Take a fish out of water and its stress hormones will go up. Adrenaline and noradrenaline, the “fight or flight” hormones, peak first, followed more gradually by cortisol. A new study reported in the Journal of Experimental Biology finds that largemouth bass whose cortisol levels rise most after a brief bout of stress are inherently harder to catch by angling. This could affect recreational fishing. If anglers are primarily capturing fish whose stress levels dictate whether they are likely to strike at a lure, “we could potentially be selecting for fish that are harder to catch,” said University of Illinois natural resources and environmental sciences professor Cory Suski, who led the new research with Illinois Natural History Survey research scientist Jeffrey Stein and graduate student Michael Louison.