Over-the-horizon tracking of marine mammals

Research into the foraging behaviour of grey seals (Halichoerus grypus. Fab.) and common seals (Phoca virulina. L.) in and around British waters, using VHF, acoustic and satellite telemetry, provides valuable information about the nature of interaction between these seals and fisheries. Because of range and/or accuracy limitations of the presently employed data retrieval methods, the Sea Mammal Research Unit (SMRU), based in Cambridge, has provided sponsorship for alternative research into accurate, long range tracking of these animals. This research will hopefully produce a valuable detailed insight into the activity patterns and foraging behaviour of these animals, and lead to a better understanding of how they interact with their environment. The aims for such a system include a tracking range of 200 km with <1 km positional accuracy, continuous multi-target capability, small profile packages, and low cost, easy implementation. An HF ground wave system was eventually proposed because of the long range over-the-horizon capability. The development of such a system has been carried out at Sheffield University over the past two years