Salmon Recycling: Waste Not, Want Not

EPA scientific diver and frequent “It All Starts with Science” contributor Sean Sheldrake recently shared some of his work on the Smithsonian’s Ocean Portal blog. The following was originally posted there.

By: Sean Sheldrake

Underwater pipe discharges fish waste.

Pipe discharges fish waste from processing factories. Photo byBruce Duncan, EPA

As a research diver for the US Environmental Protection Agency (EPA), one of my jobs is to make sure that people and companies working in the fish industry don’t dump too much waste in the ocean. On my first dive at an underwater waste site, my old salt of a dive partner hinted, “you might see a shark… or three” with a wink. “Okay,” I thought, “I can deal with a couple of sharks.”

Descending to the dump site, I soon saw circling dogfish and salmon sharks extending all the way from 80 feet to the surface—maybe 50 sharks, perhaps more. All those dogfish were drawn to a pile of Alaskan salmon fins, intestines, and other fish, legally unloaded into the ocean. I hand-signaled my partner, pointed up at the schooling swarm, and then shook my head to let him know that I wasn’t very happy with his low-ball estimate.

Every year, tons of fresh salmon are flown and shipped from Alaska to the lower 48 states. Before they’re flown south, the fish are sliced and diced into ready-to-cook filets, creating “inedible” fish waste. Under the Clean Water Act, people and industries handling fish and fish products are allowed to dump some of their waste back into the sea. But the EPA regulates these discharges with help from the states to ensure that waste does not degrade waterways. We all value our lakes, streams, and oceans, and the Clean Water Act helps to protect them.

Fish waste is often discharged down a permitted outfall, which is a pipe carrying waste into the ocean. This creates a ‘zone of deposit’ or ZOD on the seafloor. Life on planet ZOD is pretty limited—bacteria that live without oxygen predominate, and hydrogen sulfide gas (the stuff that smells like rotten eggs) is belched out occasionally. Outside of the oxygen-free zone, the ZOD attracts scavengers. On that surprising first dive, so many small dogfish filled the water that they were getting caught between my legs, in the crooks of my arms, and bumping me from every other direction to see if I had a handout—or if I were a handout!

The ZOD is supposed to be confined to a small area on the seafloor, but it often extends much further than allowed: some waste piles, though permitted only to an acre or less, extend to dozens of acres and may even grow so tall that navigation by boats can be obstructed. This is where inspections come in. I and other EPA divers check the type of waste being discharged and map out the size of the ZOD, to make sure it doesn’t cover more seafloor than allowed.

When the EPA finds that a company is violating its permit, one option is to ask its managers to recycle their waste. Seafood waste can be made into a variety of products from salmon cakes to gourmet pet food to high value fertilizer. Many fish processing plants have jumped into recycling technology, making good use of nearly all their “waste”. That’s a lot of happy kitties (although the dogfish might not appreciate the loss in food)!

Recycling fish products instead of creating a permitted outfall is better for ecosystems. To encourage this behavior, ask at your grocery store if the seafood company you’re buying from recycles their waste. Buy recycled products whenever possible—voting with your dollars makes a definitive statement that you want to see more recycling!

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About the AuthorSean Sheldrake is part of the Seattle EPA Dive unit and is also a project manager working on the Portland Harbor cleanup in Oregon.  He serves on the EPA diving safety board, responsible for setting EPA diving policy requirements.  

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