A Rapid Method for Determining Metabolism of Fish

The utility of bioenergetics models for answering fisheries and ecological questions has often been hampered by the availability of data or resources for deriving species-specific models. Among the principal components of bioenergetics models are metabolism equations that historically have been derived from series of long experiments in which fish of different sizes are acclimated and tested at each temperature for extended periods. Acclimation may take several weeks to months and actual observation on metabolism (oxygen consumption) may take several days for each group of fish with several groups often needed to provide sufficient sample size. Here, I present a rapid method for determining metabolic rates by forcing the fish through a series of rapidly declining temperatures over a 1- to 2-day period. Metabolism data from pumpkinseed (Lepomis gibbosus), rock bass (Ambloplites rupestris), striped bass (Morone saxatilis), and yellow perch (Perca flavescens) compare favorably with those obtained via more standard methods. Variability in the rapid-derived metabolism models was low with R2>0.82. Size-dependent exponents in the equations ranged from -0.23 to -0.26—well within the range of -0.2 to -0.3 reported in the literature by Winberg. Temperature-dependent exponents were also close to those reported by other methods. The rapid metabolism method permits development of metabolism models from measurements carried out over several days instead of months as is usually the case. This rapid method for determining metabolism may permit bioenergetic model development for many ecologically important species whose metabolism could not be determined before due to time or financial constraints.

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