Intra- and inter-seasonal trends in the growth and condition of broad whitefish from Pudhoe Bay, Alaska /
Daily length-frequency data were used to model in situ summer growth of age-1 broad whitefish, Coregonus nasus, from arctic Alaska. Growth for 1982 and 1985-1989 was approximated as piece-wise linear functions whose slopes were regressed against mean surface water temperature and salinity over desi...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1995.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=742161161&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Daily length-frequency data were used to model in situ summer growth of age-1 broad whitefish, Coregonus nasus, from arctic Alaska. Growth for 1982 and 1985-1989 was approximated as piece-wise linear functions whose slopes were regressed against mean surface water temperature and salinity over designated periods. Multiple regression analysis indicated that growth rate was significantly correlated to water temperature (P < 0.01) but not salinity (P 0.28). A linear function modeled the 6 years of growth data with a mean absolute error of 2.1 mm (SD, 1.5 mm) while a polynomial function modeled with a mean absolute error of 3.8 mm (SD, 3.0 mm). The model, parameterized with 1982 and 1985-1989 data, was used to predict summer growth of age-I and age-2 fish for 1990-1992. Comparisons of observed versus predicted weekly growth over 10 years yielded r = 0.789 (N 77; P < 0.01) for age-1 fish and r = 0.522 (N = 70; P < 0.01) for age-2 fish. The model predicted growth in 1991 and 1992 with mean squared errors (MSE) of 3.0 mm and 1.8 mm for age-1 fish and 6.5 and 21.2 mm for age-2 fish, but failed noticeably in 1990 for age-1 (MSE = 48.6) and age-2 fish (MSE = 29.9) fish. Data are presented suggesting trophic competition may have accounted for model failure. A hypothesis was also tested to determine if the condition of broad whitefish increases during summer in conjunction with increasing lipid and protein content, and decreases during winter as fish consume energy reserves. The condition of fish collected from 1988 to 1993 was indexed as their residual value relative to a single whole-population least-squares regression of loge weight against loge length. Lipid and protein content data collected from 1991 to 1993 were also examined. Mean residual value changed in the expected direction in 56 of 68 instances (P < 3.0e-7), while lipid content changed in the expected direction in 23 or 24 instances (P < 3.0e-6) and protein content changed in the expected direction in all 24 instances (P < 3.0e-7). |
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| Item Description: | Vita. "Major Subject: Wildlife and Fisheries Sciences". |
| Physical Description: | xi, 97 leaves : illustrations, maps ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |