An access-point survey approach to estimate recreational boat-fishing effort for stays of variable length

Management of recreational fisheries may greatly benefit from accurate and precise estimates of catch and effort. The reliable estimation of recreational boat-fishing effort is particularly challenging due to the methodologies, logistics and high costs involved. Here, we propose a two-stage approach to estimate the number of boat-fishing trips based on an access-point survey developed for situations in which boaters often stay in the area for more than one day, making several fishing trips during their stay. The two-stage approach consists of, first, estimating the total number of boat-days for the fishing season, where boats present in the coast may potentially go fishing, and, second, estimating the probability that a boat present in the coast does go fishing on a given day. We illustrate the method by applying it to a recreational fishery targeting rocky-reef fishes in the San Jose Gulf, Peninsula Valde's, Argentina. When used on simulated data the new method produced unbiased and more precise estimates of the number of boat-days compared to the traditional access-point survey method. Gains in precision varied depending on the number of survey visits, the survey schedule (random or regular visits) and the actual (simulated) number of boat-days.