The Timid Trout: Does Catch and Release Make Fishing Harder?

Many anglers, especially fly anglers know about catch and release. Catch and release offers a way to “best” nature: catching the fish, and to be “healed” through nature: releasing the fish. Still, by practicing catch and release (often referred to as C&R) we actively alter our favorite rivers and lakes by changing fish behavior. Several groups of scientists have explicitly studied the effects of C&R and I believe these findings are worth looking at for the inquisitive angler. 

Do Fish Remember Being Caught?

Evidence strongly suggests that fish who have been hooked adjust their behavior in response to human entanglement, inducing more timid behavior. Studied in several species, including bass, pike and trout, timidity leads to fish favoring refuge habitat instead of otherwise navigating open water. Unsurprisingly, this makes fish harder to find, chase and hook. As a result, based on consistent findings, some scientists have suggested restricting access to allow a level of naivety in fish populations to maximize angling quality. Undoubtedly a bold claim when you consider the traffic on many of the famous western trout rivers with public access. For rivers without closures, fish are forced to rapidly learn and adjust behavior in intense C&R environments. In a study examining the effects of continual angling on a fish population, scientists found that sustained angling for 8 hours per day led to a drop in catch rates in as little as 7-10 days. When you consider the number of anglers on popular river stretches during summer months, surely these rivers experience a similar prolonged exposure to angling pressure.

Catch and release promotes more timid behavior in fish, but what’s more surprising is that evidence may suggest these traits are passed down through generations. If bold behavior is fish (chasing lures and flies) leads to more encounters with anglers, then that fish might expend too much energy fighting its captor that would otherwise be spent on foraring, surviving and reproducing. As a result, excessive fatigue can decrease a trout’s fitness, aka their ability to successfully reproduce. (This is usually why you hear suggestions to level spawning fish alone).

If bold fish are less likely to pass their genes onto the next generation, timid fish who were able to sidestep the whole mess of getting hooked, or learned from past encounters and adapted, are more likely to pass on their traits, including their timid behavior. But wait… bold fish are the ones we want to catch, right? 

Does C&R make fishing more difficult?

If timid behavior is favored, or a likely end state from heavy catch and release, does that mean C&R rivers are more difficult for successfully fooling trout? Overall I think not, let me explain.

One overwriting factor that will keep fish biting is hunger. Fish can act as timid as they want, until eventually they need to eat. One study was conducted examining timidity in two different groups of juvenile fish where one group was starved longer than the other. When finally offered meals dangled on hooks, results found that the hungrier group was more catchable and didn’t exhibit hook avoidance. When dealing with timid fish, success might boil down to timing. For example, runoff may offer a period where starvation is increased, or night fishing may side step heavy angling pressure.

Another supporting reason for why fish will keep biting may come down to fish density, or fish per mile. In streams with robust populations, you may never notice any change in fish behavior as hooked timid fish are simply replaced by other more eager fish who take over the same runs and pools. Based on my experiences during river electroshocking surveys I’m continually surprised by how many fish live in rivers. 

Supplementing rivers with stocked fish can also side-step timid behavior by introducing naive fish into the system who are less weary or often bred to bounce back from catch and release encounters more quickly than wild fish. 

Finally, innovation in angling techniques and flies continually present knuckle-balls to trout overwriting their precautions. Human ingenuity, and angler drive has a track record of continually offering new solutions to age-old angling problems. Mainly, how to catch more fish. 

Author Note

I don’t intend to suggest C&R is a bad management technique, I simply wish to shed some light on how fish respond to pressure from angling. Humanity is in the age of the Anthropocene, where humans have greatly altered their environment, and this presents us (anglers) with new questions we must consider to continue fishing and caring for our shared cold water resources. 

Sources

• Arlinghaus et al. 2013. Understanding the Complexity of Catch-and-Release in Recreational Fishing: An Integrative Synthesis of Global Knowledge from Historical, Ethical, Social, and Biological Perspectives. Reviews in Fisheries Science, 15(1-2), 75-167.

• Arlinghaus et al. 2016. Passive gear-induced timidity in wild fish populations and its potential ecological and managerial implications. Fish and Fisheries, 18(2), 360-373.

• Young & Hayes. 2004. Angling Pressure and Trout Catchability: Behavioral Observations of Brown Trout in Two New Zealand Backcountry Rivers. North American Journal of Fisheries Management, 24(4).

• Askey et al. 2006. Linking Angling Catch Rates and Fish Learning under Catch-and-Release Regulations. North American Journal of Fisheries Management, 26(4).

• Alioravainen et al. 2019. Behavioural effects in juvenile brown trout in response to parental angling selection. Canadian Journal of Fisheries and Aquatic Science, 77(2), 365-374.

• Yoneyama et al. 1996. The Effect of Starvation on Individual Catchability and Hook-avoidance Learning of Rainbow Trout. Nippon Suisan Gakkaishi, 62(2), 224-236.

Author Bio:

Andy Witt, scientist and angler obsessed with chasing and understanding all gamefish, writes on the intersection of science, conservation, and fly fishing for Due West Anglers, based out of Denver, CO. 

duewestanglers.com