Base de données de recherche des TNO

Régions: Sahtu Settlement Area, Dehcho Region

étiquettes: biology, fish habitat, fish, habitat assessment, spawning areas, conservation plan, management strategy

Objectif(s): Bull trout is an endemic North American freshwater fish from the Salmonidae family, which is distributed west of the continental divide in the northwest United States, throughout British Columbia, and north into the Yukon and Northwest Territories. Recently, the bull trout's southern range has contracted, causing concern among sport fishing groups, conservation organizations, and fisheries biologists. Local extirpation has been observed in the McCloud River, in three major tributaries of the Willamette system of Oregon, and in many tributaries throughout southeastern Alberta. However, populations existing in the northern range appear to be expanding north into the Yukon and Northwest Territories. Impacts that have contributed to the decline of southern bull trout populations include over-fishing, habitat disturbance from industrial activities (such as oil and gas exploration, seismic, forestry, and mining work) and interaction with exotic species. Unfortunately, little is known about populations occurring north of the 60th parallel. The proposed research intends to address bull trout management concerns in the Northwest Territories (NWT) from a habitat perspective. The project will study habitat requirements and availability for bull trout in the NWT focusing on appropriate habitat protection for oil and gas development in the region. Potential and existing environmental impacts on critical bull trout habitat (i.e., spawning, rearing, and feeding sites) will be assessed and compared. The information obtained will give habitat biologists the ability to identify and protect bull trout habitat effectively during oil and gas development. The information obtained will give fisheries managers in the NWT and Alberta a unique opportunity to compare undisturbed populations and their habitat in the north to disturbed populations and habitat in the south, and allow fisheries managers in both regions to formulate management strategies to conserve and protect bull trout in future.

Description du projet: Transportation to and from sampling sites will be provided by helicopter. Basic camping equipment will be set up for a few days in each sampling location for sleeping and eating during sampling. All fish captured will be tagged with colored tags (floy tags) and some (2-5) with radio-tags to identify fish movement and locate spawning sites. Fish will only be sampled to collect information on distribution throughout the region and basic biological data. All efforts will be made to ensure that fish are not harmed and that unnecessary mortality is avoided. A small sample of fish (5-10) will be sacrificed to confirm appropriate aging techniques and obtain biological data. Most sampling will involve measuring habitat parameters such as water velocity, substrate size, available cover, water temperature, groundwater flow, and gradient. Once bull trout absence or presence data have been collected, habitat in selected rivers and streams will be described according to substrate (i.e., sand, gravel, pebble, cobble etc.), water flow, water depth, cover (i.e., woody debris, undercut bank), and elevation. Each area studied will also be divided into riffles, pools, and glides. Stream and river reaches will be separated into appropriate stretches (i.e., 200 m) based on homogeneity of habitat. The total length of the river will also be considered and randomly sampled (eg., 10 m) throughout the selected area. Areas will be compared statistically based on presence absence data to attempt to determine habitat preferences of bull trout in specific areas. The public living throughout the potential bull trout range will be asked to report all species caught to the Department of Fisheries and Oceans conservation officers in the NWT. Sampling will be conducted between July 20/2001 and August 20/2001. Further sampling work will be conducted for 1-4 weeks during September and October.