Mainland Rivers Watershed Project - Taku River

Braided channels of the lower Taku River floodplain, evident from the air.

This project will continue efforts associated with the development and implementation of a research program aimed at assessing the relationship between salmonid production and freshwater habitats in the Taku River watershed. Application of tools and protocols that will advance our ability to incorporate salmonid habitat information with existing stock assessment programs and other sources of salmonid distribution, abundance and productivity within the Taku River will be paramount to success. The Taku River was selected as a study area for the next phase of work outlined in this Plan, and is based on input from potential collaborators, specific needs identified by salmon and salmonid habitat working groups, and its critical economic and recreational importance.

An arial view of a portion of the Taku River.

Identification of habitats important to salmonids within the Taku River watershed poses a significant hurdle, requiring information on each of the individual components before the larger issue of "importance" can be evaluated and assessed. These individual components include the location, characterization, and extent of habitat(s), as well as information identifying distribution patterns of salmonids.

True Color Image - 30cm pixel size

Thermal Infrared Image - 2.4m pixel size

Thermal Infrared Image - Image Classification automates identification of watered (blue) and non-watered habitats (brown and green)

To understand which habitats are important to salmonids, accurate identification of the fluvial, geomorphic, and riparian features in the Taku River project area must first be attained. This quantitative characterization of available habitats is difficult, given the extremely large size of the watershed and the associated logistical constraints. Remote sensing technology provides a means of acquiring information on landscape features (i.e., habitat) at geographic scales larger than would be possible with traditional surveys performed on the ground. Identification and the subsequent mapping/delineation of habitats is the first step towards elucidating salmonid habitat associations.

Outputs associated with the identification and mapping of habitats include highly detailed base maps generated from satellite imagery and low-elevation digital photography, and GIS data layers consisting of point, polygon, and polyline features, representing the location and extent of available habitats. The delineation of available habitats within the Taku drainage also provides a foundation to understand how habitats change over time due to natural succession and anthropomorphic effects.

Project biologist Jeff Nichols, collecting high-accuracy Ground Control Points on the Taku River

Three-image mosaic created from aerial photographs of Canyon Island, Taku River

Identifying distribution and use patterns of salmonids within the Taku River drainage will rely primarily on data generated during stock assessment activities. Collaboration with stock assessment crews therefore, is critical. Successful collaboration will include providing methodologies and equipment to stock assessment crews allowing the spatial identification of salmonid observations.