Winterkills Due to Improper Pond Management and Construction in Ohio

While Ohio houses many types of fish in its variety of lakes, streams, and rivers, there are many fish that are housed in ponds that could potentially suffer from improper pond construction. Some of Ohio’s most popular sporting fish could be subjected to fish kills such as asphyxiation, disease, or poisoning.  Fish suffocation due to lack of oxygen is one of the more easily avoidable but potentially devastating to pond fish populations. Some Ohio fish that would be affected would be the Bluegill, Largemouth Bass, and Channel Catfish.

Since many ponds get their available dissolved oxygen from plants that perform photosynthesis and the air vegetation is key to maintaining a healthy pond ecosystem. Ironically, these plants can be the very cause of a winterkill. If the pond does not have a proper depth ratio the plants could die during the winter and start decomposing. The bacteria that is responsible for the decomposition use the oxygen available in the water. The longer and more severe the winter is the more likely that this will happen. This is more likely to occur in the northern most counties of Ohio because of the more frequent snowfall and severe winters because of the lake effect from Lake Erie.

Unfortunately, there is almost no way to tell if a winterkill has happened until possibly months after it has occurred. With a good log of water quality management, the cause can usually be determined. Some people are not able to control the construction of their pond but proper pond construction could potentially prevent a winterkill. A 3:1 gradient ratio and a proper depth of 10-12 feet that covers 25% of the pond floor can keep plants from taking root too far into the pond. Also good watershed management practices can stop extra nutrients from entering the pond, halting the growth of harmful algae’s.

Works Cited

Pond Management. ODNR Division of Wildlife (2012). Retrieved from

Brook Trout- Reintroduction in the Lake Erie Drainage

Male Brook Trout

Over recent years, brook trout, a species thought to have disappeared from Ohio, has been making a return due to reintroduction and ecosystem restoration efforts. 10,000 years ago brook trout colonized Ohio’s Lake Erie tributary streams. This genetically distinct population of fish is the only trout native to the inland waters of Ohio. However, by the 19th century, only two stream systems were suitable habitat and contained thriving trout populations.
Brook trout only survive in cold and clean water. They have a very low tolerance to pollutants and human disturbance. During the early 1990s, the Chagrin River, Grand River, and Rocky River watersheds were severely impacted by deforestation, agriculture, and residential development resulting in the loss of their pristine habitat and remaining brook trout populations.
As a result, Ohio Division of Natural Resources developed plans to address the rehabilitation and restoration of Ohio brook trout with local park systems, trout clubs, educators, and state and local agencies. The main objectives were to identify and protect native brook trout habitat, take an inventory of potential brook trout habitat, and implement reintroduction in suitable sites.
Stream Surveys:
Streams in the Lake Erie watershed were first surveyed for existing trout populations and evaluated for potential habitat for brook trout. This was done by collecting the temperature of the stream during mid-summer. If the water was less than 20 degrees Celsius, then the stream habitat and fish populations were evaluated. This was often done with the use of seines; however, they also utilized a backpack electrofishers on some occasions. The streams with cold water, good habitat, and presence of other fish species were considered possible sites for brook trout reintroduction.

Researcher collecting the temperature of the stream

The streams meeting these standards were then stocked with enough brook trout to develop a self-sustaining population. Brook Trout reach sexual maturity at age three, therefore, this would need to be done for about four years in order for the populations to be successful.
In order to preserve the genetic distinction of native Ohio brook trout, gametes from fish captured in the stream were taken back to hatcheries and raised until they were of approximately 40 mm. The releases often occurred at the beginning of April in the shallow water riffle and run habitat throughout the streams to avoid predation and allow for the best chance of survival of the population.
Population Monitoring:
In order to evaluate the successes and failures of this reintroduction, population monitoring surveys were completed in the years following the releases. This was done once the populations demonstrated evidence of natural reproduction. Similar to the stream surveys seines and electrofishers were used. If the seining survey captured less than five total brook trout an electrofisher was used to verify the population size.
Like stated above, the brook trout is a very sensitive species and therefore are under constant threat for extirpation. In order to prevent this, habitat restoration, education of sportsmen and residents, and conservation agreements were implemented. However, ODNR could not accomplish this without the help from other organizations and the public. To facilitate these processes and communication, the Brook Trout Advisory Committee was developed. This committee was comprised of stakeholders in the protection of brook trout.

The site evaluations, hatchery propagation, and stream surveys were successful in the reintroduction of brook trout in 10 Northeast Ohio streams. However, the species is still considered threatened and conservation efforts have continued to be implemented.


Burt, A. (2007, July 01). Brook Trout Reintroduction: Lake Erie Drainage, NE Ohio. Retrieved from Report.pdf


Lake Sturgeon recovery

Living Fossils in Ohio?


Ever seen a living fossil? If you said no, you may get the opportunity relatively soon. A fish farmer in Urbana, Ohio is attempting to revive the population of Lake Sturgeon in the Ohio fisheries. Lake sturgeon are a species that has been traced back to around 136 million years ago, causing many people to refer to it as a living fossil. They can grow up over six feet long and can live around 100 years. They used to be prevalent through the Great Lakes and major river systems such as the Mississippi and Hudson rivers.


Fig. 1: Lake Sturgeon


Dave Smith is the man behind Freshwater Farms in Urbana. He is attempting to successfully breed the species in captivity. Part of the challenge is the long time that the females take to reach reproductive maturity. Females require around 20 years to start reproducing, and they can only reproduce every 4 years. Smith already owns white sturgeon, and he hopes his experience with a similar species will help him breed Lake sturgeon. Smith got his Lake sturgeon from The Ohio State University, who had specimens for research, but have not researched them heavily.


For more information on Dave Smith’s Freshwater Farms of Ohio, click this link:


For more information on the Lake Sturgeon, click here:





Lake sturgeon, Ohio DNR


Ohio fish farm aims to raise ancient, endangered species


Picture reference

The Great Miami River’s Scaled Inhabitants

Every place has a story and  the inhabitants are the ones that tell that story. Natural places and the species that exist in those places are no different; such is the case of the fish found in the Great Miami River. In Southwestern Ohio, sits a roughly 165  mile long tributary of the Ohio River, called the Great Miami River. The Great Miami River watershed flows through 10 counties and drains 3,802 square miles of land, going through both Dayton and Cincinnati (Figure 1). The river currently goes through 15 metropolitan areas of the region.

The Great Miami river has suffered floods, extreme physical alterations and pollution, affecting the fish species that are able to live in it. After the 1913 floods devastated both Dayton and Cincinnati, the Miami Conservancy District would be created in 1915 and begin the building of levees and retention basins (See Image 2 for a snapshot of what this river looks like). Pollution also became a huge issue, especially as people were flushing prescription medications and birth control pills down their toilets. Medications in the water meant that there were higher levels of certain chemicals, such as progesterone, which can cause male fish to develop half-formed eggs, instead of fully-formed sperm, created reproduction issues in certain species. Fish which were more tolerant of pollutants (and were often not native to the area), became more populated in the Great Miami, while native fishes struggled.

Over the last 100 years, some levees have been removed, and thanks to Ohio EPA (Environmental Protection Agency) water quality research, policy, and enforcement, the Great Miami River has seen some improvement in water quality. Starting in 2008 and going through 2010, the Ohio EPA began surveying the Great Miami River, starting in Dayton and going the roughly 80 miles dowstream to the mouth of the Ohio River. One way that surveys were done was by doing electrofishing. This is a method where an electric current is sent through the water, not to kill the fish, but to stun them. Once the fish have been stunned, the researchers can easily collect and identify species before releasing them.


Some fish that are common in the Great Miami River are smallmouth, largemouth and spotted bass, white and rock bass, sunfish, and channel and flathead catfish. While pollutant-tolerant species may be in decline and native fish are definitely present, according to the Ohio EPA, as of 2012, 72% of the sites tested in the Great Miami River watershed failed to meet bacteria water quality standards; this is probably due to failing septic systems and agricultural use. And while the Great Miami River, itself and some of its tributaries showed good quality, overall, many of its western tributaries exhibited boor quality. The fish present and their population sizes can help to determine the threshold for pollutants in this stream system. When pollutants and turbidity (the amount of suspended sediments in the water which lead to water being “murky”) are kept in check, fish populations will remain successful and continue to be present for locals to enjoy for viewing and fishing.

(Image 2) Great Miami River, near Vandalia, Ohio.
U.S. Geological Survey, courtesy of
(Image 1) Great Miami River Watershed, courtesy of

Sea Lamprey in the Great Lakes

Kevin Fisher

Sea Lamprey in the Great Lakes


Retrieved from: on 11/02/2017

Sea Lamprey (Petromyzon marinus) (depicted above) is an invasive, eel like, jawless fish that looks like something straight out of a horror film. It was first reported to have invaded from Lake Ontario to Lake Erie in 1921, believed to have been facilitated through the opening of the Welland Canal. Sea Lamprey were initially not a problem, but with the enactment of policies to prevent pollution, salmonid stocking programs and stream restoration they began to proliferate and soon spread to the other Great Lakes (Sullivan et al., 2003). Sea lamprey have a very unique life history (shown below), spending the majority of their life in a larval stage, called an ammocoetes, in which they are sedentary filter feeders living in stream beds. Once they have reached a certain point, they emerge from stream beds and transition to a parasitic phase in lakes. One adult parasitic Sea Lamprey can apparently kill up to 40 pounds of fish in its life time (Morrison, 2017). The parasitic life stage of Sea Lamprey is especially devastating to Lake Trout (bite mark pictured below), whose population declined rapidly with increased abundance of Sea Lamprey in Lake Erie. This led the Great Lakes Fisheries Commission to establish an integrated Sea Lamprey management plan in 1986 (Sullivan et al., 2003). Control measures taken rapidly saw declines in the populations of Sea lamprey through the use of pesticides, barriers to reproduction, trapping, and even the release of sterile males (Klassen et al., 2004). With the initial success of the program people believed that the program may be able to successfully eradicate Sea Lamprey from the Great Lakes (Sullivan et al., 2003). While the program has been extremely successful, decreasing the amount of fish killed from 100 million pounds to 10 million pounds per year in the Great Lakes (Morrison, 2017). The complete eradication seems unlikely. A recent report from the Great Lakes Fisheries Commission also conveyed a startling discovery, Sea Lamprey populations have been increasing for the past few years in Lake Erie and Superior (Morrison, 2017). While the current levels are still near historic lows, the recent trend of increasing populations has fisheries managers worried (Morrison, 2017). No one really knows why there has been an increase in these populations, but two hypotheses have been given that may explain why this trend has occurred. The first, is that the restoration of stream habitats have allowed the Sea lamprey to establish into new tributaries that they were historically not present. The second, is that the mild winters that have been experienced throughout the Great Lakes region in the last two years have led to more favorable conditions during spawning (Morrison, 2017). While the integrated Sea Lamprey management plan has been a great success in curbing the spread of this species, there are still unknown factors which require continued vigilance to keep this invasive threat under control.

Retrieved from: on 11/2/2017


Klassen, W., Adams, J.V., Twohey, M.B., 2004. Modeling the suppression of sea lamprey populations by the release of sterile males or sterile females. Journal of Great Lakes Research 30, 463–473.

Morrison, A. A., Oct. 24 2017. Sea Lamprey on rise in Lakes Erie and Superior. Great Lakes Today. Retrieved from: on 11 November 2017.

Sullivan, W.P., Christie, G.C., Cornelius, F.C., Fodale, M.F., Johnson, D.A., Koonce, J.F., Larson, G.L., McDonald, R.B., Mullett, K.M., Murray, C.K., 2003. The sea lamprey in Lake Erie: a case history. Journal of Great Lakes Research 29, 615–636.


What’s the Deal With Wetlands?



Across the country, wetland habitat has been converted to different types of land uses causing massive loss of species abundance in the process.  In Ohio, we have lost over 90% of the original wetland habitat because we converted it mostly to agriculture use.  In the past 20 years, many organizations including state government agencies have worked to acquire and/or restore this habitat.  Aside from the obvious measures that they have taken, what else can they focus on to help meet their goal?  The answer is fish!

First, let me explain how wetlands are functionally important for many reasons.  They are known as Earth’s “kidney’s” because they take the contaminants out of upland water and then this water continues down to other waterways.  They help prevent flooding by taking in extra water.  They provide habitat to some of the most diverse ecosystems, which helps enhance the aesthetic value of the land.


Fish, as a whole, are very important to the wetland ecosystem.  Without being species specific, they are a major component in the food web.  Fish are a major prey source for many species and they also are a main predator of invertebrates.  If taken out of the wetland habitat, there would be major consequences for predators on fish.  The invertebrate populations would get out of control and they would eventually eat everything they could, which would have negative effects downward.  The wetland habitat could collapse.


Not only are fish extremely important to wetlands, but fish need wetlands to survive as well!  Many ocean and sea fishes use mangroves and other coastal marshes to lay their eggs in.  The cover of vegetation helps provide protection against predators and currents.  When the eggs hatch, the juveniles are also able to feed easier on the vegetation or invertebrates available.  Without these coastal marshes, fishes in Lake Erie would not be successful at reproducing.  Fishes also use seasonal wetlands to disperse to other waterways and breed.  When the seasonal wetlands do not last as long, are not as deep, or dry up completely, these fish populations are then isolated and are not able to disperse, i.e. they lose gene flow.


By protecting and restoring wetlands, recreational fisherman and commercial fisherman have a better chance at continuing to catch and do what they love.  But, with everything, there is a downside.  With increased wetlands and waterway connections come increased invasability by some of the fish that we don’t want in Ohio.  I’m looking at you, Common Carp.  As always, be sure to identify what you catch correctly.  If it is a Paddlefish or Sturgeon: throw it back; if it is a Common Carp or a Sea Lamprey: take it to your ranger.


Henning, J. A., et. Al. (2007). Use of seasonal freshwater wetlands by fishes in a temporal river floodplain. Journal of Fish Biology, 71:476:492

Johnson, David J., et al. (1997). Fish Communities in a Dike Lake Erie Wetland and An Adjacent Undiked Area. Wetlands, 17:43:54

Office of Environment and Heritage. (2017, October 24).  Fish In Wetlands.  Retrieved from

United States Environmental Protection Agency. (2017, February 27). Why are Wetlands Important?  Retrieved from

Interactions of Logperch

When most people envision fish, they oftentimes picture an individual swimming, feeding, or perhaps interacting with conspecifics (individuals of the same species). While these behaviors and interactions are important, many miss the idea of interspecific interactions (two or more individuals from different species). Streams are complex and fish encounter many different organisms, affecting one another in different ways. Recognizing these relationships can aid us in our understanding of the aquatic ecosystem, as well as, increase general appreciation of the fish within our streams (and other water bodies).  To demonstrate this, let us take a look at the Logperch darter (Percina caprodes) and a brief overview of interactions between two different species.

Logperch dwell on bottoms of streams and lakes, particularly with beds consisting of sand and gravel. This darter species can be identified by its very characteristic conical snout and striping along the body. Logperch prey upon aquatic invertebrates, using the conical snout to flip cobble and gravel to forage. This species can be found throughout Ohio as seen in the distribution map below.1-3

Figure 1: Logperch (left) distribution occurs throughout Ohio, indicated by the waterways in green (right). Photo credits: Konrad P. Schmidt (left) and Division of Wildlife (right).

Snuffbox Mussel and Logperch Interaction

The Snuffbox Mussel and Logperch interact in a very interesting way. As noted before, Logperch darters dwell near the bottom of streams and lakes. While foraging, Logperch can become entrapped by Snuffbox Mussels. The Snuffbox Mussel clamps the snout or head of the Logperch. Why does this interaction occur? Is it a protective measure for the mussel?

While this may seem strange, the Snuffbox mussel has ulterior motives. The Logperch acts as a host for the mussel larvae (called glochidia). The mussel will clamp down on the Logperch and release the glochidia, which in turn, uses the gills of the Logperch for development. Once the glochidia is released, the Snuffbox mussel releases the Logperch. Demonstration of this phenomenon can be seen in the following video:

The glochidia remain on the Logperch while developing for approximately 3 weeks. Although this ‘ride’ may seem short and perhaps insignificant, it is critical for Snuffbox Mussel development. This interaction drives the propagation of another species.4-6

Round Goby and Logperch

Another example of interspecific interaction can be seen between the Logperch and Round Goby (Neogobius melanostomus). The Round Goby is an invasive species, originating from the Black Sea. It is thought they were brought to North America through ballast ships.7 The addition of Round Gobies to North American habitats have affected many species, including Logperch. Balshine, et al. showed a displacement of Logperch by Round Gobies through displays of aggression (see graph below). This negative interaction is thought to be due to competition for both habitat and food.7 Round Gobies are also territorial, which cause displacement of Logperch, as well.

Figure 2: Round Goby. Photo credit: Sea Grant Michigan
Figure 3: Round Gobies were more aggressive than Logperch as displayed by the mean number of aggressive behaviors of Round Gobies vs Logperch. Image taken from Balshine, et al.

Why does this matter?

In order maintain healthy ecosystems, we must understand both the biology/life history of a given species, as well as, the relationships between species in a given system. By understanding the complexity, we will be more equipped to manage accordingly. For example, if Logperch darters show a decline, managers are able to expect mussels to be impacted, as well. The examples given for the Logperch are just two of many interactions. Also, by understanding interspecific interactions, we can gain appreciation for the beauty of our systems.


1.Becker, G.C. 1983. Perch family- Percidae. Pages 869-954. Fishes of Wisconsin. University of Wisconsin Press, Madison, Wisconsin.

2.Spalding, W. 2006. Percina Caprodes (Online), Animal Diversity Web. Accessed November 02, 2017 at

3.Zimmerman, B. and Division of Wildlife. N.d. Stream Fishes of Ohio field guide (Online), Division of Wildlife. Accessed November 02, 2017 at

4.U.S. Fish and Wildlife Service. 2016. Snuffbox (freshwater mussel) Epioblasma triquetra (Online), U.S. Fish and Wildlife Service. Accessed November 02, 2017 at

5.Schwalb, A.N., M.S. Poos, and J.D. Ackerman. 2011. Movement of Logperch-the obligate host fish for endangered snuffbox mussels: implications for mussel dispersal. Aquatic sciences 73: 223–231.

6.Datnow, B. 2011. Snuff Box Mussel (Video). Youtube, Accessed November 02, 2017 at

7.Kornis, M.S., N. Mercado-Silva, M.J. Vander Zanden. 2012. Twenty years of invasion: a review of round goby Neogobius melanostomus biology, spread and ecological implications. Journal of Fish Biology 80: 235–285.

8.Balshine, S., A. Verma, V. Chant, and T. Theysmeyer. 2005. Competitive interactions between Round Gobies and Logperch. Journal of Great Lakes Research 31: 68–77.

9.Sea Grant Michigan. N.d. Round Goby Neogobius melanostomus. Accessed November 02, 2017 at

Do we really need fish?

Figure 1: Young children with small carps (cyprinid fish sp.). Tonle Sap River, Cambodia (Kampuchea).

So are fish that important do we really need them? Maybe you enjoy eating fish but there are plenty of other protein sources right? Maybe you enjoy fishing but there are plenty of other things you can do with your free time. This may seem silly but this is the way many people think. People in wealthier countries or in landlocked areas may have a harder time seeing how important fish are. Not everyone relies on fish at the same degree in reference to protein consumption and economics. But looking worldwide fish are crucial to millions of people all around the world. People rely on fish for protein, jobs, recreation, and much more.

As many people may know fish are a protein source that are rich in omega-3 fatty acids, vitamins, calcium, zinc, and iron. According to the Food and Agriculture Organization of the United Nations “fish provide 6.7 percent of all protein consumed by humans”. This percentage however does not truly represent how important fish are to specific countries. For example, fish contribute 20% of all animal protein consumption in developing countries according to green facts. They also note that this percentage may be underrepresented because of unrecorded contribution of subsistence fisheries. We can continue to zoom in and see that people in more specific locations can be even more dependent on fish. For example, “It is estimated that fish contributes to at least 50 percent of total animal protein intake in some small island developing states, as well as in Bangladesh, Cambodia, Equatorial Guinea, French Guiana, the Gambia, Ghana, Indonesia and Sierra Leone” according to Green Facts. It is clear that people are dependent on fish on varying levels for protein consumption.

Figure 2: Shows the per capita fish supply of each county.

Can people benefit from fish for more than food? Yes, millions of individuals or even countries rely on the fishing industry for economic gain. The fishing industry includes, fishermen, guides, recreational fishing and equipment, aqua culture, and more. In the United States alone the fishing industry contributes nearly $90 billion annually and supports over 1.5 million jobs according to Harris et al. 2014. Fish have historically been and continue to be one of the most traded foods worldwide. According to the FAO greater than 50% of fish exports by value originate in developing countries. The fishing industry contributes substantially to economies of countries all over the world.

Figure 3: Shows how the trends of utilization and supply of fish when looking at food, nonfood uses, population, and food supply.

So it may be hard to understand the importance of a resource if you are less dependent on it yourself. If you live in the planes of the western United States where fish diversity is relatively low and cattle or various livestock appear to out number nearly all other protein food sources, it is probably easy for you to view livestock as a more valuable resource. Now this may be true for you, it is still important to understand that people outside of your state or even country may more heavily rely on fish instead. People all over the world benefit from the fishing industry for individually specified reasons. It is clear however that developing countries and more specifically smaller islands are substantially more reliant on fish for protein consumption and economic gain. Although this paper is only looking at how people benefit from fish looking at protein intake and economics there are many other ways to look at this topic. Some follow up research could be how other animals depend on fish or how various components of the ecosystem are impacted by fish and how that can effect humans or recourses that humans care about or rely on.



Work Cited


FAO. 2016. The State of World Fisheries and Aquaculture 2016. Contributing to food security and nutrition for all. Rome.200 pp.


“Fisheries Latest Data.” Fisheries: 6. How Much Fish Is Consumed Worldwide?, FAO Fisheries, Web. 31 Oct. 2017


“Global per Capita Fish Consumption Rises above 20 Kilograms a Year.” Food and Agriculture Organization of the United Nations, Web. 31 Oct. 2017.


Harris, Benjamin H., et al. “Economic Contributions of the U.S. Fishing Industry.” Brookings, Brookings, 28 July 2016, Web. 31 Oct. 2017.

“Why Is Sustainable Seafood Good for… Developing Countries?” Fish Forward (WWF), Web. 1 Nov. 2017

Why You Shouldn’t Release Your Pet Fish

The aquarium trade is a popular business and it is not difficult to obtain a pet fish. People may purchase fish for a hobby and others may have gained an additional pet goldfish when their child won at a ring toss game at the county fair.  For as many reasons people get a pet fish there are just as many reasons for why they may eventually want to it up. The fish may be sick, noncompatible with other tankmates, it may be too expensive to upgrade the aquarium when the fish grows, moving to a new apartment is a hassle with an aquarium and the list goes on.  The issue with this choice is when a fish owner decides that the most humane way to treat their pet is to release it to swim free in the wild (1).

Unfortunately releasing a pet is unethical due to the physiological stress from the new environment, it’s susceptibility to parasites and disease and possible predation from a larger predator (1).  If the pet(s) survive then there is a risk of the fish establishing a population and spreading which can be ecologically harmful if the fish is in a nonnative habitat. In the United states alone, 75 if 185 different exotic fishes that have been caught are known to have established breeding populations, with half of them being due to release or escape (1).

When a pet exotic fish becomes invasive it is not only costly to remove but can harm native species and alter predator prey dynamics. A classic example of the pet trade influencing invasive species is with the goldfish (Carassius auratus). The goldfish is a durable fish, that can tolerate a wide range of conditions, which makes all continents except Antarctica carry potential habitats for the fish (2). When the fish is established, the fish may deplete native food resources, taking away from native organisms. The fish can decrease the overall diversity of an ecosystem by uprooting plants and predation, increase cyanobacterial blooms, and alter the chemical properties of the water (2,3).

Figure 1:  A giant domesticated fish measuring 30 lb caught by Fisherman Raphael Biagini. Source:

A solution to preventing invasive establishment is to return unwanted fish to a local pet store for resale or trade. The fish may also be given to another hobbyist, public aquarium or even a public institution such as a school. The last option is to have a fish humanely euthanized and assistance can be sought by a veterinarian or fishery biologist (1).



1) Problems with the Release of Exotic Fish. USGS. Available at (Last accessed November 1, 2017).

2) Pinto L, Chandrasena N, Pera J, et al (2005) Managing invasive carp (Cyprinus carpio L.) for habitat enhancement at Botany Wetlands, Australia. Aquatic Conservation: Marine and Freshwater Ecosystems 15:447-462.

3) Guo Z, Sheath D, Trigo FA, et al (2016) Comparative functional responses of native and high-impacting invasive fishes: impact predictions for native prey populations. Ecology of Freshwater Fish 26:533-540.


Monster Goldfish


Everyone tends to think of goldfish as these small innocent fish that everyone and their brother has as a pet when they are growing up but most do not know that when they are released into larger waterways that they grow to enormous sizes.  I recently read an article that highlights Cleveland Metro Parks and their battle against these goldfish in their waterways (Johnston, 2017).  The representatives from the Metro Parks speak about how these goldfish can be found all over their waterways and cause problems for native species.  This is accurate with the idea that non-native introduced species like these goldfish take away resources for the native species (Nico et al., 2013). The Cleveland Metro Parks are especially unhappy with the goldfish being there because they tend to take the resources away from the pan fish and catfish and they reproduce very quickly.  Metro parks uses electrofishers to stun and then capture the fish for removal which is a very selective removal technique meaning that it can be used to collect the goldfish and leave the other fish alone.

This whole situation is a prime example of what happens when people release their pets into native waterways.  They do not always become this invasive or detrimental to the other species but when they do it becomes something that could have been easily avoided.  The lesson to be learned from this situation is that you should never release your pets into the wild because you never know what effect they can have on the native species.


  1. Johnston, C. L. (2017, October 26). Monster goldfish: What happens when you release that little pet into the wild. Retrieved October 31, 2017, from
  2. Lennox, S. (2016, April 9). Giant Goldfish Are Invading Alberta Waters: Reports. Retrieved October 31, 2017, from (Pictures)
  3. Nico, L.G., P.J. Schofield, J. Larson, T.H. Makled, and A. Fusaro, Carassius auratus(Linnaeus, 1758): U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL,, Revision Date: 8/2/2013, Access Date: 10/31/2017

Ohio’s Mysterious Traveler – The American Eel

The American eel (Anguilla rostrate) is a state threatened species of freshwater eel, and the only freshwater eel found in North America. These eels are found in any Ohio stream and in Lake Erie, but their home range covers most of the eastern United States. They are most normally found in large rivers with continuous flow. The American eel is a nocturnal species. They tend to hide in deep pools during the day and feed on aquatic invertebrates and fish at night. They are a prey species to larger fish, like bass, reptiles, some mammals, and fish-eating birds. 

Adults have a long, cylindrical snake-like body with a single dorsal fin running along their body. They have short, round pectoral fins on the side of their body and a mouth filled with very small teeth. These eels are very muscular and secrete a slime that creates a protective mucus layer around their body. Adult American eels can have a wide color range, most being brown with yellow on the sides. They will then turn a black and silver or bronze eel during their reproductive phase. Males can get about 18 inches long while females are larger, averaging about 36 inches.

The American eel is a catadromous species, meaning they spawn in saltwater but spend most of their lives in freshwater (Ohio DNR Division of Wildlife). Little is known about the spawning of the American eel, as no one has witnessed it. What we do know is that adult eels migrate downstream to the ocean by using what is thought to be the Earth’s magnetism and their homing abilities. These eels spawn only in the Sargasso Sea, a warm region of water located in the southeast of the Atlantic Ocean. These eels will spawn and then die. The females can lay up to about four million eggs, who, once hatched, are small transparent larvae who float on the ocean’s currents for about 12 months (The Nature Conservatory). The surviving eels will then migrate their way back towards North America and into freshwater. These baby eels will then travel upstream into rivers, estuaries, and bays, spending as much as 20 years in freshwater before beginning the life cycle over again.

The American eel populations have been on the decline. Dams and other human-made obstacles in the rivers have had the largest impact on their populations. These obstacles prevent the eel from migrating upstream or downstream, sometimes preventing populations from reaching the Sargasso Sea to spawn. These obstacles also cause habitat loss, putting stress on the eels from predators as they are a easy prey species (USFWS). American eels are also very susceptible to low water quality, meaning that habitat degradation has also negatively effected populations. These eels are harvested for food, and the overfishing of juveniles have added to the overall decline of this species. This makes it very important to conserve the American eel so these fish don’t become extinct. They are such a unique species, with their distinctive life cycle and that fact that they are the only freshwater eel in North America. American eels are a treasure to have in Ohio, so help protect their habitat so that future generations can enjoy them too.



“American Eel.” Ohio DNR Division of Wildlife, ODNR Division of Wildlife,

“Information About the American Eel.” The Nature Conservancy,

“American Eel Videos, Photos and Facts.” Arkive,

USFWS Northeast Region Division of External Affairs. “The American Eel.” National USFWS Website,


Images (In Order of Appearance):

Photo by Minnesota Department of Natural Resources

Photo by Cornell University

Photo by Melisa Beveridge

Ohio’s Living Fossils

Ohio’s Living Fossils

Sturgeon are a group of around twenty-five fish species that are in the family Acipenseridae. They are found all over the world, from Europe to Asia to right here in North America. In the United States, they are native to the Great Lakes, the St. Lawrence, Missouri, and Mississippi Rivers, and can be found on both the east and west coast and in the Gulf of Mexico. Interestingly enough, there are no known native populations of sturgeon that exist south of the Equator (Fishbase 2017). This group of fish has been found in the fossil record as early as 245 million years ago, making them the oldest of the ray-finned fishes. However, what makes them “living fossils” is that they have not evolved much in the last 240 million years; the sturgeons that exist today are very similar to the sturgeons that lived during the same time of the dinosaurs (Gardiner 1984). The image below shows a tree of the relationships between modern fish groups. The placement of the sturgeon in relation to the teleosts (which contains 96% of all modern fish diversity) demonstrates its status as a “relict” fish, a living fossil, along with the gar, bowfins, and birchirs.

Image taken from the lectures of Dr. Suzanne Gray, The Ohio State University


The Life of a Sturgeon

Sturgeon primarily are benthic feeders, which means that they feed on the bottom of rivers and lakes. They usually feed on snails and mussels, but have also been known to eat fish and plants (ODNR Lake 2012). To have babies, sturgeon move into rivers to spawn. When this happens, females can lay thousands of eggs at a time into the water column that are then fertilized by the males’ sperm. This process is called “broadcast spawning.” However, very few of these eggs to adulthood. The baby sturgeon are slow-growing and can take a long time to reach sexual maturity (20-25 years in the case of Ohio’s own lake sturgeon). Unlike salmon, sturgeon can spawn multiple times throughout their life, but do not spawn every year, sometimes going multiple years between spawning events (lake sturgeon typically spawn every four to seven years). While they may take a long time to mature, sturgeon are incredibly long-lived. Their average life-span is 60 years, but some species, like the lake sturgeon, can live longer than a century (ODNR Lake 2012).


Now that you know a little bit more about sturgeon in general, let’s take a look at the two species that call the waters of Ohio home:

Lake Sturgeon (Acipenser fulvescens)

Photo by the Tennessee Aquarium


The lake sturgeon is native to the waters of Lake Erie and the Ohio River, as well as in some of the larger inland rivers that feed into these water bodies. A large fish, this sturgeon measures 6-8 feet in length and usually weighs around 100 pounds (Trautman 1981). The largest specimen recorded was caught in 1929, weighing 216 pounds (ODNR Lake 2012) The Lake Sturgeon is “sharply bicolored” meaning that the dorsal (top) half of its body is one color (in this case olive-yellow, grey, or bluish), and its underside is a different color (in this case milky/yellow-white). These fish have a series of bony plates that run along their back and sides, forming ridges on their body. While these plates are sharp in juveniles, they dull as the sturgeon ages, becoming blunt by the time they reach adulthood (Trautman 1981).

Shovelnose Sturgeon (Scaphirhynchus platorynchus)

Photo by Ohio Division of Wildlife


The other native Ohio species of sturgeon, the shovelnose sturgeon, is the smallest sturgeon species in North America, reaching lengths of about 2.5 feet long and weighing usually 1-5 pounds. However, the largest specimen recorded in Ohio was 32 inches long and weighed 10 pounds. The shovelnose can be easily distinguished from the lake sturgeon by its wide, flat snout that gives this species its name. It also is bicolored like the lake sturgeon, but the shovelnose is usually brown, olive, or grey dorsally, and whitish underneath. The shovelnose has a long, thin caudal peduncle completely covered in bony plates, whereas the lake sturgeon’s is much wider and only has plates on the side. The bony plates covering the caudal peduncle are also sharp in both juveniles and adults, and do not dull over time like the Lake Sturgeon. In Ohio, the shovelnose sturgeon is native to the waters of the Ohio River and its tributaries, having also been caught in the Scioto and Muskingum Rivers (Trautman 1981). Interestingly, while lake sturgeons have been reportedly able to live to be 150 years old, shovelnose sturgeon live much shorter lives, rarely living past the age of 12, and spawn fewer times in their lifetime (ODNR Shovelnose 2012).



While sturgeon are incredibly interesting as living fossils, populations of sturgeon species worldwide have been in decline. Both the lake sturgeon and shovelnose sturgeon are listed as “Endangered” in the state of Ohio. Information from the International Union for Conservation of Nature (IUCN) suggests that sturgeon are one of the most imperiled groups on the planet, with 85% of the species worldwide at risk for extinction (IUCN 2010). Two important human-induced factors leading to their declines are shown below: dams and caviar.

Left image from AS Food Studio, Right image from Popular Mechanics


While dams may be beneficial to us, they play havoc with a sturgeon’s life cycle. Many sturgeon species have migration routes and preferred spawning grounds. The construction of dams blocks a sturgeon’s ability to follow these routes or get to their spawning grounds, affecting their reproduction. Sturgeon are also harvested for their eggs, which are sold as caviar at high prices. In recent years, the market for this product has grown considerably, so more and more sturgeon have been harvested, both legally and illegally, to meet this demand (WWF 2017). Because it takes so long for sturgeon to reach maturity, and because they do not spawn every year, they are incredibly susceptible to overfishing, which has been shown in their species declines over the last few decades. Although they have been around for millions of years, unless action is taken to reduce sturgeon population declines, these living relics could potentially disappear into the fossil record for good.


Works Cited

Fishbase. 2016. Family: Acipenseridae. Fishbase. Online. Retrieved November 2nd, 2017 from

IUCN. 2010. Sturgeon more critically endangered than any other group of species. IUCN. Online. Retrieved November 2nd, 2017 from

Gardiner, B.G. 1984. Sturgeons as living fossils. Pg. 148-152 in Living Fossils, Eldredge, N., and Stanley, S.M. Springer-Verlag, New York.

ODNR. 2012. Lake Sturgeon. ODNR Division of Wildlife. Online. Retrieved on November 2nd, 2017 from

ODNR. 2012. Shovelnose Sturgeon. ODNR Division of Wildlife. Online. Retrieved on November 2nd, 2017 from

Trautman, M.B. 1981. The Fishes of Ohio. Ohio State University Press, Columbus, OH.

WWF. 2017. Sturgeon. World Wildlife Foundation. Online. Retrieved November 2nd, 2017 from

Changing Water Temperatures and its Effect on the Lake Erie Yellow Perch

At approximately 9,940 square miles, Lake Erie is an incredibly important component of the Great Lakes1. Whether it is due to the lake’s aesthetic value or its economic importance, Lake Erie is an ecosystem that is heavily monitored and researched. This monitoring has revealed a couple of very concerning trends that seem to be intensifying as a result of anthropogenic disruption and alteration.  Regardless of whether it is the well-known algae blooms caused by increasing levels of dissolved phosphorous finding its way to the lake from agricultural and urban management practices or the introduction of invasive species and their effects on native fish populations, humans are disrupting the natural ecosystem of the lake at concerning levels2. One of the monitored aspects of the lake is the temperature of the water within the lake. Studies have shown that water temperatures have become warmer over the past 90 years6. Although the warming temperature is rather inconsistent in nature, resulting in up and downs in temperature on a year-to-year basis, linear trend lines indicate that water temperatures are getting warmer (refer to figure below). Water temperature readings are reaching all-time highs in the summer months and increased winter water temperature are resulting in decreasing ice cover4. Although a topic for debate, these increases in water temperature are largely a result of increased air temperatures resulting from climate change4. Understanding how these changes to the water temperature of Lake Erie may effect the organism within the lake is essential to future management and conservation strategies.

Short, Warm Winters Affect Successful Reproduction of Yellow Perch

The Lake Erie Yellow Perch (Perca flavescens) is a staple fish found in Lake Erie due to its relative importance ecologically, as well as, economically. With a harvest limit of 11.081 million pounds of total allowed catch in 2014, one can easily understand the importance of understanding the Yellow Perch physiological demands in order to best manage this species5. The Yellow Perch has a set of preferred reproductive traits and procedures that have proven essential to maintaining a healthy native population in Lake Erie. Female Yellow Perch develop ovaries in the cold winter months and spawn during the spring months3. With this in mind, studies have been conducted in order to understand how increases in water temperature resulting from warmer, shorter winters could affect the spawning success of this species. Results indicate that there are two main disruptions that arise from these shorter and warmer winter weather patterns. First, it seems that shorter and warmer winters are causing reduced size in Yellow Perch eggs, yielding smaller and less successful larvae3. In turn, this means that a reduced number of juvenile fish are advancing to the next life stage, potentially resulting in the reduction of overall surviving adult Yellow Perch in the lake. In addition, the spawning time of the Yellow Perch seems to be earlier than that of what it is typically seen under normal winter lake conditions. As seen in the figure below, spawning periods occurring around two weeks to a month earlier in shorter and warmer winter when compared to the typical longer and colder winters3. These unconventional spawning periods lead to increased food scarcity for surviving Yellow Perch juveniles, further impacting survival rates4. The study, run in an experimental setting and confirmed by actual lake conditions, show that the Yellow Perch is unable to adapt to the changing environmental conditions3.

Farmer, T.M., Marschall, E.A., Dabrowski, K., Ludsin, S.A. (2015). Short winter threaten temperate fish populations. Nature Communications, 6 (7724)


Lake Erie Yellow Perch Population Dynamics & Impacts of Continuing Climate Change

            Research has confirmed that Yellow Perch are negatively impact by shorter and warmer winters resulting from climate change, therefore it is imperative to continue researching just how fast this species is able to adapt in order to avoid a drastic population crash. The figure below indicates that Ohio temperatures will continue to increase with the consequences occurring whether we decrease carbon emissions or not7. Since the Yellow Perch is such a prominent species within the seven-billion-dollar fishing industry in the Great Lakes, a decrease in the perch population or a potential behavioral response to move out of the warmer regions of the lake could have monumental consequences to regional economies4. In addition to Yellow Perch, further research as to how other species of fish may be impacted by these warming trends could inform conservation efforts for a wide range of operations, not just recreational and commercial fishing.
  1. Lake Erie Facts and Figures. Retrieved November 1, 2017, from
  2. Michalak, Anna M. et al. “Record-Setting Algal Bloom in Lake Erie Caused by Agricultural and Meteorological Trends Consistent with Expected Future Conditions.” Proceedings of the National Academy of Sciences of the United States of America16 (2013): 6448–6452.
  3. Farmer, T.M., Marschall, E.A., Dabrowski, K., Ludsin, S.A. (2015). Short winter threaten temperate fish populations. Nature Communications, 6 (7724)
  4. Linn, M (2015, September 20) Climate change threatens perch, other warm-water fish. November 1, 2017, retrieved from
  5. Golowenski, D (2014, April 6) Lake Erie perch, walleye bag limits to stay same. Retrieved November 2, 2017, retrieved from
  6. Frankson, R., K. Kunkel, S. Champion and D. Easterling, 2017: Ohio State Summary. NOAA Technical Report NESDIS 149-OH,4 pp.

Gator or Gar? Interesting Facts About an Ohio Predator

Ohio has a variety of fish that have qualities that are considered ancient, retained from their ancestors, such as armored scales, jawless mouths, and a lack of paired fins. One such fish with ancient qualities is the Longnose Gar, in the Lepisosteidae family. A native Ohio fish, it has thick ganoid (diamond-shaped) scales that act like armor plating to protect them from other predators and an elongated, narrow snout full of sharp teeth. They look like the fish version of a crocodile and are just as deadly to their prey. They reach impressive sizes for a freshwater fish (the Ohio record is 25lbs and 49inches in length – Outdoor Writers of Ohio, 2017), and are terrifically successful ambush predators. With their heavy armor, they can’t sustain fast swimming besides a quick burst, so they lie in wait until small fish and minnows swim near and then they snatch them up with their formidable jaws. Their body coloration helps break up the shape of their body with the spots and blotches, similar to the way tigers and leopards use their coloration to their advantage in their habitats. They also display a type of coloration called countershading, which means they have a lighter stomach and a darker back. From below, the color of their stomach will allow them to blend in with the sky and from above, their back color allows them to blend into the substrate (Sea Grant 2013).  On another interesting note, Longnose Gar have poisonous roe (eggs). According to Burns & Stalling (1981), Longnose Gar roe shows negative effects on humans, lab mice, and domesticated animals. Their personal testing on natural predators of the roe showed it had a 77% mortality rate on crayfish (similar gar species had more or less of the same effect), but nothing noticeable happened to the bluegill that ate the roe. The crayfish that didn’t succumb to the poison still showed behavioral effects within 30 seconds to 4 minutes (depending on the species of gar roe eaten). The researchers noted that it made sense the crayfish were more susceptible since the timing of gar spawning coincided with peak crayfish young abundance. This would reduce the mortality of the gar spawn. Overall, this makes them deadly from egg to adult; truly an impressive species.



Lyons, J. (2013). Longnose Gar. University of Wisconsin Sea Grant Institute. Accessed November 2017 (



Burns, T. A., & Stalling, D. T. (February 16, 1981). Gar Ichthyootoxin: Its Effect on Crayfish, with Notes on Bluegill Sunfish. The Southwestern Naturalist, 25, 4, 513-515.


Outdoor Writers of Ohio State Record Fish Committee (2017). Current Ohio Record Fish. Outdoor Writers of Ohio. Accessed November 2017 ( current-ohio-record-fish/).


University of Wisconsin Sea Grant Institute. (2013). Longnose Gar. Accessed November 2017 (

Catfish Stocking Close to Home

A map of Hoover Reservoir

The Blue Catfish (Ictalurus furcatus) is one of the largest native fish in North America, behind only the Alligator Gar and a few species of Sturgeon. This fish can grow up to 6 feet in length and 120 pounds in ideal situations! Although fish this size have not been found in Ohio, the state record is still a whopping 96 pounds. Within the buckeye state they are usually found in the deep, fast flowing waters Ohio river and its tributaries, hover this has changed in recent years. In 2011, the Ohio Department of Natural Resources decided to stock Blue Catfish to Hoover Reservoir in Westerville Ohio. This was attempt to expand their range and bring them to an area where they could become a fruitful fishery.  The fish were produced and raised at the Hebron and St. Mary’s state fish hatcheries. Aged one year and younger, the fish were released into Hoover with the hopes that it would become a fishing destination within the state.

Blue Catfish caught by the Division of Wildlife during their 2017 sampling. These fish could have been some of those initially introduced in 2011.

Fast forward to 2017. The Blue Catfish stocking program was revaluated through a series of electrofishing surveys and the results were very promising. These samples have shown fish ranging in size from 4 inches up to 33 inches with the largest fish weighing 17 pounds. Although these fish have yet to reach the size of some found in the Ohio River, Hoover Reservoir is well on its way to become a sought after fishery producing trophy sized fish. With the amount of success the fish are having at Hoover, other stocking programs have been initiated, one at Clendening Reservoir and one at Seneca Reservoir. Thanks to the positive results of this pilot study, be sure to keep an eye out for Blue Catfish coming near you!



Mosquitofish: pest control or pest?

Western Mosquitofish, Gambusia affinis, is a member of the Poeciliidae family, which is a family comprised of live-bearing fish. They are one of the few freshwater fish to bear live young. Because of this, the young are able to feed like adults and increase their population quickly. They are a dull colored gray with small dark spots on their fins. Mosquitofish also have an upturned mouth and flattened head. They are rather small in size, females typically at 2-3 inches long, while males only 1-1.5 inches long (ODNR, 2017). They can be found in many ponds or slow flowing streams throughout Ohio, however they are not native to Ohio at all!

So, how did these little guys get here? Well, as their name suggests, they feed on mosquito larvae, as well as other small aquatic insect larvae. Mosquitofish are great eaters, consuming about 42-167% of their body weight every day! Because of this, they were thought to be a great pest control and alternative to insecticide for controlling mosquito populations (USGS, 2017). They were introduced to Ohio in 1947 in western Lucas County, but their region has since been expanded sporadically throughout the state (ODNR, 2017). As most non-native species introductions are, this was quite controversial.

Why may these teeny little fish be an issue? They may be small, but they are mighty! Also, as mentioned earlier, they can increase their population very fast. Mosquitofish have an extremely aggressive and predatory behavior. This makes them a threat to other small fish species through predation and competition. Mosquitofish populations may even displace native Ohio fish species, which is not good for the health of our streams. They have been found to be the reason for declines in several topminnow species, other fishes, invertebrates, and even amphibians throughout the continental United States. Recent introductions of Mosquitofish in New Zealand and the Hawaiian Islands reduced genetic diversity within the community (Purcell et al. 2012).

This invasive species causes more harm than good! It has been reported that Mosquitofish are not very effective in reducing mosquito populations. In fact, they may even benefit mosquitos by decreasing competition from zooplankton and reducing predation from other invertebrates (Blaustein and Karban 1990). Mosquitofish can also potentially cause algal blooms by feeding on an abundance of zooplankton grazers (Hurlbert et al. 1972).

Mosquitofish are only one example of a non-native species, including many plant species, introduced to Ohio to serve some purpose. It seems to be a game of chance whether the introduction causes harm or good. It is clear that research and much consideration should be taken before altering the environment in such a drastic way.

Check out other invasive Ohio fishes here (under the heading ‘Invasive Fish’):


Blaustein, L., and R. Karban. 1990. Indirect effects of the mosquitofish Gambusia affinis on the mosquito Culex tarsalis. Limnology and Oceanography 35(3):767-771

Hurlbert, S.H., J. Zedler, and D. Fairbanks. 1972. Ecosystem alteration by mosquitofish (Gambusia affinis) predation. Science 175:639-641.

Ohio Department of Natural Resources (ODNR). 2017. Western Mosquitofish. Retrieved from:

Purcell, K.M., N. Ling, and C.A. Stockwell. 2012. Evaluation of the introduction history and genetic diversity of a serially introduced fish population in New Zealand. Biological Invasions 14:2057-2065.

United States Geological Survey (USGS). 2017. Gambusia affinis. Retrieved from:

Photo credits:


Migratory fish of the Great Lakes


Migratory fish are species that move to accommodate their reproductive, feeding and refuge needs. Many fish migrate during only a small period of their lifetime. For several fish, migration takes place annually on a seasonal basis. Fish can migrate between marine and fresh water (diadromous fish) or between different fresh waters (potamodromous fish).

In the Great Lakes region, migrations are potamodromous and take on several different patterns. Some species, including Lake Sturgeon, Walleye, and Coaster Brook Trout migrate longitudinally from lakes to tributaries to spawn. Others migrate from lakes to coastal wetlands to spawn, like the Northern Pike. There are also species, such as the Lake Trout, that migrate from pelagic areas to near shore and off-shore spawning reefs. Not all migrations cover long distances, migrations by Great Lakes species range from 10s of meters to upwards of 200km. The following table summarizes a subset of Great Lakes migratory fish and their coarse migratory behaviors:

Common Name Scientific Name Most Commonly-Referenced Migratory Behavior
American eel Anguilla rostrata Between lake and river
Atlantic Salmon Salmo salar Between lake and river
Bluegill Lepomis macrochirus Within river
Brook Trout Salvelinus fontinalis Within river
Channel Catfish Ictalurus punctatus Within river
Lake Herring Coregonus artedi Between lake and river / within lake
Lake Sturgeon Acipenser fulvescens Between lake and river
Lake Trout Salvelinus namaycush Between lake and river / within lake
Lake Whitefish Coregonus clupeaformis Between lake and river / within lake
Longnose Sucker Catostomus catostomus Between lake and river
Northern Pike Esox lucius Between lake and river
Shorthead Redhorse Moxostoma macrolepidotum Between lake and river
Walleye Sander vitreus Between lake and river
Source: Great Lakes Inform: An Information Management & Delivery System,

Role in Great Lakes

Migratory fish play important structural and functional role in the Great Lakes. They influence the Great Lakes through direct and indirect mechanisms as consumers, ecosystem engineers, modulators of biological and chemical processes, and transport vectors (Flecker et al 2010). For example, species moving from one area to another move nutrients and energy between and among lake and riverine habitats. When fish or unfertilized eggs decompose, those nutrients are then available to the local foodweb.

Threats to Migratory Fish

  • Tributary connectivity. Barriers that restrict upstream movement, such as dams and road crossings, can limit migration. If fish are unable to migrate to an ideal spawning habitat, they may be forced to spawn in sub-optimal conditions that result in reduced egg survival.
  • Habitat degradation. Poor land-use practices in surrounding watersheds and pollution from urban or industrial sources contaminates migratory fish habitat.
  • Invasive species. Invasive species stress migratory fish through competition and associated shifts in food web dynamics. They can prey on native fish and potentially out-compete native fish for food sources, resulting in sub-optimal diet for native fish.

Conservation Efforts

Several agencies are working to combat threats to migratory fish. These efforts include restoring tributary connectivity by removing dams, improving road crossings, and constructing fish passageways around barriers. Efforts also include restoring habitat by returning forest cover to riparian zones, recovering key native migratory fish species by stocking hatchery-reared fish and restricting harvest, and stopping the spread and controlling established invasive species.

Tracking Migratory Fish in Lake Erie

Tracking migratory patterns of fish is important for conservation efforts. The Great Lakes Fishery Commission established the Great Lakes Acoustic Telemetry Observation System (GLATOS) in 2010, with the goal of understanding fish behavior in relation to Great Lakes ecology and to provide useful information to fish managers. Acoustic telemetry is used to track fish movement. An acoustic tag that transmits a unique signal is implanted in the target species, and an acoustic receiver is used to decode the signal (Figure 1). Some transmitters can incorporate biological and environmental information such as pressure (to determine depth), temperature, and acceleration (to determine swimming behavior). Lake Erie migratory fish projects shared on GLATOS include studies of Lake Sturgeon, Muskellunge, Walleye, Grass Carp, Lake Trout, Sea Lamprey.

Figure 1: Acoustic tag and receiver. Source:

Case Study: Assessing adult Muskellunge movement in Buffalo Harbor, Lake Erie, and the Niagara River

Recently, Justin Brewer from the New York State Department of Environmental Conservation and the Niagara Musky Association partnered with the Habitat Enhancement and Restoration Fund to determine migratory patterns of muskellunge in Buffalo Harbor, Lake Erie, and the Niagara River. Knowledge of the seasonal use of these areas will help fishery managers better understand the habitat requirements of Muskellunge and will be used to direct habitat restoration projects. They are using the GLATOS array to document Muskellunge movement. Electro-fishing techniques were used to secure 10 viable musky samples from the Niagara River and Buffalo Harbor, 5 males and 5 females. Acoustic tags were surgically implanted into the musky and 6 acoustic receivers were planted to track them. These receivers are few of many that are updated to the GLATOS database, so if a musky is picked up outside of their study region, it will be detected. This is an ongoing study that will answer important questions about prime Muskellunge spawning habitat, viability, and whether it can be expanded.

Figure 2: Muskellunge tagged for migratory study in Buffalo Harbor, Lake Erie, and the Niagara River. Source:


Great Lakes Inform: An Information Management & Delivery System. Migratory Fish. Available at (Last accessed 29 October 2017).

Great Lakes Acoustic Telemetry Observation System. Available at (Last accessed 29 October 2017).

The Buffalo News. Why this musky study is an investment in the future. Available at (Last accessed 29 October 2017).

Flecker AS, McIntyre PB, Moore JW, et al (2010) Migratory Fishes as Material and Process Subsidies in Riverine Ecosystems. American Fisheries Society Symposium 73:559–592.