It's Caviar Reality, Not Dreams, for TTU Biologist Studying Paddlefish"Lifestyles of the Rich and Famous" may be a television show about “champagne wishes and caviar dreams,” but for a Tennessee Tech University biologist researching paddlefish populations, caviar is his reality.
The caviar industry is paying attention to the Mississippi River basin paddlefish because over harvesting and illegal trade have driven Eurasian beluga sturgeon to near extinction, leaving a void for what connoisseurs consider the tastiest caviar in the world. With this collapse, female paddlefish eggs are becoming a popular substitute as an international source for caviar in both legal and illegal markets.
Phillip Bettoli, a Ph.D.-level research scientist with the U.S. Geological Survey who’s work is stationed at TTU, is working on a project to determine the extent of over-fishing to find out if current state regulations are sufficient to protect Kentucky Lake paddlefish populations.
Since the U.S. Geological Survey recently released a report addressing this research, Bettoli has garnered national and international media attention for his knowledge that affects a wide variety of audiences. Reporters from Wine Spectator have called because of the caviar industry angle. Ecological journalists are paying attention to the effects on paddlefish. Commercial fishermen and women are concerned about their livelihoods.
“Paddlefish were once common throughout the 22-state Mississippi River basin, but their range has shrunk and populations have declined in most locales because of either over-fishing or destruction of their natural habitat,” said Bettoli.
Although the Kentucky Lake population seems to be relatively abundant right now, his study shows signs that it too is being significantly over-fished.
“We’ve discovered that the population is exploited at unsustainable rates during periods of average or below average rainfall, when river flows are low and commercial fishers can easily deploy their nets,” he said.
His study has also found that the percentage of paddlefish catch actually harvested by the commercial fishers is less than 10 percent. The rest — more than 90 percent — is considered “by-catch” that is simply returned to the water.
“Any non-targeted organism that encounters fishing gear is referred to as by-catch. Dolphins caught by tuna fishers are by-catch, for example, and so are sea turtles caught by shrimp fishers,” Bettoli explained.
In the case of paddlefish, by-catch refers to the immature of either sex and adult males of the species — in other words, those that don’t produce eggs for the much-coveted caviar.
Bettoli’s project — in addition to recording many other factors — monitors the initial and delayed mortality rates of the by-catch paddlefish.
Initial mortality rates are easy to determine because that simply means counting the number of fish that are already dead when they’re removed from the nets, but delayed mortality rates — the number of paddlefish that die after being released back into the water — is somewhat more difficult to track.
For that, Bettoli and his research assistants attach radio transmitters to the fishes’ bodies to monitor their movement for several days — and that’s not always an easy task, he says.
“On a pretty cold and rainy day, we were out on the water tracking radio-tagged fish to see who lived and who died after being released the day before,” he said. “We’re currently tracking a batch of 18 fish, and most are still alive.”
In addition to a passion for the project, Bettoli’s sense of humor helps get him through the rainy days. “After many years of careful research, we’ve determined beyond a shadow of a doubt that dead fish don’t swim upriver,” he jokes.