GREAT LAKES FISHERY COMMISSION Project Completion Report 1

Transcription

1 GREAT LAKES FISHERY COMMISSION 2014 Project Completion Report 1 Feasibility of holding wild-caught Lake Whitefish and Sea Lamprey for parasite-host interaction studies by: David Caroffino 2, Ted Treska 3, Roger Greil 4, Greg Fischer 5 2 Michigan Department of Natural Resources, 96 Grant Street, Charlevoix, MI U. S. Fish and Wildlife Service, 2661 Scott Tower Drive, New Franken, WI Lake Superior State University, 650 W. Easterday Avenue, Sault Ste. Marie, MI University of Wisconsin-Stevens Point, State Highway 13, PO Box 165 Bayfield, WI January Project completion reports of Commission-sponsored research are made available to the Commission s Cooperators in the interest of rapid dissemination of information that may be useful in Great Lakes fishery management, research, or administration. The reader should be aware that project completion reports have not been through a peer-review process and that sponsorship of the project by the Commission does not necessarily imply that the findings or conclusions are endorsed by the Commission. Do not cite findings without permission of the author.

2 CONTACT INFORMATION: Corresponding Author: David Caroffino, Michigan Department of Natural Resources, phone: x232 ABSTRACT: To assess damages due to sea lamprey (Petromyzon marinus), fisheries managers must be able to calculate lamprey induced mortality. A key parameter to those calculations is the probability that a fish species will survive an attack (P). This parameter has not been examined for whitefish in nearly 50 years, and recently rates of sea lamprey marking on lake whitefish have increased to a point where fishery quotas may be affected as a result of increased lamprey mortality. There are concerns that the P currently used for whitefish may be inaccurate, leading to biased estimates of lamprey-induced mortality. Consequently, there is a need to assess P for whitefish; however, hatchery whitefish are not readily available and it is unknown if wild whitefish can be brought into captivity to accurately assess this parameter. This pilot project sought to determine if transferring wild-caught lake whitefish into captivity was a viable method to support a future assessment of P in a larger-scale project. Whitefish were captured from commercial trap nets and recreational anglers and moved to aquaculture tanks at the University of Wisconsin-Stevens Point Northern Aquaculture Demonstration Facility (NADF) near Bayfield, WI, as well as to floating cages in the power canal near the Lake Superior State University Aquatic Research Laboratory (ARL) adjacent to the St. Marys River in Sault Ste. Marie, MI during 2012 and Due to various logistical hurdles, only 12 fish could be moved to NADF. Survival of fish caught while hook and line fishing through the ice was poor, but fish caught by trap nets survived 125 days. At the ARL, 101 fish were transferred while water temperatures ranged from 9.3 o C to 19.2 o C and the resulting survival ranged from 0 to 170 days. Parasitic sea lamprey were purchased from a commercial fisher and introduced into whitefish cages at various points during the study. Overall, lamprey attacked 37 whitefish at the ARL, and none of the whitefish survived the attacks. The survival rate observed (0%) indicates that whitefish likely have a low probability of surviving a lamprey attack, but we believe the rate observed here is biased low as many fish held at the ARL showed visible signs of stress, such as fin erosion and fungal growth. We offer recommendations on using wild and hatchery whitefish for lamprey interaction trials to assess the probability of survival. INTRODUCTION:

3 Since their invasion into the Great Lakes, sea lamprey (Petromyzon marinus) have caused substantial damage to fisheries resources and have thus attracted great interest from biologists who seek to understand and mitigate their impacts (Smith 1980; Christie and Goddard 2003). Lake trout (Salvelinus namaycush) have most often been the target of both damage assessments and research aimed at an understanding of lamprey-host interactions (see Stewart et al. 2003) as they seem to be a preferred target of lamprey in the Great Lakes. Lamprey attacks, their characteristics, and the ultimate fate of the host are near impossible to view in the wild, so a series of laboratory experiments have been conducted to collect the information necessary to evaluate the extent of the damages that lamprey could inflict upon lake trout (reviewed in Swink 2003). Lake whitefish (Coregonus clupeaformis) are native benthivores that economically serve as the most important commercial fish species in the Great Lakes. As with lake trout, they also suffer consequences from lamprey attacks, but these interactions have not been the subject of intense study. Observed marking rates in the wild have varied considerably across the lakes and fish communities. Substantial marking was observed in the 1960s when whitefish stocks were reduced (Smith 1972; Spangler and Collins 1980), but after control efforts reduced lamprey populations, marking rates on whitefish have been low in most areas of the upper Great Lakes. Currently, lamprey marking is at a level (< 1%) that it is considered inconsequential and incorporated into natural mortality in the 1836 Treaty waters of lakes Michigan and Superior (Modeling Subcommittee 2011). However, in northern Lake Huron, marking rates on whitefish are high, requiring sea lamprey-induced mortality to be estimated in addition to natural mortality during stock assessments (Ebener 2011). Raw marking rates for lake whitefish are collected through commercial fishery monitoring and fisheryindependent surveys throughout the year. The relationship between marking rates and actual mortality rates depends on the probability of the host surviving an attack (Bence et al. 2003). Although widely studied for lake trout, the probability that a whitefish will survive a sea lamprey attack has only been addressed in a single study. Spangler et al. (1980) tagged whitefish in the mid-1960s, evaluated fresh and healed lamprey wounds upon recapture, and used that data to estimate total marking rate and probability of surviving an attack. They reported that for the period of June through November survival was approximately 25%. This estimate was made during a time when lake whitefish populations were substantially different from today. As compared to the present, the whitefish population of the 1960s in Lake Huron was characterized by low abundance, fast growth, and early maturation. The disappearance of the primary prey Diporeia and increases in abundance have caused whitefish to experience slower growth and lower

4 condition in present lake conditions (Mohr and Ebener 2005; Ebener 2011). It is also likely that relationships that existed between lamprey and whitefish in 1960s do not hold true in the present conditions in Lake Huron. Although assumptions are inherent in nearly all estimation techniques, Bence et al. (2003) commented that two assumptions made by Spangler et al. (1980) may have confounded their estimate of survivability. First, it was assumed that fish did not die from fresh wounds prior to them being observed, and second, it was implied that attacks lasted for precisely one month (the length of their evaluation period). These assumptions likely did not hold true in all cases and Spangler et al. (1980) did not report variation around their estimate of 25% survivability of a lamprey attack. Lake whitefish populations in many areas of the Great Lakes are assessed using statistical catch-at-age (SCAA) models (Modeling Subcommittee 2011). These models are used to describe population characteristics and to set sustainable harvest levels and require adequate information to accurately estimate all mortality sources. To assess sea lamprey-induced mortality in Lake Huron, raw marking data is converted to mortality using the equation: M a = W a (1-P) / P, where W is mean wounds per fish for a given age class (a) and P is the probability that a whitefish survives an attack (Ebener et al. 2005). The value of P is held constant at 0.25 for all ages based the work of Spangler et al. (1980). If that value differs by 0.1 due to the size of fish attacked or other variables, the calculated mortality rates would differ by more than 50%, yielding a considerably different view of the modeled lake whitefish population and the sustainable harvest limit. It would be appropriate and important to estimate the probability of lake whitefish surviving attacks by sea lamprey in a controlled setting, similar to what has been done for lake trout; however, an obstacle to performing the necessary research is the inherent difficulty of keeping wild lake whitefish alive in captivity, which may be one reason why research similar to what has been conducted for lake trout has not been done for lake whitefish (R. Bergstedt, United States Geological Society, personal communication). Prior to developing and undertaking a project to address the dynamics of the sea lamprey and lake whitefish interactions, it must be determined if it is feasible to hold wild lake whitefish in a captive setting. OBJECTIVES: This project was completed as a pilot study to determine if holding wild-caught lake whitefish in captivity was feasible for a broader-scale project. Specifically we sought to: 1) determine the conditions under which lake

5 whitefish can survive transfer from the wild to captive holding, and 2) determine if and how sea lamprey and lake whitefish can be used under the conditions identified for parasite-host interaction experiments. Although we experienced some unexpected complications during this study, we learned a great deal from these transfer experiments. We had planned to conduct numerous whitefish transfers under varying conditions, but we found commercial fishermen less than accommodating on numerous occasions. In addition, the recreational fishery failed to produce the number of samples we had hoped to attain. These constraints impacted the total number of transfers we could complete, and the range of transfer temperatures we could evaluate. Despite these complications, we were able to successfully transfer wild lake whitefish and keep them alive in captivity; however, the fish exhibited signs of stress that did not improve with the duration of time they were held. Sea Lamprey could only be obtained at one of our study locations, but at that location we successfully transferred and held sea lamprey for an extended period of time. We were able to provide opportunities for sea lamprey to parasitize lake whitefish, although we believe the results of those interactions were compromised by the condition of the lake whitefish and should be viewed in the context of the broader results of this pilot study. METHODS: Locations.-This pilot project was conducted at two locations, the Lake Superior State University Aquatic Research Laboratory (ARL) and the University of Wisconsin Stevens Point Northern Aquaculture Demonstration Facility (NADF). The ARL is located in Sault Ste. Marie, MI in the east end of the Cloverland Electric Cooperative Hydro Plant (powerhouse). It is situated over the power canal that drains into the St. Marys River immediately southeast of the Sault Locks. Our work utilized floating mesh cages placed in the power canal, adjacent to the ARL, immediately upstream of the powerhouse. Whitefish and lamprey held near the ARL were subjected to natural conditions and pathogens and were not in a controlled setting, although they were shaded from sunlight by the powerhouse. Located near Bayfield, WI, NADF is a modern research and demonstration facility equipped with a variety of aquaculture systems capable of rearing a multitude of warm, cool, and coldwater fish species. NADF provided a controlled setting (water temperature, water quality, and feed options) for conducting fish transfer trials. Post-transfer survival was evaluated for lake whitefish and sea lamprey at both of these facilities to determine if either would be suitable for larger-scale research examining whitefish-lamprey interactions. Whitefish transfers.- Because both NADF and ARL are in the Lake Superior Basin, we were limited to using

6 lake whitefish caught in Lake Superior due to Viral Hemorrhagic Septicemia Virus regulations. We contacted four commercial trap-net fishing operations, two near the ARL and two near NADF. When arrangements could be made to purchase whitefish from commercial fishermen we followed them out to their nets and immediately moved live whitefish from the trap nets to transfer tanks. Fish destined for NADF were placed into 75-liter coolers filled with lake water. Those destined for the ARL were placed into an oxygenated and salted (1%) transfer tank (300 liters). In some cases with fish destined for the ARL it was logistically difficult to follow fishers out to their nets. When this occurred we met them at their dock and moved fish from their coolers containing lake water to the aerated and salted transfer tank to be moved back to the ARL. Once fish arrived at the ARL, we recorded the length and weight of each whitefish and inserted a uniquely numbered external tag. After high levels of mortality immediately following some transfers, the handling to measure length, weight, and place individuals tags was suspended to determine if it increased survival of held fish. These practices were suspended prior to fish being brought to NADF to limit handling stress on the fish, so individual markings and measurements did not occur for fish moved to NADF. Transfers were conducted between June and October of 2012 and 2013 to allow post-transfer survival to be monitored from fish captured at a range of temperatures. We also solicited lake whitefish from recreational fishers. Because it is illegal to sell recreationally caught fish, we asked for donations from local guides and fishers who have cooperated with projects in the past. In the St. Marys River, an open-water fishery typically occurs between May and August. Some whitefish were caught by recreational anglers adjacent to the powerhouse and ARL staff were immediately called to transfer the fish from the angler s landing net to the holding cages. Other whitefish caught by recreational anglers were held in boat livewells and then brought to the ARL by anglers and transferred to holding cages. There is a popular winter hook and line ice fishery near Bayfield, WI that typically occurs between December and March. Immediately after harvest, whitefish were placed in a 75 L cooler filled with fresh lake water and moved to NADF via snowmobile and hauling truck. Our intent was to evaluate post-transfer survival of summer-caught whitefish at ARL and winter-caught whitefish at NADF and compare results to those of whitefish caught in trap nets and transferred at similar temperatures. However, due to lower than expected angler effort, poor fishing, and the timing of fishing (e.g., weekends), this method proved difficult and an insufficient number of fish were captured to compare survival between these and commercially caught fish. Holding.- Upon arrival at the ARL whitefish were placed in 1.2m x 1.4m x 2.4m floating (12.7-mm mesh)

7 cages held in the power canal immediately upstream of the ARL. Fish were subjected to natural river conditions and were not given supplemental feed after offerings of formulated pellet feed were not consumed by the initial groups of fish transferred. Cages were monitored three times daily for temperature and number of live whitefish. Mortalities were removed as soon as they were observed. At NADF, whitefish were kept in either a 2.3m x 1m x 0.58m oval tank supplied with fresh, degassed, aerated well water with a flow of 18.9 L. min -1, or a 1,510 L circle tank. Salt was added directly into the tanks to maintain a salinity of 0.1%. Oxygen levels were maintained above 8 mg. L -1, and water temperature was relatively constant and averaged 8.1ºC. Fish were provided the opportunity to feed on reconstituted freeze dried krill, formulated fish feed (1.2 mm and 4.0 mm pellets), live earthworms, live lake herring fingerlings, and cut up pieces of lake herring. Lamprey.- We requested that the commercial fishermen from whom we were purchasing whitefish keep any lamprey that came onboard their vessels attached to other species. We offered to purchase any that they were able to catch, and we spread the word to other commercial fishers in Lake Huron, where the population of sea lamprey was known to be larger. After hearing that encounters with parasitic-form sea lamprey were rare in Lake Superior commercial fishing nets, we supplied a commercial fisher in Lake Huron with a small holding net (0.3m in diameter and 0.58 m in height). The fisher placed lamprey in a bucket of water on board his boat and then transferred them to the holding cage which was tied to his dock and suspended in Lake Huron. We picked up lamprey as needed and transferred them to the ARL in aerated coolers. Lamprey were placed into 1.2m x 1.4m x 2.4m floating cages at the ARL but held separately from the whitefish. Lamprey were fed a maintenance diet of white suckers (Catastomus commersonii) when they were not in trials with lake whitefish. Interactions.- In 2012 and during June of 2013 whitefish were held between two and sixteen weeks before they were introduced into a cage with lamprey. That protocol was changed in August 2013 when whitefish were introduced into a cage with lamprey after 24 hours of holding. In all cases, interactions between the species occurred in the floating mesh cages at the ARL. In most cases a single whitefish and lamprey were placed into the cages; however, in some circumstances multiple whitefish and multiple lamprey were placed into a cage. Cages were monitored three times daily and lamprey attacks recorded. If a lamprey attacked and then detached from a whitefish, that whitefish was placed into a separate holding cage and its survival monitored. Dead whitefish were replaced with live ones from another holding cage. RESULTS:

8 NADF- We were not able to easily obtain whitefish or lamprey for holding at NADF. We were unable to obtain any parasitic form lamprey from local commercial fishers, despite our offers of payment. We were told they rarely, if ever, observed lamprey onboard their vessels. We attempted to coordinate collection of lamprey transformers as they left their natal rivers and moved into Lake Superior, but those efforts did not produce lamprey. Coordination with commercial fishers for whitefish transfer was also difficult and the recreational fishing season was shortened due to poor ice cover during the winter of We made two transfers of fish to NADF, one from a commercial fisher and one from a recreational angler. Five whitefish were caught by hook and line in 26 m of water in February The fish had experienced mild barotrauma and two were vented, while three were not. They were held in a cooler on the ice and then transported back to NADF. All five fish were alive and gilling when placed into the holding tank, but within 24 h all fish were deceased. Seven whitefish were transferred 11 July 2013 from a commercial trap net set in 18 m of water with a surface temperature of 13.3 ºC. All seven fish survived the transfer and were still alive 125 days later when the project was terminated. During holding, there was no evidence that fish fed on any of the diet options offered, and their condition visibly worsened during the course of the study. At termination the fish were visibly thin and had lost color. ARL- Transfers of whitefish to cages at the ARL were conducted between 27 June 2012 and 1 October 2013 with a total of 101 whitefish transferred (Table 1). In 2012, 35% of the total number of whitefish transferred were dead within 24 h of placement in the cages, but in 2013 that proportion fell to 16%. Average number of days whitefish survived post-transfer was influenced by the removal of cages due to ice in 2012 and deaths due to lamprey in An insufficient number of samples prevented statistical analyses of survival differences between capture methods and water temperatures, as originally planned. Rather, what follows is a summary of the results of transfers made, difficulties faced, and decisions made during the course of this project at the ARL. Only 8 fish were obtained from recreational fishers in Six of the 8 lived between 21 and 48 days in the cages, where the two others lived for 122 and 170 days. Despite the duration of successful holding, the fish that survived in excess of 120 days were emaciated and in very poor condition upon death (Figure 1). It appeared that body condition gradually declined during the course the holding period. Because of communication difficulties, the whitefish transferred on 21 August 2012 were purchased at a commercial fisherman s dock, where the fish had been held in coolers for an unknown number of hours, rather than transferring fish directly from a trap net to transfer tanks. The condition of the fish at purchase was questionable and

9 the water temperature was 19.2 o C. All of these fish were dead within 24 h of placement in cages at the ARL. Unsuccessful attempts were made during September and October to coordinate transfers with this commercial fisherman. In late October, the second commercial fisherman we had contacted offered to sell fish and we were able to arrange for a transfer on 5 November The whitefish were brought directly from trap nets to shore and moved back to the ARL. Despite fin rot and clear signs of spawning stress (Figure 1), six of the 13 fish survived until the cages were removed for the winter on 14 December Sea lamprey were transferred to the ARL on two occasions in On 2 August 2012 lamprey were purchased from a fisherman in northern Lake Huron. He was instructed by a third party to place the lamprey in a cooler with ice water to aid in their survival during the transfer. This resulted in thermal stress as the St. Marys River was 21.7 o C on the day of transfer. Despite a prolonged acclimation period four of the five lamprey were dead within 48 h of transfer. The fifth lamprey survived 86 days and fed on white suckers Catostomus commersonii. A second transfer of lamprey occurred on 5 October We requested that the commercial fisher in northern Lake Huron use the lamprey holding bag we provided him and not place them in ice water. He complied with our request and six lamprey were transferred. Only one mortality occurred prior to their termination on 14 December 2012 when the cages were pulled for the winter. The lamprey fed on white suckers while in captivity until 12 November 2012, when the water temperature was 8.8 o C. The lamprey were not provided another opportunity to feed until 19 November 2012, when they were placed in cages with lake whitefish with a water temperature of 7.2 o C. The lamprey were left in cages with the whitefish until 14 December 2012, and only one lamprey attack occurred, but it was a B-type wound that did not break the skin of the whitefish. All of the whitefish purchased on 24 June 2013 survived the transfer and first four days of holding at the ARL, but between 5 and 14 days post-transfer, 8 fish died. We obtained sea lamprey on 2 July We placed four individual lamprey and whitefish together on 8 July 2013, when the water temperature was 18.6 o C. As a whitefish was attacked and killed by a lamprey, we replaced it with a new whitefish from the control cage. All whitefish placed into cages with lamprey were attacked within 24 hours and killed between 1 and 7 days after the attack. Once we began transferring fish to treatment cages with lamprey, no whitefish mortalities were observed in the control cages. The last whitefish was moved to a treatment cage with a lamprey on 25 July Within 24 hours of transferring whitefish on 16 August 2013, four mortalities were observed. We decided to hold whitefish for only 48 hours before beginning lamprey introductions. Nine whitefish were attacked by lamprey,

10 and all died within four days of the initial attack. The other 8 whitefish died in control cages between 4 and 36 days after transfer. The handling to measure length, weight, and mark individual fish was suspended for the transfer of 25 lake whitefish that occurred on 5 September The water temperature was equivalent (17 o C) to the transfer made on 16 August 2013, and fish came from the same fisherman. Despite not handling the fish, 9 died within 24 h of the transfer. After 48 h, lamprey were introduced into the cages and 14 of the 16 remaining lake whitefish were attacked by lamprey and all died within 24 h of an attack. The remaining two died in control cages within 14 days. Three whitefish were transferred from a recreational angler on 1 October They all survived the first 24 h of holding and were then placed in cages with lamprey. All three had been attacked and died within 24 h after the introduction of the lamprey. During the course of this study, lamprey attacked 37 whitefish with attacks lasting between 1 and 6 days. Most whitefish had a single A-type wound (Figure 2), but some had up to three attachment sites. None of the whitefish survived the attacks. The average total length of lake whitefish attacked by sea lamprey was 447 mm (range mm). DISCUSSION: We were able to transfer whitefish and keep a portion of those transferred alive for several weeks; however, this method of obtaining whitefish may not be ideal for parasite-host interactions studies at the facilities we used. At NADF, whitefish were held without visible signs of stress likely due to a constant, suitable temperature and salt treatments, but because they would not feed, their body condition declined with time. The whitefish held at the ARL showed signs of stress; 65% of those that survived at least 72 hours had some degree of fungal growth, fin erosion, or both. Temperatures at the ARL climbed above the optimal range for whitefish during summer (as high as 22 o C), and although more suitable temperatures existed in the fall, the stress of spawning season compounded the stress of confinement. We allowed sea lamprey to parasitize whitefish in cages at the ARL. If the probability of surviving a lamprey attack (P) is approximately 25%, as estimated by Spangler et al. (1980), we would have expected 9 whitefish to survive. Because mortality after attacks we observed was 100%, we believe whitefish have a low P; however, we do not offer a quantitative alternative to the Spangler et al. (1980) estimate of P. We believe the 37 interactions we observed were confounded by the stressed state of the whitefish and do not mimic natural conditions. If wild whitefish are to be used to address the question of P, based on the results of our pilot study, we recommend the following considerations. Transfers should be made with water temperatures less than 15 o C and to a

11 facility where temperature and water quality can be controlled and salt can be added to tanks to eliminate fungal growth. The facility should be located in an area with multiple trap-net fishermen, to increase the chances of reliable coordination of transfers. Interaction trials between whitefish and lamprey should begin after 48 h of holding whitefish, with the understanding that the longer fish are held, the worse their body condition will become, and the estimates of P may not mimic those of the wild. These conditions cannot be met at the ARL due to a lack of control over water temperature and the inability to salt the water in which the fish are held. NADF has the potential for use in a broader study; however, buy-in from commercial fishers would be required so a steady, reliable source of whitefish could be acquired. The largest hurdle for this facility is the ability to obtain lamprey. In the present pilot project we determined that we could not acquire lamprey from local commercial fishers at the NADF. We did not have the means to personally collect lamprey transformers from local rivers in the fall of 2012, although that could be an option for a future study. Alternatively, lamprey could be shipped to this facility from locations in Michigan. However, we found that importing sea lamprey into Wisconsin required disease certification, which would be difficult to obtain from wild sea lamprey. Although the question surrounding the present estimate of P is not easily addressed with wild fish, it is highly relevant and can be evaluated by other means. In Northern Lake Huron, lake whitefish recruitment has seen an overall declined since the late1990 s, as have whitefish stocks (Ebener 2012). Increased mortality from sea lamprey limits fishing opportunities. Commercial harvest in Northern Lake Huron exceeded the model calculated harvest limit in 2011 and 2012, and these modeled limits are directly influenced by the magnitude of sea lamprey mortality. Simulations suggest that if lamprey mortality were reduced by 50%, the fishing quota in Northern Lake Huron would double (M. Ebener, personal communication). A better understanding of the results of lamprey attacks on whitefish would provide more reliable assessments of whitefish populations and the resulting harvest quotas. Due to the potential for overharvest, steps may be taken to limit fishers when modeled limits are low; however, if the estimation technique for lamprey-induced mortality on whitefish is incorrect, the fishers could be restricted unnecessarily. Based on our experiences in this study, the option for assessing P that may provide the most reliable results is to mimic what was done for lake trout and use hatchery fish, reared in a captive environment. This will require a longer-term commitment of funds as fish will have to reach mm to represent the range of sizes that are present in the Lake Huron population. This type of rearing and research cannot be completed at the ARL due to space. NADF could be used in the future; however, it is also space limited due to other projects through at least The lack of

12 access to lamprey in Western Lake Superior is another challenge that would have to be overcome should this work be pursued at NADF. Depending on the type of aquaculture facility used for the research, it would require at least two years of support simply to rear fish to a beginning experimental size. Interactions could occur over a period of 3 years as the cohort of lake whitefish ages and grows. We believe evaluating survival at different whitefish size classes is important as has been shown in studies using lake trout and could provide the most useful results for assessing the impacts of sea lamprey on whitefish. This type of research is necessary given the conditions in Northern Lake Huron in the present day. It is unclear what the future may hold for other Great Lakes. Should lake wide ecosystem changes, such as those observed in Lake Huron, occur in other Great Lakes, the spatial extent of increased lamprey marking on whitefish could increase. In this case, uncertainties about population assessments would reach beyond Lake Huron. Given that whitefish represent 87% of the commercial fishery value in the Upper Great Lakes (MDNR, unpublished data), the ability to accurately assess populations and assign harvest quotas is imperative. We highly encourage further research examining the probability of whitefish surviving a lamprey attack. REFERENCES: Bence, J. R., R. A. Bergstedt, G. C. Christie, P. A. Cochran, M. P. Ebener, J. F. Koonce, M. A. Rutter, and W. D. Swink Sea lamprey (Petromyzon marinus) parasite-host interactions in the Great Lakes. Christie, G. C. and C. I. Goddard Sea lamprey international symposium (SLIS II): Advances in the integrated management of sea lamprey in the Great Lakes. Journal of Great Lakes Research 29(suppl 1):1-14. Ebener, M. P., J. R. Bence, K. Newman, and P. Schneeberger Application of statistical catch-at-age models to assess lake whitefish stocks in the 1836 treaty-ceded waters of the upper Great Lakes. Pages in L. C. Mohr and T. F. Nalepa, editors. Proceedings of a workshop on the dynamics of lake whitefish (Coregonus clupeaformis) and the amphipod Diporeia spp. in the Great Lakes. Great Lakes Fishery Commission, Technical Report 66, Ann Arbor, Michigan. Ebener, M Northern Huron (WFH-01 to WFH-04) in Caroffino, D.C., and Lenart, S.J., eds. Technical Fisheries Committee Administrative Report 2011: Status of Lake Trout and Lake Whitefish Populations in the 1836 Treaty-Ceded Waters of Lakes Superior, Huron and Michigan, with recommended yield and effort levels for 2011.

13 Ebener, M.P Status of whitefish and ciscoes. In The state of Lake Huron in Edited by S.C. Riley. Great Lakes Fish. Comm. Spec. Pub , pp29-35 Mohr, L., and M. Ebener Status of lake whitefish (Coregonus clupeaformis) in Lake Huron. Pages in L. C. Mohr and T. F. Nalepa, editors. Proceedings of a workshop on the dynamics of lake whitefish (Coregonus clupeaformis) and the amphipod Diporeia spp. in the Great Lakes. Great Lakes Fishery Commission, Technical Report 66, Ann Arbor, Michigan. Modeling Subcommittee, Technical Fisheries Committee Technical Fisheries Committee Administrative Report 2011: Status of Lake Trout and Lake Whitefish Populations in the 1836 Treaty-Ceded Waters of Lakes Superior, Huron and Michigan, with recommended yield and effort levels for Smith, B. R Introduction to the proceedings of the 1979 sea lamprey international symposium (SLIS). Canadian Journal of Fisheries and Aquatic Sciences 27: Spangler, G. R., and J. J. Collins Response of lake whitefish (Coregonus clupeaformis) to the control of sea lamprey (Petromyzon marinus) in Lake Huron. Canadian Journal of Fisheries and Aquatic Sciences 37: Spangler, G. R., D. S. Robson, and H. A. Regier Estimates of lamprey-induced mortality in whitefish, Coregonus clupeaformis. Canadian Journal of Fisheries and Aquatic Sciences 37: Stewart, T. J., J. R. Bence, R. A. Bergstedt, M. P. Ebener, F. Lupi, and M. A. Rutter Recommendations for assessing sea lamprey damages: toward optimizing the control program in the Great Lakes. Journal of Great Lakes Research 29 (suppl 1): Swink, W Host selection and lethality of attacks by sea lampreys (Petromyzon marinus) in laboratory studies. Journal of Great Lakes Research 29(suppl 1): ACKNOWLEDGEMENTS: This project would not have been possible without the financial support of the Great Lakes Fishery Commission Sea Lamprey Research Program, the numerous technicians who assisted both at the ARL and NADF, and the cooperation of staff at the Cloverland Electric Cooperative Hydro Plant. DELIVERABLES:

14 This final report is the main deliverable from this project. As outlined in this report, through the struggles we faced during this project, we believe we have better identified how this type of work would have to be done to provide useful results. Additional photos are available upon request. PRESS RELEASE: Whitefish make poor lab rats but good sea lamprey food Over the last decade, sea lamprey have been increasing their attacks on whitefish in Lake Huron. Biologists need to quantify the impacts of those attacks in order to manage the whitefish populations and the fishery that targets them. When a lamprey attacks and kills a whitefish in the wild, it cannot be observed. Scientists can only observe wounds on fish that actually survive an attack and were then caught either in the fishery or during an agency survey. Observing the attack process in a controlled setting would allow researchers to determine how likely a whitefish is of surviving an attack. Similar work has been done for other fish species, but data for whitefish are lacking. Before a robust study could be designed to observe the interactions between lamprey and whitefish, it had to be determined if whitefish could even be kept alive in captivity, as they have a reputation of being a sensitive species. Whitefish captured in commercial trap nets and those caught by recreational anglers were brought into a laboratory setting both at Lake Superior State University in Sault Ste. Marie, MI and the UWSP Northern Aquaculture Demonstration Facility near Bayfield, WI. Some whitefish did not survive the initial transfer, but researchers found that even those that did were in a stressed state. They wouldn t eat any food and their body condition slowly deteriorated. The project s lead investigator, Michigan Department of Natural Resources Fisheries Biologist Dave Caroffino commented on the challenges the team faced, we tried transferring fish under a variety of conditions, and they did better when the water was cool, but even then, they were stressed, which would compromise the integrity of a broader study seeking to determine how likely they would survive a lamprey attack. The results of using stressed fish in a lab simply wouldn t be comparable to what occurs in nature. Even though the fish were stressed the team wanted to know if lamprey would attack whitefish in captivity. They were able to observe 37 attacks of lamprey on whitefish and in each case, the whitefish did not survive. Caroffino continued, We didn t have a problem reproducing a lamprey attack, and we have little doubt lamprey can have a negative impact on whitefish, it is just unfortunate that these methods couldn t be used to truly quantify the damage that lampreys can do. The team hopes that even though this project didn t yield the results they were hoping for, it will raise awareness of this issue and the information

15 collected can be used to stimulate new ideas about how the problem can be approached. Contact Information: Dave Caroffino, x232, 96 Grant Street, Charlevoix, MI

16 TABLE: Table 1. Details of whitefish transfers to cages at the ARL. Mean survival days is influenced by winter cage removal and death due to sea lamprey attacks. Transfer Date Capture Method Transfer Temperature o C # of fish Mean length (mm) Mean survival (days) 27 Jun 2012 Hook and Line Aug 2012 Trap Net Oct 2012 Hook and Line Nov 2012 Trap Net Jun 2013 Trap Net Aug 2013 Trap Net Sept 2013 Trap Net n/a 3 1 Oct 2013 Hook and Line n/a 4

17 FIGURE: Figure 1. Photo of whitefish after holding in cages at the ARL, top fish was caught by a recreational angler and held 170 days, lower fish was caught in a trap net and held 39 days (photo taken 12/14/2012); these are extreme examples of the stressed conditions of whitefish observed during this study.

18 Figure 2. Example of a whitefish killed after an attack by a sea lamprey.