Influence of Wind and Swelloncatch Rates in a Dive Fishery: A Case Study from the South Australian Abalone Fishery

ABSTRACT Catch per unit effort (CPUE) is widely used as an index of abundance in the assessment of abalone fisheries even though it has often been considered unreliable. This is because, it is susceptible to hyperstability and influenced by factors other than stock abundance such as increased fishing efficiency, market demand for particular product, weather, diver habits, and putative rotation of fishing grounds. These factors introduce uncertainty to the use of CPUE as an index of relative stock abundance, with some of these factors causing hyperdepletion of the index. In the western and southern zones (WZ and SZ) of South Australia, commercial fishers recently suggested that declining CPUE in 2014 was attributed to a fishing season with poor weather, and in particular higher than average swell, rather than to declines in stock abundance. To evaluate the effect of weather on CPUE in the SZ and WZ daily, logbook catch and effort data were linked with swell and wind observations. Analysis demonstrates that...