Tuna longline fishery produces the highest output among Taiwanese far sea fisheries. In 2007, it created NT$31.7 billion of sales, 1/3 of Taiwanese fisheries. In 2005, ICCAT identified Taiwanese tuna longliners because of their excessive catches and laundering activities in bigeye tuna. The identification by ICCAT initiated dramatic change of Taiwanese tuna longline fishery. This study described the characters of Taiwanese tuna longline fishery, compared catches of 4 major tuna longline countries: Taiwan, Japan, South Korea and China in 2004. The result showed that Taiwanese tuna longliners got the highest catches. In addition, Taiwanese boat owners owned and operated longliners in other flags. The huge fishing capacity which owned by Taiwanese boat owners became a threat to tuna resources. This study first analyzed the attributes of diamond of national advantage that help Taiwanese tuna longline fishery prospect in Cianjhen Fishing Port, Kaohsiung City, and how it enjoyed the benefit of industry cluster. This part depicted success of the past. Facing the global over capacity of fishing vessels and shrinkage of tuna resources, Taiwanese tuna fishery can not indulge in glory of past. Instead, disadvantage of competition condition highlighted importance of end-game strategy which help boat owners make their decision of continuation or divestment of their business. The decline of an industry derives from the weakness of itself. This study emphasizes organization change and innovation, which must be rooted from respect to the precious tuna resources, then apply fishery science to improve fishing efficiency and proper use of manpower from different nations.