Lake sturgeon keep spawning options open
A lake sturgeon can live to be 150 years old. And that’s a good thing, because when it comes to making baby sturgeon, well, they aren’t very successful.
However, a team of Michigan State University researchers has noticed something about the prehistoric-looking fish that may be giving them an advantage.
By inserting a passive inducible transponder, or PIT, tag into more than1,100 sturgeon, the team was able to track the fishes’ every move, including when and where individuals spawned and under what conditions they were successful. Or not.
What they found is some of the lake sturgeon will spawn early in the year, while others opt for later in the year. This variability, as fisheries and wildlife professor Kim Scribner calls it, helps them cope with an environment that often isn’t conducive to making baby fish during the same time or at the same location.
“If you only had fish spawning early,” said Scribner, who is leading the research team, “you’re putting all of your eggs into one basket. If the environment for that one time isn’t optimal, you’ve lost a whole year of reproduction.”
Scribner and his team have genotyped thousands of the fish for more than 13 years. Information based on genetic parentage has provided a wealth of information, including what the ecological conditions were when the fish’s parents spawned.
“It gives us an idea of what the environment was like,” he said. “Events such as large rainfall, fluctuations in temperature and so on.”
He said lake sturgeon are not the most efficient spawners. The female will release thousands and thousands of eggs which, if conditions are right, will adhere themselves to rocks at the bottom of a stream. It’s hoped that a male will come along to fertilize the eggs before they attach.
Scribner’s team also found that the rate of fertilization success and survival among lake sturgeon is quite low. Scribner said that due to several sources of mortality they have been able to document that as many as 99 percent of the eggs that are laid die.
“For the eggs that hatch, perhaps another 95 percent of those die, even before they reach their first fall,” he said.
The lake sturgeon does have a lot working against it. A fish that once thrived in the Great Lakes and beyond, it now finds itself a state-threatened species, its numbers dwindling due to overfishing, invasive species and loss of habitat.
Lake sturgeon are extraordinary fish. Around since the time of the dinosaurs, they can grow to more than 8 feet and weigh 200 pounds. They don’t have scales but rather a cartilage-like skeleton.
Despite their fierce appearance, they are bottom feeders, eating things such as crayfish, mussels, worms and insects.
For more information on Scribner’s team’s work, visit www.fw.msu.edu/glsturgeon/.