Multiple Limiting Factors and Restoration of a Brook Trout Metapopulation

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1 Multiple Limiting Factors and Restoration of a Brook Trout Metapopulation J. Todd Petty and Brock M. Huntsman Steve Brown (WVDNR), Paul Kinder (NRAC), TJ Burr (NRCS)

2 The Problem Extirpated from or highly reduced in over 50% of their native range. Exist as isolated, relict populations throughout much of the mid-atlantic. Acidification, harvest, warming, barriers, sedimentation, exotic species.

3 Shavers Fork near Cheat Bridge, WV WV Magazine Big Rivers Big Fish Brook trout from Blackwater River, WV circa

4 The Process of Restoration Specific Restoration Actions Monitoring & Adaptation Restoration Plan Foundational Knowledge Limiting Factors Goals & Objectives Re-introduction Liming Stream Channel Restoration Riparian management Barrier Removal Harvest control Exotic Removal Petty, J. T. & Merriam, E. P. (2012) Brook Trout Restoration. Nature Education Knowledge 3(7):17

5 Shavers Fork Headwater Tributaries Larger Tributaries Mainstem

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7 Foundational Knowledge Small tributaries represent source habitats within the Shavers Fork metapopulation. -> 80% all spawning occurs within streams < 3 km2 drainage area. -Spawning success is driven by acidification. -Food availability limits population size and individual growth. -Tributaries supply individuals to mainstem habitats (some more so than others).

8 Reproduction and recruitment is focused in small, alkaline streams (Petty et al TAFS) 1 km 2 = 250 acres

9 Acidification of Headwaters 80% of spawning habitat has been lost as a result of acidification. And much remaining habitat is isolated above culverts. Petty and Thorne Restoration Ecology Historic Current

10 28% 9% 19% 114% 51% 22% 4% 10% Gene Flow from tribs to mainstem

11 Important link between tributaries and mainstem sites

12 Foundational Knowledge Mainstems represent productive sink habitats. -No spawning occurs in the mainstem. -Inhabited by large, highly mobile individuals. -Used as both productive foraging habitat and as a corridor for dispersal among tributaries. -Mainstem populations are limited by the availability of thermal refugia.

13 Habitat Dependent Growth

14 Trout mobility and thermal refugia Petty et al TAFS

15 Limited Thermal Refugia in MS Fewer but larger fish during hot years Mean adult SL (mm) 200 Mainstem Mean April t -June t maximum temperature (ºC) Suggests superior fish controlling habitable microhabitat

16 6/1 6/8 6/15 6/22 6/29 7/6 7/13 7/20 7/27 8/3 8/10 8/17 8/24 8/31 Daily Feeding Hours Mainstem thermal regime Number of Hours < 21 0 C Second Fork 0 Day

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18 Restoration Plan Limiting Factor Action Effect Acidity Treatment of headwaters w limestone sand Increase spawning habitat and supply of brook trout from tribs to the mainstem Dispersal Barriers Replace culverts Increase links between source tribs and productive mainstem Thermal refugia Mainstem channel habitat enhancement Increase availability of thermal refugia increase carrying capacity during warm years.

19 Restoration Plan 1. Limestone Sand designed to maximize recovery of brook trout reproductive habitat LS 2. Culvert Replacement designed to link reproductive habitat in HW to foraging habitat in MS x LS LS 1. Natural Stream Channel Design designed to provide thermal refugia and foraging microhabitats and link Rocky Run to Second Fork. x x LS LS

20 Limestone sand treatment Start of Treatment

21 Upper Shavers Fork Watershed Beaver Creek Lamothe Hollow Oats Run

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23 Lamothe Hollow Oats Run

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26 Oats Run

27 Isotopes and assessing connectivity

28 Mainstem Restoration

29 Post-Restoration Pre-Restoration

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32 Key Conclusions If populations are structured as metapopulations rather than fragmented isolates, then: 1.Dispersal matters as much or more than habitat quality. 2.Restoration actions in one area will affect populations in another. 3.Populations are likely limited by multiple factors operating over multiple locations.

33 Brook trout Channel Unit Use Predicted abundance IGR IGRRC LGRGC SPC STRUCTURE Distance from nearest Source (m)