Fisheries science, a branch of aquatic ecology, undertakes the scientific study of fisheries. Fisheries are harvested for commercial purposes. The fish harvested can be marine, freshwater, wild or farmed. The oceans and seas contribute nearly 90% of the total fishery catches. An understanding of aquatic ecology is essential for continued sustenance of fisheries. Some of the factors that are crucial for the sustainability of aquatic ecosystems are water depth, nutrient levels, salinity, temperature, flow, etc. Any activity that results in a change in any of these parameters results in a stress on the aquatic ecosystem. This book covers in detail some existing theories and innovative concepts revolving around fisheries and aquatic ecology. Different approaches, methodologies and advanced studies on these domains have been included in this book. It is meant to assist students and experts who want to broaden their knowledge in these fields.