Opercular differential pressure as a predictor of metabolic oxygen demand in the starry flounder

The feasibility of using a differential pressure sensor connected to an acoustic telemetry device to monitor opercular activity as a correlate of oxygen consumption was investigated. Four starry flounders Platichthys stellatus were fitted with a miniature differential pressure sensor mounted close to the operculum. A cannula was connected to the sensor and inserted under the operculum, inside the branchial cavity. Measurements of oxygen consumption and opercular activity were carried out over a broad range of metabolic activity, from the post-surgery stress (high metabolic rate) to routine metabolic rate the following day. Relationships between differential pressure changes (rate and amplitude) were highly correlated with oxygen consumption (r(2) =0(.)74 and 0(.)60 respectively). The results indicate that monitoring opercular activity offers an alternative method for measuring aerobic metabolism in free-swimming fishes in nature. (C) 2003 The Fisheries Society of the British Isles