Several years ago, a professor at Chatham University reached out about the concept of using native brook trout in their aquaculture lab to serve the dual purpose of teaching students about rearing coldwater species for food and using the resulting offspring as seed stock to restore reclaimed brook trout waters in Pennsylvania. We engaged the Pennsylvania Fish & Boat Commission to see if there were any potential restoration projects in the state to which this concept could be applied and were effectively told there were none. So, the project died on the vine.
I mentioned in my last post that the EBTJV had compiled a list of all the reclamation projects for brook trout in their eastern native range. The results of that survey are here: https://easternbrooktrout.org/science-data/ebtjv-assessment-data/eastern-brook-trout-restoration-summary-table/view. As I mentioned previously, Pennsylvania has only carried out two reintroduction projects to date (unless more have happened since that list was compiled). I am concerned about the Big Spring project as I strongly suspect that the state simply used a hatchery strain of brook trout for that project. Effectively, it was just a stream stocking rather than a restoration, though I’ll admit it’s pure speculation without any concrete answer from the state. The state has maintained brook trout stocking on Big Spring since the closure of the hatchery there, and I know that the fish they’re using are from the Huntsdale state fish hatchery and they’re produced using the same production technique used for any other put-and-take trout at the hatchery (mass produced from limited hatchery source stock).
Meanwhile, in West Virginia, the WVDNR has raised genetically appropriate wild-sourced native brook trout in a special hatchery they built at one of their fish hatcheries. The hatchery-reared offspring of these “heritage” strain brook trout are stocked in reclaimed or restored brook trout streams across the Mountain State.
Brookiebum produced a great video where WVDNR staff explained the purpose of the hatchery, gave a tour of the operation, and gave an example of reintroducing the genetically appropriate native brook trout to a stream.
I can support this kind of hatchery use, and I can’t commend WVDNR and other states enough for their focus on brook trout restorations and reclamations.
While monitoring online news about brook trout, I found an article about Minnesota’s efforts to maintain and restore native brook trout in the driftless region. According to the Minnesota Volunteer Conservation Magazine article, Minnesota DNR is now using a genetically appropriate “heritage” strain in its hatchery system. From the article:
Through the early 2000s, DNR researchers sampled the genetics of brook trout in the Driftless and identified a lineage of “heritage” brook trout in some small headwaters streams that didn’t share ancestry with the brook trout that had been stocked in the area. This suggested that these were remnant populations of native Minnesota trout.
https://www.dnr.state.mn.us/mcvmagazine/issues/2024/may-jun/dispatch.html
The paper published based on their research is here: https://apps.dnr.state.mn.us/volunteer_index/api/v1/article_pdf?id=8495, which is an interesting read.
While using “heritage” strain brook trout in the hatchery system is better than using whatever source stock strain they had been using before, I still have some concerns about the fitness of the resulting fish. Research has shown that fitness is reduced in as little as one generation in a hatchery environment.
When reproductive success of these two types of hatchery fish were compared with that of wild fish (rather than with that of each other), the relative fitness of the first generation fish was 70–88% and that of the second generation fish was only around 30% (Table 1). Again, differences between wild-born and hatchery-born individuals are confounded by the different environments they experienced, but the substantial difference between first and second generation hatchery fish suggests a rapid and cumulative genetic effect of hatchery culture during the first few generations of captive rearing.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3352433/#:~:text=When%20reproductive%20success%20of%20these,few%20generations%20of%20captive%20rearing.
This is where the WVDNR approach is far superior in spawning wild (F1) fish and rearing the offspring to fingerling size for reintroduction to the wild. The MNDNR approach seems to use the F1 fish but then hold them back as broodstock in the hatchery environment. In theory, while more genetically appropriate to the driftless region, the resulting fish will be less fit than if they were spawned from wild fish.
Regardless, it’s good to see fisheries managers working to limit the impact of hatchery brook trout on wild trout populations by researching population genetics and using more genetically appropriate source stock. More broadly, it’s great to see the focus on brook trout and their survival success as opposed to creating purely temporary fisheries that exist for put-and-take only.
It would be great if Pennsylvania implemented any of these approaches to brook trout management. Recently, Pennsylvania has reduced the number of brook trout raised in the state hatcheries and transitioned to more rainbow trout. You can read about the justification for this HERE. The document suggests that they eliminated brook trout stockings because they tended to be the first species to leave an area after they were stocked. However, they note the potential impacts of stocking brook trout over top of wild native brook trout, such as disease introduction and introgression (genetic pollution by hatchery stock breeding with wild native brook trout in the wild).
One use case where an approach somewhere between WVDNR’s conservation hatchery and MNDNR’s “heritage” strain source stock would likely be beneficial is Big Spring in Cumberland County. Since the PFBC continues to stock Big Spring with brook trout, they could have at least used source stock from the stream or researched nearby populations’ genes to find a more appropriate strain to stock there.
More importantly, though, Pennsylvania should have a conservation hatchery and should be attempting to restore and/or reclaim more streams in Pennsylvania. It’s part of the Chesapeake Bay agreement’s brook trout goal of increasing brook trout populations by 8% by 2025. A goal that we’re failing to achieve and could possibly reach by creating a conservation hatchery for brook trout and restoring/reclaiming more streams.
