two men walking beach seine upstream

We use the beach seine to sample fish that inhabit shallow, nearshore habitat such as suckers and northern pike.

three men pulling beach seine up onto shore

After we seine down the shore, the person along shore stops moving and the person in the water pivots the far end of the seine toward the shoreline. The third person helps guide the bottom of the net on to the shore so that no fish escape from underneath.

spraying beach seine with hose on shore to wash catch to center of net

Once hauled up on to the shore, we use a portable hose to work down the fish (little silver things) to the bag in the center of the net.

sampler leaning over side of boat in river deploying miller sampler.

The high speed miller sampler is used to catch fish that inhabit the water column (pelagic), such as perch. The sampler is a long tube with a flow meter (for estimating sample volume). Larvae are swept back into the net and then into the plastic cod-end (here, being attached).

sampler leaning over side of boat in river deploying miller sampler.

It is deployed by lowering it into the water column, generally a couple of feet deep (any deeper and it might get caught on the bottom or a log!).

two men in boat sampling open water

A critical factor affecting primary production (algae) in wetlands is light because it is sunlight that provides the critical energy for photosynthesis. We measure light in the water column using a specialized light sensor, seen just below the surface, attached to a pole that has depth markings. Readings are taken at various depths to determine how far the light penetrates into the water ("attenuation").

tucker trawl being lowered off the side of a boat in open water

We use the tucker trawl to sample fish larvae that inhabit open waters ("pelagic") in large rivers and deep portions of coastal wetlands. It's a big gear - the mouth opening is 1 m x 1 m. The electronic sensor on top measures water quality - conductivity, depth and temperature (CTD) - and communicates the data to the vessel.

tucker trawl listed out of the water over the side of a boat

The tucker trawl is brought back onboard

Spraying water on lower net of tucker trawl to wash catch into sample cup

After the trawl is retrieved, the net is hosed down to wash all the fish larvae into a plastic bucket at the end of the net (the cod-end)

Sample cup with small fish and larvae

Here is what we caught!

Graph of temperature and conductivity vs time

One goal of the study is to understand how coastal rivers influence the organisms, water quality and habitats of the coastal zone. For example, we sampled the coast of Lake Superior at the Amnicon River mouth with the tucker trawl to determine if there was a mix of riverine and lake fish larvae (there was!). The water quality sensor on the tucker trawl, called a CTD, shows the environmental change associated with the river plume - higher temperature and lower conductivity water - compared to Lake Superior.

conical zooplankton net being deployed off side of boat.

Lowering the zooplankton net into the waters of Allouez Bay. Zooplankton are important because they are a major food source for larval fish. If zooplankton are scarce, the larval fish will starve and the fish population will not reproduce succesfully.

Sampler leaning over the side of boat towing zooplankton net in river

Deploying a zooplankton net in a shallow coastal wetland can be a major challenge! Here, we lower the net from a makeshift davit off the side of our john boat.

sampler removing flow meter from zooplankton net

To obtain quantitative estimates of zooplankton abundance, we use a flow meter in the net. The flow meter is a tool to measure the volume of water sampled by the zooplankon net.

sampler hoseing down zooplankton net over the side of a boat

After sampling, the zooplankton net is hosed down to wash the entire sample into a plastic bucket attached to the end of the net (the cod-end).

Jetboat docked on the side of river, beach seining in background

We use the jetboat on the Amnicon River because it is wide enough to accomodate the vessel (jet boats take wide turns) and because the river has lots of woody debris over which the jet boat can "hop".

john boat docked on the side of river

We use the john boat on Fish Creek because the river is very narrow and extremely shallow.

Large vessel in shipping lane

There are many obstacles when sampling coastal wetlands - both man-made and natural. Sampling at the mouth of the Nemadji River in Duluth-Superior harbor was a challenge because it lies right along a shipping lane used by the giant ore boats. These boats are up to 1000 feet long. You can see the plume of clay associated with the Nemadji River as it flows into the harbor and intersects a mix of less sediment-laden water from the St. Louis River and Lake Superior.

Thunder clouds on the horizon

We are always aware of the weather when working on the water - from snow to high winds to encroaching thunderstorms. On this today, we kept a close eye on these thunderclouds.