Releasing a bass makes us feel good. But does catch-and-release really help sustain fisheries?
Based on results from a tagging study at Texas’ Amon Carter, a 1,539 acre fishery north of the Dallas/Fort Worth Metroplex, the answer is a resounding “Yes!”
Sixty-three percent of 786 tagged bass were taken. In other words, fishermen caught nearly 500 of those fish.
Forty-three percent were weighed in by tournament anglers. Another 16.3 percent was caught and released by recreational fishermen, with just 3.7 percent harvested.
There’s plenty more evidence too.
Nearly 75 percent of tagged fish were caught at Florida’s Lake Santa Fe.
“Another study we did on Rodman years ago was 40 percent caught by anglers,” said Mike Allen, professor of Fisheries and Aquatic Sciences at the University of Florida.
On Tennessee’s Norris Reservoir, meanwhile, the “adjusted annual angler catch rate” for tagged largemouth bass was 47 percent in 1996 and 34 percent in 1997.
And Jacob Westhoff encountered some powerful anecdotal evidence while doing a smallmouth telemetry study on the Jacks Fork River for the Missouri Cooperative Fish and Wildlife Unit. Eighteen of the 33 bronzebacks with transmitters were caught by anglers.
“Also of note, is that eight of our fish were caught by a single angler in one day during the winter at the confluence of Alley Spring and the Jacks Fork River,” he said.
Clearly, the evidence is there to support the wisdom of catch-and-release--- and more.
“Those findings highlight the importance of proper fish care,” said Randy Myers, a fisheries biologist for Texas Parks and Wildlife. But he is quick to add that not all bass fisheries reveal such dramatic findings. For example, just 38 percent of more than 6,000 tagged fish were caught on Sam Rayburn, a lake more than 70 times the size of Carter.
Allen added that the statewide estimate for Florida lakes is about 20 percent.
“It obviously varies widely among water bodies and probably among regions,” he added. “In Florida, we have so many lakes. It’s probably higher in states without as many fishing sites.”
Allen’s point is important. The percentage of a bass population caught ties directly to angling pressure. At Amon Carter, tournament and recreational effort was a combined 14 hours per acre, while it was 5.2 at Rayburn. And in Florida, drought had reduced accessible areas at other fisheries, likely forcing more anglers than normal to fish Santa Fe.
Other factors can influence how great a percentage is caught as well.
“Rayburn has better habitat than Carter,” Myers said. “Overall, it’s a better lake for bass production.”
Still, angling pressure is a top consideration for resource managers in maintaining healthy bass fisheries. That’s why Myers is hopeful that removal of a protective slot at Ray Roberts will attract tournaments away from Carter.
“At Carter, more than half of the effort was from tournament anglers,” he said. “Because they are so popular, we have to think long and hard about restrictions that would limit tournaments. But if 50 percent of tournament-retained fish die (at Carter) it would have some impact on the fishery.”
Consequently, how fish are cared for before they are released also is a concern for Myers and other fisheries managers.
“If a fish is gilling, lots of experienced anglers still assume that it will live,” Myers said. “But that’s not always true. Some of those fish do die.”
The Texas biologist pointed to statistics gathered as part of a fizzing study during five tournaments at Lake Amistad in 2009.
On days when the water temperature was in the 50s and 60s, mortality, both immediate and delayed, was less than 10 percent. On a day when the temperature was 79 to 80, total mortality was 23 percent and delayed 18.3. And, most sobering, when the temperature was 83, total mortality was 50.8 percent and delayed 42.1.
“What we saw at Amistad is that 75 degrees is the critical temperature for bass health in a livewell,” he said. “That high mortality was strictly related to water temperature.”
Hot Days and Heavy Limits
Research like that at Amistad prompted Texas biologists Randy Myers and James Driscoll to recommend an oxygen injection system for livewells, particularly when an angler has a hefty limit as often happens at Texas reservoirs.
“Oxygen injection has long been used by Texas Parks and Wildlife Department hatcheries to maintain the health of fish being stocked into reservoirs,” they said.
“Fisheries staff regularly transport or hold fish in ratios equal to or greater than one pound of fish to a gallon of water. However, boat manufactures do not offer oxygen injection system options, and very few tournament anglers have installed oxygen equipment on their boats.”
Proper installation and operation of such a system, they added, “will ensure oxygen levels remain above the preferred level of 7 milligrams per liter, even when livewells contain heavy limits.”
More information is available in a Power Point presentation.