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Fish Movement and Passageway
Between Lake Erie and Metzger Marsh

Monitoring of an Experimental Fish Passage Structure
1999 Progress Report

January 2000

Susan Wells
U.S. Fish and Wildlife Service
Fishery Resources Office
Alpena, Michigan
and
Ottawa National Wildlife Refuge
Oak Harbor, Ohio
susan_wells@fws.gov

Provisional data, not to be cited without permission.

Abstract Metzger Marsh is a 906 acre coastal wetland jointly managed by US Fish and Wildlife Service (Service) and the Ohio Department of Natural Resources Division of Wildlife (ODOW). In 1995, construction of a 7700 foot dike designed to mimic the eroded barrier beach completed the Metzger Marsh Wetland Restoration Project. In order to prevent further isolation of wetlands to Lake Erie fish communities, a fish passage structure was integrated into the design. The structure consists of two trap baskets which hold fish moving into and out of the marsh. The Corps of Engineers permit requires the water control gates to be open for four years, allowing the marsh to fluctuate naturally with lake levels. The concept is to allow the system to function as a wetland component of Lake Erie. The gates were opened in March of 1999 and fish sampling began in the spring of 1999. Monitoring of the fish movement will reveal important fish utilization information for wetland management purposes. As of fall 1999, 40 species of fish from 16 families were identified moving into and out of the marsh. Redesigning parts of the structure is underway in order to better assess the movement of fish communities between the wetland and Lake Erie.

INTRODUCTION

Coastal wetlands provide many attributes including buffer zones between upland and aquatic habitats. These Great Lakes wetlands are important sources for high productivity, providing nutrient exchanges and export production into the lake. They also provide habitat for many species. The loss of coastal wetland habitat in Ohio has been substantial. The development along the shoreline of Lake Erie has been growing at a faster rate than any other part of the Great Lakes (Bookhout et al. 1989). Approximately 90% of the Ohio’s original marshes have been lost to development and agricultural activities (Dahl and Johnson, 1991). The majority of the remaining coastal wetlands are closed off to Lake Erie because of diking activities. These activities, to promote waterfowl habitat by controlling water level regimes, has resulted in a decline of water quality and aquatic species diversity (Steedman and Regier 1987). The coastal wetlands and the nearshore of Western Lake Erie no longer function as a single ecosystem. Runoff from surrounding lands is no longer filtered through these wetland buffers, which normally would trap sediment and moderate flood events. Diversity of habitat and species has declined, and those remaining are limited to the extremely tolerant.

Most of the coastal marshes on Lake Erie are managed for optimal food production for migrating waterfowl. Fishery management in this type of systems has been given little consideration. Fish communities utilize these habitats for spawning, nursery, feeding and protective areas. Species diversity within a freshwater coastal marsh can be quite extensive. Almost all freshwater fish species use wetland areas at some point in their life (Mitch and Gosselink, 1993). It has been estimated that 47 species of Lake Erie fish are or have been associated with the coastal marshes (Johnson, 1989). Inaccessibility, due to diking and draining of wetlands for agriculture, have been attributed to the decline in fish abundance since 1850 (Trautman, 1957).

In an effort to maintain connectivity with Lake Erie, an experimental structure was proposed for Metzger Marsh. The design for a newly renovated dike would maintain an opening to the lake and allow for nutrient exchange and species migration between the two systems. The concept behind this experimental structure is to explore other methods of marsh management that would embrace an ecosystem approach and optimize species diversity.

BACKGROUND

Metzger marsh is a 906 acre coastal wetland on Lake Erie. It is approximately 20 miles east of Toledo Ohio. The Service and ODOW jointly manage the marsh. The restored lake front dike is the site of an experimental fish passage structure to promote species diversity and maintain a connection with Lake Erie.

From the 1930’s until the mid 1940’s the marsh was owned and operated as an onion farm. At that time, a barrier beach existed in front of the marsh. This beach acted as a buffer, protecting the farm from wave energy and other erosion forces. In the early 1960’s lake levels began to rise. Water levels continued to rise and maintained their high levels for three decades. The resulting wave energy finally caused the barrier beach to erode away during a storm event in 1972 leaving the marsh open to unimpeded wave action.

The ODOW, Service, and Ducks Unlimited initiated a joint wetland restoration project for Metzger Marsh in 1992. The purpose of the project was to restore 906 acres of lucastruine/palustrine habitat by building a 7700-foot dike to mimic the eroded barrier beach. A fish passage and water control structure was added to the design after the initial design plans for the marsh.

Fish passage was added to the restoration project after concerns were raised for the lack of available fish access into coastal wetlands.   Declines in the abundance of wetland dependent species over the last 50 – 60 years have been attributed to wetland loss and diking with subsequent wetland isolation (U.S. Department of the Interior, 1994). Management of coastal Lake Erie marshes has traditionally been based on controlling moist soil conditions and plant succession. Intensive management of water levels on a seasonal basis influences aquatic plant production (U.S. Department of the Interior, 1994). However, these Lake Erie wetlands are vital habitats for approximately 47 species of fish for spawning, nursery, and rearing areas. Twenty-six of these species have significant recreational, commercial or prey value (Herdendorf, 1987). Their access into wetland habitats has been decreased significantly due to development.

The Corps of Engineers permit requires that research before and after the construction of the dike be performed in order to monitor any effects to the biotic and abiotic conditions. The permit also states that after revegetation of the marsh, the five water control gates into Metzger Marsh are to be left open for a minimum of four years. This will allow the marsh water levels to fluctuate “naturally” with lake levels. During this time the fish passage structure will be in operation in order to monitor the migration of fish into and out of the marsh while excluding carp. Nutrient production and export will also be monitored at the same time. The final results of this study can then be used to determine fish migration timing in order to allow fish access into the wetland while still managing for other wetland dependent plant and animal species.

STRUCTURE

The structure containing the fish passage and water control mechanisms is approximately 40 feet in length (Figure 1). There are five openings connecting Metzger Marsh and Lake Erie. Each opening has a 5’ x 5’ gate that can be operated mechanically. The fish passage structure consists of two trap baskets. One of the baskets is set to trap the ingress fish while the second basket is set to trap the egress fish. These baskets are set in the far east bay and the far west bays respectively. They are used to examine a sub - sample of the population moving between the two systems since baskets are not used in front of all five openings.

The current baskets are 9’ in height, 6’10” in width and 4’5” in length. They are made out of galvanized steel wire mesh surrounding the lower 3’ of the baskets. A 5-ton overhead crane is used to maneuver the baskets. A series of removable grates are placed in front of all five openings. The purpose for the grates is to prohibit large carp from entering the marsh and destroying aquatic vegetation through substrate disturbance and increased turbidity during feeding. There are various grate sizes, ranging from 5 to 20 cm, which will be used to determine the best grate size for prohibiting entry to the carp but allowing any desirable fish to pass freely.

CHALLENGES

Since this was the first year operating the experimental structure, there were a few challenges to work through. The two most intensive challenges involved the sampling baskets and the grates.

The baskets were laden with design flaws from the beginning. As mentioned earlier, the sides of the baskets were only 3’ in height and they were being used in water with an average depth of 6 – 7 feet. Therefore, fish in the upper water column could not be sampled unless they were too slow to move out of the way when the basket was being lifted for sampling analysis. Another problem with the baskets involved the actual trapping mechanism. Once the fish were in the basket there was no way to keep them in there. They were free to swim about, again biasing the sample.

The most troublesome challenge this past year involved the grates.   At times there is a significant amount of water flowing though the opening of the marsh. During periods of high winds coming from the southwest, vegetation from the marsh becomes uprooted and caught on the grates as it is carried out towards the lake. When these events occurred, vegetation clogging grates would block much of the water flow. There was a period when the water level on the marsh side of the grates was 3 feet higher than the lake side of the grates. It is during these periods when the purpose of the structure fails (Figures 4 and 5). Fish are unable to migrate between the two systems and there is no nutrient exchange or export production into Lake Erie occurring. If vegetation is not removed from the grates in a timely fashion, the grates can become damaged by the tremendous pressure caused by the backup of water.

The grates also cause damage to fish. When storm events and water flows are extremely strong, fish can be caught up against the grates (Figures 2 and 3). Some fish are so determined to get into the marsh, that they are gilled in the grate trying to push their way through. Most of the fish found gilled on the grates have been walleye. Of the 15 walleye trapped, most were females 400 mm or larger.

Since the structure is right on Lake Erie, weather plays a major role in its operation. There have been many times when operation was stopped due to heavy water flows, and thunderstorms suddenly coming upon us. When the water flow is too strong it pushes the baskets up against the concrete wall, making it virtually impossible to lift the basket without damage to fish and equipment. Ice can also cause damage to the grates. As it piles up against the grates, it exerts a lot of stress and eventually the grates give way. In December one grate was broken in half and completely lost. Most were damaged extensively. For a few of them, we were only able to recover half the grate. The grates have been removed for the winter and will be replaced after ice out.

PROTOCOL

Intensive sampling in 1999 began in early April and concluded in September. Additional sampling was attempted periodically through October and the beginning of November but equipment failure prevented successful sampling during those months. The baskets were lifted twice a day during the spring months and then reduced to once a day during the summer. As fish migration slowed down sampling occurred only three times a week once a day.

The fish captured in the baskets were identified to species, counted, weighed, and total length in millimeters is taken. All sport fish were tagged with t-bar anchor tags and the right pectoral fin is clipped. Fin clipping was employed on all species of fish over 100 mm in length. Scale samples were also taken from sport fish for age determination.

Abiotic parameters are sampled for every lift and set of the trap baskets. Dissolved oxygen, pH, conductivity, bottom water temperature, surface water temperature, air temperature, wind direction and speed, water depth, flow direction, and secchi disc readings were measured. These same parameters were also sampled during larval sampling.

Larval sampling was conducted once a week during the evening hours beginning in the middle of April. Four ten-minute samples were taken using a 0.5 m ichthyoplankton net (303�m). Larval sampling concluded at the end of August. Samples were preserved in alcohol for identification at a later date.

RESULTS

In the first year of sampling the results illustrate the potential of the structure. This first year of sampling will be used in conjunction with the remaining three years of monitoring to determine the effectiveness of the structure for fish passage and nutrient exchange. As of fall 1999, 40 fish species from 16 families were identified passing through the structure.

There were a total of 9314 fish sampled in the trap baskets in 1999 (Table 2). The combined majority of the fish sampled were emerald shiners (38.4%) followed by gizzard shad (32.3%). Common carp made up 3.48% of the total catch. Carp were most prevalent from the end of April through mid May. Five other species of fish were more abundant than carp. Four of the five species of fish are regarded as lake species and not largely wetland dependent. The fifth most abundant species of fish was the round goby. The rock and cement surrounding the structure likely created good habitat for the round gobies.

Wetland dependent species made up approximately 10% of the total catch while 90% of the catch was made up of lake species (Table 1). The ingress basket had a higher catch number than the egress, consisting of approximately 74% the total catch in 1999. The catch per unit effort for the ingress was higher (3.88) compared to the egress (1.97) CPUE. Total combined CPUE was 3.05. Total effort was measured in hours. There was a combined effort of 2808 hours of sampling time (Table 3).

Species diversity was calculated using the Shannon – Weaver model. The Shannon – Weaver reflects the abundance of different species from a subsample of a larger community. It is used to indicate the importance of the fish passage structure to the fishery of Lake Erie. The evenness of catch (also known as relative diversity) was measured using the results of the Shannon – Weaver model.

Shannon – Weaver model:                    Evenness of Catch:

    H’ = - x Pi log Pi                            J’ = H’/ Hmax’

Where Pi = number of “ith” species divided by the total number of catch and Hmax’ = logarithm of the total number of species. The diversity index is measured between 0 and 1. The closer to 1 the greater the diversity. Evenness of catch was converted to percent. The greater the percentage the better the distribution of catch between all species

Species diversity was greatest for the egress basket with July being the highest month (Table 3). However, evenness was greatest for the ingress sampling (Figure 3). Once again July was the month of the greatest even catch distribution for the ingress. Combined species diversity for the structure was at 0.8061. The evenness of catches, sometimes referred to relative distribution, was greatest for both the ingress and egress in July. The ingress values decreased in August while the egress remained around 50% and showed a slight decrease in June.

A difference in catch between the ingress and egress traps is difficult to quantify. The ingress basket began sampling in the beginning of April while sampling for the egress didn’t begin until the end of April. Lack of equipment and labor was the main cause for the differences in sampling times. A possible hypothesis for the variation in catches could be attributed to a lack of motivation. When they first enter the marsh they have a distinct purpose to fulfill. Once completed their motivation is not as strong and finding a way out becomes more difficult.

The movement of carp into the marsh is an important factor. Carp have been attributed with causing increased turbidity and decreased macrophyte production in diked wetlands. In open systems this may not be the case since carp are free to come and go. In impounded wetlands, carp are trapped and continue to grow larger in a finite area. Determining timing of carp migration into and out of the Metzger Marsh is a major objective and important to management strategies. By the end of April, carp were moving in and represented 24% of the monthly catch. By May their number began to decrease and the monthly catch consisted of less than 2%. Carp numbers moving into the marsh were highest in June (35%) and continued to decrease until they made up less than 1% of the monthly catches (Figure 4). Less than 1% of the total egress catch consisted of carp. The carp movement into the marsh was heaviest with water temperatures in the range of 18.0 to 28.5 degrees Celsius and when the water was flowing out of the marsh.

All of the carp were fin clipped, similar to the other fish, and returned to the lake. They were not allowed entry into the marsh. There have not been any fin clipped fish recaptured in 1999. The tagging program provided information on three recaptured fish. All which were largemouth bass. A fisherman caught one approximately 2-3 miles down the shoreline one month after leaving the marsh.

DISCUSSION

The results of this first year show great promise. Overall diversity was high despite the design flaws. The design flaws in the trap baskets are currently being modified and are expected to be in use for the 2000 sampling season. It is important to keep in mind that this was the first year of operation. No one knew what to expect. It has been pleasing to discover the variety of fish species, especially lake species, using the structure. Since Metzger Marsh was opened to Lake Erie, the interior of the marsh has become an excellent largemouth bass fishery for the public.

With increased pressure on water resources and lack of habitat for a multitude of wetland dependent species, it is crucial to look at alternatives that encompass an ecosystem approach for a divers number of species. Agriculture and other development have greatly reduced coastal wetlands and have been attributed to decreases in the Lake Erie fish communities. Metzger Marsh is an experiment, which can lead to opportunities to expand fish spawning, nursery, and protective habitats around the Great Lakes. This is a project that promotes habitat for fish, bird, amphibian, invertebrate, and plant species. It is imperative that we take a hard look at innovations such as Metzger Marsh in order to obtain maximum utilization of the few remaining areas for our fish and wildlife species.

ACKNOWLEDGEMENTS

I would like to give special thanks to all of those who had helped with this project during the first year of trials and tribulations. Included is Ohio State University Fisheries Management Unit, USGS Great Lakes Science Center, Ohio Division of Wildlife, Ohio Division of Geological Survey.

REFERENCES

Bookhout, T.A., K.E. Bednarik, and R.W. Kroll 1989. The Great Lakes marshes. Pages 131– 156 in L.M. Smith, R.L. Pederson and R.M. Kaminski eds. Habitat management for migrating and wintering waterfowl in North America. Texas University Press.

Dahl, T.E. and C.E. Johnson, 1991. Wetlands Status and Trends in the Conterminous United States Mid – 1970’s to Mid – 1980’s, U.S. Fish and Wildlife Service, Washington, D.C., 28p.

Herdendorf, C.E. 1987. The ecology of the coastal marshes of western Lake Erie: a Community profile. U.S. Fish and Wildlife Service. Biological Report 85.

Johnson, D.L. 1989. Lake Erie Wetlands: fisheries considerations. In Lake Erie estuarine systems: issues, resources, status, and management, ed. K.A. Krieger, pp. 257 – 274. NOAA Estuary – of- the – Month Seminar Series No. 14. NOAA Estuarine Programs Office, Washington, D.C.

Mitsch, W.J. and J.G. Gosselink 1993. Wetlands, 2^nd edition. International Thompson Publishing.

Steedman, R.J., and H.A. Regier, 1987. Ecosystem science for the Great Lakes: Perspectives on degradative and rehabilitative transformations. Canadian Journal of Fisheries and Aquatic Science. vol. 44 (supplement 2) pp 95-103.

Trautman, M.B. 1981. The Fishes of Ohio, 2^nd edition. The Ohio State University Press, Columbus.

U.S. Department of the Interior. 1994. Metzger Marsh coastal wetland restoration project: draft environmental assessment and finding of no significant impact.

FIGURES

TABLES

Last updated: August 7, 2009

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