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Title: Aspects of the ecology of the brown trout (Salmo trutta L.) in relation to management of the fishery on the River Don, Aberdeenshire
Author: Shields, Brian Alexander
ISNI:       0000 0001 3405 7476
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1996
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Juvenile trout were found predominantly in the tributaries while older trout and juvenile salmon were found predominantly in the main river. Localised reductions in juvenile salmonid abundance in relation to the degradation of the stream habitat were demonstrated. HABSCORE habitat evaluation models appeared to be reasonably accurate in predicting juvenile salmonid numbers. The recruitment of juvenile trout from a tributary into the main river during spring was assessed by trapping. Predictive models based on environmental parameters accounted for 64% and 78% of the variation in the timing of migration of brown trout and trout smolts respectively. The fecundity of adult sea and brown trout was significantly and positively correlated with the fork length and the somatic weight of the female. Fecundity at a standardised body length varied between the brown trout and sea trout. Survival to hatching, of planted trout eggs was high at sites in the upper part of the catchment but was relatively low at sites in the mid and lower catchment. Low survival rates appeared to be related to a high degree of infiltration of fine organic sediments. Displaced trout failed to return to the home site. Home range estimates were less than 20 metres of stream. Large numbers of small trout were taken by anglers in the past. Recorded catches have decreased since 1980 while the mean weight has increased. Fishing effort was shown to be the most important determinant of catch. A small percentage of the anglers accounted for a disproportionately large percentage of the total catch and fishing effort. The age structure diversity of the catch was reduced in areas where the fishing effort was high.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Aquaculture