Mapping Michigan’s lake habitats

Our main hypotheses are that habitats affect the distribution, abundance, diets, and growth rates of Largemouth Bass. How do we get this habitat data? In previous posts I’ve discussed how we catch fish and collect their gut contents, so this article will focus on our vegetation mapping.

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We mapped patches of vegetation in lakes, such as these lily pads near a developed shoreline with its vegetation cleared.

Vegetation mapping techniques have advanced rapidly in the past decade with new technologies allowing us to do things that we never thought possible. Some of the first aquatic vegetation maps in Michigan were produced in the 1930’s and 1940’s, but required careful surveying and were limited in resolution. Computer programs now enable digital mapping, which in turn makes research such as ours possible. In a perfect world, we would simply use aerial or satellite photos taken around the same time as our surveys. These techniques have been used with some success on the Great Lakes, but their application to small inland lakes can be hampered by water clarity, tree canopy cover, and expense. The NASA option out, the next best plan was to visually map each lake in the field. Continue reading

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The night shift begins! Electrofishing 16 Michigan lakes

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.

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Michigan Inland Lakes Convention

Later this week I’ll be attending the firstĀ Michigan Inland Lakes Convention up in Boyne, MI to discuss some of my results from last season’s fieldwork and to conduct my first foray into economic and social research! The conference brings together lake associations from the Michigan Lakes and Streams Association, members of the Michigan Chapter of the North American Lake Management Society, and others that conduct research, manage, or have some stake in Michigan’s lakes. Continue reading