Environment Planet Earth Less Sharks Mean an Ocean Jam-Packed With Sardines By Sara Novak Writer University of Georgia Sara Novak is a journalist and writer who specializes in food policy and health writing. She covered these topics on Treehugger from 2005-2012. our editorial process Twitter Twitter Sara Novak Updated October 11, 2018 Migrated Image Share Twitter Pinterest Email Planet Earth Conservation Weather Outdoors Sardines have made a serious comeback in terms of sustainable food trends. Sardines are on the Monterey Bay Aquarium Seafood Watch green list. There's also an overpopulation of sardines as a result of a lack of predators, namely sharks and other larger fish species, according to a story in the Daily Mail reported on Be More Eco. Researchers say that the number of small fish including sardines, herring, and anchovies has doubled in the last 100 years. They're just aren't enough natural hunters like sharks, tuna, cod, and swordfish. In fact, in the last 120 years, these larger fish numbers have gone down by two thirds. Lead researcher Dr. Villy Christensen, of the University of British Columbia, said: Overfishing has absolutely had a "when cats are away, the mice will play" effect on our oceans. By removing the large, predatory species from the ocean, small forage fish have been left to thrive. What impact does this have on the sea? Well, sardines feed on floating organisms called zooplankton and zooplankton feed on plant plankton. But an overpopulation of sardines means less zooplankton and more plant plankton. As plant plankton gets out of control, blooms of green algae get out of control creating a "green soup." In the future, such algae blooms could choke the ocean. Eating Sardines Up?That's why sardines and other small fish are so much easier on the planet. Rather than eating this delectable oily fish by itself, we feed 80 percent of the Pacific sardine catch to bluefin tunas raised in Mexico and Australia. From a nutrition standpoint, sardines are loaded with Omega 3 fatty acids. So you can have that pickled herring and eat it too.