The Origins and Causes of Alewives Die-Off
For the past few decades, Lake Michigan has been experiencing an erupting phenomenon of alewife deaths. Up to 80 percent of the alewife population has been wiped out since the 1990s. This loss of alewives results in a drastic decrease in the fisheries of this great lake, leading to a huge economic burden that has a downstream environmental impact.
The alewife is a species of fish closely related to herring and is commonly found along the Atlantic coast of North America. Alewives migrate upriver to spawn in freshwater during the spring. Lake Michigan, geographically located in the Great Lakes region of North America, is one of the largest lakes in the world, providing an ideal habitat for alewives.
Unfortunately, this great lake also provides an ideal environment for an array of exotic species. These include the zebra mussel and the round goby. Prior to the arrival of these species, alewives had an abundance of food and an open environment, making them the perfect prey.
The zebra mussel and the round goby are two species of parasites that feed on the nutrients of the lake. This includes the eggs and fry of alewives. It has been found that the round goby is a predator of the juvenile alewife, while the adult alewife is a prey species to the zebra mussel. It is not surprising that the alewives have been declining since these two species were introduced.
Apart from the two invasive species, the depleted oxygen levels of the lake is also a major factor for the decrease of alewives in Lake Michigan. It has been noted that the dissolved oxygen levels in the lake have decreased by almost 30 percent in the lower zones. As a result, the alewives die by suffocation as they cannot breath in the low oxygen environment.
Lastly, the overfishing of alewives has also contributed to their decrease in numbers. The alewife population is highly sought after by commercial and sport fishers, leading to a over-harvesting of the fish. Despite the regulations and restrictions, commercial fishing policy of the states that border Lake Michigan have not been able to prevent over-fishing.
Consequences of Alewives Die-Off
The die-off of the alewife population of Lake Michigan has affected the environment, fisheries, and economy of the great lake. The alewife is an important link in the food webs of Lake Michigan, as it is a popular food source for many commercial and native species, such as lake trout, bass, walleye, and salmon. The depletion of the alewives has caused a decrease in the fish production in Lake Michigan, leading to a decrease in the income of the commercial fisheries.
The economic implications of the alewives’ population decrease cannot be understated. Fishers who depend on the alewives for their livelihoods have seen their incomes decrease drastically as
a result. This has a domino effect; fewer fishing trips and boats mean that suppliers of fishing-related goods and services, such as tackle shops, hotels, and restaurants, have seen a decrease in patronage as well. It also means that taxes related to fishing have decreased in the region, leading to less money for conservation and research efforts.
In addition to this, the alewife is a very important link in the cycling of nutrients within the lake ecosystem. As the alewives die, the nutrients they have absorbed during their life cycle are released back into the lake. This leads to a decrease in the oxygen content of the lake, leading to further death of fish and other aquatic life.
Mitigation Efforts to Counter Alewives Die-Off
In order to address the alewives die-off, states bordering Lake Michigan have implemented several efforts to prevent further ecological disaster. The first is to introduce natural predators, such as salmon and perch, which feed on the same food that the alewives are consuming in order to counteract their predators. The second is to set restrictions on commercial fishing and provide incentives to abide by these regulations. Additionally, citizens of the region have been educated on how to properly harvest and discard the alewives in order to protect their populations.
The government has also started to introduce artificial hatched fry propagules, which provide the fishes with the necessary environment and nutrients for survival. This has seen some success in increasing the alewife population, as the propagules help the eggs and fry of the alewives survive and thrive despite the unfavorable conditions in the lake.
Furthermore, the Michigan Department of Natural Resources has started to stock lake trout in Lake Michigan to combat the alewife die-off. It was discovered that lake trout are natural predators of the round goby and since their introduction, alewives have experienced a slight increase in their population.
Environmental Impact of Alewives Die-Off
The alewives die-off has had an immense impact on the ecology of the lake. Firstly, the loss of this species has created an imbalance in the food web as it is an important food source for native and commercial fish species. This leads to competition among fishes for lesser food, leading to further mortality of species.
Secondly, the decrease in the population of alewives has resulted in a decrease in the cycling of nutrients to the lake. This has caused the lake to become depleted of its nutrients, making it a less hospitable environment for fishes. Lastly, the acidic content of Lake Michigan has increased as the ratio of alewives to other species has decreased, leading to further decrease in the oxygen levels of the lake, resulting in decreased fertility and an increase in the mortality rate of the fish species living in the lake.
Conservation Of Alewives
In order to protect the species and prevent further ecological damage in Lake Michigan, several initiatives and conservation programs have been implemented by the state of Michigan. Firstly, lakes and rivers in Michigan have been designated as no-fishing zones. This prevents mass fishing of alewives and other species, ensuring that their habitats remain undisturbed.
In addition to this, hatcheries and replenishment programs have been set up to restock the lake with alewives. These programs have seen some success as they provide the necessary environment and nutrients needed for the fry and eggs of alewives to survive. Moreover, the Michigan Department of Natural Resources has also implemented a round-goose removal program, as the round goby is the primary natural predator of the alewives.
Lastly, the Michigan Department of Environmental Quality has also taken steps to reduce the amount of phosphorus present in Lake Michigan. This is done by controlling the runoff from agricultural land and curbing the amount of sewage and other pollutants from entering the lake. This reduces the amount of algae and weeds that form in the lake, which decreases the food and oxygen availability for the fishes.
Public Support For Alewives
In order to ensure the future of the alewife population of Lake Michigan, public support and awareness are key. Educational campaigns and initiatives have been implemented to inform the locals about the importance of alewives and the consequences of their population decrease. This has seen some success and more and more people are beginning to understand the importance of this species and are actively taking part in conservation efforts.
It is essential that these initiatives continue in order to preserve the alewife population and protect Lake Michigan and its related ecosystems. Thus, means need to be identified to raise more funds and support conservation efforts. More research and data gathering should also be conducted to improve the understanding of this species and identify the most effective means of sustaining their population.
Conclusion
The die-off of the alewife population of Lake Michigan has had a devastating impact on the ecology, fisheries, and economy of the great lake. To prevent further ecological disaster, states bordering Lake Michigan have implemented several conservation initiatives in order to protect the species and mitigate its negative impacts. However, for these initiatives to be successful, public support and awareness are essential. It is important that people understand the importance of the alewives and its effects on the environment, and actively take part in conservation efforts.
