The Ecology of the Perch (Perea fluviatilis L.) of Lough Neagh, Northern Ireland

Abstract

The ecology of perch (Perea fluviatilis L.) in Lough Neagh, a large eutrophic lake in Northern Ireland, was studied from October 1985 to March 1987. The perch dominated the fish community throughout the study period and is thus the lough's most important zooplanktivore.

The population structure of the perch was overwhelmingly dominated by O+ and 1+ individuals, despite recruitment being consistent throughout the study period. Growth of underyearlings was slow in comparison with values reported for perch from other European waters, while growth rates of older fish were typical. Males matured during their second summer as I+ (75 - 100 mm in length), while females did not do so until they were III+ (greater than 140 mm in length). Fecundity values were similar to those reported from other European populations.

The perch population showed complex patterns of distributions in both the vertical and horizontal planes. Migrations were evident on both diel and seasonal timescales, and were specific to the different age groups. Feeding conditions were probably a major factor behind these movements and the perch population as a whole showed the typical mixture of zooplanktivorous, benthivorous and piscivorous individuals. In terms of numbers, and thus overall consumption rates, the zooplanktivorous perch were by far the most abundant trophic group and so were studied in greatest detail, including laboratory observations of their feeding behaviour.

An assessment was made of the activities and impact of the lough's commercial perch fishery, although this was very limited due to the lack of comprehensive catch statistics. Suggested recommendations for future management were made. Finally, the competitive interactions of perch within the Lough Neagh fish community and its general role in the ecosystem were discussed.

Date of Award	Apr 1990
Original language	English