Does anyone know why southern subspecies of brook trout are not good candidates for raising in the hatchery?

The state of NC stocks sterile brook trout but not the native subspecies.

I was curious about this and waiting to see an answer but when none came I googled it. I know brookies in general are easy to raise in hatcheries with the right conditions, My understanding was that the hatchery brookies are basically a domesticated strain dating back 50 or more years and having no close genetic ties to any one strain or locality. Typically the long established hatcheries raise their own strain which may be as old as the facility itself.

When I googled NC brookies, I found that was the case there as well. The Armstrong State Hatchery [McDowell County] was built in 1957 and according to the state website,

"The hatchery maintains its own strains of brook and brown trout broodstocks that have been bred and maintained on the site for 40 years."

I found that, plus discriptions of the other trout hatcheries here: http://www.ncwildlif...ries.htm#marion

I didn't see any mention of sterilized trout. WHere did you hear they use sterilized trout?

Edited by mikez, 14 January 2011 - 07:23 AM.

Brown trout! This.

When I googled NC brookies, I found that was the case there as well. The Armstrong State Hatchery [McDowell County] was built in 1957 and according to the state website,

"The hatchery maintains its own strains of brook and brown trout broodstocks that have been bred and maintained on the site for 40 years."

I found that, plus discriptions of the other trout hatcheries here: http://www.ncwildlif...ries.htm#marion

It seems strange to me that we are warned against releasing captives, even those collected from the same locations weeks earlier, while the hatcheries 'apparently' create, for all intent and purposes intentionally, genetically divergent non-wild subgroup with which to release into the wild. I know that's not the only reason we are warned against such releases, but... Should the worst case happen, and future wild populations became completely dependent on the genetic stock (diversity) of the hatcheries, it could be disastrous.

It seems to me that the hatcheries are failing what I thought was one of their primary functions. The defense and genetic diversity of the wild stock. Maintenance of sports fishing is fine in itself, but I was under the impression that they played a larger role in maintaining the health of the species in general.

I'll leave the OP question for the more knowledgeable about hatchery practices. If Gambusia could offer sources on the 'sterile' trout it would be helpful.

Naw, it's all about money and a sometimes warped sense of "giving people what they want". The cynical defense would be that most hatchery introductions are caught or die quickly, but of course that's not really true.

I live in NC and the past few years now the NCWRC (Wildlife Resources Commission) has switched over to stocking only triploid trout.

Not sure if that is the case on the Cherokee Indian Reservation which also stocks trout.

Now where'd you get a crazy idea like that? |;>)

... the hatcheries are failing what I thought was one of their primary functions. The defense and genetic diversity of the wild stock.

Native southern brookies generally stay small, so hatcheries looking to maximize production use broodstock derived from larger-growing northern pops, far as I know. I dont know of any other disadvantage of southern brookies besides their small size. NC-WRC has finally recognized and tries to protect our few true native brookie streams. (not to be confused with "native trout" in the fishery sense: natural-breeding stocked trout).

Do we even know what the maximum size is of a Southern mountain brook is?

Now where'd you get a crazy idea like that? |;>)

Admittedly just an assumption. I understand the legal limits placed on me and generally respect them, even when I can argue my actions are not relevant to any actual harm. The aggravation level goes up when I can't even take certain species from under a bulldozer. One of my favorite tadpole pools got a good dose of diesel fuel a couple of years ago.

The least they could do is take their own actions as seriously as they take mine. Since joining here I have been playing catchup on the terminology, such as "recruit", used in this field. Not something I'm accustomed to playing catchup with in most sciences.

Native southern brookies generally stay small, so hatcheries looking to maximize production use broodstock derived from larger-growing northern pops, far as I know. I dont know of any other disadvantage of southern brookies besides their small size. NC-WRC has finally recognized and tries to protect our few true native brookie streams. (not to be confused with "native trout" in the fishery sense: natural-breeding stocked trout).

So not only is genetically divergent stock being used, but the genetic stock it is divergent from is not itself, strictly speaking, native to the waterways they are stocked in. Then the response, to recognize a legitimate concern, is to subdivide a few waterways to be 'protected' from conservation programs.

Although I'm new to this field, I do understand the basics of population genetics, gene structure and functions, genetic algorithms, and evolutionary biology in a general way. I've also written a few artificial genetic algorithms. Unlike the general perception of particular gene functions either being present or not, on or off, more generally functionality come in degrees, which are balanced for a particular environment. When a particular function is lost evolution does not have mechanisms to return it, because evolution is stochastic and does not 'progress' according to any particular mechanistic sequence. Lost function becomes more like the turkeys we buy for thanksgiving, which can't even mate without artificial insemination. I don't want to end up with a trout population which is entirely dependent on fisheries just to be able to breed, or survive adolescents. Long term this is exactly what these practices can result in.

Genetic drift is normal and natural, and will occur with or without fisheries and artificial breeding conditions. Worrying about some genetic variability that creeps in through the fisheries is a non-concern, so long as this gene base doesn't effectively define the whole population. What is lacking in the fisheries, it appears, is to maintain within the gene pool of their breeders any requirement of a full life cycle survivability outside the fisheries, or even a base gene pool containing such a capacity. As if our fisheries are producing an invasive subspecies with artificial survival advantages, which then directly competes with natives in the food chain. There's no need in worrying about gene alleles originating in artificial fisheries being introduced to wild populations. This only provides genetic variability that can drive adaptations in the wild, as the less fit alleles tend to die out naturally. Only, with fisheries continuing to flood the environment with their specialized gene pool, the only thing that will die out (naturally) is fish capable of surviving completely independently of the fish hatcheries.

Fisheries should be required to reintroduce wild population genes back into their breeding stock every year. These fisheries are conservation programs. Not some private breeder developing some new prized Fancy Goldfish for the aquarium market. Hopefully I'm not being too naive thinking that agencies that turned my childhood hobby into a potential felony should take their own actions as seriously.

You're arguing against over 100 years of practice. In most streams they don't give a poop about native genomic adaptations, because they don't have to. And I'd guess that most license buyers don't either, which is what really drives this market. Under ESA or some other statutory mandate they'll care about it in very specific situations because they're either under court order to do so, or fear being under court order to do so. Personally I hope they just minimize the harm and cut the crap with introducing browns, etc., all over the place more than they've done so already.

Shame. And a major hit to credibility when imposing rules and penalties on the public.

Try to remember, back when state F&G depts were first conceived and implemented, they were specifically given one task - providing opurtunities for sportsmen. Conservation was not a concept that was important.
Even in the 21 century, in a progressive state like Ma, I recently heard [at a land acquisition talk] a F&G rep state that their job was to take care of hunters and fishermen. Specifically, in context, she said they do not give funds or support the purchase of land unless hunting and fishing will be allowed.
We have a Natural Heritage dept that cares for wildlife conservation, but they have no power over the much longer established F&G.

Also, understand that fishermen have a loud collective voice and provide through license revenue a big chunk of F&G's budget. Your average fishermen is not the least bit concerned with the issues we discuss here. They want lots of fish to catch. Period. They raise holy hale whenever they're told that can't do something they've always done and consider a Right.
In much of the northeast, if we didn't have introduced species to persue, we'd almost have to give up fishing all together.

The good news is, some states are coming around, often with the help [or lawsuits] of Trout Unlimited. The western states seem to be a bit ahead on the concept, at least partly because their habitat is a bit more intact compared to the east. Check out this site http://www.westernnativetrout.org/ to see what they have going on with over a dozen different species or subspecies. A top priority is changing stocking practices and poisoning out non-native or even genetically inferior natives.
Even here in heavily developed and compromised habitat Ma, some interesting things are happening. This project http://www.ma-ri-tu-...ve-Brookies.htm is very exciting to fishermen and anyone who love native trout. This project has had marked success and has attracted attention with conservationists around the country. The state is onboard and recently helped aquire more land for the project. http://www.ma-ri-tu-...-Expansion.html

edited to fix link

Thanks Mike. I've been reading till my eyeballs hurt trying to play catchup on these issues. My foundational understanding of ecology in a general sense ill prepared me to confront the state of the political situation. I have no problem with sportsman, or catering to them within reason, with the exception of those who want open and uncontrolled hunting. Hunting however doesn't happen to be a personal interest. Just like I have no problem with hobbyist collections, like I am interested in. The issues of hunters and collectors is dwarfed by habitat and general ecological issues. Yet these not only erode with the least resistance, but the effects are often not so tacitly blamed or offloaded on the hobbyist. Even taking the brunt of the legal consequences, while the same agencies imposing these penalties are violating the very policies they impose penalties for on the individuals. Intentionally or not it appears to often take on a legal structure as if it's a protection device for their business model, a legally protected monopoly.

I'm not trying to bash the honest efforts of many well intentioned people. When a bottled water commercial can propagate a myth that if you lived by a natural mountain stream then fresh water wouldn't be a problem, getting policies based on empirically sound data can be a problem in the public arena. It's more difficult to accept the personal limitations with such policy incongruencies, but the fundamental issues are too important to allow personal interest to dictate positions. I can't even legally keep a green anole, which there is no shortage of here by any stretch of the imagination, or a captive breed corn snake with a morphology that couldn't possible be mistaken for wild specimen. To a large extent this state limits people to keeping potential invasives. I can catch and keep a pet rattlesnake though, however I've yet to actually see one in the wild here.

Anyway I'm tired, and will continue educating myself tomorrow.

I can't even legally keep a green anole, which there is no shortage of here by any stretch of the imagination, or a captive breed corn snake with a morphology that couldn't possible be mistaken for wild specimen. To a large extent this state limits people to keeping potential invasives. I can catch and keep a pet rattlesnake though, however I've yet to actually see one in the wild here.

Anyway I'm tired, and will continue educating myself tomorrow.

I hear ya.
Not only can you keep a rattler, you're free to kill 'em or put 'em in buckets and bring 'em to a roundup.
And the bulldozers roll over everything unchecked.
Sorry for the derail.

At least the guy I met with a box of rattlesnakes in his truck for religious reasons is part of a small minority.....

Naw, it's all about money and a sometimes warped sense of "giving people what they want". The cynical defense would be that most hatchery introductions are caught or die quickly, but of course that's not really true.

I always assumed they were caught or die quick myself as the trout are stocked in spring and are easy to catch, later in the year you catch almost none. I assumed the big trout do not survive or reproduce at least not into the natural settings they are released into.

As opposed to the little native trout you can catch all year round but are tiny.

So they DO survive? If so where do they go and why do they become scarce later in the season?

I would guess that the low percentage who survive that long figure out to go to deeper, cooler water as temperatures increase, and then maybe they'll survive long enough to reproduce, even if not well adapted genetically to that specific environment.

They survive much better than most people think. Granted many state dump them into plenty of compromised streams where the survivors, called "holdovers" by fishermen, will die.
But when they go into streams that have deep pools and/or springs, they survive. Ironically, colonial era fieldstone dams which ruined so many of our native brookie streams actually provide refuge in the plunge pool below them dam where cold water seeps out from the bottom of the dam in summer. They get hard to find because the holdovers get smart. I can find holdovers, mostly temp resistent browns, 12 months of the year in the suburbs. Mostly though those waters are not suitable for reproduction. You have to go the western part of the state to the colder faster streams.
Breeding populations of stocked trout occur over most of the range of trout stocked waters. We have confirmed brown trout in Ma and I believe you have both brown and rainbows in NH.
In the western US, where brook trout are the exotic, populations of stocked brook trout have taken over many smaller streams and out compete and eat various threatened native trout. In fact, they are now being poisoned out of many streams to make room for natives. Go up and click on the link for western trout and read about some of they're projects.

Edited by mikez, 15 January 2011 - 10:02 PM.

On the survival rate issue, in the links mikez provided I noticed something strange the graph here at the bottom:
http://www.tu.org/at...dscapemedia.pdf

It graphs the hatchery and wild Steelhead trout returns in the Snake River Basin. The most important variable I don't know is the release rates variations of the hatcheries over these same years. To make sense of this data I'm going to have to make an operational assumption, i.e., the hatchery release rate is related to the return rate of hatchery Steelhead trout. If this assumption holds, then increasing the release rate of hatchery Steelhead trout results in an increase the the return rate of wild Steelhead trout.

Now the only way I know how to make sense of this is food chain dynamics and canabolism. If this is so, then the primary function of hatcheries are to provide a prey source to a system lacking a sufficient food chain. This would also explain why the initial hatchery returns in the 70s didn't result in a similar increase in wild returns, as the initial releases would have competed for the existing food base, till the food chain dynamics stabilized with the new hatchery fish. In fact crash of wild Steelhead trout below the 50k mark could reasonably be blamed on the hatcheries release increases. This would also explain the non-linearity in the release rates and return rates for of wild stock.

If the initial assumption holds, then in ecological terms the hatcheries are playing the ecological role of a monoculture beaver pond. Thus replacing the food chain with a system dependent on canabolism, with the primary food base provided by the hatchery and what microfauna the released fingerlings can catch before being eaten. This would indicate that hatcheries converted to sanctuaries for raising prey to support a food chain would be far more productive in maintaining healthy trout populations. Or better yet, to improve the ecology rather than release numbers. This would include beaver populations, with constraints.

I would like to have more data than what was provided. Given the assumption provided, the crossover in food system dynamics results in a wholly different dynamic that what a natural system would have. Thus merely shutting off the hatchery releases could result in a catastrophic food system collapse, like what appears might have happened when they presumably back off the releases in the 70s.

Does anyone have the actual release rate data, not just return data, for the Snake River Basin for those years?

Getting preety far off topic, but steelhead, spending as much time as they do in the ocean, are subjected a whole slew of variables stream trout never see. Also increased protection over the years affects return rates. Not really an answer, but all I got.

Getting back a bit toward the topic, after stating above "we have confirmed brown trout" spawning, I went back and checked Fishes of Massachusetts and saw that they documented wild brown trout spawning over most of the state where where native brookies should be. That's very depressing considering that at a guess, I'll bet brookies have been pushed back into the headwaters of those stream or eliminated altogether. That's why Gambusia was asking about the genetic strain of stocked fish in his original post.
FWIW, apparently we have several documented breeding rainbow populations as well which I didn't remember when I posted above.

Something encouraging that I'd heard before but saw in the TU link I posted above, is that the streams that still have breeding brookies in modern times seem to be genetically unique, not only from hatchery trout, but even from stream to stream. That's why I am so excited to have discovered breeding populations in the heavily developed suburbs of Boston. If they can hang on after thousands of years of human harvest [I found remains of native american weirs], not to mention the devestation of the last 300, maybe there's hope for the future.