bass underwater
April 8, 2014

Catch And Release Fishing Has Negative Impacts On Some Largemouth Bass Males

Brett Smith for - Your Universe Online

Many anglers preach catch-and-release fishing methods as not only humane, but a good practice for maintaining stocks of fish living in a lake.

However, a new report from researchers at the University of Illinois has found that catch-and-release fishing could still have a negative impact on largemouth bass. The study, published in Environmental Biology of Fishes, revealed that nest-guarding male bass are critically affected by a catch-and-release event and the exhaustion it creates.

"One of the main conclusions of the study was that in a lake where there are very few brood predators, when you angle a male away from his nest and then immediately release him, the chance of a negative impact is less, but if the nest is located in a part of a lake where there is a high density of brood predators, once the male is removed, predators get into the nest very quickly," said study author Jeff Stein, a fisheries expert from U of I. "On average, the time it took brood predators to begin eating bass young was less than five minutes in cases where the nest was located near schools of brood predators."

Stein advised catch-and-release anglers to try to get their catch back into the water as fast as possible – especially during nesting season in the early part of the year and if the surrounding water is home to brood predators such as bluegill, pumpkinseed, or rock bass.

The study included 70 nests that were situated within nine lakes in southeastern Ontario and southwestern Quebec. These lakes, which were closed to public fishing during the information collection period, held normal largemouth bass communities, with differing numbers of known brood predators.

Using a wet suit and snorkel, Stein studied the nests and allocated scores addressing the amount of brood predators and the quality of parental care shown by the largemouth bass fathers, since mothers have no parental role.

The males were caught and held in water for 15 minutes, then released. The researchers found that the bass took an additional 30 minutes on average to come back to their nests.

"A pro who isn't interested in anything about the fish other than that he caught it will rip that fish over in about 15 seconds into the boat and spend only about another minute or two with the fish before releasing it back into the water," Stein noted. "Casual recreational anglers may be afraid they're going to lose the catch and so may play it a little more, which exhausts the fish more.”

“After the fish is caught, it might accidentally flop around on the floor of the boat for a while,” he added. “They may put it in a live well if they're thinking of keeping it or until they get the camera out. Five minutes or more elapse."

Stein said after these fish are released “they’re disoriented so they go to the bottom to sit and recover for a while and get their heart rate back to stasis.”

"The fish is saying, 'Okay, I lived through whatever that was. Now where is my nest?' and by the time it actually gets back to the nest it has been gone from it 30 minutes,” Stein said.

The Illinois researcher pointed out that since bass typically spawn only once per year – the predation of an unguarded nest could result in a reduction of a lake’s bass population.

"We definitely know that the success rate of largemouth bass nests when parental care is interrupted is lower," Stein said. "During catch-and-release angling, the male may become so physically taxed that it doesn't continue parental care. The big question we're still looking at is how it affects the whole population."