Eyeball Challenge


Angler with trophy bass


How big do you think this bass is? Ten pounds? Seven? Fifteen? A unique study by the FWC along with partner, Bass Pro Shops, recently revealed that guessing right is harder than you think — whether you are an experienced bass angler, fishing guide or even a bona fide fisheries biologist. The Eyeball Challenge arose from FWC’s TrophyCatch program, which collects data on bass eight pounds or larger from anglers for use in fisheries management and conservation. The core requirement for submission is a photo or video of the entire bass on a scale with the weight reading clearly visible. And, every trophy bass must be released.

“Given the very specific submission requirements, I’m still a bit mystified whenever I get the ‘That bass isn’t ten pounds!’ comment on one of our posts,” says biologist and TrophyCatch Facebook Manager, John Cimbaro. “If there’s one thing I’ve learned from looking at thousands of bass photos, it’s that the same fish can look very different depending on how the picture is taken and how the fish is held. A hero shot of the angler holding his trophy bass up is usually the best-looking photo for a Facebook post. But the fish-on-scale photo is the one that matters for the research program, and that’s the photo l point a doubting commenter to.”


How the Eyeball Challenge Works

The Eyeball Challenge asked anglers to estimate the weights of bass in three separate challenges, each with a series of photos. Each bass was weighed by a biologist with field scales to ensure accuracy. Besides offering anglers a fun distraction during the infamous summer of 2020, The Eyeball Challenge was designed to gather specific data about how accurate anglers are in assessing the weights of bass in photographs. Anglers’ guessing acuity was represented by a score that was the average error (difference between the guess and the actual weight) across all the bass in each round. Rounds 1 and 2, featuring six bass each, introduced the Eyeball Challenge format and served as “warm up” rounds. The challenge culminated in August with Round 3, featuring twenty-four new bass and a $50 Bass Pro Shops gift card as a prize for the angler with the best score. Nearly 900 anglers completed the final round, and the results were quite revealing: on average, anglers were off by plus or minus 2.22 pounds per bass. Even the top 5% of all guessers — the A-pluses at the head of the class — were only able to shave their error down to plus or minus 1.35 pounds of the actual weight. Collectively, participants were quite consistent, and the average score and the top 5% mark were nearly the same across all three rounds.


Eyeball Challenge promotional graphic


Table of Eyeball Challenge data


Experience Is No Help

Does fishing experience endow anglers with weight-guessing skills? Eyeball Challenge participants told us if they identified as novice, intermediate or avid anglers, and they provided the number of years of bass fishing experience they had accrued. Interestingly, statistical testing indicated that there was no performance difference among the three levels of anglers. Technically, increased years of bass fishing experience translated into statistically significant improvements in guessing bass weights, but in practical terms, it takes anglers a lifetime of fishing experience (60 years) to gain only about one-half pound of accuracy over inexperienced anglers. The bottom line is that no matter how good you are at catching fish or how long you’ve been fishing, a variety of factors makes it hard to accurately guess the weight of a fish from a photo.


YES, Hold That Bass Out!

One key result from the Eyeball Challenge was that how an angler holds his or her bass in a photo makes quite a difference in how we perceive it. One-half of the bass featured in Round 3 were held out toward the camera, at arm’s length. The others were held much closer to the angler’s torso. As many of us might have guessed, there was a highly significant difference in anglers’ ability to accurately guess the weights of bass in the two groups. Anglers were much more accurate at guessing weights of bass held at arm’s length but had a slight bias towards overestimating those bass. For bass held close to the body, anglers underestimated those bass by over 1.25 pounds on average.

“It’s now scientifically proven — If you want the best photos of your catch, do hold that fish out toward the camera,” says biologist Drew Dutterer, who helped to design the study. “If not, it may be impossible to convince your fishing buddies just how big that bass really was!”


Two anglers holding two bass in different poses

How you hold your bass for the camera can make a dramatic difference in how the fish is perceived in the resulting photo. These are the same two fish in both pictures.


The Two Bass That Fooled Everyone

If the take-home message from the Eyeball Challenge is that determining bass weights from a photo is not nearly as easy as we first assumed, there were several conspicuous examples among the bass included that exemplified that message. Most of the bass had about as many over guesses as under guesses. Some, however, tipped that balance nearly completely in one direction or the other. The bass featured at the top of the article threw most folks for a loop. This beauty from Lake Istokpoga weighed in at 10 pounds even. It was just a little over 23 inches long and measured 20 inches in girth. Ninety six percent of guessers over guessed on it. Furthermore, two-thirds of guessers thought it was more than 13 pounds. The bass below fell in the opposite direction. From Lake Walk in Water, it weighed 12.4 pounds, was over 26 inches long and had a 20-inch girth. Ninety-seven percent of participants under guessed the weight of that fish, and its average guessed weight was 8.7 pounds. What gives?

Besides how the bass is being held, there are certainly other factors that affect how we assess photographed bass. Anglers and biologists have frequently commented that bass condition (how fat or skinny it is) and the size of the person holding the bass influence our perception. These two bass could be good examples of those influences, since the dimensions of the bass at the top of the article give it an unusually high condition factor, and the bass below was held by a bigger-than-average individual. Hopefully, additional analyses of the Eyeball Challenge data will shed more light on these ideas. Stay tuned for additional results in the future.


Angler holding 12 pound bass

This bass stymied most Eyeball Challenge participants. It weighed 12.4 pounds, but 97% under-guessed the weight of the fish, with the average guess almost 4 pounds low at 8.7 pounds.


The TrophyCatch program has been popular for not only allowing citizen-scientists to contribute their data, which anglers report is their primary reason for submitting catches, but because industry partners like Bass Pro Shops provide rewards for participation. To register for TrophyCatch and learn more, visit the TrophyCatch main page. For more information about the TrophyCatch program or the Eyeball Challenge, email the TrophyCatch team at TrophyCatch@MyFWC.com.