Smallmouth bass aren’t small anymore, according to a recent SUNY-ESF study.

As part of his dissertation at the State University of New York College of Environmental Science and Forestry, Derek Crane published the article “Trends in body condition of native piscivores following invasion of Lakes Erie and Ontario by the round goby.” Crane’s article revealed an increase in the weight of smallmouth bass due to the rising round goby population.

Crane was the lead investigator in the study analyzing the fish populations in the Great Lakes and highlighted the research he has done in collaboration with the Department of Environmental Conservation Lake Ontario and Lake Erie Research Units in his article.

The round goby is a fish native to central Eurasia that has established many non-native populations in the Great Lakes when it was brought in through ballast water — discharge from ships — in the 1990s. As the round goby population grew, they affected the ecology and ecosystem of the Great Lakes. Anglers, a type of fisherman, as well as employees at the lake had been noticing weight changes in the native fish since round goby invaded Lake Erie and Lake Ontario, specifically in smallmouth bass.

Crane and his team set out to put numbers to these empirical observations.

“Basically what we’re looking for is, for specific length fish, has the weight changed? And if so, how much?” Crane said.

All the information that Crane studied was based off of long-term data obtained by the DEC during its annual fish surveys, which have been taking place since the 1970s. It took Crane and his research partners about a year to collect the data and compare the samples of weights of the fish from 1993 to the present. He spent another six months working on the publication of his findings.

Other studies had already proven that round goby had been readily incorporated in the food web, but Crane’s research has shown that the increase has resulted in changes in weight. The increase is linked to how much the new species is being incorporated into the diet of the fish, Crane said. Up to 75–80 percent of the smallmouth bass diet is now round goby, which was a fast shift from their typical feeding on crayfish, native shiners and other fish.

Crane’s research demonstrated the ecological trade-offs going on with invasion of round goby; the positive side is that the fish, particularly smallmouth bass, seem to be in better condition which can lead to faster growing, healthier fish.

“If you are in better condition, the thought is that you have better fat reserves and you are better able to survive because you have more energy stored and also more energy to put into reproduction” he said.

But a largely negative implication of this is that fish that grow faster tend to live shorter lives. There could be increased mortality in the fish in these lakes, which Crane hopes to investigate in his next project.

“There is definitely a trade-off and it’s a really messy picture,” said Crane. “It hasn’t totally been sorted out but we can definitely say that smallmouth bass do seem to be in better condition in both lakes based on our analysis but the overall effects on the population or the long-term effects … we’re still trying to sort that out.”

Crane is working on another study that relates to this data that focuses on the rate of growth of the fish in Lake Erie and Ontario; he had noticed during this study that the fish appear to be growing faster after the invasion of the round goby.

The round goby is just one example of how human action can dramatically and quickly alter an ecosystem, Crane said.

“We’ve brought in a massive number of invasive species — over 188 species — that have been documented in the Great Lakes, a large number of them through ballast water and shipping.”

Crane said he hopes that this type of research will help when making policies on maritime shipping and trade and bait trade as they will encourage thoughts about what can happen to an ecosystem when invasive species are introduced.

Published on November 11, 2014 at 12:01 am

Contact Anjali: acalwis@syr.edu