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The early life history and ecology of Columbia Lake burbot Taylor, Joshua L.
Abstract
This thesis examines aspects of the early life history and ecology of the Columbia Lake burbot population in southeast British Columbia. Growth was examined using otoliths from burbot sampled in shoreline habitats, a recreational ice fishery, and the spawning population. Columbia Lake burbot begin to recruit to the fishery, and no longer inhabit shoreline habitats, by age 2 or 3 (39 cm in length). The mean density of age 0 burbot per km of shoreline on 12 sites sampled from 1997 to 1999 ranged from 400 in 1997 to 62 in 1999. This suggests that recruitment is not seriously depressed and, thus, the decline in the burbot population may be best explained by changes in environment that affect post settlement life stages. Recruitment, as estimated by shoreline surveys of juvenile abundance and the age distribution of adults in the fishery and spawning population, varied greatly among cohorts. This variation is not well explained by spawner numbers and, presumably, is partly driven by environmental fluctuations. Reduced lifespan, as occurs with decreasing latitude and increasing fishing pressure, should reduce the survival of adults over periods when conditions are unfavorable for recruitment and, thus, reduce population stability. Egg development and early larval life were investigated under laboratory conditions. Egg survival peaked about 3°C and all embryos died at temperatures above 6°C. This narrow temperature tolerance during incubation may cause density independent mortality, especially when egg incubation temperatures are variable and borderline for survival. The minimum time to hatch at 5, 4, and 3°C was 28, 32, and 38 days, respectively. Newly hatched larvae averaged 3.47 mm in length and were positively phototactic. The mouth and swimbladder form between 5 and 10 days after hatching. After 27 days (mean length 4.25 mm) all larvae were neutrally buoyant and feeding exogenously. Habitat use by juvenile burbot was modeled statistically. Juveniles use crevices, especially the interstitial spaces between substrate particles, as cover. Because much of the shoreline habitat suitable for juvenile burbot is above water from late fall to early spring, competition for cover may regulate recruitment in Columbia Lake.
Item Metadata
Title |
The early life history and ecology of Columbia Lake burbot
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2001
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Description |
This thesis examines aspects of the early life history and ecology of the
Columbia Lake burbot population in southeast British Columbia. Growth was examined
using otoliths from burbot sampled in shoreline habitats, a recreational ice fishery, and
the spawning population. Columbia Lake burbot begin to recruit to the fishery, and no
longer inhabit shoreline habitats, by age 2 or 3 (39 cm in length). The mean density of
age 0 burbot per km of shoreline on 12 sites sampled from 1997 to 1999 ranged from 400
in 1997 to 62 in 1999. This suggests that recruitment is not seriously depressed and, thus,
the decline in the burbot population may be best explained by changes in environment
that affect post settlement life stages. Recruitment, as estimated by shoreline surveys of
juvenile abundance and the age distribution of adults in the fishery and spawning
population, varied greatly among cohorts. This variation is not well explained by
spawner numbers and, presumably, is partly driven by environmental fluctuations.
Reduced lifespan, as occurs with decreasing latitude and increasing fishing pressure,
should reduce the survival of adults over periods when conditions are unfavorable for
recruitment and, thus, reduce population stability. Egg development and early larval life
were investigated under laboratory conditions. Egg survival peaked about 3°C and all
embryos died at temperatures above 6°C. This narrow temperature tolerance during
incubation may cause density independent mortality, especially when egg incubation
temperatures are variable and borderline for survival. The minimum time to hatch at 5,
4, and 3°C was 28, 32, and 38 days, respectively. Newly hatched larvae averaged 3.47
mm in length and were positively phototactic. The mouth and swimbladder form
between 5 and 10 days after hatching. After 27 days (mean length 4.25 mm) all larvae
were neutrally buoyant and feeding exogenously. Habitat use by juvenile burbot was
modeled statistically. Juveniles use crevices, especially the interstitial spaces between
substrate particles, as cover. Because much of the shoreline habitat suitable for juvenile
burbot is above water from late fall to early spring, competition for cover may regulate
recruitment in Columbia Lake.
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Extent |
6738965 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-07-29
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0099526
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2001-05
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.