To estimate the total catch in a sport fishery sampled by a roving cre
el survey, we multiply an estimate of the total fishing effort by the
estimated catch rate (i.e., catch per unit of fishing effort). While t
he statistical theory for estimating the fishing effort from instantan
eous or progressive counts is well established, there is much confusio
n about the appropriate way to estimate the catch rate. Most studies h
ave used the ratio of means or the mean of the ratios of individual ca
tches and efforts. We analyzed the properties of these estimators of c
atch rate under the assumption that fishing is a stationary Poisson pr
ocess. The ratio of means estimator has a finite second moment, while
the mean ratio estimator has infinite variance. Simulation studies sho
wed that the mean of ratios estimator tends to have high and unstable
mean squared error relative to the ratio of means estimator and this i
s in accordance with empirical observations. We also studied the prope
rties of the mean of ratios estimator when all interviews with people
fishing for less than epsilon minutes duration were disregarded for va
lues of epsilon up to 60 minutes. There was typically a marked reducti
on in mean squared error when the shorter trips were not included. We
recommend that the mean of ratios estimator, with all trips less than
30 minutes disregarded, be used to estimate catch rate and hence total
catch under the roving creel survey design. It has the correct expect
ation (at least approximately after the truncation) and almost always
had smaller mean squared error than the ratio of means estimates in ou
r simulations.