Reply to Buckley et al.’s "Comment: Larval Atlantic cod and haddock growth models, metabolism, ingestion, and temperature effects"

Abstract

In reexamining recent modeling work on Atlantic cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) larvae, Buckley et al.1 conclude that the procedure used in Laurence (1985) to calculate daily metabolic rates may have been incorrect. Buckley et al. suggest that the actual daily metabolic rates should be nearly three times higher for both Atlantic cod and haddock. At the same time, they also point out that total assimilation may be much higher (70% rather than <50%) based on more recent data, including laboratory experiments conducted on larval fish of other species (Kiorboe et al. 1987; Wieser and Medgyesy 1990; Letcher et al. 1996). Besides these points, Buckley et al. suggest that the value of Qa, a temperature-dependent “overall” assimilation term used by Leising and Franks (1999), was unrealistically high (we used a value of 1.6). Instead, Buckley et al. suggest that this value should be closer to 1.07–1.14 based on their analysis of data from several experiments on other species of fish. At the time of creation of our model (Leising and Franks 1999), we used our best estimates of these parameters. However, in light of Buckley et al.’s arguments, we agree that their estimates for these parameters may be more appropriate for Atlantic cod and haddock larvae. We therefore reran our model for Atlantic cod only using their suggested parameters to determine the impact on our model results, with specific attention to the effects of temperature versus food availability.