Brook Trout Life History: a paucity of diversity

Brian MorrisonFisheries Biologist

Ganaraska Region Conservation Authority

November 19, 2015

Outline

• Historical narrative of Brook Trout• Importance of life history diversity• Preliminary Results• Recommendations/Implications

Historical Context

• 1796 - Small red-trout (brook trout) (S. fontinalis) were caught through holes in the ice on the Don River at Castle Frank (January 23rd)

• 1832 - Brook Trout were so plentiful, they were caught with a bucket in Orono Creek (tributary of Wilmot Creek)

Newcastle Hatchery

• First Government hatchery in Canada built on Wilmot Creek in 1876 by Samual Wilmot

• Reared Atlantic Salmon, Brook Trout, Whitefish, Lake Trout, and Chinook Salmon

Wilmot’s Observations

• 1879 – “speckled trout must soon become a luxury of the past in the older and more cleared sections of Ontario”

• 1881 – “…the time is gone by forever for the growth of salmon and speckled trout in the frontier streams of Ontario”

• 1884 – Wilmot’s hatchery closed

Historical Context

• 1914 Fish and Game Annual Report

• 1974 Ganaraska R. Creel

Background

• A belief that Brook Trout are headwater specialists in southern Ontario• Managers have followed the ‘shifting baseline syndrome’, truncating abundance and life history diversity

Background

• Life history shaped by interactions– Genotype– Individual condition (e.g. size, growth rate,

energy stores)– Environment

• Extend of diversity has implications for:– Population viability– Influence on abundance– Intra-interpopulation diversity, resilience,

structure and productivity

Kendall et al. 2015

Background

• Four pillars of resiliency– Abundance– Spatial distribution– Productivity– Diversity (life history, genetic)• Tie in with Portfolio Effect (PE)• Biocomplexity thought to stabilize spatio-temporal

variance of population1

• Linkages between life history diversity and popn

stability21 Schindler et al. 20102 Moore et al. 2014

Background

• Four pillars of resiliency– Abundance– Spatial distribution– Productivity– Diversity (life history, genetic)• Tie in with Portfolio Effect (PE)• Biocomplexity thought to stabilize spatio-temporal

variance of population1

• Linkages between life history diversity and popn

stability21 Schindler et al. 20102 Moore et al. 2014

Methods

• Scale samples collected from 2013-2015• n=10 scales • Individuals ≤ 120mm excluded; focus on adults • All fish captured via backpack electrofisher during

annual index efishing stations, and supplemental shocking

• Length, sex, and weights also recorded

Study Site

• Wesleyville Creek– 9 km2 watershed– Typical suite of historic landuse abuses– Current issues include watershed

fragmentation and sediment loading– Periodically cut off from Lake Ontario– No history of Brook Trout stocking– Work conducted on OPG portion of watershed

Results

Results

Results

4

5

6

7

1,6 - Wesleyville Creek2,4,7 - Cobourg Creek3 - Portage Creek – Lake Superior5 – Wilmot Creek

Results

1,6 - Wesleyville Creek2,4,7 - Cobourg Creek3 - Portage Creek – Lake Superior5 – Wilmot Creek

ResultsIndicator General Scoring Rules Score AssignedPopulationViability

5 = Highly viable, exhibiting highproductivity or abundance4 = Above average viability3 = Moderate productivity andabundance2 = Below average viability1 = Critically low viability

2.5

HatcheryInfluence

5 = > 95% 4 = 75 ‐ 95%3 = 50 ‐ 74%2 = 25 ‐ 49%1 = 0 ‐ 24%

5

Life historydiversity

5 = All life history strategies present 4 = Robust, multiple, &/or rare life histories, representing majority of historical3 = Few life histories present andmodest representation of historical2 = Few life histories present andsignificantly simplified from historical1 = Extremely simplified or single life history strategy

2

Total Scoring 9.5

Discussion

• Narrow breadth of life history diversity– Likely loss of historical suite of traits– Popn may be susceptible to environmental

stochasticity, perturbations, etc.• Mark-Recapture would facilitate PVA• Expand scope of project to explore PE

Discussion

• Work towards habitat restoration that facilitates processes to rebuild diversity

• Examine exploitation as a plausible effect on population dynamics Power 1980

• Jon George, Jon Tost – North Shore Environmental Services

• Nick Jones, Sarah Hogg - OMNRF• Gerry McKenna, Lindsay Parks - OPG

Acknowledgments/Questions?