“…The relationship between heart rate and metabolism is not straightforward in fish (Thorarensen et al 1996). However, heart rate is liable to provide information about the environmental impact on fish physiological state, thereby widening our understanding of the general relationship between fish and their environment (Priede & Young 1977, Priede & Tytler 1977, Armstrong 1986, Lucas et al 1991. Moreover, heart rate is one of the few correlates to metabolic demand that can be monitored in free-swimming fish using telemetry (Armstrong 1986, Bushnell & Brill 1991, Lucas et al 1991, Sureau & Lagardère 1991, Claireaux et al 1995.…”