| Summary: | This workshop, chaired by Jon-Helge Vølstad (Norway) and Mike Armstrong (UK) was held in Bilbao, Spain, from 8–10 November 2011. Twenty-eight participants representing eleven countries including Iceland and the United States were present. Alan Lowther (USA), an external contributor, provided particular expertise in sampling small-scale fisheries. Prior to the workshop, participants from each country were provided with a questionnaire to collect standard descriptions of their on-shore and at-sea sampling pro-grammes. These were collated at the workshop. The objectives, descriptions and the practical issues relating to setting up national programmes were looked at in more detail in presentations of eight case studies covering at-sea sampling (Denmark and Sweden), sampling using a reference fleet (Norway), port sampling (UK England & Scotland; Iceland) and sampling of small-scale, artisanal fisheries (Malta, Basque Countries). WKPICS recommends the use of probability-based sampling schemes with sampling frames, primary sampling units and strata optimised to deliver the required estimates for species, fleet metiers, fishing grounds or other variables of interest. Such schemes allow samples to be easily extrapolated to the target population using weighting fac-tors based on inclusion-probabilities. For sampling on shore, sampling frames generally consist of sites and days (sites being ports or other access points). For sampling at sea the frame is based on a list of vessels. The key advantages of a probability-based sampling scheme, with simple random sampling within strata, is that different types of fishing trips (gears used; areas fished etc.) within a sampling stratum will tend to occur in roughly the same proportion in the samples as in the fleet as a whole. This is an advantage if the fishing areas or gears used change unpredictably between years. The desired balance of sampling across métiers is achieved by adjusting sampling rates within vessel or port strata according to the expected distribution of ...
|
|---|