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chub. Except chub growth these values. eniles grow much food e of growth -onstruction ,ed summer- ,erage (p = Lt the end of the size pre- ; g versus 16 would have tive to post- his increase availability ;rew to 24 g 121 %; Table ipback chub dam, and in- )od required from 378 g 7%) and 709 are and pre- the higher prey avail- TCD appli- :w to 158 g conditions), e 6). L-s using the as relatively HUMPBACK CHUB BIOENERGETICS 1.2 115 0.4 0.; 30 FIGURE 3.-Effect of varying food availability (p; range, 0.1-1.0) and temperature (range, 5-32°C) on the growth of a (A) juvenile (starting size, 4 g) and (B) subadult (starting size, 115 g) humpback chub based on a bioenergetics model. Growth simulations were run over 365 d. Growth rates are hypothetical. simple, and this methodology may have applica- tions for other rare species. For many rare or im- periled species, researchers face problems obtain- ing collecting permits, obtaining a sufficient sam- ple size because of limits on the total number of individuals that can be collected, and sampling an appropriate size range of fish from field popula- tions. Laboratory work with endangered species may also be subject to strict regulations on the types of experiments that are allowed and the mor- tality rate for experimental groups. Rare, endan- gered, or imperiled species are, however, often of great concern to conservation and management 969 agencies, and thus bioenergetic models and anal- yses would be useful in decision making. The ap- proach that we used relied upon fitting the model parameters to temperature-dependent growth, so we did not completely avoid some of the issues mentioned above. Growth experiments at different temperatures are, however, relatively easy to con- duct, and mortality of test animals is usually low. The model we developed was further corroborated using values of p derived from observed growth rates of humpback chub in independent laboratory" and field studies. Using the existing literature to obtain ranges in parameter values (such as those listed in Table 1 for cyprinids) for bioenergetics modeling provides a useful supplement to field and laboratory experiments. Using growth experiments and Monte Carlo fil- tering to fit model parameters provided an alter- native to simple "borrowing" of parameters from related species. Based on the coefficients of var- iation in humpback chub parameters fit with Monte Carlo sampling (Table 5), laboratory experiments on respiration rates (RA and RB), activity (ACT), and perhaps maximum consumption (CA and CB), could improve or corroborate this parameter set. The intercept and slope for respiration had high coefficients of variation (>45%; Table 5), sug- gesting a wide range of these parameter values were acceptable. Except for the ACT multiplier, the coefficients of variation for other parameters were much lower (<20%; Table 5), suggesting nar- rower ranges and variability for acceptable param- eter values. Many other bioenergetic models have been shown to be highly sensitive to respiration and consumption parameters (e.g., Bartell et al. 1986; Duffy 1998; Petersen and Ward 1999). Lab- oratory or field experiments that provide specific estimates for these parameters could improve the humpback chub bioenergetics model. The high correlation between RA and food availability is probably a result of the very broad range for RA that we allowed during Monte Carlo sampling. The bounds for RA allowed this param- eter to vary by several orders of magnitude where- as other parameters were much more restricted (Table 2). When high values of RA were randomly selected, only parameter sets with quite high val- ues of p would fit the test criteria of the growth experiment, thus the strong positive correlation be- tween these parameters. The narrower range for other parameters did not allow for such a broad range of p values, causing lower correlation co- efficients. Corroboration of this model was indirect, using