The problem of acoustic abundance estimation is briefly reviewed. Under proper conditions, fish density can be measured with high accuracy along line transects. Observed variations in fish density consequently reflect biological variations, or inhomogeneity in spatial distribution. The particular problem of estimating fish abundance over an area from line-transect measurements of fish density is defined. Related problems of estimating the variance of the abundance estimate and of mapping the spatial distribution are also defined. A partial list of candidate methods for solving the several problems is given. Among these, the so-called spatial statistical techniques appear to be most promising because of their exploitation of the observed spatial structure.
Abstract:
The CCAMLR.AUS dataset available to the Subgroup on Survey Design was derived from a survey of Prydz Bay, Antarctica, in December 1990. Swarm length, depth, thickness, MVBS and interswarm length was calculated for swarms of euphausids encountered along a 78 km transect over the continental shelf close to the CEMP study site at Magnetic Island. The euphausid species was probably Euphausia crystallorophias. An increase in swarm length was seen with increasing distance from the coast.
