Detecting Temporal Trends in Freshwater Fisheries Surveys: Statistical Power and the Important Linkages between Management Questions and Monitoring Objectives
by T.Wagner et al., ABSTRACT: Monitoring to detect temporal trends in biological
and habitat indices is a critical component of fisheries
management. Thus, it is important that management objectives
are linked to monitoring objectives. This linkage requires a
definition of what constitutes a management-relevant “temporal
trend.” It is also important to develop expectations for the
amount of time required to detect a trend (i.e., statistical power)
and for choosing an appropriate statistical model for analysis.
We provide an overview of temporal trends commonly encountered
in fisheries management, review published studies that
evaluated statistical power of long-term trend detection, and
illustrate dynamic linear models in a Bayesian context, as an
additional analytical approach focused on shorter term change.
We show that monitoring programs generally have low statistical
power for detecting linear temporal trends and argue that
often management should be focused on different definitions of
trends, some of which can be better addressed by alternative
analytical approaches.
Publication Date: 2013
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