I think that most people familiar with the menhaden issue know that the state secretary of commerce has placed a moratorium on fishing for the menhaden in the Chesapeake Bay to begin effective June 17. Omega Protein (owned by Cooke of Canada) is the only company still in the business of catching menhaden in the bay.
Much has been discussed and written about how important the menhaden are to the bay. Menhaden have been called the most important fish in the sea. It is always mentioned that menhaden feed numerous other fishes like striped bass and bluefish, as well as whales and sharks, but there is more to the menhaden story.
We seem to dwell on the oyster as the great water filterer to clean the bay. Oysters do not move. They lie on the bottom or may be in some manmade floats at the surface. They have to wait for the tide or the current to bring them food, or they filter the same water over and over. The opening of an oyster shell to feed is almost imperceptible. Menhaden have large mouths compared to other fish and they leave them wide open as they move through the water, collecting anything that floats. They feed mostly on plankton: phytoplankton (tiny plants) and zooplankton (tiny animals), the two things that cloud so much of the water.
We need to improve the clarity of the water to a point where the sun can penetrate it. This would allow grasses to grow, which in turn would remove more nutrients and help clear the water. You may notice that menhaden swim in schools near the surface of the water. This is because phytoplankton grows there, where they can receive the sunlight they need to grow.
Zooplankton then feed on the phytoplankton. As part of the food chain, several species of whales eat zooplankton. The largest fish in the sea is the whale shark, and it also eats zooplankton. Doesn’t it seem a little strange that some of the largest creatures on earth eat the smallest creatures? Shrimp, snails, jellyfish and menhaden also feed on zooplankton. Even most baby fish feed on some plankton. We need to have enough filter feeders in the water to keep it clean or stop putting so many nutrients into the water. The filter feeders, grasses and oysters are all part of cleaning up the bay.
Many people use omega-3 oil as a supplement. It is touted as being good for your health. Omega-3 oil is extracted from commercially caught menhaden and sold as fish oil. The actual omega-3 oil is not produced by the fish but comes from the plankton they eat. It is a plant oil and no animal can produce it. We could grow phytoplankton to produce omega-3 oil instead of getting it from the menhaden.
Another scenario we must look at is filial cannibalism. This is where fish eat their own young. Many fish do this and also eat each others’ young, though studies suggest they would prefer to eat menhaden. If there were enough menhaden around, maybe so many young fish would not be eaten by other fish. This same theory could also be applied to fish eating crabs.