Use this URL to cite or link to this record in EThOS:
Title: Fecundity in relation to variation in life history of Salmo trutta L. in Scotland
Author: Walker, Andrew Forret
ISNI:       0000 0001 3551 4229
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 1994
Availability of Full Text:
Access from EThOS:
Full text unavailable from EThOS. Please try the link below.
Access from Institution:
The reproductive characteristics of a wide range of freshwater-resident and anadromous Scottish forms of Salmo trutta were examined. A total of 653 females were sampled from 27 wild and two long-term domestic populations covering a fork length range of 116-725mm. Total fecundities of the wild fish were 51-5952 eggs. Egg diameters ranged from 3.6 to 6.4mm. Gonadosomatic indices ranged from 5-26%. The youngest females were 2+ years. Trout from fast-growing populations matured earlier and were shorter-lived than slow-growing trout. Regression equations for the relationship between body size and fecundity and egg diameter are provided for the national data set and for individual and grouped populations. Significant differences in fecundity and egg diameter were found between populations. After standardisation to a common body length, fecundity and GSI were found to be positively and egg diameter negatively correlated with trophic status of the water bodies and with early growth rate. The domestic populations provided the overall highest relative fecundities and smallest egg diameters. Fecundity of wild trout was negatively and egg diameter positively correlated with latitude. There was no relationship with numbers of other fish species present. Above-falls trout were short-lived, yet had high relative fecundity and small egg size. In these populations, age was more important than length in determining egg diameter. The rate at which maturity is reached, varying between populations, may be more important than absolute growth rate in determining fecundity and egg size. Lifetime eggs per female and instantaneous production by 1000 females were estimated for individual populations. The significance of the estimates for the River Ewe System in north west Scotland, an area of recent sea trout population decline, is discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Trout; Reproduction