Due to the lack of oxygen, 25,000 Atlantic Menhaden, also known as pogies, have been found dead in Inner Harbor, located in Baltimore, Maryland. The fish were found from Canton to Locust Point. The current running theories are seasonal algae die off and a possible turnover event.
What Caused This?
While a specific pollution event isn’t currently connected to the die offs, nutrient runoff isn’t exactly in menhaden’s favor. Nutrient runoff includes fertilizers and waste, these nutrients cause algae to over flourish. Inner harbor is no stranger to pollution, months before the event in June and July of 2025, the Harbor Splash was cancelled due to “heavy rains that washed harmful pollutants from city streets and from sanitary sewer overflows into the harbor.” When algae dies off as the seasons change, the bacteria that breaks down the dead algae depletes the oxygen in the area, causing fish kills. More nutrient runoff= more algae, more algae= less oxygen and in this case less menhaden. According to the Maryland Department of the Environment (MDE), there were also signs of a possible turnover event meaning that they suspect oxygen poor water from the bottom of the harbor mixed with water at the surface.
Bad for Business
25,000 dead animals aren’t good for any business especially water based tourism but when those animals are industry staples, things get even worse. Water activities such as utilizing a water taxi, going on a sight-seeing cruise, kayaking, paddle boating, and sailing, would be heavily affected if not stalled completely. The affected areas smell like rotten fish, so even if you’re not partaking in a waterside activity, the fish smell lingers so visitors at the National Aquarium, the many waterside museums, restaurants, and more would smell it, too. Frequent visitor to the area, Kywon McCain told CBSnews, “It’s inconvenient because I do Uber Eats, and I’m around here every day, and this sucks,” and “No one’s really doing anything about it right now.” , meaning that this affects others too, non-harbor affiliated workers are affected by the fish kill, too. The smell can only be remedied by time when inorganic materials fall to the bottom of the harbor.
Let’s refocus on the KIND of fish found dead: Atlantic menhaden. The small oily, fatty fish are crucial to the fishing industry. Even though only 1/3 of menhaden come from the Chesapeake Bay, which the inner harbor is a part of, the industry is going to be affected, even if only slightly. The bacteria aren’t contained to the harbor; nearby sections of the bay will likely feel the impact of the die offs and bacteria. Menhaden are used for bait, oil, and pet food. The fish oil industry is at a current market value of $10.4 billion and the fish meal has a market value of $46.42 billion in 2025. It may not seem like an event seemingly sequestered in a harbor could make a dent in the industry, but bacteria travels, water carries bacteria and die-off, if one body of water is affected, everything that leads to it is, too.
Menhaden are a keystone species in the Chesapeake Bay that serve as both filter feeders and prey animals. Keystone species play a key role in the health and diversity of an ecosystem. Menhaden ingest and filter out phytoplankton and zooplankton from the water at a rate of 7 gallons per minute, maintaining a healthy environment for inhabitants. Diverse species such as striped fish, bluefish, ospreys, and more prey on menhaden. The Chesapeake Bay brings in 500 million pounds of seafood each year, since menhaden are a keystone species that is predated by larger species, mass die offs such as this one affect more than just the menhaden fishing industries but other ones as well. This isn’t the first die off this year, it’s not even the first one this year in Maryland, the MDE estimates that 61,000 fish were found dead on August 22nd, 2025, 6 days later 125,000 dead fish were found between Harbor Point and Fort McHenry. This proves that it’s not just Menhaden or Inner Harbor in Baltimore that this is happening to so what can we do as humans to lessen these numbers?
Moving Forward
When dealing with environmental issues, it’s important to remember that everything is connected. Nutrient runoff feeding algae causes seasonal fish die offs. This year it’s 25,000 menhaden that have paid the price. Yes the die offs are naturally occuring but the more algae there is, the more oxygen is taken away after they perish. The bacteria sinks to the bottom of the harbor and during turn over events, the bacteria and the low oxygen quality water rise to the surface, and the cycle starts again. What can we do to alleviate these numbers? Die offs are naturally occurring but we as humans can control our run-off. We can abstain from using fertilizing and leaving pet waste to be carried off into the harbor to lessen the flourishes, saving more oxygen for pogies.
