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Report: 2003 Arctic Graylin (Thymallus arcticus) fry surveys in the Ingenika River
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- 2003 Arctic Grayling (Thymallus arcticus) Fry Surveys in the Ingenika River
The objectives of the Ingenika River study were to: determine the distribution and relative abundance of Arctic grayling fry; identify critical habitats (spawning and early rearing areas) for habitat protection purposes; and compare habitat use with those found in other areas to assess consistency of habitat selection in different drainages.
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The objectives of the Ingenika River study were to: determine the distribution and relative abundance of Arctic grayling fry; identify critical habitats (spawning and early rearing areas) for habitat protection purposes; and compare habitat use with those found in other areas to assess consistency of
habitat selection in different drainages.
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Author: Cowie, D.M.; Blackman, B.G.
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Old Reference Number: PWFWCP Report No. 291
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Old Reference System: FWCP Fish Wildlife Compensation Program Peace
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Date Published: Apr 2004
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Report ID: 39972
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Audience: Government and Public
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Arctic grayling (Thymallus arcticus) were once widely distributed throughout the Williston Watershed. Evidence now suggests that over the past few decades, populations of grayling have declined (Northcote 1993). Many studies are currently being conducted to try and determine the status of the species. As part of these ongoing investigations, annual surveys are being conducted on major tributary streams of the Williston Reservoir to assess Arctic grayling distributions, relative abundance and identify critical habitats (spawning and early rearing areas).
In August 2003, the Ingenika watershed was examined to determine Arctic grayling fry distribution and habitat use of the mainstem and tributaries. Backpack electrofishing was used to look for the presence/absence of grayling fry. Angling data was used to assess adult distribution. The Ingenika River is 143 km in length with a drainage area of 5,491 km2. Limited resource extraction activity has taken place in this drainage. Road access is possible only in the lower 36 km of the Ingenika River.
Ninety-five electrofishing sites were examined and 198 Arctic grayling fry were captured from 33 of the sites. No grayling were caught in any of the tributaries sampled. No barriers were identified on the Ingenika River in the area surveyed. Although a small pool cascade exists at km 96, adult grayling were angled upstream of this location.
Grayling fry caught were captured from a 76 km section of the Ingenika mainstem (km 2.4 - 78.4). Within the 76 km section, there were 28 grayling fry captured per km of shoreline sampled (7,000 m sampled in 49 sites). Eighty-two percent of the grayling fry were captured from isolated pools, backchannel or sidechannel habitats. Two sections of multi-channel braided areas (a 29.3 km section of the 76 km grayling distribution area) yielded 138 of the 198 grayling fry caught. This area appears to be the core grayling fry rearing area.
Substrate did not appear to be a factor in site selection for fry as seen in other systems, such as the Table and Anzac Rivers (Blackman 2002c). Rearing location is frequently a function of spawning habitat preferences as fry tend to remain near spawning areas (Armstrong 1986, Blackman 2002a).
The number of Arctic grayling fry captured per unit length from the Ingenika River (28 fish per km in 76 km) was slightly higher than the Omineca River (19 fish per km in 182 km). The multichannel braided habitat of the Ingenika appears to support a higher density of fry, rather than fish being distributed throughout the system as was found in the Omineca (Cowie et al. 2003).
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Report Type
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Fish and Aquatic Habitat Information |
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Subject
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Fish Species - Arctic Grayling - Thymallus arcticus |
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Region - Omineca |
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Fish and Fish Habitat - Fish Inventory |
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Fish and Fish Habitat - Habitat and Stream Assessment |
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Watershed Groups - 230 - Peace River |
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