Network analyses reveal intra- and interspecific differences in behaviour when passing a complex migration obstacle

1. Network theory offers new perspective on movement data by evaluating the relationships between animal movements (links) and detection locations (nodes) in spatially complex systems, including human-altered landscapes.

2. We applied network analyses to intra- and interspecific movement patterns in the migration behaviour and dam passage success of two anadromous fish species, Pacific lamprey Entosphenus tridentatus Gairdner and Chinook salmon Oncorhynchus tshawytscha Walbaum, when moving through a large multi-fishway hydroelectric project (Bonneville Dam, USA).

3. Network analyses revealed greater variation in movement for Pacific lamprey compared with Chinook salmon. Salmon that passed the dam had networks consisting of more direct passage routes with fewer overall movements compared with lamprey that passed the dam. Lamprey that did not pass the dam exhibited a wide range of behaviours, from approaching only one fishway site to testing all possible passage routes. Accounting f...