The papers presented in this thesis represent my contributions to the empirical study of marine biological resources. This research has adopted the same experimental approach to: (i) develop scientifically validated techniques to solve specific problems; (ii) use these techniques to detect patterns and form conceptual models about the processes that may have caused them; (iii) do manipulative field experiments to support or refute hypotheses derived from these models; (iv) use these results to develop new models and hypotheses and to test them in new experiments; and (v) recommend, where appropriate, changes to the management of the resources examined. A rigorous, empirical approach is the common feature throughout my research (in its overall direction and subject-to-subject execution) and represents one of the few attempts to adopt such an approach across the three fields in which I have worked: (1) the ecology of underwater kelp systems; (2) the biology of and fishery for a commercially exploited crab; and (3) solving by-catch problems in commercial trawl fisheries.

The papers presented in this thesis represent my contributions to the empirical study of marine biological resources. This research has adopted the same experimental approach to: (i) develop scientifically validated techniques to solve specific problems; (ii) use these techniques to detect patterns and form conceptual models about the processes that may have caused them; (iii) do manipulative field experiments to support or refute hypotheses derived from these models; (iv) use these results to develop new models and hypotheses and to test them in new experiments; and (v) recommend, where appropriate, changes to the management of the resources examined. A rigorous, empirical approach is the common feature throughout my research (in its overall direction and subject-to-subject execution) and represents one of the few attempts to adopt such an approach across the three fields in which I have worked: (1) the ecology of underwater kelp systems; (2) the biology of and fishery for a commercially exploited crab; and (3) solving by-catch problems in commercial trawl fisheries.