Using Migratory and Sex Pheromones to Manipulate Sea Lamprey Dr

Great Lakes Fishery Commission F RUM FOR STEW ARDSHIP AND SUST AINED BENEFITS Fall 2000

Using Migratory and Sex Pheromones to Manipulate Sea Lamprey Dr. Peter Sorensen and Dr. Weiming Li have embarked on a course of study that could one day change the way sea lampreys are controlled in the Great Lakes.

Dr. Sorensen, who is with the University of Minnesota, and Dr. Weiming Li, who is now with Michigan State University, have embarked Photo: Weiming Li Weiming Photo: on a course of study that could one day change the way sea lampreys are controlled in the Great Lakes. Their work could provide the Great by Heather Glock Lakes Fishery Commission and its agents with VER A DECADE AGO, as a young the tools to move away from lampricides and assistant professor, Dr. Peter toward an alternative control technique that Sorensen opened a journal article uses pheromones to redirect lamprey movement Dr. Li’s two-choice maze used to examine and noted that the nose of a sea lam- and behavior to both increase captures and pre- the behavioral responses of adult sea lamprey Oprey is bigger than its brain. To most people, vent successful sea lamprey spawning. to pheromones (top). The above figure illustrates the design of the device. that fact would be merely curious. To Dr. Sorensen and his former Ph.D. student, Reducing Lampricides Weiming Li—two scientists devoted to study- Any person who has fished the Great Lakes ing the sense of smell in fish—that observa- knows that the exotic sea lamprey is more than tion suggested that lamprey heavily rely on just a pest, it is devastating to a fishery valued water-borne odors for such things as finding at billions of dollars and it has dramatically host fish, spawning streams, and ultimately changed the nature of the fish community. For- mates. Drs. Sorensen and Li found that olfac- tunately, biologists have been successful in driv- tory cues, or odors, can be powerful in deter- ing down sea lamprey populations in the Great mining sea lamprey behavior and thus can be Lakes. Primarily through the use of the lampri- exploited for use in lamprey control. They cide TFM, and with the help of other tech- reasoned that if this species utilized phero- niques such as traps, barriers, and the sterile- mones (specific and potent chemical signals male-release-technique, lamprey populations that pass between members of the same spe- have been reduced by 90%. cies), these cues might be identified, synthe- Despite the success of TFM, the commission sized, and released into rivers to manipulate is reducing its use by half, largely because TFM lamprey behavior. PHEROMONES, CONTINUED ON PAGE 6

From the Chair… Pere Marquette Barrier on the “Vampire Hunter” Where Have All 2 GLFC and Corps of 3Cutting Edge of Technology 5 by Heather Glock 8 the Males Gone? Engineers Collaborate on by Ellie Koon and and Marc Gaden by Randy Eshenroder Great Lakes Fisheries John Schrouder Protecting Mudpuppies, and Ann Krause by Bernie Hansen Lake Champlain Grapples 7 Protecting Stream 4with Its Own Sea Lamprey Ecosystems INSERT: Problem by Gavin Christie GLFC Seeks Nominations by J.E. Marsden, et. al. The U.S. Army Corps of Engineers houses a major sea lamprey trap at the Soo Locks in Sault Ste. Marie, MI. lampreys from reaching their spawning grounds while still allowing other fish to migrate upstream. Once a barrier is built in a sea lamprey-producing stream, it is no longer necessary to treat upstream of the barrier with lampricides. Traditionally, the commission has designed the barriers and contracted the construction to others. Now, thanks to new legislation passed in 1999 (The Water Resources Development Act), the Corps will partner with the commission to design and construct those barriers. The advantages of this partnership are enormous. Not only does this legislation help the commission leverage funds, but it also GLFC and Corps of allows us to draw upon the Corps’ considerable expertise in barrier construction. Engineers Collaborate The Corps’ partnership with the commission has also been on Fisheries pivotal to the control of sea lampreys in the St. Marys River, a From major challenge for the commission. Until very recently, the the hair... Bernie Hansen St. Marys River produced more sea lampreys than all of the C Great Lakes combined. Two major elements of control on the St. Marys River are traps and the sterile-male-release-technique. When you think of the Army Corps of Engineers, the Soo Locks, Sea lamprey traps can remove spawning sea lampreys from the dredging, or shipping canals usually come to mind. Indeed, the system and serve as a source of males for the sterile-male-re- Corps has a long and successful history of aiding navigation in lease-technique. Permanent traps constructed by the Corps and the Great Lakes region. What is perhaps less known is the Corps’ located at the Corps’ facility at the locks provide the commis- involvement in protecting the Great Lakes fishery, an activity sion with thousands of sea lampreys for use in the successful that has been strengthened through a partnership with the Great sterile-male-release-technique. Lakes Fishery Commission. It is the Corps’ expertise in such The Great Lakes Fishery Commission is pleased to partner areas as barrier construction and trap design that the commis- with the Corps on critical fisheries protection projects in the sion finds most valuable, as it strives to realize its goal to reduce Great Lakes region. With the Corps’ help, we can improve sea the use of lampricides. lamprey control, reduce lampricides, and facilitate the passage Sea lamprey barriers are a tested and true method to control of desirable spawning fish in our tributaries, all with the goal of sea lampreys in the Great Lakes. Low-head barriers prevent sea protecting our resources long into the future. ≈

Commission Honors Doug Dodge Upon His Retirement Krueger Joins During the GLFC’s 2000 annual GLFC Secretariat meeting in Duluth, Dr. Doug Dodge was honored for 30 years of exemplary The GLFC welcomed Dr. Charles Krueger to the secretariat in service to the Great Lakes. His out- September, 2000. Dr. Krueger, former GLFC chairman and pro- standing contributions on behalf of fessor of fisheries at Cornell University, became the new Great Lakes fish and fish habitat are senior scientist, replacing Randy Eshenroder, who retired commendable. During his career in earlier this year. As senior scientist, Dr. Krueger will be government service at the Ontario responsible for coordinating Great Lakes fisheries research, in Ministry of Natural Resources, he was accordance with the Convention on Great Lakes Fisheries. Dr. a longtime member of the IJC’s Water Krueger will retain an adjunct appointment at Cornell Univer- Quality Board where he ensured the sity and a term appointment at Michigan State University. “Dr. Doug Dodge (left) receives a certificate quality of water for Great Lakes’ spe- Krueger is a world-class research scientist,” said GLFC chair- of recognition from commissioner cies. Dr. Dodge was also a member Burton Ayles. man Bernie Hansen. “Krueger has a long history of dedicated and chairman of the Habitat Advi- work to the Great Lakes fishery and to the commission. We are sory Board for the commission. His earnest interest in fish and fortunate to have him on board.” ≈ their habitat, combined with his dedication, has left a lasting legacy that will be valued by future generations. The commission wishes him the best in his retirement. ≈ 2 VER FORTY YEARS AGO, on Michigan’s Pere Marquette River, biologists experi- Omented with their first attempts to control the sea lamprey. Back then, sea lamprey experts had few tools to control the destructive pest, relying mostly on crude AC electrical barriers to prevent lampreys from ere arquette reaching their spawning grounds. Al- P M though the old AC electrical barriers blocked sea lampreys, they also blocked the Sea Lamprey Barrier upstream migration of desirable fish, zapped wildlife, and shorted-out frequently. It did on the Cutting Edge of Technology not take long for biologists to abandon the Pere Marquette’s first electrical barrier and opt instead for a control effort that used By Ellie Koon and John Schrouder the lampricide TFM. Today, the U.S. Fish and Wildlife Service and the State of Michigan are testing a new A new high-tech sea lamprey barrier on the Pere Marquette and improved DC electrical sea lamprey uses electricity to repel sea lampreys and a fish passage device to pass desirable fish while trapping lampreys. The barrier on the Pere Marquette River (PM). barrier does not block the flow of the stream.

The new barrier uses state-of-the-art Photos: USFWS technology to block upstream migration of sea lampreys while attracting desirable around the electrical current. The pas- fish into a fishway, while not impound- sageway is designed to allow desirable fish ing water or blocking the flow of the river. to leap over a series of false weirs to get The new barrier went into operation in upstream while capturing sea lamprey. early 2000 and has worked successfully The revised design of the PM barrier throughout the year. All indications are is the first time that the U.S. Fish and that this new barrier design will represent Wildlife Service has used a combination the future of sea lamprey barriers in the of an electrical barrier and a pumped pas- Great Lakes. sageway in the Great Lakes to get fish around the barrier. Observations con- The Pere Marquette: A Very firmed that the new barrier design is Productive Sea Lamprey Stream Learning From the Past to successful. The barrier denied lampreys The PM is one of the Great Lakes’ most Improve Our Future upstream migration while allowing steel- productive sea lamprey streams, and with- The first electrical barrier method used head and other desirable fish to enter the out sea lamprey control, it would produce to control sea lampreys on the PM was fishway and successfully pass to spawn- tens of thousands of sea lampreys annu- costly and ineffective because of inad- ing grounds upstream. Researchers at ally. Clearly, sea lamprey control on the equate design. The new electrical barrier Michigan State University are conducting PM is a top priority if we want to protect design applies lessons learned from the further evaluations of the effectiveness of our fishery. The PM is also one of past by allowing fish to get around the the barrier. Their evaluation will serve as Michigan’s most popular streams for anglers barrier, while blocking the destructive a means to formulate modifications to the and recreational users, so a primary goal sea lamprey. barrier to make it even more effective in for biologists is to make sea lamprey con- The new barrier on the PM is built passing sport fish upstream. trol as unobtrusive as possible. into the streambed of the river and as a Sea lamprey experts have been battling Barriers in use today prevent sea lam- result does not block the natural flow of the pest for more than forty years and will preys from accessing reproductive habitat the stream or impound water. The barrier continue to pursue alternative control in Great Lakes tributaries at a fraction of has a grid on the stream bottom with an techniques. Barriers, such as the one on the the cost of a typical lampricide treatment. increasing electrical field that works by PM, are a step in the right direction. Some A top priority is to stop lampreys while not repelling lampreys and fish, not zapping sea lampreys may spawn below the barrier, blocking the passage of other fish. To reduce them as with the old AC electrical barrier. but the reduced numbers of lamprey makes the impacts on fish passage, sea lamprey It is augmented with a state-of-the-art fish it easier and far less expensive to deal with ≈ control agents have invested in the design passage device that contains a pump to the PM’s lamprey problem. and operation of a new DC electrical bar- create an attractant stream. The fish re- Ellie Koon is the barrier coordinator for the U.S. Fish & Wildlife Service. John Schrouder is the fish- rier on the PM that operates only during main blocked by the electrical current eries field coordinator for the Michigan Dept. of the spring lamprey migration. until they find the fish passageway to get Natural Resources. 3 Atlantic Ocean➚ Richelieu R. Chambly Canal OUR COMMON NEMESIS St. Lawrence R. LAKE Lake Champlain Grapples CHAMPLAIN LAKE with Its Own HURON LAKE ONTARIO Champlain Canal Mohawk R. Sea Lamprey Problem Welland Erie Canal Canal Abstracted from a forthcoming article entitled “Sea Lamprey Control in Lake Champlain” Hudson R. by J. E. Marsden, J. K. Anderson, W. Bouffard, LAKE ERIE B. D. Chipman, L. E. Durfey, J. E. Gersmehl,

L. J. Nashett, W. F. Schoch, N. R. Staats, and Atlantic Ocean➚ A. Zerrenner Sea Lampreys in Lake Champlain lamprey are native to Lake Champlain, Today, Lake Champlain is at a Lake Champlain is a long, narrow lake that based largely on the absence of effective lies between New York and Vermont, barriers to block their migration into the crossroads: after an experimental extending northward into Quebec. The lake. Most conclude, however, that sea effort to control sea lampreys, lake has a surface area of 1,127 km2, about lampreys invaded the lake more recently and through a close relationship the same as Lake St. Clair. Lake either from the Hudson River via the Champlain contains a diverse fish com- Champlain Canal, opened in 1823, or with lamprey control specialists in munity, similar to that of the Great Lakes, from the Richelieu River via the Chambly the Great Lakes region, biologists which includes lake trout, Atlantic Canal, opened in 1843. By 1929 there was in Lake Champlain now have the salmon, rainbow trout, brown trout, lake no doubt—sea lampreys were reported to whitefish, yellow perch, walleye, bass, and be moderately common. opportunity to formulate an sturgeon. Like the Great Lakes, Lake integrated pest management Champlain supports a thriving sport fish- Improving the Lake Champlain Fishery ery; unlike the Great Lakes, there is no Joint efforts to improve fisheries in Lake program that suppresses sea traditional commercial fishery on the lake. Champlain began in 1973 with the for- lampreys while protecting the Unfortunately, Lake Champlain and mation of the Lake Champlain Fish fishery now and for the future. the Great Lakes share another member and Wildlife Management Cooperative, of the fish community: the sea lamprey. composed of the U.S. Fish and Wildlife As in the Great Lakes, sea lampreys and Service, Vermont Department of Fish and

ENEATH THE PICTURESQUE WATERS other problems have stressed the fish Wildlife, and the New York State Depart- of Lake Champlain lurks the community and reduced sport-fishing ment of Environmental Conservation. sea lamprey, a notorious benefits. In Lake Champlain, the These agencies have worked diligently to predator the people of the presence of sea lampreys substantially sustain and rehabilitate the aquatic eco- Great Lakes know all too well. The sea inhibited efforts to rebuild salmonid system in Lake Champlain. The long-term B populations and fisheries that had been goals of this cooperative effort includes lamprey, the Great Lakes’ most noxious pest, has a lengthy and equally horrendous extirpated by overfishing, the construc- habitat restoration, stocking, and sea reputation in Lake Champlain as the exotic tion of mill dams on spawning tributar- lamprey control. nuisance limiting the health of an other- ies, and environmental degredation in the Sea lamprey control on Lake Champlain wise vibrant fishery. 1800s. For example, in the worst hit areas, —though critical to the success of the 87-100% of the fish surveyed exhibited fishery—so far has been strictly experi- sea lamprey wounds. To make matters mental. In 1990, the Lake Champlain Wayne Bouffard, worse, Lake Champlain, despite its small Management Cooperative initiated an a biological size, has an inordinately large number of eight-year program of sea lamprey control technician with the U.S. Fish and tributaries (over 100 permanent streams), based on the use of the lampricides TFM Wildlife Service, creating ample habitat for a constant bar- and granular Bayluscide, though the ef- measures sea rage of sea lampreys into the lake. Because fectiveness of alternative techniques— lampreys in Lake a high potential for sea lamprey produc- including barriers and traps—was also Champlain to assess tion is concentrated in a small volume of considered. This first round of sea lamprey the status of the spawning water, sea lampreys can easily overwhelm control concluded in 1997 and future sea population. the fish in Lake Champlain. lamprey control efforts will depend on the Photo: USFWS The origin of sea lampreys in Lake results of a program evaluation and the Champlain has long been a topic of de- preparation of an Environmental Impact bate. Some researchers suggest that sea Statement. 4 One thing is clear, the experimental program of sea lamprey control on Lake “Vampire Hunter” Champlain was successful. Spawning-phase sea lampreys declined by 80–90% from Pursues Sea Lampreys 1989–1997, estimated angler catch of lake trout increased by 76%, and returns of in the Great Lakes Atlantic salmon to tributaries increased The sea lamprey — the Great significantly. All told, sea lamprey control Lakes’ most notorious vampire — facilitated a 3-fold increase in economic will be featured alongside other returns to the Lake Champlain sport fishery. bloodsuckers including leeches, The Future of Sea Lamprey Control mosquitoes, ticks, and vampire Biologists from the Great Lakes and Lake finches in a Discovery Channel Champlain have a long history of coop- documentary to be aired this fall. eration on lamprey issues. Lessons from the successful sea lamprey control program on the Great Lakes suggest that Lake Champlain would benefit from an integrated effort that uses lampricides and non-chemical control techniques. Lam- Nigel Marven (left), cameraman Gavin Thurston, and producer Colin Collis film a nighttime scene on the Trout River. pricides have proven effective in Lake Champlain with minimal impact on non- by Heather Glock and Marc Gaden target species. Managers in Lake ILM PRODUCER Nigel Marven is no has been severe,” said Marven. Lampreys Champlain are also taking a look at the stranger to the world’s fierce crea- have had a devastating impact on fish alternative techniques that have worked Ftures. As the star in wildlife television populations since they were accidentally so well in the Great Lakes. Sea lamprey features around the globe, Marven has introduced into the Great Lakes through barriers that allow passage of migrating found himself face-to-face with grizzly shipping canals in the early 20th century. fish may be useful on some streams, and bears, skulking with komodo dragons, Considering the film crew needed to in a few small streams, trapping may provide wrapped in anacondas, and swimming shoot approximately 40 minutes of film for adequate control. Research into the use of (uncaged!) with sharks. And when he every minute used in the final produc- pheromones as attractors for spawning sea searched the world to produce a Discovery tion, they spent a significant amount of lamprey could be conducted on a number of Channel program about blood sucking time filming the lampreys and learning small tributaries in the basin. Application animals, the Great Lakes’ sea lamprey was about the sea lamprey control program. of other techniques such as sterile-male- a natural. The blood feeding sea lamprey will be release will be considered if future research In late May, Marven and his film crew included in a show on the Discovery demonstrates their efficacy. traveled from the United Kingdom to Channel entitled “Bloodsuckers, with The Great Lakes sea lamprey control Rogers City, MI and Sault Ste. Marie, Nigel Marven.” It will be broadcast this program benefits from the work in Lake Ontario to film the sea lamprey portion fall in the U.S. The date to air in Canada Champlain as well. Many sea lamprey- of this television feature. “I became in- is yet to be announced. The show prom- laden streams in the Lake Champlain terested in this story not only because ises spectacular travel sequences and fas- basin have never been treated to remove lampreys have a ‘face for television’ but cinating encounters with blood feeding lamprey larvae. Research funded by the also because their impact on the environ- creatures, so be sure to tune in. You don’t Great Lakes Fishery Commission is allow- ment and the people of the Great Lakes want to miss it! ≈ ing biologists to acquire critical information about changes in sea lamprey growth Nigel Marven (right) and his crew film sea lamprey spawning nests in the Trout River and age at maturation in these streams near Rogers City, MI (below). The crew observes the impact that a parasitic sea lamprey has on lake trout and whitefish after the lamprey has fed on its blood (right).

before and after a first treatment. Very Photos: GLFC little such research was carried out prior to and after the first sea lamprey treatment in the Great Lakes region. Lake Champlain and the Great Lakes have much in common. The high level of cooperation that exists between managers in both regions has been and will continue to be instrumental in the protection of valuable fish communities. ≈ The authors are affiliated with federal, state, and academic institutions interested in the health of the Lake Champlain fishery. 5 PHEROMONES, CONTINUED …it is not far-fetched is expensive and because any sound pest to think about using management program uses several techniques together to achieve its goals. To these pheromones add to the lampricide reduction challenge, in spawning streams a cut in TFM must not result in a reduction in sea lamprey control. to disrupt the Today, Drs. Sorensen and Li are on the natural chemical

cutting edge of sea lamprey control and Photo: GLFC fish pheromone research. Through their Dr. Peter Sorensen (middle) and student researchers Jared Fine (left) and communications among respective research, they have zeroed in Lance Vrieze of the University of Minnesota, explore the role of migratory spawning individuals. on a handful of naturally occurring phero- pheromones on sea lamprey behavior. mones which they believe are a key to Two key elements of the pheromone sexually mature males emitted an odor the lamprey spawning cycle. have been identified, synthesized, and that induced mature females to heighten Studies of the sea lamprey sense of measured in river waters. They are unique their search for a mate. The searching smell have clearly demonstrated that adult bile acids produced only by lamprey and activities ultimately led the females to the lampreys, like many migratory fish, rely are detected by the lamprey olfactory source of the odorant, the mature males. on water-borne pheromones to locate system at minute concentrations. The “The odor emitted by the sexually spawning streams. Sorensen and Li have search is now on to identify an additional mature male is indeed a pheromone that identified two types of cues: a migratory unknown component of this cue. Field modifies the behavior of adult females,” attractant released by larvae and a sex trials are planned to explore how phero- said Dr. Li. “These results indicate that pheromone released by mature males. mone additions to streams might be the male sex pheromone could be used Sorensen and his colleagues have revealed instituted most effectively. to influence the behavior of adult females that the larval pheromone is so important “Odors appear to be almost everything to in their natural habitat. We believe this to the life of lamprey that if the nostrils migrating sea lamprey,” said Dr. Sorensen. knowledge could be a potent tool in the of migratory adults are blocked, they fail “In fact, their reliance on this sensory lamprey control arsenal.” to find spawning streams. Similarly, the system may be one of the greatest among sex pheromone appears to be quite potent the fishes and this can be exploited to our The Future in attracting mature females. Thus, these advantage.” Adult sea lampreys depend on “The potential use of the current phero- naturally occurring cues could be used to their keen sense of smell to locate and then mone research is exciting,” said Commis- lure lamprey into traps or into streams that migrate up spawning streams. “The lam- sioner Roy Stein of Ohio State University. are not suitable for reproduction. This prey is guided by trace amounts of unique, “The Great Lakes Fishery Commission sees would supply more males for the sterile- environmentally safe pheromones which tremendous opportunity to manipulate sea male-release program and reduce the need we should be able to synthesize and add lampreys during their spawning phase. to treat rivers with TFM. into streams. Pheromones are a new tool Right now, it is not far-fetched to think “Pheromones could be the future for with which to exploit an important dimen- about using these pheromones in spawning sea lamprey control,” said Dr. Chris sion of this species’ biology,” he added. streams to disrupt the natural chemical Goddard, Executive Secretary of the communications among spawning indi- Great Lakes Fishery Commission. “We Dr. Li: Discovering Adult Male viduals. We could use lamprey attractants are so confident in the work of Drs. Sex Attractants to trick them into spawning in areas that Sorensen and Li that the commission Dr. Weiming Li has focused his research are not optimal for their reproduction. wholeheartedly supports their research.” on another attractant: a pheromone We could use these attractants to lure secreted by adult male sea lampreys to lampreys into traps.” Dr. Sorensen: Identifying attract spawning females. Sexually mature Stein continued: “Above all, the work Larval-Emitted Pheromones female sea lampreys are strongly attracted of Drs. Sorensen and Li may one day allow Through the support of the Great Lakes to the potent odor secreted by male sea the commission to significantly reduce the Fishery Commission, Dr. Sorensen and his lampreys. Dr. Li set out to identify that use of lampricides while still maintaining students have made great advances during attractant so that it could one day be syn- effective sea lamprey control. More than a the past ten years in understanding how thesized and used as another tool to decade ago, we set out under our Strategic adult sea lampreys use migratory phero- manipulate sea lamprey behavior. Dr. Li Vision for the Decade of the 1990s to reduce mones secreted by larval sea lampreys to serves as a Partnership for Ecosystem lampricide by 50%. Careful application of locate rivers and streams for spawning. Their Research and Management (PERM) sci- migratory and sex pheromones may be- research has led to a fundamental under- entist at Michigan State University, a pro- come a valuable and environmentally standing of the lamprey migratory gram partially funded by the Great Lakes friendly tool in the integrated management pheromone, the identity of its principal Fishery Commission. of sea lamprey. We are excited about what components, and the knowledge of how the During Dr. Li’s research trials—carried the future holds.” ≈ pheromone affects sea lamprey behavior. out using a two-choice maze design— Heather Glock is an intern at the GLFC. 6 Protecting Mudpuppies, Protecting Stream Ecosystems

By Gavin Christie

HE HEALTH OF FISH COMMUNITIES in that larval stage that sea lampreys are United States. Nevertheless, concern the Great Lakes depends on the vulnerable to the lampricide TFM. As about this sensitive species has focussed success of sea lamprey control. larval sea lampreys take several years to the effort of sea lamprey control biolo- But that success cannot come at mature in a stream, the stream only needs gists and researchers. Tthe expense of the health of the streams to be treated about once every 3-6 years. Recent research by the GLFC, carried and rivers entering the lakes. Therefore, The key to a successful TFM applica- out at the USGS Upper Midwest Envi- sea lamprey control agents make every tion is to apply the lampricide at exactly ronmental Sciences Center, has shown effort to protect even the most sensitive of the concentration necessary to kill larval that by carefully monitoring stream creatures during sea lamprey treatments. sea lampreys while not affecting other water chemistry, precise dosages of TFM Among the most mysterious and fas- organisms. Prior to and during each TFM can be applied to streams that can sig- cinating creatures inhabiting the Great application, sea lamprey control agents nificantly reduce mortality of sensitive Lakes and their tributaries is the mud- conduct a thorough assessment of the species. Scientists were able to carry out puppy (Necturus maculosus). This primitive water chemistry and amphibian is the largest species of sala- flow in a river to deter- mander living in the region, growing to mine just how much By about a foot (25-30 cm) long. During the TFM should be used to protecting day, they hide under rocks or in weeds. At maximize sea lamprey this sensitive night they feed on crayfish, worms, small removal and minimize fish, and insects. Unlike other amphib- or eliminate non-target animal, ians, the mudpuppy spends its entire life mortality. This work biologists in the water without metamorphosing to ensures that non-target protect live on land. mortality is very small, In the Great Lakes region, studies are with only a few of the the entire underway to monitor the status of weakest individuals of stream The GLFC is implementing methods to protect mudpuppies amphibians, including the mudpuppy. any species being af- ecosystem. during sea lamprey control. Photo: Michael Oldham, OMNR While there is very little direct informa- fected. This work is tion about the status of the mudpuppy, painstaking but critical they are widely observed around the to the success of the treatment and to the laboratory studies that defined new lower Great Lakes. Mudpuppies are often found protection of non-target species in the river. concentrations of TFM that would not in streams where sea lamprey larvae are The results of sea lamprey control have harm mudpuppies, but would still kill sea found, which puts them into contact with been astounding. Agents have been able to lamprey larvae. This new application sea lamprey control efforts, particularly reduce sea lamprey populations by 90% in protocol has been used successfully dur- stream treatments and the lampricide the Great Lakes, facilitating healthy fish ing the treatment of the Conneaut River, TFM. While most species of fish and communities free from the terrible dam- a tributary to Lake Erie, this past summer animals are not sensitive to TFM at the age caused by sea lampreys. This success where post-treatment surveys showed mini- concentrations applied to streams, the has allowed agencies to undertake fisher- mal impact on mudpuppies. Continuing primitive mudpuppy is more sensitive ies rehabilitation and to stock fish with research into the effects of lampricides than most. This sensitivity means that sea confidence knowing that fish will live to will lead to even more improvements in lamprey control agents must take special reproduce or to be harvested by humans. how sea lamprey control is carried out. precautions to ensure that TFM causes This success has happened with almost Sea lamprey control in the Great Lakes minimal impact on mudpuppies, while no impact on non-target organisms. is one of our region’s great success stories, still killing the maximum number of sea reversing a major insult to Great Lakes eco- lampreys in a stream. By protecting this Mudpuppies and TFM systems and the valuable fisheries they sup- sensitive animal, biologists protect the The mudpuppy has a special relationship port. Steadfast respect for species like the entire stream ecosystem. with the sea lamprey control effort, and mudpuppy and continued research into its interaction with TFM illustrates the minimizing non-target mortality will en- TFM: A Selective Lampricide commitment to non-target-mortality sure that the success of the sea lamprey Sea lampreys live for many years in Great reduction. Mudpuppies remain widely control program is realized by everyone Lakes streams as larvae before they trans- distributed and are not listed as endan- who values a healthy environment. ≈ form into parasitic adults and migrate to gered or threatened; they do not have Gavin Christie is the sea lamprey program the open waters to prey on fish. It is during special status in either Canada or the manager for the GLFC. 7 males. At the end of a cycle, weak recruitment means that few fish of either sex are available to replace those adults that are taken in fisheries, eaten by predators, or die of natural causes. The adult population is then dependent on fish with advanced ages, and females, living longer than males, then become the dominant sex. Recruitment improves eventually, sometimes markedly, and the cycle begins anew. This explanation is in- sightful but it does not account for why males do not live as Tom Todd of the long as females and why recruitment is suppressed in the first USGS Great Lakes place. These questions remain to be answered. Science Center The consequences of bloater femaleness are becoming bet- identifies ciscoes. ter recognized. When recruitment slacks off, fewer juvenile bloaters are available to top predators like trout and salmon. If other forage species are not abundant enough to replace bloaters in top-predator diets, growth and survival of top predators may decline. This scenario played out in Lake Michigan in the early 1990s and may have aggravated an already shortened forage Where have all supply that occurred at that time. The consequences of femaleness are different for commercial the males gone? fisheries than for top predators because commercial fisheries unlike top predators target adult rather than juvenile bloaters. By Randy Eshenroder and Ann Krause Commercial fishing may actually improve when bloater recruitment initially declines because the remaining adults grow faster Photos: GLFC making a larger proportion of the adult population marketable. Too much fishing at this time, however, can deplete the spawn- HAT CAUSES a disproportionate number of ing population before recruitment has a chance to kick-in. females in some Great Lakes fishes and what Recent research suggests that this scenario—intensive fishing— are some of the consequences of unbalanced played out in Lake Huron in the late 1950s causing a popula- sex ratios? Femaleness, sex ratios tilted towards tion collapse. Wmore females and fewer males, can be extreme in an important Femaleness in bloaters presents challenges for fishery man- Great Lakes fish—the bloater. This species, one of three sur- agers. Changes in management such as in the number of top viving deepwater ciscoes marketed as chubs, occurs in all three predators stocked or in the allowable catch can have big effects of the upper Great Lakes and is also being considered for rein- on fisheries. Yet, the life cycle of the bloater, and for other ciscoes troduction in Lake Ontario. as well, requires flexible, responsive management for sustained Femaleness as high as 90% has been observed in bloater popu- benefits. Biologists can now better predict cycles of femaleness. lations from Lakes Michigan and Huron. Researchers have Whether they can get the needed changes implemented remains concluded that such bouts of femaleness are cyclical and are to be determined. ≈ associated with two factors: reductions in the supply of recruits Randy Eshenroder is the former senior scientist at the GLFC. to the spawning population and shortened life spans of adult Ann Krause is a research associate.

GREAT LAKES FISHERY COMMISSION 2100 Commonwealth Blvd., Suite 209, Ann Arbor, MI 48105-1563 Phone: 734/662-3209 FTS: 734/741-2077 FAX: 734/741-2010 NON-PROFIT ORG. The Great Lakes Fishery www.glfc.org U.S. POSTAGE Commission was P A I D established by convention PERMIT NO. 87 between Canada and the COMMISSIONERS F RUM ANN ARBOR, MI United States in 1955 to Burton Ayles (Can.) improve and perpetuate Bill Beamish, Vice-Chair (Can.) fishery resources. Joseph Day (U.S.) FORUM is published by Dave Dempsey, alternate (U.S.) The Great Lakes Fishery Bernie Hansen, Chair (U.S.) Ray Pierce (Can.) Commission. For a free Jamie Rappaport Clark (U.S.) subscription to FORUM, or to Roy Stein (U.S.) provide change of address FORUM EDITOR information, please Marc Gaden contact the commission FORUM ASSISTANT EDITOR at 734-662-3209. Heather Glock Printed on recycled paper