Simple assumptions predicting prey selection by piscivorous fish

Background/Question/Methods

Trophic interactions in ichthyology can be described by direct studies of stomach contents. However, identifying partially digested prey fishes of piscivorous species can be quite difficult. A theoretical probabilistic model with ecological assumptions was proposed to estimate the potential prey of piscivorous fish, increasing trophic analyses precision in fish communities. The following assumptions were adopted: (i) predation window, given by prey/predator length ratio, (ii) predation probability and (iii) prey abundance. We have tested the ability of this model to reproduce the empirical data of two predation matrices. A null model, which all prey had the same chance of being predated, was created and applied to test whether the assumptions adopted were able to enhance the model’s predictability.

Results/Conclusions

Models’ best fit were 33% and 51% of the interactions predicted in Matrix A and in Matrix B, respectively. Even though, only the best Matrix B model was significantly better at predicting interactions than null model. However, considering piscivorous species strictly, models’ best fit were 44% and 66% of the interactions predicted in Matrix A and in Matrix B, respectively, and both models were significantly better than the null model. The results suggest that simple ecological assumptions may be considered to predict prey selection of piscivorous fish, contributing to a better understanding on structure and functioning of aquatic food webs.