"In the world of bass, 'big' does
not equal 'old." Thus wrote senior writer for ESPN/BASS Publications Robert Montgomery back in September 2011. "In Florida, for example," he continued, "scientists used otoliths (ear bones) to determine that a 10-pound-plus largemouth bass was just 4 years old.
"By contrast," continued Montgomery, "an angler recently caught and released a 3.5-pound bass in Montana that was judged to be 19 years old, based on a tag inserted 14 years ago, when it weighed 1.5 pounds.
So a 4-pound bass in Minnesota or Montana might not be impressive in terms of weight, but it could be a real trophy if age is given equal consideration. Does that mean that bass fisheries in northern waters should be subject to stricter regulations to protect a vulnerable, slow-growing population? Not necessarily.
That same 4-pound bass could be 6 or 7 years old, instead of 18 or 19. Just as not all southern bass grow to 10 pounds, not all northern bass live to be 19.
"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. "These old fish are not the bulk of the sport fishery."
In a Florida study, 822 trophy bass (10 pounds and up) given to a taxidermist showed a mean age of 9.7 years. That's a growth rate of about a pound a year. As previously mentioned, the youngest was just 4 years old, while the oldest, likely from the northern part of the state, was 16.5.
Bass grow large and/or live long because of a number of variables, including genetics; forage species and abundance; climate and latitude; and type of fishery, its water quality, and habitat. Fish in more northern climates typically live longer but grow slower and don't get as big as their counterparts in the South, especially Florida-strain bass.
Also, whether in the North or the South, bass tend to grow their entire lives. Rate of growth slows as the fish age but never stops.
Most every angler knows that bass in rivers and tidal waters don't grow as large as fish found inland. But why? For rivers, it's mostly about flow.
"Productivity in a static body of water (lake or reservoir) is easier to maintain," said Oklahoma fisheries biologist Gene Gilliland. "You're more likely to have abundant food in static water. In flowing water, you don't have as many good options, and fish can't get as many calories from insects and crawfish. Also," he added, "river fish 'exercise' constantly, burning calories to maintain position in the water column and fighting currents to feed."
Tidal bass, meanwhile, have evolved in a different environment in terms of flow, salinity and forage base. Their diet usually is dominated by less nutritious invertebrates.
"Estuaries can be productive, but bass can't take advantage as well (as other species)," Gilliland added. "Currents are moving in and out, which means more exercise, and bass must spend more energy in maintaining their internal salt balance. They use more calories just making things work and have fewer to go into growth."
Dennis DeVries has studied coastal bass for years in the Mobile-Tensaw Delta. "We found that these fish move hardly at all, even in downstream areas, where salinity increased in the summer, sometimes to high levels," he said. "The fish just remained in those areas until salinity decreased again."
He added that coastal bass seem to spawn earlier in life but don't live as long.
"They are shorter and stubbier," Florida biologist Wes Porak said. "They're not necessarily different genetically, but they've evolved in unusual conditions."
The 19-year-old, 3.5-pound Montana bass mentioned earlier was first thought by many to be the oldest largemouth on record, but research revealed a 6.78-pound bass caught in New York's Mariaville Lake still owned that honor. In 1992, biologists used otolith rings to determine the latter fish was at least 23 years old, and it still was in good condition, meaning that it could have lived longer. That fish, however, was kept by 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 reported in literature was 18 years old, 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 have entered more than 500 bass in Texas' ShareLunker program, but fisheries manager Dave Terre said that the oldest fish that he had seen was 12 years old. "And it was not a trophy-size bass," he added. "It was a 6-pound male, which is huge for a male bass."
In Florida, biologists took two 6-year-old bass from Lake Kissimmee. One weighed more than 8 pounds, the other just 14 ounces. How can such a growth difference exist in the same fishery? Possibilities include 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.
Texas Parks and Wildlife biologists tried to harness that biological truth to create an entire population of bass blessed with great growth genes. In 2005 and 2006, they stocked bass from ShareLunker parents in seven reservoirs as part of the Operation World Record Program. In other words, the females used were 13-pound-plus bass, while males were offspring of equally large ShareLunker entries.
"Texas Parks and Wildlife recognizes genetics as one of the factors important for growth of trophy bass, at least in Texas," said Dave Terre, chief of management and research for Inland Fisheries. "We're assuming these fish are genetically unique. What that means exactly, we don't know. But we're trying to maximize those traits."
After four years, researchers found that the stocked bass from ShareLunker parents were a half-pound heavier than resident fish of equal age.
"We're going to keep monitoring those fish," Terre said. "They're tagged and, with DNA fingerprinting, we know the parents of each of them. We have reason to believe that these bass possess unique genetic characteristics that enable them to grow larger. The ultimate test will be down the road."
