We characterize optimal fishery management in an age-structured, bio-economic model where two age groups are harvested with costly and imperfect selectivity. We show that a system of tradable fishing permits, each allowing to harvest a specific number of fish that differs with age group,...

We study the impact of learning by doing, learning spill-overs, and imperfect competition in a model with two types of electricity producers, an oligopolistic sector of polluting fossil-fuel utilities and a competitive fringe of non-polluting generators of electricity from renewable energy...