Bass anglers might be hurting their fish by improperly holding them for photographs.
You know the traditional bass fishing "hero" shot. An angler holds up a trophy bass by the lip, usually cocking the jaw downward to open the mouth and add curvature to the image.
I've long wondered if it injures a fish to exert excessive pressure on the delicate joints and tendons of the jaw. Apparently it does, according to a recent study conducted by a team of veterinarians and Steven Bardin, a leading fisheries biologist and owner of Texas Pro Lake Management.
The results were posted online by wired2fish.com.
Bardin collaborated with Dr. Casey Locklear and Dr. Steven Mapel, of Hat Creek Veterinary Services in Early, Texas, to study the effects of handling bass by the mouth.
Bardin said the team captured fish using electrofishing on a private lake. They selected individuals that weighed between 2-6 pounds with a relative weight of 100-125 percent.
"Relative weight is a body condition score that fisheries biologists use to compare the actual weight of a fish to what it should weigh based on its length," Bardin said in the wired2fish article. "These higher relative weight fish are overweight for their length, giving them the appearance of what we would expect a trophy fish to look like."
After calculating the relative weight of the test subjects, Locklear and Mapel took radiographs of each bass being held in four common positions. One was a thumb hold with the bass supported by a second hand horizontally. Another was a bass being suspended with a thumb hold. A third was a bass suspended on a digital scale, and the fourth was the one-hand, cocked-jaw hold.
The veterinarians did not observe any broken bones in the lower jaw after being held in any position in the radiographic images. They concluded that broken bones are not as probable as are injuries to soft tissue injuries.
"The excess weight and pressure being applied to the jaw is not resulting in one bone location taking all the stress," Locklear said in the wired2fish article. "Instead, the entirety of the lower jaw bones, joints and other soft tissue areas tend to absorb the stress. The weakest parts of the jaw are actually the soft tissue areas."
The team focused on that aspect because so little information exists.
"We carefully attempted to isolate specific joints and bone junctions that were potential locations for injury," Bardin said. "These areas of interest are places where excessive pressure would likely be applied or over-flexion or over-extension of the joint could occur. Potential areas of concern in the lower jaw were found to be the mandibular symphysis, located centrally where the left and right dentary bones meet, and the joints where the angular bones and the quadrate meet."
In summary, the team determined that it is possible to damage soft tissue with the vertical thumb hold and the cocked-jaw hold because they exert stress and pressure to multiple points.
The risk increases proportionally with progressively bigger fish, Bardin said. In fact, the study concluded that the cocked-jaw hold is unacceptable.
"The jaw of the largest fish we radiographed actually made an audible pop when it was placed into the exaggerated vertical position," Bardin said. "Following the study, this fish also had visible laxity in the mandibular symphysis that I would consider to be abnormal. This damage was not observed in smaller fish, nor did they have the same pliability in the jaw that the larger fish did."
Unknown, Bardin said, is whether damage from improper handling is permanent, or how long a fish takes to recover. A fish can swim away after being released with no visible signs of injury.
The scale hold and the supported thumb hold are the least stressful. Bardin said that the clip on a scale actually acts as a pivot joint that alleviates stress on the jaw.
Tournament anglers often pose with two or more big fish on weigh-in stages. It's better to display only one fish in a supported hold.
Done correctly, it is more photogenic than the cock-jaw hold, and it demonstrates respect for the resource that provides their income.
Sports on 11/12/2017