The 2012 Great Lakes Water Quality Agreement states that “the Waters of the Great Lakes should be free from the introduction and spread of aquatic invasive species and free from the introduction and spread of terrestrial invasive species that adversely impact the quality of the Waters of the Great Lakes.”
Prevention (rate of establishment of aquatic non-native species)
Impacts of Aquatic Invasive Species
Assessment highlights
The assessment for this indicator is based on two components: Prevention, measured as rate of establishment of new aquatic non-native species in the Great Lakes (assessed as Good with a trend of Unchanging), and Impacts of Aquatic Invasive Species (AIS) (assessed as Poor with a trend of Unchanging). The assessments for these two components highlight that there has been success with the prevention of establishment of aquatic non-native species (species that are not native to the Great Lakes basin that may or may not have known negative environmental and/or socioeconomic impacts); however, already established AIS (species that have known negative environmental and/or socioeconomic impacts) continue to expand their ranges.
To date, 188 aquatic non-native species have been reported as established in the Great Lakes, of which 64 are considered invasive. However, there has been tremendous success in reducing establishments in recent decades. This is largely due to the implementation of regulations on ballast water from transoceanic ships and implementation of the joint inspection program to confirm that these ships are managing ballast. No new aquatic non-native species confirmed to be introduced through ballast water have become established in the Great Lakes since 2006. Various efforts, such as the Great Lakes Aquatic Non-indigenous Species Information System Risk Assessment Clearinghouse, which incorporates binational data, have been important in supporting the prevention of establishment of new aquatic non-native species.
From 2011 to 2020, four new aquatic non-native species (all zooplankton) established overwintering and reproducing populations in the Great Lakes (Thermocyclops crassus, Mesocyclops pehpeiensis, Salmincola californiensis, and Diaphanosoma fluviatile). The entry route for these four species is uncertain. Despite establishment of these four species, there has been a significant slowdown in establishments of aquatic non-native species compared with the previous two decades.
Populations of AIS can spread within and between the lakes, including by hitching rides on boats, trailers, and gear used by anglers, boaters, and other recreationists. Stopping the spread of invasive species is essential for protecting Great Lakes native species and habitats.
The Sea Lamprey is a prominent invasive species and a lethal parasite of many Great Lakes fish species such as Lake Trout. Annual control activities in the Great Lakes have successfully suppressed Sea Lamprey populations by approximately 90% since pre-control efforts and Sea Lamprey populations have declined in most lakes. Currently, adult Sea Lamprey indices are meeting targets in lakes Michigan, Erie and Ontario, but are above targets in lakes Superior and Huron.
Dreissenid mussels (zebra and quagga mussels) are aquatic invasive species in the Great Lakes. Their impacts include altering nutrient cycling, increasing water clarity and modifying zooplankton and phytoplankton communities. In lakes Michigan, Huron and Ontario, populations in the shallow and mid-depth regions appear to be stable or declining, however, in the deep zone, populations of quagga mussels continue to increase. In Lake Erie, overall dreissenid mussel densities are much lower than the peak levels of the 1990s; but there is variability across the lake.
Terrestrial invasive species such as emerald ash borer, mute swan and garlic mustard, are widely distributed in the Great Lakes basin and have detrimental impacts to the ecosystem. Participatory science (community science) data collection systems are valuable sources of information for terrestrial invasive species distribution and are used to inform the sub-indicator.
Sub-indicators supporting the Invasive Species assessment
Sub-Indicator | Lake Superior | Lake Michigan | Lake Huron | Lake Erie | Lake Ontario |
Great Lakes Basin assessment is Good and Unchanging | |||||
Poor and Undetermined | Poor and Undetermined | Poor and Undetermined | Poor and Deteriorating | Poor and Deteriorating | |
The overall trend for the Impacts of Aquatic Invasive Species sub-indicator is not an averaging of the lake assessments, but is based on separate calculations using basin-wide data.
Sub-indicators provided for background information, but not included in the Invasive Species assessment
Sub-Indicator | Lake Superior | Lake Michigan | Lake Huron | Lake Erie | Lake Ontario |
Poor and Improving | Fair and Improving | Poor and Undetermined | Fair and Undetermined | Fair and Unchanging | |
Poor and Deteriorating | Good and Improving | Fair and Improving | Good and Improving | Good and Improving | |
Good and Unchanging | Poor and Deteriorating | Poor and Deteriorating | Fair and Unchanging | Poor and Deteriorating | |
The methodology used to assess this sub-indicator is being updated. | |||||
The overall assessment for the Rate of New Aquatic Non-indigenous Species Establishment in the Great Lakes sub-indicator is solely based on new establishments in the Great Lakes; the lake-to-lake spread component is provided here for additional information. Sea Lamprey and dreissenid mussels are among the species already included in the Rate and Impacts assessments. Their separate sub-indicator assessments provide more detailed information.
Status
