Metabolic measurements and parameter estimations for bioenergetics modelling of Pacific Chub Mackerel Scomber japonicus

As a crucial step in developing a bioenergetics model for Pacific Chub Mackerel Scomber japonicus (hereafter chub mackerel), parameters related to metabolism, the largest dissipation term in bioenergetics modelling, were estimated. Swimming energetics and metabolic data for nine chub mackerel were collected at 14 degrees C, a low temperature within the typical thermal range of this species, using variable-speed swim-tunnel respirometry. These new data were combined with previous speed-dependent metabolic data at 18 and 24 degrees C and single-speed (1 fork length per second: FL/s) metabolic data at 15 and 20 degrees C to estimate respiration parameters for model development. Based on the combined data, the optimal swimming speed (the swimming speed with the minimum cost of transport, U-opt) was 42.5 cm/s (1.5-3.0 FL/s or 2.1 +/- 0.4 FL/s) and showed no significant dependence on temperature or fish size. The daily mass-specific oxygen consumption rate (R, g O-2 g fish(-1) day(-1)) was expressed as a function of fish mass (W), temperature (T) and swimming speed (U): R = 0.0103W(-0.490) e((0.0457T)) e((0.0235U)). Compared to other small pelagic fishes such as Pacific Herring Clupea harengus pallasii, Pacific Sardine Sardinops sagax and various anchovy species, chub mackerel respiration showed a lower dependence on fish mass, temperature and swimming speed, suggesting a greater swimming ability and lower sensitivity to environmental temperature variation.