Old Lefty,
In a stratified random sample that type of activity is "captured" by the creel clerks in the relative frequency with which it occurs. If it is infrequent, then it is recorded infrequently. If it is moderately frequent, then it is recorded moderately frequently, and so on.
Just in case it is necessary for clarification purposes, stratified in the sense that it is used above means that random samples occur equally within various strata. In the statewide study, weekend days and holidays were one stratum and weekdays were another stratum. Within the weekend/holiday days, there were also two strata: mornings and afternoons/evenings. Likewise for weekdays. Additionally, streams were broken down into two groups based on avg width...larger streams and smaller streams with 6 meters used as the break point.
As I have said regarding stocked trout fisheries, the sum of the harvests by those relatively few who keep limits is unimportant in comparison to the sum of the harvests by those many anglers who keep only a single fish when you look at the impact on the populations. In the big picture, that is most likely true for wild trout fisheries as well. Heck, the harvest of wild trout is low anyway...only 7 per kilometer on avg. throughout the season and less than one trout per trip on average.
Limit keeping, because it is a somewhat rare event, is more of a social and emotional issue than a biological problem when it comes to stocked or wild trout fisheries in Pa. Harvest of wild trout is low in Pa whether those harvests are occurring as single fish or as limits. In the simplest terms, it matters not at the population level whether one angler makes four trips and keeps five trout each time or 20 anglers make 20 trips and each keep a single fish; the impact at the population level is the same and in Pennsylvania that impact is low.
One thing that I will say about limits, however, is that they may become a target when anglers get close to the limit. When conducting stocked trout creel surveys, particularly when the creel limit was 8, we usually saw more 8 fish creels than 7 fish creels or 6 fish creels in the harvest data. The creel limit was obviously a target as I described.
RLeep2: The harvest estimate on small brook trout streams was 4 brook trout per kilometer.