Comparison of Alewife Young‐of‐the‐Year and Adult Respiration and Swimming Speed Bioenergetics Model Parameters: Implications of Extrapolation

Abstract

AbstractParameters derived from laboratory experiments that separately measured the routine metabolic rates (respiration) and swimming speeds of young‐of‐the‐year (age‐0) alewives Alosa pseudoharengus were compared with values published for a bioenergetics model for adults. Respiration rates of age‐0 alewives were significantly influenced by water temperature and scaled isometrically with weight (range, 0.0001–1 g). Swimming speed was strongly related to fish weight and, unlike for adult alewives, water temperature significantly influenced the swimming speeds of age‐0 fish. Temperature coefficients, along with the slopes for the weight dependence of age‐0 alewife respiration rates and swimming speeds, significantly differed by 51–709% from published parameters for adults. Using adult parameters, the standard respiration rates at 15–25°C of age‐0 alewives weighing less than 0.02 g were overestimated by 7–88% and the swimming speeds for fish weighing less than 1.0 g were overestimated by 130–4,270%. Application of our age‐0 alewife swimming speed parameters in the exponential activity function used in the adult bioenergetics model resulted in no activity costs for age‐0 fish smaller than 0.2 g, which is clearly unrealistic. Because no data relating respiration to activity level (i.e., concurrent measurements of respiration and swimming speed) currently exist for age‐0 alewives, we recommend using routine respiration rates without an activity multiplier to represent the costs of normal activity in the field. All parameters derived in this study for age‐0 alewives differed from those of adults by more than 10%, a deviation commonly used in sensitivity analyses of bioenergetics models, which indicated that application of adult parameters to early life stages was not warranted. Use of metabolism–weight relations from the literature derived for multiple species also are not recommended because the estimated routine metabolic rates of age‐0 alewives differed by 2–311% from rates measured in this study.