Water Stewardship Information Sources

Citation Balke, JME, Tschaplinski, PJ, Crockford, SJ and Suther, G. 1998. River Otter predation on juvenile salmonids in winter: Preliminary report of the otter scat collection and diet analysis. In: Hogan, D.L., P.J. Tschaplinski, and S. Chatwin (Editors). B.C. Min. For., Res. Br., Victoria, B.C. Land Manage. Handb. No. 41.
Organization FLNRO
URL https://www.for.gov.bc.ca/hfd/pubs/docs/Lmh/Lmh41.htm
Abstract/Description or Keywords Several creeks in the Queen Charlotte Islands,
British Columbia have been identified as sites where
the rates of river otter (Lutra canadensis) predation
on overwintering juvenile coho salmon (Oncorhynchus
kisutch) and rainbow trout (O. mykiss) might
be high. A study was undertaken in six watersheds
on Graham and Moresby islands to determine the
presence or absence of river otters, to assess the
feasibility of collecting analyzable river otter scats in
winter, and to identify river otter prey species from
scat analysis.
Over 500 river otter scats were collected from
seven creeks during surveys in November 1992 and
February 1993. The November sampling period
corresponded with the end of salmon spawning runs
and bones of adult salmonids were found in scats
from all creeks and shorelines. In February, when
spawning salmon were unavailable, the scats
contained bones from salmonids as well as 19 other
freshwater and marine fish species/genera. River
otters using these creeks were also foraging in the
ocean. Juvenile salmonid bones were found in the
scats from four creeks in November and from all
creeks or adjacent shorelines in February. Fresh
samples of at least 97 scats, collected in February
from four river systems, contained 347 salmonid
otoliths. Ninety-three percent of these otoliths were
between 1.5 and 2.5 mm long.
This study confirmed that river otters use these
river systems in the Queen Charlottes during winter
and that, despite the adverse weather conditions,
river otter scats can be readily collected and the prey
species determined. To further quantify the impact
of river otter predation on overwintering slamonids,
a more detailed study of river otter populations in
these watersheds would be required.
Information Type abstract
Regional Watershed Coast Region
Sub-watershed if known
Aquifer #
Project status complete
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