Over the past half-century, habitat changes have drastically affected production of northern pike in all over the world. Pike are keystone predators responsible for determining the structure of certain fish community assemblages. Therefore, predicting their habitat needs is critical for river management. This book determines the appropriate variables and ecosystem processes by using a set of data driven models to predict habitat suitability of pike in rivers. To achieve this, the use of suitable ecological modelling methods can be very important to support river management and water policy because a better interpretation of the river status can be possible, the causes of the status of a river can be detected and assessment methods can be optimised. Models can allow for calculating the effect of future river restoration actions on aquatic ecosystems and supporting the selection of the most sustainable options. They can also help to find the major gaps in our knowledge of river systems and help to set-up cost effective monitoring programmes. Based on the developed model, focusing on the structural-habitat variables would be the main priority for the survival of pike population.