April, 2011 – Reedville, Virginia is like most small fishing villages along the Atlantic Coast. The town has a couple churches, some bed and breakfast inns, an annual fishing contest, and even a fishing museum. However, Reedville is strikingly different than most other fishing towns. It is completely dependent on one fish and one fishing company – the menhaden and Omega Protein, Inc. Despite the town’s quaint appearance, Omega Protein’s dominance over the menhaden fishery “reduction” industry has led Reedville to become the second largest port in the country in terms of total poundage. At one point, the menhaden industry made Reedville the wealthiest town in the country per capita, but today the historic Victorian mansions that line Reedville’s main street are the only surviving testaments to the heyday of the once vibrant fishing town.
To understand the ecological significance of the menhaden, it is important to have a basic understanding of the Bay ecosystem. The Chesapeake Bay is the country’s largest estuary and is home to over 350 species of fish, shellfish, and plants. However, their survival is threatened by the declining water quality of the Bay. The poor health of the Bay ecosystem is mainly contributed to the excessive levels of nutrients, particularly nitrogen and phosphorous. These nutrients come primarily from discharged wastewater, air pollution, and urban and agricultural runoff from fertilizer and livestock waste. As the Bay region’s population has increased over the years, the land surrounding the Bay has been transformed from forests to farms and residential areas. These forests that once prevented excessive levels of these nutrients from reaching the Bay are now gone, and the menhaden is now one of the Bay’s last natural defenses.
The menhaden’s filtering capabilities enable them to consume large amounts of these excess nutrients. According to the Chesapeake Ecological Foundation, a single menhaden can filter one million gallons every 180 days, and the entire Atlantic menhaden population has the potential to remove 25% of the Bay’s nutrients in one year through its consumption of plankton. By consuming such vast quantities of these microscopic plants, menhaden help to prevent the growth of algae blooms and allow sunlight to reach plants growing at the bottom of the Bay. As these bottom-dwelling plants grow, they increase the water’s oxygen levels, making conditions healthier for the rest of life in the Bay.
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Analysis: While the article discusses menhaden's role as a filter feeder in the Bay, the amount of phytoplankton that menhaden consume is not universally agreed upon. There are several studies, including a recent 2010 study from the Virginia Institute of Marine Science, that conclude menhaden have little, if any, net impact on improving water quality in the Chesapeake Bay. These studies have found that adult menhaden, rather than consuming phytoplankton, consume mostly zooplankton. While juvenile menhaden consume phytoplankton, the amount they consume is not enough to significantly influence Bay water quality, especially considering the amount of nutrient imputinto the Bay, one of the causes of excessive phytoplankton growth.