Reducing bias in trends in dolphin relative abundance, estimated from tuna vessel data

Estimated the relative abundances of E tropical Pacific stocks of spotted Stenella attenuata, spinner S. longirostris and common Delphinus delphis dolphins. Estimates corresonding to each year from 1975-1987 are given for a new procedure. Conclusions are generally similar to those of Buckland and Anganuzzi (1988); the stocks for which we have most information (the E stock of spinner dolphin and the N offshore stock of spotted dolphin) both appear to have been relatively stable in size during the 1980s, with evidence of reductions in the latter stock in the late 1970s. -from Authors