An Aggressive Invasive Species: Starry Stonewort

By on March 3, 2016
Starry stonewort bulbil. (Credit: Paul Skawinski via Michigan.gov)

Mention natural, glacially formed lakes to most anglers and it will bring thoughts of productive waters. Healthy aquatic vegetation is almost always a main habitat component in these types of waters. It’s also one of the main reasons the fisheries are usually healthy and alive with many different species of fish. However it seems more and more that lakes are moving away from the “healthy” trend.

They are increasingly facing a growing number of stressors. One of the most noticeable is the rapid spread of an invasive species called starry stonewort. Unfortunately for those of us in the Great Lakes State, Michigan is ground zero for the starry stonewort invasion. Likely making its way to the Great Lakes via ballast water, it was discovered in Lake St. Clair in the 1980s. However, it hasn’t been until the last decade that starry stonewort has become a real problem.

Starry stonewort is actually an algae and not a type of rooted vegetation. It forms a dense “carpet” that grows from the bottom up. Most forms of vegetation in a lake provide vertical structure and habitat for many species of fish. Starry stonewort, however, grows so dense that it doesn’t allow fish to swim, hunt or seek refuge in it. It restricts spawning habitat for many species and doesn’t provide any habitat for young-of-year fish to avoid predators. Once established, it covers the bottom so densely that rooted vegetation struggles to ever become established in those areas.

It’s capable of growing 7 feet tall and all the way to the surface in some areas, completely crowding out the water column. In lakes where it has really taken hold, you will find nothing but acres and acres of bottom covered in stonewort. This is not really the monoculture of vegetation that makes a healthy ecosystem.

Starry stonewort. (Credit: Progressive AE via Michigan.gov)

Starry stonewort. (Credit: Progressive AE via Michigan.gov)

Seemingly when it comes to aquatic vegetation, the answer is some form of “chemical control.” While the chemicals used to kill weeds in lakes are effective on many species, there isn’t one that will eradicate starry stonewort. The best they can do is knock the starry stonewort back and closer to its home along the bottom.

From what I’ve observed, the overuse of chemicals is the main factor that gave the starry stonewort its opportunity to take such a strong hold in so many lakes. It seems it is a lot easier to outcompete other forms of vegetation when there is no vegetation to compete with. Harvesting starry stonewort is another possible method. But since it can be so prevalent and also spreads via fragmentation, it has not proven to be a good form of control.

The best way to combat starry stonewort at the moment is to do the simple things to control its spread. It spreads by fragmentation, oocytes and bulbils, all of which can easily attach to boats and trailers. A close inspection and removal of any vegetation found is a critical step in preventing its spread. Draining livewells, bilges, and cleaning a boat’s exterior is very important when going from a starry stonewort-infested lake to waters not yet affected.

Preventing the spread of this plant is something that needs to be of high priority to every fisherman or boater. If you don’t have it, you definitely don’t want it.

Top image: Starry stonewort bulbil. (Credit: Paul Skawinski via Michigan.gov)

About Jeff Elliott

Jeff Elliott is a 2014 Bassmaster Team championship qualifier. He has 75 tournament wins, including the 2012 Detroit Lions/Kevin VanDam Charity tournament. He is a seven-time points champion and a Bust’in Sticks TV show champion.

Leave a Reply

Your email address will not be published. Required fields are marked *