The number of prey taxa consumed differed markedly among
seasons, but the pattern of seasonal variation was similar in both
regions. In the northern region, fish had the most diverse diet in
autumn and winter (47 and 27 taxa) and the least diverse diet
in summer (7 taxa). The same trend was apparent in the eastern
region, where fish had the most diverse diet in autumn and winter
(29 and 17 taxa) and the least diverse diet in summer (7 taxa).
With respect to diet composition, nMDS ordinations showed a
similar grouping of samples in both regions in that the proximity
of samples in autumn and winter were far closer than those in
summer and spring (Fig. 3). Because diets of individual fish were
aggregated into monthly samples, there were too few possible
sample permutations for ANOSIM to calculate a test statistic to
determine whether diets statistically differed among seasons in
each region. However, SIMPER revealed that the dissimilarity in
diets among seasons was very high for both the northern region
(73–92%) and the eastern region (69–80%).