• INLAND FISHERIES/INVASIVE SPECIES • Ogaa cannibalism, habitat research slated for Mille Lacs Lake BIA grant supports 2018 interagency study In spring of 2018, the Mille Lacs Band of Ojibwe, GLIFWC, Fond du Lac Band of Lake Superior Chippewa, and US Fish & Wildlife Service will begin an ogaa (walleye) tracking study in Mille Lacs Lake. Currently in Mille Lacs Lake, adult ogaa are primary consumers of juvenile ogaa, which is resulting in a decline of adult/harvestable fish. While the causes behind the walleye cannibalism are unknown, a recent Minnesota Department of Natural Resources (MDNR) diet study showed that it is occurring during the warmest months of the year (mid-July to October). The MDNR diet study result is interesting because ogaa (and all giigoonh, or fish) prefer to occupy depths and habitats that are close to their preferred tempera- ture (juvenile walleye >22°C / >71.6°F; adult walleye 18-22°C / 64.4-71.6°F). It is possible that increased water clarity (partially due to invasive species) and climate change are increasing water temperatures at deeper depths in Mille Lacs Lake, thereby shrinking the amount of colder habitat that ogaawag and other coldwater giigoonh species need to optimize growth and survival (i.e., squeezing coolwater fish into a smaller habitat; Figure 1). Areduction in thermal habitat during the warm months may also be changing the abundance and location of coldwater wiisiniwi giigoonh (food fish) that buffer/ protect juvenile ogaa against cannibalism. These changes may result in overlap of juvenile and adult ogaa thermal habitat, leading to increased encounter rates and as a result, cannibalism. To test these predictions, biologists will use acoustic tags to track juvenile and adult ogaa in Mille Lacs Lake, and evaluate changes in habitat use (including thermal habitat) across seasons. By doing so, we hope to shed some light on why and where ogaa cannibalism is occurring in Mille Lacs Lake. This research will contribute to the ongoing efforts to rehabilitate walleye stocks in Mille Lacs Lake. Funding for the project comes from a Bureau of Indian Affairs Tribal Fish and Wildlife Grant. For more information contact Mille Lacs Band Biologist Carl Klimah at Carl.Klimah@millelacsband.com. —Carl Klimah, Aaron Shultz, Adam Ray, Mark Luehring, Joe Dan Rose and Ben Michaels Figure 1. Feeling the squeeze: potential reduction of ogaa thermal habitat in Mille Lacs Lake under warmer conditions. By Mille Lacs and GLIFWC Inland Fisheries Biologists Aquatic invasive species infestations multiply GLIFWC staff wrapped up the annual aquatic invasive species (AIS) survey in September. It was a busy summer as staff surveyed 21 lakes for aquatic invasive species (AIS) in the Ceded Territory of northern Wisconsin and western Upper Michigan. More than 30 new aquatic invasive species occurrences comprising 11 taxa were found in 2017. Samples for zebra musselsandwaterfleaswillbeexamined this winter. Study lakes were chosen in coordi- nationwithtribal,state,countyandlocal management partners. Most sites have high recreational visitor numbers or are in close proximity to infested waters; many are important for tribal ogaa and manoomin harvest. GLIFWC staff also surveyed three LakeSuperiorcoastalwetlandsandarea roadsidesforcommonreed(Phragmites australis). In addition, over 1,000 miles of roadsides,trails,beachesandshorelines were assessed. Surveys were done by motorvehicle,motorboat,canoe,biking and walking, as needed. Four non-native common reed (P. australis subsp. australis) popula- tions and 69 native (P. australis subsp. americanus) populations were mapped this summer. (The native subspecies is much less aggressive than the non- native subspecies, and generally isn’t a problem in natural habitats). Using a combination of manual, chemicalandbiologicalcontrols,GLIF- WC crews treated over 200 invasive plant populations, including popula- tions of wild parsnip, yellow iris, purple loosestrife, teasel, and non- native Phragmites. GLIFWC staff continued to work cooperatively with the Minnesota DepartmentofNaturalResources,1854 TreatyAuthority,FondduLacBand,and St.LouisRiverAlliancetomanagenon- nativePhragmitesontheMinnesotaside oftheSt.LouisRiverEstuary.Treatment on the Minnesota side was carried out by Duluth Community Action. —Steve Garske Native to the southeastern US, Georgia mystery snails are now found in a number of Ceded Territory lakes. (S. Garske photo) By Bill Mattes, GLIFWC Great Lakes Biologist Invasive sea lamprey are fero- ciousfeedersandwillattackjustabout any fish that swim their way. While lake trout are a historic favorite of parasiticlamprey,GLIFWCresearch- ers are finding wounds on less likely suspects like suckers. Damageinflictedbysealamprey on Great Lakes fish populations is estimated by tracking wounding rates on lake trout. To accomplish this, fisheries technicians that are out monitoring commercial and sport fishing, or doing research and assessments, make note of lamprey-wounded lake trout while collecting data like measurements and length. These observations are used to develop wounding rates; combined with adult sea lampreyspawningpopulationestimates,biologiststrackthesuccessofsealamprey control in the Great Lakes. Wounding rates, however, might not always follow expected sea lamprey abundances. For instance, in years when sea lamprey num- bers have been low, wounding rates on lake trout have been high and vice-versa. Field staff have observed wounds on various species including lake white- fish, cisco, walleye, and even on the softer undersides of heavily-plated adult lake sturgeon. To better document the scope of lamprey attacks, GLIFWC Great Lakes Section staff have recorded sea lamprey wounds and length from all the fish they handle in assessments and monitoring for the past several years. Sea lamprey clearly prefer more than just lake trout as a meal. By continuing to track sea lamprey wounds on other species fisheries managers anticipate that valuable insights into conflicting trends between lake trout wounding rates and sea lamprey spawning abundances will be gained. For more information on sea lamprey control in the Great Lakes visit the Great Lakes Fishery Commission website at www.glfc.org/. The commission coordinates fisheries research and sea lamprey control, and facilitates cooperative fishery management among the state, provincial, tribal, and federal management agencies surrounding the Great Lakes. Sea lamprey wounds reveal a broad diet B. Michaels photo MAZINA’IGAN PAGE 6 WINTER 2017/2018