Influence plots and metrics: tools for better understanding fisheries catch-per-unit-effort standardizations

Standardization of catch per unit effort using generalized linear models (GLMs) is a common procedure that attempts to remove the confounding effects of variables other than abundance. Simple plots and metrics are described to assist understanding the standardization effects of explanatory variables included in GLMs, illustrated with an example based on New Zealand trevally (Caranx lutescens) data.