Trophic level scales positively with body size in fishes

Results Across all species, trophic position was positively related to maximum length (r = 0.194, b = 0.065, P < 0.0001), meaning that a one-level increase in trophic level was associated with an increase in maximum length by a factor of 183. On average, fishes in orders that showed significantly positive trophic level–body size relations [mean = 51.6 cm 11.8 (95% confidence interval, CI)] were 86 cm smaller than fishes in orders that showed no relation [mean = 137.1 cm 50.3 (95% CI), P < 0.01]. A separate slopes model ANCOVA revealed that maximum length and trophic level were positively correlated for 47% (27 of 57) of orders, with two more orders showing marginally non-significant positive relations; no significant negative correlations were observed. The full model (order ¥ body size) explained 37% of the variation between body size and trophic position (P < 0.0001).