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Estimating the relationship between sea lamprey-induced mortality onlake trout and observed marking rates

We will estimate the relationship between sea lamprey-induced mortality on lake trout and observed marking rates in the upper Great Lakes. We will do this by modifying existing lake trout stock assessment models so that the relationship is estimated at the same time other parameters of the assessments are determined. We will explore whether the data support current assumptions used in assessment models based on laboratory derived estimates of lethality and healing and an assumption that sea lamprey-induced mortality is directly proportional to attack rates inferred from marking statistics. Our suggested approach takes advantage of the existing assessment models to adjust for effects of fishing on the relationship, and of recent contrasting temporal patterns in marking rates among lakes.  In more detail our methods are as follows.  (1) Existing statistical catch-at-age models used to assess lake trout abundance and mortality in 1836 treaty waters of Lakes Huron, Superior and Michigan will be modified so that the parameters of all the models will be estimated simultaneously.  These models currently assume a known direct proportionality between marking rates and the sea lamprey component of natural mortality.  This approach will first be replaced by allowing the proportionality constant to be estimated at the same time as all other parameters in the assessment model.  We will then explore model variants for which the proportionality constant is allowed to vary by lake or region within lake, or for which the proportionality assumption is replaced by a curvilinear relationship.  In this process we will use a Bayesian approach and evaluate evidence in favor of different hypotheses based on posterior distributions and the Deviance Information Criterion, an information theoretic model selection approach.Although of critical importance, much uncertainty remains about the relationship between damage caused by sea lamprey on host populations and observed host marking statistics (see sea lamprey assessment theme and draft damage theme cited therein (Ebener and Christie July 2  4 draft)).  This proposal addresses the first research need expressed in Ebener and Christie in a draft damage theme paper for the GLFC to replicate the earlier analysis of Koonce and Pycha that relates sea lamprey marking to lake trout mortality.

Status
In progress
Type
Project
Start Date
End Date
Researchers
Travis BrendenPrincipal Investigator
Associated with 5 projects
James BenceResearcher
Associated with 5 projects
Agencies
Great Lakes Fishery Commission $ 36,296.00USDActual

Funding 54 projects for a total of $5,089,137.00
Scope of Study
Literature / Existing Data
Theoretical
Scale of Phenomena
Community
Organism
Population
Impact of Pollutants
Exotic Species
Processes
Natural Ecological Processes
Resource Management
Fisheries
Lake Basin Connecting Channels
Lake Huron
Lake Michigan
Lake Superior
State Province
Michigan
Annex Numbers
Research & Development
Annex 17
Impact of water quality and AIS on fish and wildlife populations and habitats
General
Annex
  • Annex Numbers
    Annex Numbers
    Research & Development
  • Annex 17
    Annex 17
    Impact of water quality and AIS on fish and wildlife populations and habitats

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