Catalase activity was below the detection limit (1.0 U mg− 1 protein) in 80% of the samples from I. oxyrinchus, 72% from P. glauca, 67% from M. henlei, 34% from K. audax, 37% from C. hippurus and 67% from T. macdonaldi. Regardless, CAT activity was 82% higher in teleosts than in elasmobranchs as a group (p = 0.001) (Fig. 1-II).