R. Watson (1984). “Changes in the Average Weight and Catch Per Unit Effort of Tunas from Papua New Guinea Waters,” PNG Fisheries Reports (Fisheries Research and Surveys Branch, Papua New Guinea Dept. Primary Industry, Port Moresby, Papua New Guinea
Average weight of skipjack and yellowfin from the domestic pole-and-line fishery oscillated in synchrony with a period of four years and the weights of both species decreased significantly from 1970 to 1981. Although there were some significant changes in average tuna weight
between years, there were no observable trends for teh Japanese longline, or Japanese and American purse-seine fisheries. The annual average weight of yellowfin from the domestic pole-and-line fishery was between 2 and 3kg, from the Japanese purse-seine 5kg, and from the Japanese longline between 23 and 26kg. The average weight of skipjack from the domestic pole-and-line and Japanese purse-seine catch was between 2 and 3 kg. The CPUE of skipjack from the Japanese pole-and-line followed that of the domestic fishery but the yellowfin CPUEs were out of phase. No long-term trends in CPUE were observed for the purse-seine or longline fisheries. The CPUE of skipjack and yellowfin from the Japanese and American purse-seine fisheries were comparable for 1982. Best CPUE fo domestic pole-and-line skipjack occured when average sizes were greatest but the converse was true for yellowfin. Generally in the various fisheries when the CPUE of skipjack increased, that of yellowfin decreased.