XII. FISH STATION INTRODUCTION Fish are fascinating animals for students and adults alike. Many people in the Grand Traverse Bay area have seen Coho, Chinook, and steelhead in tributary streams or lying in someone s freezer. But there are many less well-known fish that play an important role in the ecology of the bay, such as the ninespine, threespine, and brook sticklebacks, mottled sculpin, spottail shiner, and johnny darter. These fish are called forage fish and are eaten by predatory fish such as trout and salmon in the bay. Zooplankton, insect larvae, and crustaceans are the standard fare of smaller forage fish. During each Schoolship Program, an otter trawl (type of net) is lowered and towed behind the boat. The lead instructor chooses several students to help lower and raise the otter trawl. Students learn the distinguishing characteristics of the fishes caught and how they fit into the food web. They learn about the life histories and impacts of exotic species like sea lamprey, alewife, and round goby. Students also gain an understanding of the economic importance of fishes to this region and state. LEARNING OBJECTIVES Students will be able to: 1. Identify the collection device used to sample fish. 2. Name parts of a fish s anatomy with the aid of a diagram. 3. Use the fish key to correctly identify fish caught in the trawl. 4. Recognize the place of forage fish in the food web. 5. Identify existing threats to fish populations and habitats in the Great Lakes. 6. Discuss the contribution of fish and fishing to the economy of the region. 7. Give reasons for sampling and monitoring Great Lakes fish populations, and for keeping scientific log books. 8. Using the Great Lakes food web diagram, describe feeding relationships between Great Lakes organisms, and how invasive species disrupt those relationships. TOOLS 1-quart aquariums Fiberglass tub Round goby/sculpin display 5-gallon bucket Fish identification book Rubber fish (lamprey, trout) 10-gallon aquarium Fish Station manual Rubber mat Aerator Measuring board Towel/rag Dip nets TEACHING THE STATION Setting Up The volunteer instructor teaching the Fish Station should help the lead instructor ready the fish trawl. Fill the 10-gallon aquarium, the fiberglass tub, and a 5-gallon bucket with water until each is approximately 1/2 full. Setting the Trawl The trawl is generally set by the crew and lead instructor, with the assistance of the fish instructor. 1. The lead instructor will work with the crew to ensure the trawl is ready. Inland Seas Education Association - 123 -
2. The lead instructor explains the operation of the trawl to the students. Four or five students line up amidship on the port side of the vessel. The student most aft in line is responsible for throwing out the float line attached to the cod end of the net. The other students in the group hold the body of the net. The lead instructor or first mate will get the OK signal from the Captain and tell the group to lower away. 3. At this point, the student holding the float line will heave it overboard, followed by the other students who bring the net over the lifeline and drop it into the water. The lead instructor or mate will handle the otter boards. 4. When the trawl is out, the Captain will announce the start depth and start time for the students to record. The average trawl time is 10 minutes. During the trawl, the mate or lead instructor may talk about the history of schooners and teach the students shipboard commands (and possibly a sea shanty). 5. Several students line up on the port side to haul in the trawl. On Inland Seas, the Fish Station instructor empties the fish into a fiberglass fish tub, and then transfers the fish to the aquarium. The lead instructor will handle this on Manitou since the Fish Station instructor will have a small group. The aquarium should be covered with the fiberglass tub to prevent distracting the students and the sun from warming the water too much. During the Schoolship Program, it is a good idea to aerate the aquarium. Make sure to remove zebra and quagga mussels from the aquarium, as they rob the water of oxygen. Use an air stone (a type of air bubbler) or fill a bucket with water and pour fresh water into the sample. Teaching the Station Have the group gather around the aquarium. You may wish to keep the aquarium covered at first, to keep the students attention while you introduce the station. Turn to the parts of a fish page in the Fish Station manual (also shown on page 130 of this manual). Some good leading questions include: 1. What would a fish biologist want to do with these fish? Identify, count, perhaps measure. 2. Why identify and count? Types and numbers of fish provide an indicator of ecosystem health. 3. Can anyone tell what kinds of fish these are? There are rarely correct responses. If there are any, ask how they know for sure, and how a scientist would find out for sure. 4. What kinds of characteristics could we use on these fish in order to identify them? You can compare this process to identifying one student in the group from the others (hair color, eye color, coat, etc.). At this point, you can introduce how to use a dichotomous key. Ask if they have ever used a key before 6 th grade, many students have not used a key. To use this key, students will have to recognize parts of a fish these are observable characteristics. Use the parts of a fish chart (page 130) and rubber fish supplied to review the part of a fish students will need to recognize. Explain how to use a dichotomous key, particularly if they have little experience with keys. Some students recognize the dichotomous key as being similar to a choose-your-own-adventure book. For each question in the key, students have two choices. Depending on the answer they choose, the key will direct them to a new question. Eventually, the key will lead them to the proper identification of the fish. Be sure to stress to the students the importance of using the key, rather than simply looking at surface characteristics like color and guessing at the fish type. It is easy to be fooled! One student should select a fish to identify and place it in a small aquarium that has been filled with water. This makes the fish easier to see (limited movement) and the students can pass the small aquarium around. Help guide the group through the key with the students reading the key. Using this process, identify and count all the fish in the tank. Inland Seas Education Association - 124 -
Make sure the students think about where these fish came from the trawl was towed along the bottom of the bay in approximately 30 feet of water. Engage students in questions about what specific fish eat, and what eats them. Use the food web diagram to help them visualize these connections. This is a good time to bring together knowledge the students have gained in previous stations (like the importance of dissolved oxygen and plankton or benthos as food items for these fish). Talk a little about threats to fish populations this is best done as a brainstorm. What threats do they believe are out there? Try to infuse the discussion with examples of how people are making a living from Great Lakes fish: charter boats, commercial fishers, boating and fishing supply stores, marinas, etc. You may have crayfish present in your trawl sample. Be sure to specify to the students that crayfish are crustaceans and not fish. You may discuss the role of crayfish in the food web, and the potential impacts of the exotic rusty crayfish. Stewardship Component To really understand the Great Lakes food web relationships, students need to also understand the impact of invasive species on the ecosystem. All organisms need a good habitat, a good food source and have predators. An invasive species has an advantage over native species because they do not have natural predators. Frequently, this enables the invader to dominate an ecosystem and radically alter the structure. For example, round gobies have chased native forage fish off-shore (less ideal habitat), eat native fish eggs and have no natural predators in the Great Lakes. This coupled with their high fecundity (reproduction) means more gobies each year. Recently, native fish such as rock bass and smallmouth bass have been found to feed on round gobies. When discussing the impact of invasive species incorporate the Great Lakes food web and have the students reconstruct the feeding relationships between the organisms and how invasive species disrupt that relationship. At the end of the program, after all fish species are counted and recorded, the contents of the fish tank are dumped overboard. This should be done at the dock, or in water less than 30 feet deep. A few fish from the morning session are often saved for the afternoon session in case no fish are caught. Be sure to keep the two samples (morning and afternoon) separate. Drain and dry all equipment before storing it below. Teaching Tips If you have a diverse catch, begin identification with a fish that is easily keyed. The spottail shiner and johnny darter are fairly distinctive and thus easier to identify. DATA COLLECTION It is important to identify and count all fishes in the trawl. For large fish, like white suckers, it is also helpful to measure the length of the fish using a measuring board. Be sure to count and sex the crayfish before placing them back. Please note any growths, tumors, or any unusual features on any fish. If there are any unusual features, please keep those fish (there are sample preservation kits in the lead instructor box). Inland Seas Education Association - 125 -
VOLCABULARY Bioaccumulation: accumulation of contaminants in the tissues of organisms (also known as bioaccumulation). Biomagnification: increase in the concentration of contaminants as you move through the levels of a food web. Carnivore: consume only animals. Decomposer: organism that breaks down organic material, such as dead plants and organisms. Dichotomous key: series of questions that lead to the identification of an item. Ecosystem: group of living and non-living things that interact with each other. Exotic species: species introduced into an area beyond its native range. Food web: complex network of feeding relationships between organisms in an ecosystem. Forage fish: smaller fish that provide food for larger fish or birds. Herbivore: consume only plants. Invasive species: exotic species that causes or is likely to cause economic or environmental harm or harm to human health. Omnivore: consume both plants and animals. Otter trawl: device used to collect forage fish. Inland Seas Education Association - 126 -
BACKGROUND INFORMATION Fish Key Instruct students on the proper use of the fish key: 1. Read and become familiar with the parts of a fish from the diagram. 2. Read the questions in the key aloud. 3. After each characteristic is read, decide if the selected fish shares that characteristic. 4. After each decision, the key indicates which number in the sequence to follow. 5. Proceed through the key until the characteristics match the fish and there are no other choices available. Students should agree on the final decision. 6. Record the species and number of each fish in the student log books. Food Web A food web describes the feeding (trophic) relationships between different organisms. All fish are consumers, so they have to eat other organisms to obtain the energy they need to function. See pages 160-161 of this manual for more information on food webs. Bioaccumulation refers to the accumulation of contaminants in the tissues of organisms. Organisms at higher trophic levels on food webs (such as predatory fish) tend to have greater concentrations of contaminants stored in their bodies than those on lower trophic levels on food webs. The increase in the concentration of contaminants in each successive trophic level is called biomagnification. See page 114 for more information on bioaccumulation. Engage students in questions about what forage fish eat (plankton and benthos) and what eats them (predatory fish and water birds like cormorants). Relate this to the food web by pointing to the parts of the aquatic food web diagram in the fish station notebook. Threats to Fish Populations Engage students with questions and discuss threats to fish populations, such as over-harvesting, pollution, impacts of exotic species, and habitat destruction. Over-Harvesting In Michigan, the Department of Natural Resources (DNR) is the government entity responsible for monitoring and regulating the Great Lakes fisheries. The only exception is in treaty waters, where regulations are jointly administered by state, federal, and tribal governments. Government officials research the catch of fish each year and make recommendations based on their findings. Decisions about fishing limits can be complex and controversial. That is why it is important for citizens to become educated about the Great Lakes ecosystem, so they can participate in making wise decisions about the use of this natural resource. Pollution In addition to pollutants that are discharged directly into the watershed (point source pollution), many of our bigger problems result from non-point sources. Examples of non-point source pollution include silt, nutrients, and petrochemicals from storm sewers, agriculture, lawns, parking lots, and construction. Atmospheric pollution in the form of acid rain and snow may be a problem in some areas (like the western UP). Atmospheric deposition is a major pathway for contaminants entering the Great Lakes. Pollutants such as PCB s and dioxin are magnified in the food web through biomagnification. These pollutants are soluble in fatty tissue. While present in smaller amounts in microorganisms, by the time they are eaten by fish and humans, these contaminants reach harmful levels (the contaminants are stored in the fatty tissues of each of these organisms, rather than being excreted). Advisories on fish consumption by humans are issued regularly by various government agencies. Inland Seas Education Association - 127 -
Exotic Species The sea lamprey is a predator that preys on trout, salmon, whitefish, and other game fish. It attaches itself to fish and sucks out the bodily fluids. This kills or injures fish and leaves an ugly scar. The sea lamprey migrated from the Atlantic Ocean through the Erie Canal to Lake Ontario in the early 1800 s. The first Lake Michigan sea lamprey was recorded in 1936. By 1947, lake trout had already suffered serious damage from the lamprey. The life cycle of the sea lamprey is illustrated in the Fish Station manual (also shown on page 148 of this manual). The round goby is another exotic fish species in the Great Lakes. The round goby was first discovered in Lake St. Clair in 1990 and has since spread to all five of the Great Lakes. It is believed the round goby was introduced through oceanic ballast water, and its spread within the Great Lakes is due to transportation by Lakers (ships traveling within the Great Lakes). The round goby is a benthic fish that feeds on benthic invertebrates, zebra mussels, and eggs of fishes such as bass, lake trout, and whitefish. Since first being seen by the Schoolship in Grand Traverse Bay in 2005, the round goby population has exploded, making up more than 92% of the total fish catch in the 2007 trawl samples (shown in the Fish Station manual and the graph on pages 149-150 of this manual). Other exotic species that affect fish populations include zebra and quagga mussels, alewife, Eurasian ruffe, Bythotrephes, and Cercopagis. In general, the introduction of exotic species is detrimental because although conditions in the Great Lakes may be similar to those of their native environment, the Great Lakes lack the natural predators that keep the populations of these organisms in check. As the populations of exotics grow in size, they may have a variety of impacts on the native food web in terms of competition for food, predation, water quality modification (ex: filtering capabilities of zebra mussels), etc. More information on exotic species can be found on page 181 of this manual. Habitat Destruction Habitat destruction is most relevant to shoreline development and watershed protection because many fishes breed in shallow (littoral) areas, or in rivers and streams that empty into the bay. Hydroelectric dams also inhibit upstream migration of a number of species preventing them from reaching productive habitat for spawning. Economic Importance to the Great Lakes The Great Lakes range from cold, deep, clear water with heavily forested shorelines such as Lake Superior, to the warmer, shallower water of Lake Erie surrounded by farms and urban areas. The cold, clear waters produce commercially desirable fishes such as whitefish, trout, and salmon. The warm waters of Lake Erie with their heavy nutrient load are more biologically productive, but the varieties of fish taken generally are less commercially desirable species, such as varieties of buffalo shad and white perch. Although Lake Erie still supports one of the largest commercial freshwater fisheries in the world, commercial fishing on all the Great Lakes is declining. Commercial fishing, while still important for a few, does not generate nearly the returns that sport fishing does in the area. The local economy is enhanced far more by sport fishers who buy boats, gasoline, bait, equipment, and food for their expeditions. Local motels and restaurants also benefit. Charter fishing is a continually expanding portion of the economy of the Great Lakes region. For example, in Michigan in 1985 over 200,000 clients spent an estimated $21 million in addition to charter fees, and the total statewide investment by charter boat firms was estimated to exceed $30 million. Charter boat Captains are required to keep an up-to-date log of their catch and fishing activity and submit these records monthly to the Michigan Department of Natural Resources (DNR). Reasons for Sampling and Monitoring Types and numbers of fish provide an indicator of ecosystem health, and this data is used in management of both habitat and fishing regulations. The DNR uses fish catch data to determine fish stocking levels Inland Seas Education Association - 128 -
and sport and commercial fish catch limits. Data collected on the Schoolship since the program began in 1989 can be used to see long-term trends in the abundance of different types of fish in the bay. REFERENCES Bailey, R.M., W.C. Latta, and G.R. Smith. 2004. An atlas of Michigan Fishes with keys and illustrations for their identification. Museum of Zoology, University of Michigan No. 192. Miscellaneous Publications, Ann Arbor, MI. Becker, G.C. 1983. The Fishes of Wisconsin. University of Wisconsin Press, Madison, WI. Page, L.M., and B.M. Burr. 1991. A Field Guide to the Freshwater Fishes. Houghton Mifflin Co., Boston, MA. Scott, W. B. and E. J. Crossman. 1973. Freshwater Fishes of Canada. Galt House Publications Ltd., Ontario, Canada. Smith, P.W. 1979. The Fishes of Illinois. University of Illinois Press, Urbana, IL. Trautman, M. 1981. The Fishes of Ohio. Ohio State University Press, Columbus, OH. Internet Sites of Interest http://www.seagrant.wisc.edu/greatlakesfish/ (photographs and descriptions of common Great Lakes fish) http://www.great-lakes.org/ (Great Lakes Sport Fishery Council) http://www.glfc.org/lampcon.php (sea lamprey control) http://www.fisheries.org/afs (American Fisheries Society) DIAGRAMS & RELEVANT DATA Parts of a Fish (page 130) Schoolship Fish Key (page 131-142) How to Distinguish Between Native Sculpins & Exotic Gobies (page 143) Crayfish Identification (page 144) List of Fishes in the Grand Traverse Bay Watershed (page 145-147) Life Cycle of the Sea Lamprey (page 148) Fish Catch Data (page 149-150) Inland Seas Education Association - 129 -
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LIST OF FISHES IN THE GRAND TRAVERSE BAY WATERSHED COMMON NAME SCIENTIFIC NAME STATUS Lamprey Family Chestnut lamprey Ichthyomyzon castaneus American brook Lampetra appendix lamprey Sea lamprey Petromyzon marinus Exotic Sturgeon Family Threatened Lake sturgeon Acipenser fulvescens Gar Family Longnose gar Lepisosteus osseus Bowfin Family Bowfin Amia calva Herring Family Alewife Alosa pseudoharengus Exotic Gizzard shad Dorosoma cepedianum Minnow Family Common carp Cyprinus carpio Exotic Common Shiner Luxilus cornutus Northern pearl dace Margariscus nachtriebi Golden shiner Notemigonus chrysoleucas Emerald shiner Notropis atherinoides Blackchin shiner Notropis heterodon Blacknose shiner Notropis heterolepis Spottail shiner Notropis husonius * Roseyface shiner Notropis rubellus Sand shiner Notropis stramineus Mimic shiner Notropis volucellus Northern redbelly Phoxinus eos dace Finescale dace Phoxinus neogaeus Bluntnose minnow Pimephales notatus * Fathead minnow Pimephales promelas Longnose dace Rhinichtys cataractae Western blacknose Rhinichthys obtusus dace Creek chub Semotilus atromacluatus Sucker Family Longnose sucker Catostomus catostomus White sucker Catostomus commersonii * Catfish Family Black bullhead Ameiurus melas Yellow bullhead Ameiurus natalis Brown bullhead Ameiurus nebulosus Channel catfish Ictalurus punctatus Pike Family Northern pike Esox lucius Muskellunge Esox masquinongy Inland Seas Education Association - 145 -
Mudminnow Family Central mudminnow Umbralimi Smelt Family Rainbow smelt Osmerus mordax Exotic* Trout Family Lake herring Coregonus artedi Threantened Lake whitefish Coregonus clupeaformis Bloater Coregonis hoyi Pink salmon Oncorhynchus gorbuscha Introduced Coho salmon Oncorhynchus kisutch Introduced Rainbow trout Oncorhynchus mykiss Introduced (Steelhead) Chinook salmon Oncorhynchus tshawtscha Introduced Round whitefish Prosopium cylindraceum Atlantic salmon Salmo salar Introduced Brown trout Salmo trutta Introduced Brook trout Salvelinus fontianlus Lake trout Salvelinus namaycush Trout-perch Family Trout-perch Percopsis omiscomaycus * Cod Family Burbot Lota lota Killifish Family Western banded Fundulus diaphanous menoma * killifish Silverside Family Brook silverside Labidesthes sicculus Stickleback Family Brook stickleback Culaea inconstans * Threespine stickleback Gasterosteus aculeatus Exotic* Ninespine stickleback Pungitius pungitius * Sculpin Family Mottled sculpin Cottus bairdii * Slimy sculpin Cottus cognatus Spoonhead sculpin Cottus ricei Deepwater scuplin Myoxocephalus thompsonii Striped Bass Family White perch Morone americana Exotic White bass Morone chrysops Sunfish Family Rock bass Ambloplites rupestris * Green sunfish Lepomis cyanellus Pumpkinseed Lepomis gibbosus Bluegill Lepomis macrochirus Northern longear Lepomis peltastes sunfish Smallmouth bass Micropterus dolomieu * Largemouth bass Micropterus salmoides Black crappie Pmoxis nigromaculatus Inland Seas Education Association - 146 -
Perch Family Iowa darter Etheostoma exile Johnny darter Etheostoma nigrum * Yellow perch Perca flavescens * Northern logperch Percina caprodes semifasciata Walleye Sander vitreus Drum Family Freshwater drum Aplodinotus grunniens Goby Family Round goby Neogobius melanostomus Exotic* Extinct/Extirpated Arctic grayling Thymallus arcticus Extirpated Deepwater cisco Coregonis johannae Extinct Blackfin cisco Coregonis nigripinnis Extinct Shortnose cisco Coregonis reighardi Extinct Blue pike Sander glaucus Extinct *Fishes commonly caught in Schoolship trawls. Names and spellings from: Bailey, R.M., W.C. Latta, and G.R. Smith. 2004. An atlas of Michigan fishes with keys and illustrations for their identification. Museum of Zoology, University of Michigan, No. 192, Ann Arbor, MI. Inland Seas Education Association - 147 -
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Suttons Bay Fish Trawl Data 2005-2013 Inland Seas Education Association - 149 -
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