Juvenile fish surveys

Lee Hastie, Adrian Hudson, Robert Laughton & Willie Shearer: March 2008

A short report on the status of eels (Anguilla anguilla) in four major river systems (Dee, North Esk, South Esk and Spey) in the Cairngorms National Park (CNP) was prepared for the park authority (CNPA). This comprised a short literature review of the trophic ecology of eels in freshwater ecosystems and preliminary analyses of historical eel data recorded opportunistically during electro-fishing surveys for juvenile salmonids. In terms of overall biomass and distribution, A. anguilla is probably an ecologically important species. Eels are widely distributed in the CNP, occurring in a number of major catchments. Significant changes in the status of eels at different sites may have occurred during a 20 yr period. At present, however, very little is known and, in consideration of the recent catastrophic decline in the numbers of elvers returning to European rivers, it is very important that targeted scientific research is carried out on the status and ecology of eels in the Cairngorms National Park as soon as possible. Any change in the status of eel populations in the freshwaters of the Cairngorms is likely to impact local salmonid stocks in some way and studies should focus on this relationship. In addition, the impacts on other species that utilise eels as part of their diet should also be examined further.

R Laughton

Fisheries Research Report 02/93

A survey of the distribution and population densities of juvenile salmon and trout in the river Spey was implemented in 1990. The 1990 survey results are presented in Laughton (1991). During 1991 a further 53 sites were examined throughout the catchment. This short report presents data on the distribution and population densities of salmon and trout at the sites examined on the Spey during 1991. Where 1990 sites were revisited data from both years are presented and compared.

Laughton. R.

Fisheries Research Services Report 14/91.

An electro-fishing survey of the distribution and population densities of juvenile salmon and trout in the River Spey was implemented in 1990. This report provided data from the initial years survey.

The effect of temperature on growth and early maturation in a wild population of Atlantic salmon parr. D. Baum, R. Laughton, J. D. Armstrong and N. B. Metcalfe. J. Fish Biol 67, 2005.

In the River Fiddich, a tributary of the River Spey, Atlantic salmon (Salmo salar) parr exposed to heated water effluent were larger than parr living upstream of the discharge. There was no effect, however, of temperature on the incidence of male parr maturation, despite the link between growth and maturation found in other studies. Mature parr upstream of the effluent were smaller than mature parr downstream of it,suggesting a higher size threshold for maturation in those parr exposed to the heated water. The small distance between upstream and downstream sampling sites probably precluded genetic differences between the parr, thus implying an environmental influence on the threshold size above which male parr matured.

Fish Populations and Invertebrates in Some Headwaters of the Rivers Dee and Spey 1983-1985.
B R S Morrison and R Harriman Scottish Fisheries Research Report Number 53 1992

This reports provides data on the water chemistry, fish, invertebrate and zooplankton populations in the upper reaches of the Rivers Spey and Dee during 1983 to 1985.