MAZINA’IGAN PAGE 16 SUMMER 2017 • SUCKERS/LAKE HERRING/MERCURY • Kewis (cisco or lake herring) have long been an important fish species in Lake Superior; they serve as a food source for predators such as lake trout, and after lake herring spawn during the latefall,lakewhitefishwon’thesitateto feast upon their developing eggs. Asidefromtheirecologicalsignifi- cance,lakeherringplayanimportantrole regarding human consumption, as it has had a history of being a commercially- targeted species, especially near the ApostleIslandsregionwithinWisconsin waters of Lake Superior. The abundance of lake herring in the Apostle Island area has been on a rollercoasterrideofupsanddownssince the late 1800’s. Management agencies around Lake Superior are currently considering actions to limit harvests of lake herring to ensure both the viability of the commercial fishery and stability of the fish community. How we got here As fishing gear technology and boat equipment developed throughout theearly20thcentury,commercialyield of lake herring began to increase into the mid 1900’s. From the 1930’s to the late 1950’s commercial gill net effort and harvest appeared to have been fairly stable until the early 1960’s when fishermen dra- maticallyincreasedtheirfishingeffortin an attemptto sustain profitableyields of lake herring. Ultimately the abundance of lake herring decreased to such low levels that commercial fisherman no longer found it economically viable to fish for them. Thereductioninfishingeffortafter the 1960s, coupled with several large year classes recruiting to the fishery in the1990’s,allowedforsomerecoveryof thelakeherringpopulationinWisconsin waters where there has been a small but viable commercial fishery for over two decades. Since the early 1990’s, yield of lake herring had remained stable but at low levels. However, the large year classes that were supporting the fishery began to disappear, and recruitment events were becoming more sporadic and less frequent into the 1990’s and 2000’s. By 2008, fish buyers began purchasing lake herring in-the-round in response to an increase demand for roe in the European market. This meant that com- mercial fisherman did not have to spend valuable time processing their catch. Unsurprisingly, more time was devoted to increasing fishing effort and catching more fish to meet market demands. The increased demand on the lake herring population in conjunction with results from bottom trawl surveys con- ducted annually by the US Geological Survey, which show that recruitment of lakeherringremainslowandthatstrong year classes do not occur very often, is especially worrisome considering that both commercial fishermen and the fish community rely on lake herring. This lack of recruitment is not exclusive to Wisconsin waters. In fact, adownwardtrendofforagefishproduc- tion has been observed on a lakewide scale not just for lake herring, but for a multitude of species. While the exact reason for this decline remains unclear, predator/preyratios,changesinthermal habitat due to warmer surface water and reducedwintericecovercouldbeattrib- uting to poor lake herring production. The ups and downs of Lake Herring By Ben Michaels GLIFWC Fisheries Biologist Sucker phenology citizen science study All of life has its rhythms, with certain events tied to very specific environ- mental conditions. Phenology is the study of the timing of biological events, like the seasonal migration of animals, and how these natural phenomena relate to climatic change. For example, how do white and longnose suckers know when the time is right to migrate from the Great Lakes into the tributaries to spawn? Are they looking for cues from the water temperature, or is it how much water is flowing from the rivers? What happens if changes in climate shift the timing of sucker migrations? These are all questions being investigated in a new citizen science study launched last March, led by SheddAquarium’s research biologist Dr. Karen Murchie in col- laboration with researchers at the University of Wisconsin-Madison and the Lake Superior National Estuarine Research Reserve. Citizen scientists along the western shore of Lake Michigan and southern shore of Lake Superior are spending approximately 15 minutes each day monitor- ing a designated tributary to document when the suckers arrive for spawning. In addition to looking for the presence of suckers and how many are there, citizen scientists write down information on weather, water clarity, and water depth as well. This will allow the researchers to analyze whether fish are responding to water temperature, stream flow, or lunar cycles as cues to initiate their spawning By Aaron Shultz, GLIFWC Inland Fisheries Biologist February is known as “Namebini-giizis” (the Suckerfish Moon). It was at this time (long ago) that the Anishinaabe people would set their nets under the ice in order to catch the suckers. It is said that the Anishinaabe people were starving and on the brink of death when the suckerfish (namebin) took pity on the people, and decided to bless them by swimming into the nets, thus giving themselves to the Anishinaabe. migrations, and to document the rolling wave of migrations along a latitudinal gradient. The project will be an ongoing commitment to collect long-term data to determinewhetherthetimingofsuckermigrationsisshiftingwithclimaticchange. Though they receive little attention, suckers are important to Great Lakes ecosystems. When the suckers spawn in a tributary, they contribute nutrients from the eggs and waste they deposit. These nutrients are important in kick-starting the growth of insects and plants living in the streams where spawning occurs. Shifts in sucker spawning runs can change the dynamics of nutrient inputs, affecting the stream ecosystem. Thanks to the Bad River Natural Resources Department and GLIFWC, the Bad River is being monitored for the timing of sucker migrations. As the project continues, researchers hope to engage more citizen scientists in the Ceded Ter- ritory in subsequent years! For more information on project findings see: www. sheddaquarium.org/Conservation--Research/. prescribed burning. By educating homeowners how to identify and report invasive phragmites,agencieshopetoavoidthechallengesfoundinthesouthernWisconsin areaoftheLakeMichiganbasinwherephragmitesremovalhasnotbeensuccessful. Phragmites removal is an integral component of the remediation process for the St. Louis River estuary which is an Area of Concern, a geographic area that fails to meet general or specific Great Lakes Water QualityAgreement objectives. A key objective of the Lake Superior LAMP is to restore the St. Louis River estuary to the condition where it meets the remediation standards to be delisted. GLIFWC will continue work on phragmites treatment this summer in the St. Louis River estuary. Removal of the phragmites will create a more favorable environ- ment for the restoration of manoomin in the area and ensure that biodiversity of other native aquatic plants is protected. Phragmites control (Continued from page 8) Namebin. (Karen Murchie/Shedd Aquarium photo) Mercury in the environment Common questions tribal members ask Why do different lakes near each other have walleye with different levels of mercury? There are many factors that affect the level of mercury in a lake’s fish. Local sources of mercury can increase the amount of mercury deposited in a given lake. The physical and geochemical properties of a lake can affect the amount of mercury that settles into lake sediment. Each lake also has its own unique biota, or makeup of organisms. A particular lake may have a higher activity of the bacteria that produce meth- ylmercury due to the unique water chemistry of that lake. Lakes may also have different combinations of fish species present would affect how high in the food chain ogaa are in that lake. Where does mercury come from? Nationally, the largest source of mercury emissions is the burning of fos- sil fuels, especially coal-fired power plants. Within the Lake Superior basin, the mining and metals processing industry is the largest source of mercury emissions. Installation of scrubbers in industrial smokestacks, removal of mercury from products such as thermometers and medical devices, and other pollution control measures have greatly reduced U.S. mercury emissions. Since U.S. emissions peaked in the 1970’s, the mercury levels in the air, water, and fish within the Ceded Territories have been generally declining.