Chapter 1 Age and growth of bigeye tuna 1.1 Age and growth ofbigeye tuna, using fin spines 1.1.1 Introduction 1.1.2 Materials and methods 1.1.3 Results 1.1.4 Discussions 1.2 Age and growth ofbigeye tuna, using vertebra 1.2.1 Introduction 1.2.2 Materials and methods 1.2.3 Results 1.2.4 DiscussionsChapter 2 Biological characteristics of tunas 2.1 A comparison of biological characteristics of yellowfin tuna 2.1.1 Introduction 2.1.2 Materials and methods 2.1.3 Results 2.1.4 Discussions 2.2 The length structure of bigeye tuna and yellowfin tuna catch 2.2.1 Inlaoduction 2.2.2 Materials and methods 2.2.3 Results 2.2.4 DiscussionsChapter 3 Integrated habitat index 3.1 A comparison of methods about the prediction of integrated habitat index 3.1.1 Introduction 3.1.2 Materials and methods 3.1.3 Results 3.1.4 Discussions 3.2 A comparison on calculation methods about an integrated habitat index 3.2.1 Introduction 3.2.2 Materials and methods 3.2.3 Results 3.2.4 DiscussionsChapter 4 Tuna catch rate calculation methods 4.1 A comparison of two catch rate calculation methods 4.1.1 Introduction 4.1.2 Materials and methods 4.1.3 Results 4.1.4 Discussions 4.2 A comparison of catch rate on bigeye tuna of two longline fishing gears 4.2,1 Introduction 4.2.2 Materials and methods 4.2.3 Results 4.2.4 DiscussionsChapter 5 Effects of fishing gear and environmental factors on catch performances 5.1 A comparison of catch performance between circle hooks and tuna hooks 5.1.1 Introduction 5.1.2 Materials and methods 5.1,3 Results 5.1,4 Discussions 5.2 Effects of environmental factors and fishing gear on catch rates of sharks 5.2.1 Introduction 5.2.2 Materials and methods 5.2.3 Results 5.2.4 Discussions 5.3 The relationships between the catch rates and the depth and sea surface temperature 5.3,1 Introduction 5.3.2 Materials and methods 5.3.3 Results 5.3.4 Discussions 5.4 Development of a three-dimensional nnmerical model for pelagic longlines 5.4.1 Introduction 5.4.2 Materials and methods 5,4.3 Results 5.4.4 Discussions