Size May Matter, But It Can Be Misleading When Predicting a Fish's Age

Case in Point: When then-10-year-old Garrett Frost (pictured right) caught and released a Montana bass that weighed 3.5 pounds in the summer of 2011, many thought it might be the oldest largemouth on record. A tag that it carried allowed resource managers to determine that it was 19 years old.

As it turned out, however, the record at that time continued to be a 6.78-pound bass caught in 1992 in New York's Mariaville Lake. Biologists back then used otoliths (ear bones) to determine a fish's age, and those otoliths revealed that the 6.78-pound bass was at least 23 years old...and still was in good condition, which meant it could have lived longer.

The fish eventually was kept by angler Mark Lenegar after he caught it for the third time in one day and noted that it was bleeding around the tail.

Until that catch, the oldest bass on record in literature was age 18, but estimations before the early 1980s were based on scale rings, a method not nearly as accurate as using otoliths.

In a press release related to Lenegar's catch, Cornell University's Warmwater Fisheries Unit said that most bass populations in New York "have individuals reaching age 15." It also reported that a 12-year study, using scales, "judged three bass to be age 18 and eight to be age 17 out of nearly 18,000 largemouth bass examined.

By contrast, anglers at the same time had entered more than 500 bass in Texas' ShareLunker program, but the fisheries manager said the oldest fish he had seen was 12 years old. And it wasn't a trophy-sized bass, at that. It was a 6-pound male.

In Florida, biologists took two 6-year-old bass from Lake Kissimmee--one weighing more than 8 pounds, the other just 14 ounces. What could account for such a growth difference in the same fishery? Possibilities, according to the biologists, included disease, habitat/forage choices, and even how early in the year the fish were spawned. Genetics could factor in, as well. Some bass are genetically disposed to grow larger than others.

In 2005 and 2006, Texas Parks and Wildlife biologists stocked bass from ShareLunker parents in seven reservoirs as part of the Operation World Record program. The females used were 13-pound-plus bass, while males were offspring of equally large ShareLunker entries. After four years, researchers found that the stocked bass from ShareLunker parents were a half-pound heavier than resident fish of the same age.

So, what's the take-away here? I reckon that it's when people use the term "big, old bass," they're implying that "big" equals "old," but that's just not necessarily true. Scientists in Florida found a 10-pound largemouth that was only 4 years old. For contrast, of course, we just read about a 3.5-pound bass from Montana that was judged to be 19 years old.

"Very old fish are rarities, just like human beings who live to be more than 100 years old," said Roy Heidinger, who, before his retirement, studied age and growth in bass for years at Southern Illinois University.

Adapted from a piece by Bassmaster's Robert Montgomery.