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Bighead and Silver Carp

DESCRIPTION: Bighead and silver carp are invasive fish moving toward Wisconsin waters from the Illinois River and the Mississippi River at a rate of about 50 miles a year. The term "Asian Carp" is sometimes used to describe these two invasive species, along with the black and grass carp (neither of which are currently considered to pose an imminent threat to Wisconsin waters). Bighead and silver carp were brought to North America from China in the early 1970s to improve water quality by removing algae from aquaculture ponds, and possibly to be marketed as a food fish. Both species have low-set eyes and large upturned mouths without barbels. Their heads have no scales, and their body scales are very small. The bighead carp has dark blotches along the top of its body (in the dorsal region). DISTRIBUTION AND HABITAT: Bighead and silver carp are spreading to lakes, rivers and streams in several areas of North America, particularly the Mississippi River and Great Lakes region. Their populations have been doubling annually, with the fastest expansions occurring in the Missouri and Illinois Rivers. They live in temperate freshwater in both their native and introduced habitats, requiring bodies of water with some current for eggs to float and develop properly. They are well-suited to the climate of the Great Lakes region, which is similar to that in their native Asian habitats, and particularly favor large rivers and connecting lakes. LIFE HISTORY AND EFFECTS OF INVASION: Asian carp migrate up streams or rivers to breed; eggs and larvae float downstream to floodplain zones. These fish are fast growing and become very large: They can weigh up to 100 pounds, and can grow to a length of more than four feet. Asian carp also reproduce prolifically. Bighead carp females produce between 200,000 to 1 million eggs in their lifetime, while silver carp females produce between 300 to 5,000 eggs. Bighead and silver carp are filter feeders, straining tiny animals and plants (plankton) out of the water. Some may eat their weight in plankton daily. In eating plankton, these fish directly compete with native filter feeders such as mussels and fish. This competition for food can potentially disrupt the entire food web in a water body. Some scientists fear that, if introduced, they could become a dominant species in the Great Lakes. Silver carp (and bighead carp to a lesser extent) are renowned for leaping high out of the water when disturbed by watercraft. Boaters traveling at high speeds can actually be injured by these leaping fish. (Imagine hitting a 100-pound, four-foot-long fish at 30 miles per hour!). They also diminish the opportunities of fisherman as native fishes decline from carp competition. CONTROLLING ASIAN CARP: The only thing that is keeping these fish from moving into Lake Michigan is an electrical barrier system on the Chicago Sanitary and Ship Canal, though this is not a fail-safe system. Although the barrier acts to repel the fish, it doesn't actually kill them. Also, flooding on the Des Plaines River could carry water (and carp) overland into the Canal upstream of the barrier. The construction of similar barriers at two points along the Mississippi has been recommended, though this system will need to be more technologically advanced and thus will be more expensive. This is because the design must allow the free flow of native fish up and downstream for spawning while simultaneously blocking movement of the Asian carp upstream. University of Minnesota researchers are evaluating the possible release of sterile or genetically modified fish, as well as the use of pheromones or other sensory cues, to reduce the numbers of Asian carp in the wild. Early detection of isolated populations may help slow or restrict the spread of these Asian carp. To report a sighting, note exact location. Freeze specimen in a sealed plastic bag and call your local DNR Service Center.

Hydrilla

Hydrilla verticillata (L. f.) Royle Frog-bit family (Hydrocharitaceae) Origin: Central Africa Background Hydrilla first appeared in the Crystal River system of Florida in 1960. Imported by the aquarium trade, its presence on the Delmarva Peninsula was confirmed in 1981. It attracted national attention when infestations were found in the Potomac River in Washington, D.C. in the early 1980s. It is a federal noxious weed. Distribution and Habitat Hydrilla is documented throughout the southern United States from California to Delaware. In the mid-Atlantic, it occurs in much of the Potomac River, in Virginia and Maryland freshwater tributaries of the Chesapeake Bay, in the Delaware portion of the Nanticoke River, most southern Delaware ponds, and in sites in eastern Pennsylvania. It is not salt tolerant. Ecological Threat Hydrilla outcompetes native submerged aquatic vegetation and can quickly fill a pond or lake, thus choking off the water body for boating, fishing, swimming and other recreational uses. Although non-native and invasive, it provides good quality habitat for fish and shellfish as well as water quality benefits. Description and Biology • Plant: rooted aquatic plant. • Leaves: in whorls of 4-5; about ½ in. long; fine-toothed margins, spine at tip. • Flowers, fruits and seeds: tiny, translucent to white flowers produced on the upper branches in late summer and fall; tubers grow from the roots; winter buds (turions) are produced in the leaf axils. • Spreads: vegetatively through fragments of stems, stolons, or rhizomes, turions, or tubers which are carried on boat livewells, motors and trailers, bait pails and other items, and by ingestion of tubers and turions by waterfowl. • Look-alikes: native common waterweed (Elodea canadensis) with leaves in whorls of 3 and no teeth or spines. Prevention and Control Physical, chemical and biological controls have been used for control of hydrilla, with varying levels of success. Water level drawdowns have generally been ineffective in our area. Mechanical aquatic weed harvesters provide temporary relief and open boating lanes, but resulting plant fragments can help spread the vegetation faster. Contact herbicides provide temporary control, but systemic herbicides provide more long-term control. Herbivorous fish such as sterile grass carp have been used for hydrilla control where allowed by law. Other biological controls are still being investigated. Each control method has its drawbacks and liabilities. On the Potomac River and other parts of the Chesapeake Bay watershed, resource managers struggle with hydrilla because submerged aquatic vegetation, including hydrilla, provides water quality benefits and habitat for fish and shellfish. Native Alternatives Aquatic plant species are difficult to tell apart to the untrained eye. Contact your state natural resource agency, native plant society or other resource (see References) for assistance.

European Starling Sternus vulgaris

Native Range: Europe to Central Asia Introduced: 1890released 80-100 birds in New York City Present day:East to west coast, Arctic in Alaska to tropics in Mexico Totals ~ 1/3 of world starling population Identification: pointed wings, short, square tail Glossy black, irridescence Male/female ID Eye and bill difference Molt in fall Noisy birds Mainly in cities, suburban areas and agricultural areas Forage in open grasslands Eat soil insects; fruit, seeds, grain Use nesting cavities Well adapted to human disturbance such as crop land Pest; cause severe crop damage Responsible for more damage costs than any other bird in U.S.

Marine Toad

Nonindigenous Aquatic Species website (nas.er.usgs.gov) Rhinella marina (Linnaeus, 1758) Common name: Cane Toad Taxonomy: available through Identification: Rhinella marina is an enormous, warty bufonid (true toad) with snout-vent length 4-over 9.25 in. Individuals found in the U.S. rarely exceed 178 mm (7 in). Females may weigh up to 1.5 kg (3.3 lbs). Large individuals sitting on roadways are easily mistaken for boulders. Adult males have more robust forelimbs than adult females. These massive brown or dark-mottled toads have a pair of enormous, deeply pitted parotoid glands, each extending from the temporal region of the head, far down the side of the body, well past the axillary region. The call is a low-pitched, staccato trill that is slow and often likened to the sound of a distant tractor. Recordings of the calls of R. marina are available on several CDs (Library of Natural Sounds, 1996; Bogert, 1998; Rivero, 1998). The tadpoles are black dorsally, with a venter (belly) that is silvery white with black spots. Native Range: Cane Toads are indigenous to northern South America (Argentina, Bolivia, Brazil, Ecuador, Colombia, Paraguay, Venezuela, the Guianas, mainland Honduras, Peru, Trinidad and Tobago), Central America, and Mexico northward to extreme southern Texas. Nonindigenous Occurrences: In Florida, 200 R. marina were intentionally introduced to Canal Point and Belle Glade, Palm Beach County, prior to 1936 (Lobdell, 1936, 1937), and another group of Cane Toads were introduced to Clewiston, Hendry County, prior to 1944 (Oliver, 1949; Riemer, 1958; Lever, 2001). Further introductions were made to Miami-Dade and Sarasota Counties prior to 1958 (Riemer, 1958; Crowder, 1974; Lever, 2001). Other introductions of R. marina occurred in Miami-Dade County (Kendall) in 1964 and prior to 1966 (Miami International Airport), and Pembroke Park, Broward County in 1963 (King and Krakauer, 1966; Crowder, 1974). Over the years Cane Toads have been recorded from the following Florida counties: Bay, Citrus, Clay, Glades, Highlands, Hillsborough, Lee, Marion, Martin, Monroe, Okeechobee, Orange, Pasco, Pinellas, and Polk (Duellman and Schwartz, 1958; Krakauer, 1968; Stevenson, 1976; Easteal, 1981; Wilson and Porras, 1983; Ashton and Ashton, 1988; Lazell, 1989; Stevenson and Crowe, 1992; McCann et al., 1996; Butterfield et al., 1997; Meshaka, 1997, 1999a, b; Conant and Collins, 1998; Meshaka et al., 2000, 2004; Lever, 2001; Krysko et al., 2005; Himes, 2007). Several introductions of R. marina to Louisiana have been made, many prior to 1935, one of which could have been on the Grand Terre Islands (Jefferson and Plaquemines Parishes) (Easteal, 1981; Lever, 2001). Rhinella marina were first introduced to Oahu, Hawaii in 1932 (Pemberton, 1933; Oliver, 1949; Oliver and Shaw, 1953; McKeown, 1978, 1996; Lever, 2001). Descendants of this original introduction were subsequently spread, intentionally, throughout the Hawaiian Islands (Oliver, 1949; Oliver and Shaw, 1953; Easteal, 1981; McKeown, 1996; Lever, 2001, 2003). For references and other worldwide introductions - see Means of Introduction: Both in the U.S. and worldwide, R. marina is normally introduced intentionally in a misguided attempt to control insect agricultural pests, primarily in cane fields. In Florida, intentional and accidental releases from animal importers also have occurred (King and Krakauer, 1966). Those R. marina collected from Bay County, in the Florida Panhandle, escaped from a local zoo (Himes, 2007). Some nonindigenous Cane Toads released in Papua New Guinea were from animals used in laboratories for human pregnancy testing. Impact of Introduction: In many nonindigenous localities, such as Florida and Hawaii, the exact impact of R. marina on indigenous ecosystems remains unclear. Pets that eat or bite Cane Toads become seriously ill from the milky venom contained within the massive parotoid glands and human poisonings are not unknown (Oliver, 1949; Ashton and Ashton, 1998; Lee, 1996; McCann et al., 1996; Lever, 2001, 2003; Beltz, 2005). The complex toxic secretion from these glands can be squirted into the eyes when toads are handled roughly, causing intense pain and a potential medical emergency (Blair, 1947; Lewis, 1989; Lever, 2001). The widely touted use of R. marina venom as a narcotic in the U. S. may be an urban myth, at least for this particular species of bufonid; it is difficult to determine what complex method would have to be devised to selectively neutralize some of the toxins so that it can be used as a hallucinogen (Lee, 1996; Lever, 2001; Beltz, 2005). However, some cultures utilize extracts from the venom to concoct traditional medicines (Crump, 2000; Beltz, 2005). Lee (1996) provides an extensive discussion on the toxicity and potential pharmacological properties of Cane Toad venom.

Giant Toad (cane or marine toad)Bufo marinus

Origin: South America Introduction: to control  sugar cane pests Preys on native species Highly toxic to predators Accidental release of 100 toads in 1955 by pet dealer

Eurasian Ruffe

Ruffe (Gymnocephalus cernuus) are a small but aggressive exotic percid species native to Eurasia. It was introduced into Lake Superior in the mid-1980s in the ballast water of an ocean-going vessel. Eurasian Ruffe Impact Explosive growth of the ruffe population means less food and space in the ecosystem for other fish with similar diets and feeding habits. Because of this, walleye, perch, and a number of small forage fish species are seriously threatened by continued expansion of the ruffe's range. Eurasian Ruffe Control Different chemicals and control methods are being looked at to control ruffe, but nothing has been successful yet. Ruffe were accidentally introduced to the Great Lakes at the St. Louis River near Duluth, Minnesota in the early to mid-1980s. Ruffe were first collected in the St. Louis River during 1986 and were identified in 1987. The Great Lakes Science Center has been studying the St. Louis River fish community since 1988 to evaluate any impacts the establishment of this exotic species may have on the native fish community. The graph to the left illustrates changes in the percent composition of bottom trawl catches for three species commonly captured in the St. Louis River. • Ruffe have steadily increased from about 10% of the catch in 1989 to nearly 90% of the catch in 1996. • Unlike ruffe, emerald shiners have declined from nearly 80% of the catch in 1989 to about 5% of the catch in 1996. • Little change has been observed for yellow perch, which have consistently made up about 10% of the catch for these three species. Bioenergetics modeling of prey consumption was used to determine the efficacy of a top-down predator control strategy implemented in 1989, and used to limit the dispersal and control the increasing abundance of ruffe in the St. Louis River, western Lake Superior. Northern pike, walleye, smallmouth bass, bullheads, and yellow perch were modeled to determine their consumption of ruffe, along with that of four native prey fish species. Northern pike, brown bullhead, and walleye were the major predators of ruffe, with northern pike being the primary predator each year. All predators selected the native prey over ruffe. Top-down control is unlikely to occur in this system, by these specific predators, due to the many complex predator-prey interactions in the turbid St. Louis River environment, and the open nature of the system, which allows stocked predators to freely leave.

Sea Lamprey

The sea lamprey (Petromyzon marinus) is a marine invader from the Atlantic Ocean that entered the Great Lakes through the ship canals and locks built to bypass obstacles like Niagara Falls. An unintended consequence of these canals has been the introduction of invasive species. The sea lamprey was one of the first to invade the Great Lakes. It has been very damaging because part of its life cycle is spent feeding parasitically on the blood of host fish like the native lake trout. Sea lampreys are a very primitive, jawless fish. In the Great Lakes, people mistakenly referred to them as "eels or lamprey-eels." But, sea lampreys are only very distantly related to eels and are correctly referred to only as "lampreys". Although they are classified as a vertebrate, they lack bones and have only a cartilaginous rod or "notochord" for a spine. The paired fins found on most fish are also absent. The most remarkable feature of the sea lamprey is the toothstudded oral disk. During the parasitic period of their life cycle, they use the oral disc like a suction cup to attach to the side of a host fish. The many teeth on the rim of the disc provide traction and make it very difficult for a fish to dislodge a sea lamprey. Once attached, they use the teeth on the tongue in the center of the disk to rasp through the skin. An anticoagulant in their saliva maintains blood flow as they feed. Often the host dies from the blood loss. Estimates of the number of pounds of fish killed by each sea lamprey vary from about 15 to 40 pounds. Several characteristics of the sea lamprey made it an effective marine invader of the Great Lakes. First, the sea lamprey is an "anadromous" fish. This means that it spawns in fresh water streams, the juvenile phase is spent in salt water in the ocean (or one of the Great Lakes as a substitute), and the adult returns to freshwater streams to spawn. Other anadromous, non-native fish in the Great Lakes include coho salmon, chinook salmon, pink salmon, Atlantic salmon, brown trout, rainbow trout, rainbow smelt, and alewives. Special modifications of their kidneys allows these species to live in either fresh or salt water. If you haven't thought of these species as non-native, they are. Second, sea lampreys produce large numbers of eggs. The Great Lakes contained several smaller, native lampreys, but the sea lamprey rapidly out competed them wherever their range overlapped. Third, we believe that lampreys locate streams for spawning using a pheromone excreted by larvae. This pheromone identifies streams successfully producing young. Because the native lampreys also produced this pheromone, the larger, invading sea lampreys had an effective "road map" for expansion. Sea Lamprey Impact Sea lampreys quickly devastated the fish communities of the Great Lakes. Sea lampreys probably entered Lake Ontario in the 1830s via manmade locks and ship canals. Improvements to the Welland Canal in 1919 allowed sea lampreys to bypass Niagara Falls and enter Lake Erie. After sea lampreys were discovered above Niagara Falls (in Lake Erie in 1921 and Lake Huron in the early 1930s), they spread throughout the upper Great Lakes by 1939. The lake trout was the main predatory species at that time and the sea lamprey's preferred host. Although early declines in lake trout abundance in the 1940s are suspected to have been caused by overfishing, sea lampreys are believed to be responsible for the very rapid decline in the later 1940s and 1950s. Lake trout actually became extinct in Lakes Ontario, Erie, Huron (except a few inlets of Georgian Bay), and Michigan. Only remnant native stocks remained in Lake Superior. Two factors contributed to the devastating effect of sea lampreys. First, sea lampreys lacked effective predators. Second, the Great Lakes probably have as many miles of tributaries and as many acres of larval habitat as the native range of the sea lamprey along the Atlantic Coast. Host fishes in the Great Lakes are much smaller than those attacked in the Atlantic Ocean and are more likely to be killed by a sea lamprey attack. Between 40% and 60% of lake trout attacked by a sea lamprey will die from loss of blood. These attacks were a major cause of the collapse of lake trout, whitefish, and chub populations in the Great Lakes in the 1940s and 1950s. Lake trout harvests in the U. S. and Canada averaged 15 million pounds per year before the sea lamprey, but declined to record lows within 20 years of the sea lamprey's appearance. Other equally important secondary effects were caused by cascading changes in the fish communities. After the elimination of predators like lake trout, the populations of invasive prey species like the rainbow smelt and alewife increased rapidly in the absence of predation. Those invasive species then out competed native species or preyed on their young. Extinctions of sculpin and deepwater cisco species have been suspected of being linked to extended periods of high abundance of smelt and alewives. The massive annual die offs of alewives that fouled the beaches in Michigan during the 1950s and 1960s were due to overcrowding and poor condition and were a secondary effect of the invasion of the sea lamprey. Alewives also prey heavily on zooplankton. Because zooplankton graze on phytoplankton, the density of phytoplankton increased and the color and clarity of water were affected, particularly in the lower Great Lakes. Human activities were affected first through the loss of sport and commercial fisheries across the Great Lakes. Following those losses, came other, equally important economic effects caused by the disappearance of fishery-related jobs and the loss of fishing tourism. With the beaches fouled with dead alewives, there were also losses of tourism associated with beach use. Sea Lamprey Life Cycle Fortunately, only one year in the life of a sea lamprey is spent in parasitic feeding. They are unusual in having a complex life cycle, whereas most fish have a simple life cycle. A. Sea lampreys go through an extended larval phase before metamorphosing into the bloodsucking parasitic phase. Each summer and fall there is one group of parasitic sea lampreys actively feeding in the Great Lakes. B. The next spring, that group leaves the lake and migrates into tributary streams where they must build nests in clean gravel with flowing water. C. Each female spawns an average of 60 to 70 thousand eggs. D. After hatch, the larvae drift downstream to areas with slower currents and sand/silt bottoms. There, they establish permanent burrows and enter a larval stage varying in duration from 3 to 10-ormore years. E. Larvae lack eyes and the oral disc. Living concealed in their burrows, they are harmless and filter microscopic material from the water for food. When they reach lengths of 120 mm or more, some individuals begin metamorphosis in mid summer. F. During metamorphosis they develop eyes, the oral disc, and changes in their kidneys that (in their native range) would allow them to enter the salt water of the Atlantic Ocean. That fall or the following spring, they instead enter the Great Lakes to feed parasitically on fish that summer and fall, and mature and spawn the next spring—completing their life cycle. Sea lampreys only spawn once and then die after spawning. Sea Lamprey Control The sea lamprey is one of the few aquatic invasive species that is being successfully controlled. In the late 1940s the State of Michigan began investigations into the biology of sea lampreys. In 1950, this became a federal program. In 1955, the Great Lakes Fishery Commission (GLFC) was created under a convention between the United States and Canada for the purpose of restoring fisheries. One of the GLFC's primary duties was the control or eradication of sea lampreys. It currently manages sea lamprey populations across the Great Lakes to about 10% of their former levels. Control is delivered through its control agents, the U.S. Fish and Wildlife Service and the Department of Fisheries and Oceans, Canada. The commission also funds research on sea lampreys at the U.S. Geological Survey's Hammond Bay Biological Station, at Michigan State University, and at the University of Guelph, Ontario. Control depends on breaking the life cycle. The first control efforts attempted to do that by blocking access to the spawning areas in streams. This was only partially successful because the weirs used to do this were impossible to maintain 100% of the time. There were attempts to use electric fields alone or in conjunction with the weirs, but that was eventually abandoned as too dangerous. A second vulnerable point in the life cycle is during the larval stage, when sea lampreys spend at least three years burrowed in the stream sediment. During the 1950s, over 6,000 chemicals were screened before finding one that was selectively toxic to sea lampreys. That chemical, TFM, has been carefully applied to infested streams, beginning in Lake Superior in 1958. Treatments quickly decreased sea lamprey numbers to 10% or less of their former numbers. Reduced lamprey numbers allowed native and stocked lake trout to survive and the lake trout populations to rebound. Recently, the restoration of lake trout in Lake Superior was declared a success and federal stocking of lake trout was stopped. Lake trout stocks in Lake Superior are once again selfsustaining. Treatments with TFM start with electrofishing surveys of the Great Lakes tributaries known to potentially produce sea lampreys. Based on estimates of the number of metamorphosed sea lampreys to be produced and on treatment costs, a list of streams to be treated is made each year. Because of the duration of the larval stage, streams are treated at intervals of 3 to 5 years or longer. We now have extensive knowledge of the effect of water chemistry on safe levels of TFM and treatments rarely kill fish. TFM also degrades and does not bioaccumulate. In over 40 years of use there has been no documentation of accumulation or of long-term effects on streams despite repeated studies with that objective. The return on treatments is the reestablishment of predators and predator/prey balance in the Great Lakes and protection of native species from extinction. Treatment with TFM is currently still the primary tool for control, but the GLFC, partnered with the Great Lakes Science Center, is committed to providing an integrated program of sea lamprey management in the future that will rely on an increasing number of new control methods. We are now revisiting some of the older concepts such as blocking spawning migration, but using new technologies. Ineffective and labor-intensive screen weirs have been replaced with low-head barriers that block sea lampreys but allow jumping fish to pass. We are also investigating adjustable height barriers that can be lowered after the spawning run, new electrical barriers that use safe levels of pulsed-DC current, and velocity barriers that use the relatively poor swimming ability of sea lampreys to block them but pass other fish. Lampricide Together with the UMESC in LaCrosse, the Hammond Bay Biological Station has played a major role in the discovery of lampricides and the refinement of techniques for their use. We continue to provide technical assistance to that program by supporting purchases of lampricide through a QA program, providing FWS personnel in the field with analytical support and standards, and through continuing research to refine our capability to predict safe and effect concentrations of lampricides in stream treatments. Ecology and Assessment Research done at Hammond Bay accounts for a significant part of our knowledge of the life cycle and ecology of sea lampreys in the Great Lakes, including effects on host species. Recent accomplishments include the first comprehensive analysis of parasitic growth, proof that there is no fidelity of sea lampreys to a natal stream, introduction of coded wire tags and mark recapture to estimate lake wide populations of parasites, estimates of attack lethality, and proof of the relationship between sea lamprey marks observed on fish and losses of lake trout. We contributed substantially to development of a spatial approach to assessment and treatment of sea lamprey larvae in the St. Marys River, resulting (in combination with sterile male releases, below) in lamprey populations in Lake Huron approaching fish community goals. Alternative Control Methods The station has played a key role in the development of several alternatives to lampricides. Initial development of barriers to block sea lampreys from spawning areas in stream was done at Hammond Bay. The most recent evolution of that technology, a combination of a low head barrier that blocks lampreys under normal spring flows and a pulsed-DC barrier that blocks them under flood conditions, was developed at the station. Nearly 30 years of research into the sterile male release technique resulted in successful implementation by the FWS on the St. Marys River and publication of proof of the effect on recruitment. New Directions: Alternative Control Methods Key to Future Sea Lamprey Management Sea Lamprey Pheromones Exciting new discoveries in pheromone communication by sea lampreys promise new tools. In part due to fieldwork conducted at the HBBS over the last decade, Michigan State University and University of Minnesota researchers identified two pheromones. Larvae burrowed in streams excrete a "migratory" pheromone. HBBS scientists had previously shown that sea lampreys do not home to natal streams, yet spawners are consistently found in the same streams. Evidence from tests by Peter Sorensen in two-choice mazes in raceways at the HBBS suggests the migratory pheromone is the method of stream selection. Field tests in the Hammond Bay area will attempt to direct movements of migrating adult sea lampreys. A second "sex" pheromone is released only by spermiated (ripe) adult male sea lampreys. It appears to trigger ovulation in females, and later (but only after the females are ovulated), attracts ripe females to the ripe males. Recent tests by Weiming Li in the Ocqueoc River showed that every ovulated female that made a choice between traps containing a ripe or non-ripe male chose the ripe male. Both pheromones may disrupt sea lamprey migrations or reproduction, or enhance trapping. Emerging Technologies in Telemetry to Address Knowledge Gaps in Fish Community Ecology Most of what we know of species interaction on temporal, depth, or thermal scales are derived from point observations with fishing gear or hydroacoustics. Progress in telemetry will soon allow us to reveal these interactions on a scale not imagined a decade ago. We are currently using new data storage tags to gain new insights into the depths and temperatures occupied by different strains of lake trout and by lake whitefish, chinook salmon, lake sturgeon and sea lampreys. Currently, we are limited to studying species where commercial or sport exploitation produces tag recoveries. Depths and distance in the Great Lakes preclude conventional radio or ultrasonic telemetry. We are presently working with the GLFC and LOTEK to develop a new type of tag for use with unexploited species or populations. Barriers Reemerge A combined low-head and electrical barrier was constructed on the Ocqueoc River, which functions effectively as a low-head barrier but also blocks sea lampreys during high water on this flood-prone stream. This combination of proven technologies allows effective blockage of migrating sea lampreys and passage of jumping fishes under a much broader range of stream flows. Under normal flows, the low-head barrier is functional, no current flows to the electrical barrier, and jumping fish can pass. During flood conditions, when the low-head barrier is inundated, the electric barrier automatically turns on and blocks sea lampreys. Scientists at HBBS will be working in the future with Robert McLaughlin and Gordon McDonald of the University of Guelph to better block sea lamprey migration and improve passage of other fishes at electrical, low-head, and inflatable barriers, and further reduce any negative effects of barriers on stream communities.

Water Hyacinth

Water hyacinth (Eichhornia crassipes) has been called the world's worst aquatic weed. It is a free floating water plant that is native to South America. It can vary in size from a few inches tall to over three feet. This plant has blue-green leaves, thick stalks and a showy purple or lavender flower. It thrives in tropical regions and in waters that are high in nutrients. Its beautiful, large purple and violet flowers have made it a popular ornamental, and the plant is now naturalized in most of the southern United States. It reproduces mostly by clonal propagation, but seeds also play a role in its survival and colonization. Massive weed colonies can grow when introduced into areas that are conducive for their proliferation. In addition, infestation can occur given a disruption in the natural ecological balance by human activities such as impounding of flowing waters by dams, channeling and allowing the buildup of eutrophication. Identification • free-floating, robust plant grows up to three feet off the water's surface • shiny green leaves are round to oval, four to eight inches in diameter, with gently incurved sides • leaf veins are dense and numerous so leaves stand erect • stalks are bulbous and spongy, and help keep the plant buoyant • flowers have six petals, purplish blue or lavender with yellow • several flowers grow at the top of a single stalk • a mass of fine purplish black and feathery roots hangs in the water underneath the plant The primary attribute of water hyacinth is its ability to grow under a wide range of nutrient and environmental conditions. The plant is able to develop at an astounding rate, effectively out-competing other native aquatics. Its growth rate is among the highest of any plant known: hyacinth populations can double in as little as 12 days. This rapid growth can cause an imposing amount of biomass. The level of biomass accumulation will determine its nuisance value and the impact on water quality. Excessive infestation by this weed can severely constrain human activities, affecting accesses to water, navigation, irrigation and fisheries. In other words, Incredibly dense mats of free-floating vegetation block boat traffic and prevent swimming and fishing, and keep sunlight from reaching the water column and submerged plants. Water hyacinth is native to South America, and was introduced to the United States in the 1880s. It probably originated in the swamps associated with the great river systems of northern and central South America. Water hyacinth has not yet (1998) been found in the wild in Washington State, but has been sold as an ornamental in plant nurseries. Its use as an ornamental means that it could be introduced to our lakes and rivers, and this is expected to be its primary method of spread. Water hyacinth can be controlled by harvesting, aquatic herbicides, and biological control agents. Locally, the best way to manage water hyacinth is to prevent it from becoming established. Plants purchased at local nurseries should be disposed of away from waterbodies. Mechanical Control: Swamp Devil & Harvester The Swamp Devil is a heavy duty aquatic vegetation cutter that features tow blades at the front which measure 2.4 meters across. It had a 234 horsepower engine and can easily shred trees up to 15 cm in diameter. It will be collecting and removing a portion of the chopped debris. The harvester has the ability to carry four tons of vegetation on board in a single load. Depending on the weight and volume of the vegetation and the distance to the shore, the harvester can potentially remove 16 to 32 loads of chopped hyacinths in eight hours. Boiled water hyacinth is used in Southeast Asia as a feed for pigs. The plants are chopped and sometimes mixed with other vegetable wastes, such as banana stems, and boiled slowly for a few hours until the ingredients turn into a paste, to which oil cake, rice bran and sometimes maize and salt are added. The cooked mixture is good for only three days, after which it turns sour. A common formula is 40 kg of water hyacinth, 15 kg of rice bran, 2.5 kg of fish meal and 5 kg of coconut meal.