A Simple Empirical Model Of Data Fouling In
Marine Fisheries
Author(s)
C. M. Wernerheim & R. L. Haedrich
Abstract
One of the most serious problems facing fisheries managers is how to improve
estimates of the distortion (‘fouling’) of commercial landings data resulting from
misreporting. Data fouling (legal or illegal) drives a wedge between what is
caught and killed at sea, and what is landed and reported to the regulator. This
can obscure the true state of the stock causing it to appear healthier than it is,
resulting in quotas being set too high. We propose an analytical model of data
fouling that can be used with empirical data to estimate what we call the data
fouling factor. The model is solved analytically and numerically for the profit
maximizing effort level and the associated number of high-grading operations.
Some illustrative policy implications are derived.
Keywords: misreporting, high-grading, fisheries data, fisheries policy.
1 Introduction
The estimation of stock abundance and the determination of quotas alike depend
in large measure on accurate and precise statistics on commercial landings. One
of the most serious problems facing fisheries managers is how to improve
estimates of the distortion resulting from misreporting. Failure to obtain an
accurate account from harvesters about activities at sea undermines the reliability
of catch data, which can in turn introduce an (avoidable) element of uncertainty
into the outcomes of fisheries policy: the greater the inaccuracy in the data the
wider the confidence intervals around the estimate of stock size. Our main
contention is that unless official landings data are adjusted for the discrepancy
Keywords
misreporting, high-grading, fisheries data, fisheries policy.
Related Book
Other papers in this volume
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