| Report Documents
|
|
|
| |
| Map Plotfiles
|
-
No files of this type available
|
| |
| Data Files
|
-
No files of this type available
|
| |
| Digital Map Files
|
-
No files of this type available
|
| |
| Image Document
|
-
No files of this type available
|
| |
| Video Files
|
-
No files of this type available
|
| |
|
All Documents
|
|
|
| Contact
|
|
-
If you have any questions on the information presented, or require additional report data or attachments, please contact the Report Contact
|
|
|
|
Author: John Hagen
|
|
|
Date Published: May 2008
|
Report ID: 49483
|
Audience: Government and Public
|
Lacustrine populations of large-bodied, piscivorous rainbow trout in British Columbia are relatively small, and highly vulnerable to exploitation pressure. Babine Lake sport fisheries and a First Nations gillnet fishery have for many years targeted a population of large rainbow trout whose natal stream is the Sutherland River at the lakes southeastern end. Because the current status of this population is unknown, the British Columbia Ministry of Environment in 2008 initiated a population monitoring study. Monitoring of spawner abundance is not currently feasible, so juvenile rearing habitats of the Sutherland River system were sampled instead using electrofishing in enclosed sites. To increase sampling efficiency, a single-pass electrofishing methodology was employed, with first-pass catches calibrated against three-pass removal abundance estimates at a portion of the total number of sites. Electrofishing sites included those approximate locations sampled during a baseline inventory study in 1988, to increase the power of comparisons across the twenty-year time gap. Juvenile rainbow trout dominated electrofishing catches at all locations. Based on the age structure of the sampled population, the dominant age of lake entry appears to be age-3, with a small number of precocious male parr remaining in the system for a fourth year. First-pass capture efficiency, relative to three-pass abundance estimates at calibration sites, was high and relatively precise across the most commonly sampled age classes 0+ to 2+. Juvenile rainbow trout production, from the portion of the system that could be electrofished effectively, was generally comparable to 1988 estimates (22,901 versus 20,484 for age-2+ parr in September 2008 versus September 1988, respectively), suggesting either comparable levels of brood spawner abundance or density-dependent population regulation resulting from adequate seeding of juvenile rearing habitats. These results are consistent with the notion that the populations status is not greatly degraded relative to 1988, but increasing confidence in this conclusion will require additional years sampling data. Comparisons of empirical density estimates with modeled predictions of maximum density were less clear. Good agreement was exhibited between sampling data and predictions from a general salmonid model of maximum density based on fish size and total alkalinity (within 4%), but estimated maximum density was only 61% of predictions from a more recent model developed for coastal cutthroat trout streams.
|
Report Type
| |
Fish and Aquatic Habitat Information |
| |
Subject
| |
Fish Species - Rainbow Trout - Oncorhynchus mykiss |
| |
Region - Skeena |
| |
Fish and Fish Habitat - Research |
| |
|
|
