Alewives are a species of fish that exist in Lake Michigan. They are a vital part of the lake’s environment, providing important food sources for lake predators such as lake trout, bass, and walleye. Unfortunately, alewives are in decline in Lake Michigan, and their numbers have been drastically reduced over the last decade. So why are alewives dying off in Lake Michigan? Let’s take a look at some of the potential causes.
Ongoing Pollution
Lake Michigan is a popular destination for boat tourism and many larger cities, such as Chicago, have lakeside residences nearby. Unfortunately, all of these activities often result in the dumping of pollutants such as fertilizers, pesticides, sewage, and industrial waste into the lake. Pollutants can contaminate the water and have an incredibly negative effect on the fish, causing them to become weakened and more susceptible to diseases and parasites. This could be one of the main reasons for the decline in alewife populations.
Overfishing
The alewife population in Lake Michigan has also been affected by overfishing. Many of the local fish species, such as lake trout, bass, and walleye, are also food sources for humans. As a result, these species are being over-harvested and their populations are declining, making them an unreliable food source for alewives and other fish species. This could be another factor in the decline of the alewife.
Water Pollution Has Led To Habitat Loss
Pollution has directly caused serious habitat damage in Lake Michigan. Algal blooms, caused by pollution, have led to large parts of the lake having low oxygen levels, preventing the growth of suitable habitats for alewives. As a result, the fish have been forced to migrate to more polluted areas where their numbers have declined significantly.
Climate Change
Climate change is another major factor in the decline of alewife populations in Lake Michigan. Warmer temperatures caused by climate change can cause die offs of adult fish, leading to a decrease in overall populations. Furthermore, climate change can cause fluctuations in water levels, leading to further decreases in alewife numbers.
Predator-Prey Dynamics
The alewives in Lake Michigan have also been adversely affected by changes in predator-prey dynamics. As their predators become less abundant, due to factors such as overfishing, there is no longer enough pressure on the alewives to ensure their survival, leading to further declines in population.
Unwanted Invasive Species
Invasive species are also a major threat to alewives in Lake Michigan, as they can compete with the alewives for food and resources and can spread diseases to the native fish populations. Many of the invasive species that have been introduced to Lake Michigan, such as the round goby and the bloater, are voracious predators that can consume large numbers of alewives, significantly reducing the populations of native fish.
Land Use Practices
In some parts of Lake Michigan, land use practices such as shoreline development and dredging can also reduce suitable habitat for alewives. Removing vegetation and altering the structure of the lake can prevent the alewives from spawning or feeding, leading to lower populations overall.
Excessive Nutrient Inputs
Finally, excessive inputs of nutrients into Lake Michigan can be a major cause of the decline in alewife populations. Excess nutrients can cause high levels of eutrophication in the lake, leading to an increase in algae, which in turn can cover the lake bottom and smother the eggs of alewives. The result is an overall decrease in suitable spawning sites for alewives, leading to a decrease in their population.
Human Interference
Humans have a major role to play in the decline of alewives in Lake Michigan. Humans are continuously engaging in activities that can decrease the alewife population, such as polluting the lake and overfishing. Other activities, such as dredging and shoreline development, can also lead to the loss of suitable habitat for the alewives. Humans must act quickly to improve conditions in the lake and work to restore the alewife population to its former level.
Limiting Nutrient Inputs
Limiting nutrient inputs into the lake is an effective way to reduce eutrophication and protect the alewife population. Local organizations can work together to reduce runoff from agricultural and urban areas, as well as reduce the use of fertilizers and other sources of pollution. Furthermore, organizations can encourage people to limit the amount of waste that enters the lake, as this can have a significant impact on the alewife population.
Limiting Fishing
Limiting commercial and recreational fishing is another way to protect the alewife population. Limits on catch sizes, as well as restrictions on fishing areas can ensure that predators have enough food sources and are not over-harvested. This can ensure that a stable food source exists for the alewives and prevent their populations from declining.
Creating Spawning Habitats
Creating spawning habitats is an important way to support the alewife population in Lake Michigan. Projects such as restoring wetlands and reed beds can help create habitats for the fish, allowing them to feed and reproduce. Furthermore, local organizations can also create artificial reefs and spawning beds, which can provide excellent habitats for the alewives and increase their numbers significantly.
Raising Awareness
Promoting and raising awareness of the importance of alewives in Lake Michigan is critical to their preservation. Educating the public and local communities on the importance of alewives, as well as the threats that they face, can help ensure that their populations remain healthy and sustained in the lake. Furthermore, activities such as clean-up days, lake studies, and educational seminars can increase people’s knowledge of the fish and lead to meaningful action to protect them.
