The summer is flying by, and we’re almost done with our experiment at Blue Lake. We’re testing our hypothesis that young Largemouth Bass grow faster in habitats with vegetation. Every month we place a new batch of fish in the nets and look for differences in growth rates, diet, and body condition. We’ve already finished our July and August time periods, and recently put the fish into the nets for September. The good news is that with the new turtle fences we’re getting good survival rates in our pens and will have plenty of data to analyze. Just before we netted the August fish I shot some video to better understand behavior of our bass. Check it out below! Continue reading
What’s it eating? In the fishing world, whenever a fish is cleaned for the frying pan, inevitably the curious fisherman will take a few seconds to remove the stomach and see what the fish was eating. Minnows were dinner last night? Time to get out the Rapala. Damselflies and mayflies? Break out the flyrod tomorrow evening. In fisheries research, scientists are also interested in what the fish are eating to better understand their biology and the ecosystem in which they live. How can we see what they ate without dissecting them? We pump their stomachs! Continue reading
In a past life, I worked with the National Marine Fisheries Service outside of Washington, D.C. Interested in protecting habitat to improve fishing and other ecosystem services, we set out to conduct the largest ever assessment of US estuaries. Estuaries are the mixing zones where rivers flow into oceans. They are dynamic ecosystems, and support teeming fish and wildlife populations. One of their most important functions is to serve as a nursery for young fish. Hiding in seagrass or mangroves is a lot safer than swimming with tuna for a little fish, and there are plenty of food sources for these fish during the early part of their lives. After they grow up in the ocean, fish like Striped Bass, Atlantic Salmon, King Salmon, Steelhead, and others swim through estuaries on their way to spawn. This makes estuaries a critical transition zone for many commercial and recreational fish species.
Our team has started conducting nighttime electrofishing surveys of 16 Michigan lakes, meaning long days and lots of excitement!
I mentioned in the previous post that our big research question is, “what habitats are best for Largemouth Bass?” We are using net pens to confine fish to particular habitats and follow their growth, but of course fish can swim from habitat to habitat in many lakes. So, we are complementing the net pen research with a study of Largemouth Bass populations across lakes that provide different habitats. Some lakes have lots of aquatic vegetation while others have only a few spots. How much is enough? How much is too much? These are questions that have been addressed in the fisheries research to some extent, but most studies are from southern lakes choked with vegetation. Not much use up in Michigan! So, we are setting out to study these questions by comparing the Largemouth populations of many lakes to maps of aquatic vegetation and other habitat characteristics.
That means we get to go out and catch thousands of fish. The best way to do that is electrofishing, which I’ve already written about here. Here’s what it looks like from my perspective on the boat.
Our big research question is “what habitats do Largemouth Bass survive best in”, but breaking it down scientifically into testable hypotheses is really tough! One way to approach the question is by confining the fish to particular habitats and seeing how they do. Of course, there are some big assumptions confining mobile fish, but more on that later.
On July 2, we began our first experiment of this year. We placed 12 net pens in Blue Lake (near Fountain, MI) and stocked them each with baby Largemouth Bass. The net pens are 10 feet by 10 feet, with an open bottom. We put the pens in areas with 0%, 50%, and 100% vegetation coverage, to see whether the fish grow better or eat differently. Our results from last year suggested that bass in pens with no vegetation grew more slowly. However, we were challenged by a major issue: turtles! Continue reading
This summer we will be conducting research on Largemouth Bass in over twenty lakes in Michigan. Largemouth Bass are an economically and ecologically important game fish commonly targeted by anglers in Michigan. The vegetated habitats that Largemouth Bass utilize in some north temperate lakes are changing as human development intensifies. Study of the relationship between vegetation and age-0 Largemouth Bass growth and survival is needed to better manage this species. This information may be important for fishery and aquatic habitat managers as well as lake associations and property owners as decisions impacting aquatic vegetation are made. Our research will have two components, described below. Continue reading
“The juice is on!” I shouted over the roar of the generator. As the words left my mouth orchestrated chaos erupted in front of me. Nine-foot nets plunged into the water, scooping largemouth bass as they arched toward the surface in front of our boat. Nets swung into the waiting hands of another researcher, transferring stunned fish into the livewell before technicians returned their focus to the water in front of our boat.
Electrofishing may be one of the most adrenaline-packed moments in the professional life of a fisheries biologist. The technique is used to capture fish by temporarily stunning them with electricity, and can be astonishingly adaptable and effective. Continue reading