Correction of Relative Fish Abundance Estimates from Catch Data for Variable Fishing Intensity during Lake Surveys

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Ryan, P. M., Kerekes, J. J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1989
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Newfoundland
• Online Access: http://dx.doi.org/10.1139/f89-132; http://www.nrcresearchpress.com/doi/pdf/10.1139/f89-132

Six small Newfoundland lakes were fished with gillnets over a 3–6 yr period in a manner typical of standard lake surveys where surveyors have a fixed amount of gear available, but lake size varies. Catch and effort data for brook trout (Salvelinus fontinalis) were examined for the purpose of selecting an appropriate measure of the relative abundance of trout. Fishing effort was not a function of lake area but fishing intensity or fishing effort per unit area varied inversely with lake area. Brook trout yield (kilograms per hectare) was positively related to fishing intensity Catch per unit effort (kilograms) of brook trout was inversely related to fishing intensity. Methods are suggested to correct for the bias in catch data resulting from variable fishing intensity during lake surveys and improve the recognition of differences in relative fish abundance.