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Addendum to James Suleski's Story "Pennsylvania Natives"

Links and sources for his article on watershed-wide management and why we need to stop stocking invasive species.

Addendum to James Suleski's Story "Pennsylvania Natives"

(Photo courtesy of James Suleski)

The following is an addendum to Dr. James Suleski’s sources for the story "Pennsylvania Natives: Disjointed habitat improvements won’t save PA’s brook trout, we need watershed-wide management and we need to stop stocking invasive species" in the April-May 2023 issue.


Welcome!

This page was created to connect those reading this article with a wealth of reliable and trusted sources of fisheries science information about native brook trout relevant to their management. You can quickly scroll through each topic reading take home points from publications  (in quotes) and context I have provided (not in quotes). Or click the link to each individual study/publication to read it in its entirety and take a deeper dive into a topic of interest to you.

Many of the below resources are links from the Eastern Brook Trout Joint Venture website. There is an enormous wealth of wild native brook trout fisheries science, restoration projects, mapping(many interactive GIS maps), and more featured on this site. I highly encourage you to browse the website and familiarize yourself with all it has to offer you for everything wild native brook trout conservation.  Also there are links to follow on facebook and twitter on the site for even more great content from them. 

https://easternbrooktrout.org/

Native Brook Trout Status and Threats

Native Fish Coalition FAQ/Terminology (wild, native, stocked)

Five Components of Streams Model

  • Stream Habitat Needs for Brook Trout and Brown Trout in the Driftless Area
    • Authors: Douglas J. Dieterman, and Matthew G. Mitrob
    • “Hydrology, water quality, connectivity, biotic interactions and physical habitat/ geomorphology regulate fish population abundance in streams. Management of only one component will be ineffective if another component limits the population”
    • “An important implication of the five-component approach is that management emphasis on only one component, such as restoring physical habitat/geomorphology, may still fail to protect and enhance fish populations if other components, such as water quality or biotic interactions, are also limiting to a population.”
    • Harmful interactions with invasive trout species are biotic interactions
  • Evaluating Trout Stream Restoration Benefits: A Case Study at Pine Creek, Wisconsin
    • Author: Kent Johnson
    • This case study I have shared is an unfortunate example of what can happen when one of the 5 components of streams model components, such as biotic interactions (invasive trout species), is not factored into a stream restoration project originally intended to help native brook trout by improving some of the other 5 components. In this example a stream project intended to help native brook trout actually helped brown trout reduce their numbers and may ultimately result in elimination of native brook trout  from the stream. 
    • “On average, pre-restoration trout abundance in Pine Creek was 3,991 trout/mile, with brook and brown trout present in a 96%:4% proportion.”
    • “Within eight years post-restoration, numbers of brook trout per mile decreased by 70% (3,800 to 1,200), while numbers of brown trout per mile increased by 3,150% (175 to 5,600). A continuation of this trend may lead to the loss of the brook trout fishery.”

Pennsylvania Wildlife Action Plan

  • Brook trout listed as a species of greatest conservation need in this plan developed in large by PA fish and boat. 
    • “Action: Remove brown trout in areas managed for brook trout. Objective: Reduce competition.”
    • Despite above recommended actions, PA does not have any invasive trout removal projects to date listed on a recent EBTJV summary chart detailing invasive trout removals and native brook trout reintroductions by state.

Eastern Brook Trout Joint Venture Brook Trout Related Publications

  • A large compilation of research shared with the general public online via EBTJV website that touches on many different topics related to conservation of native brook trout. 

The Troutlook

  • A science communication website built by brook trout ecologist and PhD Dr. Shannon White. It takes fisheries science concepts important to native brook trout conservation and translates them into language understood by the general public. 
  • “The purpose of The Troutlook is to take research an extra step and make it more accessible to the general public. We believe that conservation, while often guided by science, can only be enacted by the public. However, scientists do a poor job of fostering this partnership by hiding important information behind privacy walls and complicated jargon. We can do better.  In fact, we must do better. Brook trout, and countless other native species, are depending on us to get this right.” 

The Negative Effects of Stocking Invasive Trout Downstream of Brook Trout in Pennsylvania

Why Managing Entire Watersheds for Native Brook Trout, Not Just Stream Sections, is Critical to their Success

  • A novel quantitative framework for riverscape genetics
    • Authors: Shannon L. White, Ephraim M. Hanks, and Tyler Wagner 
    • “Accordingly, brook trout management efforts are rarely put into a metapopulation context, and the significance of conservation actions or disturbance events are generally considered to be restricted to a single stream. However, results of the BGR model question the validity of these assumptions for brook trout in Loyalsock Creek with results suggesting that mainstem Loyalsock Creek serves as a seasonal movement corridor that increases population connectivity across relatively large spatial scales. Consequently, changes in habitat suitability at one site can have significant, unintended consequences to large-scale metapopulation genetic structure and demography (Letcher et al. 2007). In addition, maintaining the ecological integrity of habitats that are only seasonally suitable for brook trout occupancy appears to be critical for maintaining gene flow and population connectivity in this system.”
  • Brook Trout Restoration
    • Authors: J. Todd & Eric P. Merriam
    • “Historically, most studies of brook trout population ecology have focused on isolated populations within relatively small headwater streams. There is emerging evidence, however, that brook trout population dynamics may be influenced by factors and processes operating at the drainage network scale (Petty et al. 2005, 2012). We have found that the factors limiting brook trout populations vary depending on the location of the focal population within the drainage network. For example, headwater stream populations may be strongly limited by acidification and reduced reproductive success. However, populations in medium sized streams are dependent on immigration from smaller streams, and consequently, may be limited by the productivity of nearby streams and by dispersal barriers. Finally, brook trout populations in larger rivers are fully dependent on highly mobile individuals that move between headwater spawning habitats and larger river foraging habitat (Figure 6). These populations can be strongly limited by poor habitat, high water temperatures, angler harvest, and dispersal barriers. If brook trout populations are influenced by watershed scale processes rather than localized stream segment scale processes, then it is likely that: 1 — factors limiting populations in one area will affect populations in another area; 2 — the overall metapopulation will be limited by multiple rather than single factors; and 3 — connectivity among subpopulations will be more important to population viability than local habitat conditions.“
  • DNR looks to enhance native brook trout waters
    • Author: Chris Lawrence, Metro News
    • Quote from biologist David Thorne of West Virginia DNR in regard to their watershed level brook trout management zones that are catch and release for native brook trout with no stocking allowed. 
    • “They need to be a large, contiguous and well connected native brook trout watershed,” said Thorne. “This is a watershed idea based on a lot of the research I and other people have conducted. Connectivity between the tributaries and main stems is how we see increased growth in fish. They have larger habitat, more food available, and can move to different habitats during different parts of their life cycle.”
  • The Upper Savage River Brook Trout Special Management Area – A Decade of Learning!
    • Authors: Maryland DNR
    • Details the success story of the Upper Savage River Brook Trout Special Management Area in Maryland. Here watershed level management with catch and release regulations and very little stocking has allowed the Upper Savage River Watershed native brook trout population to survive to 7 years old and grow into the mid-teens in inches.

Invasive brown trout exclude native brook trout from important resting habitat

  • Competition Between Brook Trout (Salvelinus fontinalis) and Brown Trout (Salmo trutta) for Positions in a Michigan Stream
    • Authors: Kurt D. Fausch and Ray J. White
    • “After brown trout removal, brook trout larger than 15 cm chose resting positions with more favorable water velocity characteristics and more often in shade. The position shift was greatest for the largest brook trout, those of 20-38 cm. Feeding positions of brook trout changed little upon brown trout removal according to our criteria. The shift in resting positions of brook trout after release from competition with brown trout indicates that brown trout excluded brook trout from preferred resting positions, a critical and scarce resource. The combined effects of such interspecific competition, differential susceptibility to angling. differential response to environmental factors, and predation of brown trout on juvenile brook trout may account for declines of brook trout populations while brown trout populations expand in many streams of the northeastern United States where the two species are sympatric. “

Research Demonstrating Invasive Trout Impair Brook Trout’s Ability to Use Critical Focal Cold Areas in the Stream During Warmer General Stream Temperatures

Research Highlighting a Relatively Small (Less than 1 degree Celsius) Difference in 7 Day Upper Lethal Temperature Limits for Brown and Brook Trout

Brook Trout Response to Invasive Brown Trout Removal

  • Demographic Responses of Brook Trout to Removal of Brown Trout from a Driftless Area Stream in Minnesota
    • Authors: John H. Hoxmeier and Douglas J. Dieterman
    • ”Brook trout abundance increased in lower Coolridge after brown trout suppression (2-way ANOVA interaction term, logtransformed; Age-0, P = 0.04; Adult, P = 0.01). The magnitude of response was greater in the lower reach compared to the upper reach of Coolridge Creek where few brown trout were present before removal efforts. Adult brook trout increased from a pre-treatment mean of 51/mile to 164/mile in lower Coolridge. Recruitment of age-0 brook trout was higher in lower Coolridge after brown trout removal, increasing from a mean of 67/mile to 326/mile. Abundance of both adult and age-0 brook trout steadily increased after the initial brown trout removal, and reached their highest levels at the end of the study”

Acid Mine Pollution Remediation Project in PA Stream Allows Brown Trout to Invade Brook Trout Stream Post Project and Eat a Large Amount of the Population (Video)

Habitat Restoration Projects-Invasive Trout Species Prevent Native Brook Trout from Benefiting from Them and Can Even Use These Projects to Reduce or Eliminate Native BrookTrout in the Stream

  • Non-native species limit stream restoration benefits for brook trout
    • Authors: Brock M. Huntsman, Eric R. Merriam, Christopher T. Rota,J. Todd Petty
    • "We used a joint species occupancy model within a BACI sampling design to show that brook trout occupancy of main stem habitat was highest post-restoration within restored sampling reaches, but this benefit to native brook trout was conditional on brown trout (Salmo trutta) not being present within the main stem habitat. Collectively these results indicate that habitat restoration was only beneficial for native brook trout when non-native trout were absent from the restored sampling area. Proactive approaches to restoration will be integral for supporting resilient ecosystems in response to future anthropogenic threats (e.g. climate change), and we have shown that such actions will only be successful if non-native competitors do not also benefit from the restoration actions.”
  • Non-native trout limit native brook trout access to space and thermal refugia in a restored large-river system
    • Authors: Cory T. Trego, Eric R. Merriam, J. Todd Petty
    • “Non-native trout consistently occupied more thermally suitable microhabitats closer to cover as compared to brook trout, including the use of thermal refugia (i.e. ambient–focal temperature >2°C). These results suggest that non-native trout influence brook trout use of restored habitats by: (1) displacing smaller brook trout from restored pools, and (2) displacing small and large brook trout from optimal microhabitats (cooler, deeper, and lower velocity). Consequently, benefits of habitat restoration in large rivers may only be fully realized by brook trout in the absence of non-native species.”
  • Evaluating Trout Stream Restoration Benefits: A Case Study at Pine Creek, Wisconsin
    • Author: Kent Johnson
    • This case study I have shared is an unfortunate example of what can happen when one of the 5 components of streams model components, such as biotic interactions (invasive trout species), is not factored into a stream restoration project originally intended to help native brook trout by improving some of the other 5 components. In this example a stream project intended to help native brook trout helped brown trout reduce their numbers and may ultimately result in their elimination from the stream. 
    • “On average, pre-restoration trout abundance in Pine Creek was 3,991 trout/mile, with brook and brown trout present in a 96%:4% proportion. ”
    • “Within eight years post-restoration, numbers of brook trout per mile decreased by 70% (3,800 to 1,200), while numbers of brown trout per mile increased by 3,150% (175 to 5,600). A continuation of this trend may lead to the loss of the brook trout fishery.”

Invasive Trout Species can Act as Barrier to Movement of Native Brook Trout Much Like a Poorly Passable Culvert

Hatcheries Themselves can Harm the Ecosystems that Native Brook Trout Live in. PA Fish and Boat Experiences an Outbreak of Invasive New Zealand Mud Snails that Could be Swallowed by Hatchery Fish and Transferred to New Waterways to Spread Where Stocked

  • Mudsnails found in two state hatcheries in central Pa., but trout stockings continue
    • Author: Brian Whipkey, York Daily Record
    • “The big concern? “They don’t need a partner to reproduce, so they reproduce asexually, each individual can produce a couple hundred offspring a year. It just takes one snail and it can really explode if the conditions are right,” Brian Niewinski, chief of the division of fish production services, said.”
  • Big Spring Creek in Cumberland County, Pennsylvania, gets a makeover for wild brook trout fishery
    • Author: Marcus Schneck, Pennlive.com
    • “According to Bill Ferris, who helped to launch the Big Spring Watershed Association in 2001 and was fighting for the restoration of the stream years before that, most of the amazing brook trout fishery passed out of its prime when the Pennsylvania Fish and Boat Commission built a fish hatchery at the headwaters of the stream in 1973. “When the hatchery came in, we lost the brook trout,” he said. “They crashed because of the high levels of phosphorus” discharged into the stream from the hatchery and the accompanying loss of oxygen from the water in the stream.
    • After years of often bitter debate and increasingly tougher discharge restrictions issued by the heavily pressured state Department of Environmental Protection, the commission closed the hatchery in 2001.The stream quickly began to heal itself and by 2008 the headwaters section again had a brook trout population of more than 350 pounds per acre of water, which rates it as one of the most productive brook trout streams in the country.”
    • How many brook trout populations in the state of PA would similarly greatly  benefit from hatchery closures? This is a topic we do not hear alot about in a state with a surprisingly high number of private and state run hatcheries.

A list of invasive trout removals and brook trout reintroductions by state 

  • Eastern Brook Trout restoration summary table
    • Chart displayed on Eastern Brook Trout Joint Venture (EBTJV) website
    • This chart on the EBTJV website illustrates PA is well behind many other states in terms of numbers of projects for native brook trout. PA has only one listed project for it’s state fish in the below link, a reintroduction of brook trout into Big Spring Creek where a PA Fish and Boat trout hatchery largely wiped out the original population necessitating this reintroduction. Big spring is still stocked with harmful hatchery brook trout to this day capable of causing harmful genetic pollution to wild native brook trout. Also wild invasive rainbow trout are still protected with regulations to this day in the upper big spring. The state of Pennsylvania has performed no known removal projects of invasive trout species to date and still stocks them in many brook trout streams and watersheds statewide. 

Pennsylvania Fish and Boat Commission Aquatic Invasive Species(AIS) Web Page

  • PA Fish and Boat’s AIS web page does not list brown and rainbow trout, currently stocked statewide, as an invasive species with a control plan. They are not mentioned at all despite their ranking in the International Union of Conservation of Nature’s top 100 world’s worst invasive species list, numerous publications documenting their invasion of native trout streams, current removal efforts in other eastern states because of invasion, and meeting the listed definition for invasive species featured on the commission’s AIS web page. 

Conservation Genetics, an extremely critical part of native brook trout management and conservation but largely unheard of by the angling public.

  • Scicomm webinar: development of a genetic baseline for brook trout in North Carolina
    • Webinar by NCWRC Biologist Jake Rash
    • Watch this video to understand the importance of conservation genetics and genetic diversity. (Skip in Webinar to 15 min 35 sec)
  • Brook Trout Genetics
    • Eastern Brook Trout Joint Venture
    • A sizable collection of research, videos and presentations about the importance of conservation genetics and how it can be used for reintroductions, genetic rescues, determining the health of populations and much more. 
  • STAC Brook Trout Workshop: Understanding Genetics for Successful Conservation and Restoration of Resilient Chesapeake Bay Brook Trout Populations
    • A link to highly informative presentations given by experts in native brook trout conservation genetics at this workshop to fisheries managers from different states. Good information included on the forces shaping native brook trout genetics in both positive and negative ways. Each gene a brook trout population has is potentially a different tool that can be used by brook trout to better survive their environment and the threats they face. If a brook trout population is genetically diverse, has more different genes, they have more tools to adapt to better survive a warming environment and  other threats.  Then if that population can move and share those genes with brook trout in another stream, a process called “gene flow”, it can potentially make other populations more genetically diverse as well by sharing all those survival tools. Large waterways are critical highways where this gene flow takes place. As mentioned  in one of the presentations from this conference, invasive trout can decrease gene flow  as pointed out by Casey Thomas Weather’s dissertation.  PA Fish and Boat currently stocks many large waterways connecting multiple brook trout streams across our state.
  • Are Hatcheries Bad for Brook Trout?
    • Author: Shannon White, Troutlook
    • The “Are Hatcheries Bad for Brook Trout?” section explains the dangers of stocked hatchery fish in terms of the negative effects of hatchery brook trout genes that are ill-suited for survival on wild native brook trout.

Brown and Rainbow Trout as an Invasive species: Research

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