Migratory Connectivity in Basking Sharks

Simon Thorrold and Leah Houghton, Biology

Grant Funded in 2007

Animal migrations represent one of nature’s most spectacular and yet mysterious phenomena. Movement patterns also have considerable biological significance, determining gene flow among geographically separated populations over ecological time scales and migratory connectivity among populations over ecological time. Unfortunately studies of migration in ocean ecosystems have lagged behind those in terrestrial environments due to the logistic constraints associated with tracking aquatic animals that may travel vast distances in an opaque 3-dimensional environment. We propose to develop a new approach for estimating dispersal and migratory connectivity of basking sharks (Cetorhinus maximus) based on natural geochemical markers in vertebrae. We will test the validity of 3 hypotheses relating to the technique by reconstructing the bomb carbon curve using specific amino acids in vertebral pair-bands. The results will provide insights relevant to conservation efforts directed at the world’s second largest fish species that is globally distributed but listed on the IUCN Red List of Threatened Species as vulnerable due to overfishing throughout its' range. The tools will also be readily applicable to other large pelagics that make basin-scale migrations and particularly those that take advantage of high primary and secondary productivity in high latitudes during summer months.