Data on technical specifications, numbers, catch, fishing power per boat and CPUE of purse-seining boats for the tuna fishery in the Turkish waters between 1994 and 2000 periods are presented. The number of the purse-seining boats operating during the period varied between 22 and 62. In recent years, the bluefin fishing fleet and the fishery have been transformed. The fleet now consists of larger boats with more powerful engines, bigger fishing nets, and the use of sophisticated electronics like echosounders, sonars and sea bird radars. Those factors combined with the increased captain's experience and skill in using the technologies are important factors that have resulted in significant changes in the traditional measures of effectiveness of the Turkish tuna fishery. (C) 2004 Elsevier B.V. All rights reserved.