200750000 - A New Aging Technique For Lake Trout and Northern Pikeminnow Using Allometric Relationships Between Fish Size and Otolith Mass

Sponsor: University of Montana

Short description: We propose to develop and test multiple regression age models for northern pikeminnow and lake trout using allometric relations between fish size and otolith mass.

Location: Mountain Columbia province, Flathead subbasin

Budgets: FY08: $86,644 | FY09: $28,596

Primary species:
Resident: Westslope Cutthroat
 Resident: Kokanee
 Resident: Northern Pikeminnow
 Resident: Bull Trout
 Resident: Lake Trout

Objectives

ObjectiveDescriptionSubbasin planStrategies
1. Develop age models for lake trout We propose to use lake trout from Flathead Lake to develop a cost effective, accurate multiple regression model to predict age by exploiting allometric relationships between body size and otolith mass. The criteria for cost effectiveness will be at least a 5 fold increase in ages determined per hour compared to conventional thin sectioning of otoliths for both species. The goal for model accuracy is length versus age relationships that lie within a 4% deviation of the empirical relationships when absolute values of deviation are averaged over all age classes. This goal applies to Flathead Lake fish captured from all three time periods and to fish captured in Lake McDonald. Flathead Bull Trout Objective BT4 strategy supported: Implement control of non-native fishes where found to be feasible and appropriate. Exotic lake trout are the primary introduced species of concern and efficient aging in needed to guide management.
2. Test otolith mass vs. fish size We propose to develop the use of otolith mass versus body size relationships for assessing changes in growth rate within the Flathead Lake lake trout population. Our objective will be the ability to detect a 5% change in growth rate at the mean TL as assessed by a power analysis using a sample of 100 fish per time period. Flathead Same as objective 1.
3. Develop age models for northern pikeminnow We propose to use northern pikeminnow from Flathead Lake to develop a cost effective, accurate multiple regression model to predict age by exploiting allometric relationships between body size and otolith mass. The goal for cost effective will be at least a 5 fold increase in ages determined per hour compared to conventional thin sectioning of otoliths for both species. The goal for model accuracy is length versus age relationships that lie within a 4% deviation of the empirical relationships when absolute values of deviation are averaged over all age classes. This goal applies to fish captured in Flathead Lake and the Clearwater Chain of Lakes. Columbia Gorge Large scale removal of pikeminnow is in place to reduce predation on juvenile salmonids. Suppression and monitoring of this species would benefit from the development of fast and accurate aging techniques.

Narrative

Recommendations

  • ISRP: Unranked
  • Council: Not fundable
  • BPA: Not fundable