hemlocks flip brook trout to brown trout. While they hide their incoherant managment’s effects kn critical factora like biotic interactions/invasive species and connectivity/ adaptive potential.

Take away who gives a flying you what if a stream is class a b c d. Protect it, connect it to others, don’t drop invasive competitors on it or at its doorastep. And yes restore it for temp/water quality, BUT NOT IN A VACCUM IGNORING ALL THE FORMER FACTORS.

I think education, or the lack thereof, is immensely important. That's the biggest benefit to C&R regs in my opinion. Ironically, I just looked at PFBC's facebook page before reading your post and saw they posted a big stocker brown trout promoting stocking on the Yough. Then scrolled through their feed. Not a single brook trout to be found. A casual visitor to their social media wouldn't even know brook trout exist in this state. It's like they actively avoid any mention of brook trout.

 

[Fish Sticks]

I think education, or the lack thereof, is immensely important. That's the biggest benefit to C&R regs in my opinion. Ironically, I just looked at PFBC's facebook page before reading your post and saw they posted a big stocker brown trout promoting stocking on the Yough. Then scrolled through their feed. Not a single brook trout to be found. A casual visitor to their social media wouldn't even know brook trout exist in this state. It's like they actively avoid any mention of brook trout.

Yea i think at this point brook trout has become a real point of shame for the commission, i noticed there is no real effort at public promotion of conservation need/ education. Our state fish completely abandoned less symbolic gestures. Any post would probably just invite massive amounts of due criticism

 

[silverfox]

Yea i think at this point brook trout has become a real point of shame for the commission, i noticed there is no real effort at public promotion of conservation need/ education. Our state fish completely abandoned less symbolic gestures. Any post would probably just invite massive amounts of due criticism

I noticed they removed the brook trout from their logo and replaced it with a "yellow trout". Fitting.

 

[Fish Sticks]

I noticed they removed the brook trout from their logo and replaced it with a "yellow trout". Fitting.

Yea they had a facebook post about “educational” tours of the hatchery with an organge creamsickle trout on it. Glad the public are going to learn about the human created skidmark in natures underpants instead of the issues facing our state fish.