Saving Seafood

Flood Prediction Helps People and Fish

November 18, 2019 — The following was released by NOAA Fisheries:

In the last 50 years, as the northeast has gotten significantly rainier, flood prediction has become increasingly important. In addition to helping the public, town planners, and emergency responders, understanding flooding is also important for fishway operators and fisheries managers. Floods can affect the timing of fish migrations. For example, as spring rains swell rivers, some sea-run fish swim upstream—sometimes for many miles—to spawn. American eels are known to migrate to the ocean during fall floods. Knowing what’s coming can help biologists and dam operators work together to create the best conditions for migration at dams and fishways.

While some watersheds flood quickly when it rains, others have natural or human-built storage. Reservoirs behind dams, as well as naturally occurring ponds and wetlands, can reduce flooding by delaying runoff into streams and rivers. Knowing which kinds of rain events will lead to flooding in particular river systems is key for communities in the watershed.

A Tale of Two Rivers: The Mystic and the Charles

The Mystic River watershed is a relatively small urbanized basin north of Boston, home to more than 20 communities. The Charles River drains an area approximately four times larger than the Mystic River watershed. It contains 23 Boston-area communities, including some to the west and southwest of the city.

In a recent study, researchers found that almost 90 percent of Mystic River flooding is immediately preceded by one to two days of large rainfall. In contrast, only about half the flooding events for the Charles are preceded by large rainfalls.

The researchers considered whether other factors besides large rainfalls could be associated with Charles River flooding. They found that flooding tends to happen when the watershed is “primed” for maximum streamflow. For example, if rainfall, soil moisture, and snowmelt increase for a month, the Charles watershed is more likely to flood. Since the Charles watershed contains more upstream storage, it is less likely than the Mystic to flood because of large rainfalls alone.

Read the rest of the story on our website or read the paper on which the story is based.

MASSACHUSETTS: Thousands of fish found dead on banks of Mystic River

August 6, 2018 –Last week about 40,000-50,000 Atlantic menhaden (pogies) were found dead along the Mystic River in Everett and Somerville, MA.

There are no perpetrators responsible for the mortality. Menhaden are victims of their own success, flourishing in large, dense schools that can cause them to “suffocate” and die off from lack of oxygen.

David Pierce, director of Massachusetts Marine Fisheries said, “When large schools of fish enter warmwater estuaries and rivers in large numbers during the summer months, they can deplete the water’s dissolved oxygen, making survival impossible. Oxygen must pass across and through fish gills, and when used up by tightly-packed fish in shallow waters, the inevitable occurs.”

Pierce said, “Management and regulation of menhaden is overseen by the Division of Marine Fisheries (DMF), having adopted compliance criteria of the Atlantic States Marine Fisheries Commission Menhaden Plan and approaches best suited for the Massachusetts menhaden fishing industry. Our commercial quotas were raised this year due to high menhaden abundance finally re-establishing itself north of Cape Cod and (somewhat expectedly) causing re-occurrences of past years’ typical hot-weather kills – over 20 years ago.”

Read the full story at The Sun Chronicle