Large scale movements of basking sharks (Cetorhlnus maxlmus) from archival tagging in relation to a zooplankton prey field in the north-east Atlantic

• Main Author: Wltt, Matthew J.
• Other Authors: Faculty of Science
• Format: Thesis
• Language: English
• Published: 2004
• Subjects: Cetorhinus maximus; North East Atlantic
• Online Access: http://hdl.handle.net/10026.2/2130

Selecting habitats that lead to profitable feeding is essential for free-ranging fish. The spatial and temporal variations in prey availability that are characteristic of a heterogeneous habitat necessitate predator strategies that increase the chance of encountering prey. Such strategies are particularly important for large planktivorous fish such as the basking shark (Cetorhinus maximus), which travel considerable horizontal distances in the search of prey. To learn more about the foraging strategies employed by basking sharks, prey encounter rates were estimated for 7 pop-up archival transmitter (PAT) tagged individuals. Movement tracks for these individuals were reconstructed and applied to a long-term zooplankton biomass prey field. These prey fields were constructed from zooplankton abundance data for the north east Atlantic obtained from the Continuous Plankton, Recorder survey. The relative success of these observed movements for encountering prey was established by comparison to random foraging scenarios. Real sharks consistently outperformed their random walk counterparts in this search for prey. The adopted approach demonstrated that tagged basking sharks fed profitably by selecting forage rich habitats using a selection of movement strategies, Biomass prey fields also highlighted the importance of coastal-pelagic and shelf-break habitats for these filter-feeding elasmobranchs. Marine Biological Association of the United Kingdom & Sir Alister Hardy Foundation for Ocean Science