when the fish clears the water start holding your breath. when you need to breathe so does the bass.

This article I found online

This is the lab test comparing largemouth to smallmouth. Bass were physically exercised to simulate angling and then held by the jaw ("thumbed" just like most every angler does) for a randomly chosen amount of time up to 10 minutes out of the water and exposed to the air. Afterward, fish were placed back into a holding tank and observed and tested for some chemical parameter monitoring, then ultimately placed back into a raceway for 24 hours to observe for delayed mortality. Water temps ranged between 18-23 deg. C. in this test. Largemouth recovered faster than smallmouth as expected, but there were no documented mortality cases after 24 hours.

Behavioral and physiological responses of the congeneric largemouth (Micropterus salmoides) and smallmouth bass (M. dolomieu) to various exercise and air exposure durations

Two of the major stressors associated with the catch-and-release of recreationally angled fish are exercise and air exposure. This study investigated the combined effects of exercise and air exposure duration on the congeneric largemouth bass Micropterus salmoides and smallmouth bass M. dolomieu, two of the most popular sportfish in North America. We simulated angling by exercising the fish (i.e., chasing by hand) for either 20 or 180 s and then immediately exposed fish to air for random durations ranging from 0 to 10 min. To assess the combined effects of increased exercise and air exposure durations, and the time needed to recover, we monitored several behavioral responses for both species. For largemouth bass, we also measured hematological variables (i.e., lactate, glucose, and hematocrit). Never did exercise and air exposure have a significant effect on the same response measured in the same species, suggesting that there are two separate responses occurring: likely an exercise response and a stress response associated with hypoxia. Our results also indicate that largemouth bass recover from combined exercise and air exposure faster than smallmouth bass. Smallmouth bass took longer to regain equilibrium, to stop leaning, and to return to very shallow (i.e., normal) ventilation depth, as a result of the treatments of exercise and air exposure, than the largemouth bass. This is likely due in part to behavioral and habitat differences between the two species as well as their different aerobic capacities and sensitivities to hypoxia. Interestingly, no mortality was observed despite air exposure durations of up to 10 min. It is still unclear how air exposure interacts with environmental stressors, such as water temperature. We conclude, based on these findings and as suggested from other studies, that air exposure is a significant stressor, and that species-specific guidelines are needed for catch-and-release practices to be most effective, and to best insure the sustainability of fisheries.

Then the lake test:
In this test of largemouth bass only, bass were angled from the lake and then held out of the water for a varying amount of time that ranged from 0 up to 15 minutes. Tests were conducted during two specific environmental time frames, once at 15 deg. C. water temps and again at 21 deg. C. Bass were also tested for various bodily (chemical) parameters and were then placed in a holding tank for 30 minutes of recovery/observation. During this time they were fitted with an external transmitter and then released back into the lake and tracked for 5 days. Again, no delayed mortality occurred for any of the fish including those held out of the water for the maximum 15 minutes. Fish held out of the water longer took longer to recover, as well as longer to leave their release area in the lake (at higher temps vs. short duration cooler temps, but not significant).

We've always figured "bass aren't trout" and could be subjected to greater stressors (i.e., air exposure) and still come out OK. That bass could be held out of water for 10-15 minutes and returned relatively unharmed was a bit of a surprise to me. That is a rather lengthy bit of time even for the most unpracticed of bass anglers. I am actually quite shocked at the result, but certainly love the practicality of the study. That said, keep in mind that all testing occurred at water temps at or under 75 degrees F., the temp. threshold that has long been thought to be the dividing line between safe and unsafe when it comes to fish care handling practices. Both studies warned of possible high mortality if repeated in these warmer water temps. The general rule of thumb that you'll hear bass anglers espouse is to hold bass out of the water no longer than you could hold your own breathe. While this still remains good practical advice to follow, we now have some concrete evidence to actually make specific statements concerning this subject.

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