Optimum size of sampling unit for estimating the density of marine populations
Original version
This report is not to be cited without prior reference to the authorsAbstract
Data from several trawling experiments and from some scallop dredge surveys
indicate that, within limits, a srnaller sampling unit can be more effective
than a larger unit for marine abundance surveys. Taking into account survey
costs and sampling variability, the unit size is found which produces the most
precise density estimate given a fixed amount of survey resources or, if a
certain level of precision is required, the size of sampling unit which
minimizes the total cost of the survey. As an illustration, the optimum
sampling unit sizes are derived for surveys of some fish populations and for
a scallop stock on Georges Bank.