In some circles, catch-and-release angling is contentious. Certainly hooking, fighting and air exposing a fish can cause harm and even death, in some circumstances. Most catch-and-release anglers know that air exposure harms fish, and have heard that we should ‘keep ’em wet’. However, most fish that are released are still air exposed for some amount of time, whether during netting and unhooking, or if an angler wants a photo of their catch.
While there is good scientific data on how different amounts of air exposure influence the health of fish, we don’t really know how long anglers typically air expose fish. At least that was true until the publication of a recent study by Idaho Department of Fish and Game biologists. The researchers discreetly observed trout anglers on rivers and lakes in Idaho and Oregon, and timed the amount of air exposure of their catches.
They found that the average air exposure time was 29.4 seconds, which may or may not be a long time depending on how you look at it. Additionally, 4% of anglers held fish out of water for a period of longer than 60s, with the longest air exposure being 160 s. Previous studies have shown that air exposure for less than 30 seconds probably doesn’t influence the likelihood of mortality for trout, but could have sub-lethal effects than might decrease growth or reproduction. Regardless, air exposure of 29 seconds is certainly longer than required to take a photo, and anglers should aim for no air exposure if possible.
Interestingly, the researchers also found that certain factors influenced the amount of air exposure. For example, trout that were netted were air exposed for an average of 10 seconds longer than those landed by hand, and larger fish (> 45 cm in length) were air exposed longer than small or medium sized fish. Additionally, trout that were caught on flies were air exposed less that bait or lure anglers, which could be due to increased difficulty in unhooking fish caught with the latter methods. However these factors did not explain very much of the variation in air exposure times, so it seems that how long fish were air exposed might be more about an individual’s anglers behaviour and choices.
The authors argue that the average fight and air exposure times seen in this study probably don’t have negative effects of fish. I won’t dispute that claim, but certainly some individuals are air exposing fish for much longer than is necessary, and harming fish by doing so. We should all aim to decrease handling and air exposure stress in fish we are releasing, so they can grow into the types of fish we will tell our grandkids about.
Citation: JA Lamansky & KA Meyer. 2016 Air exposure time of trout released by anglers during catch and release. North American Journal of Fisheries Management, 36:5
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