In the belly of the fish
By Lisa Cavanaugh
There is a memorable scene in the 1975 movie “Jaws,” when Chief Brody watches as Hooper cuts open the stomach of a large shark. Their intent is to determine if the shark consumed a human (it hadn’t).
Recently, there has been a growing body of research focused on just that question: What’s inside the bellies of fish? Many of us have seen images of large patches of sea trash, but some scientists are more concerned with what you can’t see, micro-plastics, fragments of five millimeters or less. Marine life is ingesting these pollutants, accidentally or deliberately.
One local young man is conducting his own research to measure micro-plastics in fish, using species from our region. Charlie Widing is a high school senior at Tabor Academy in Marion who, supervised by his teacher Jay Cassista, Director of Marine Science, is in his third trimester studying micro-plastics entering digestive tracts of locally caught fish.
It’s important to note that the overwhelming majority of fish that Widing has tested so far had no discernible micro-plastics in their digestive systems. What’s more, humans rarely, if ever, eat that part of a fish.
So we can feel confident in the safety of the fish fillets we all enjoy while understanding the concept that Widing and others are stressing: How can we can lessen the amount of plastics in our marine environment? A healthy ecosystem is a goal we all embrace, whether we catch fish, eat fish or just enjoy being on the ocean.
Widing, from Brookline, was first introduced to the subject during a term at the Islands School in the Bahamas. He partnered with a PhD candidate studying micro-plastics in the marine environment, and then continued the focus with an independent study project back home.
“I was lucky to be able to take advantage of all the resources here at Tabor,” says Widing. “We have one of the best marine science centers in the country for secondary education.”
Known as “the school by the sea,” Tabor is located on Buzzards Bay, and has a long tradition of marine and nautical science. Courses include seven electives devoted to the study and care of the ocean, semesters at sea to research coral reef ecology, a Naval Honor certificate program, a shellfish propagation project and the chance to learn aboard a 92-foot schooner SSV Tabor Boy.
For Widing’s project, area fishermen (including Fishermen’s Alliance members) have donated black sea bass, bonita, bluefish, striper and haddock. Widing has been given a general idea of where the fish were caught, and also has gone aboard the Academy’s smaller vessels and utilized a special plankton net to skim the surface and gather up whatever is floating.
“We have used two GPS points and done a transect between them for our 10-minute tows in the local harbor,” says Cassista.
Once Widing has his specimens in the academy’s lab, he has to open up the stomachs. “I learned how to dissect fish at the Islands School,” he says, “and it was tough at first. But working on this project, I’ve gotten much better.”
Helping scientists of tomorrow is a part of the mission of the Fishermen’s Alliance. Many of the regulations fishermen work under are based on research and scientific studies; improving that core data improves management.
“We are glad to help a future marine scientist who cares deeply about our ocean and sustainability,” says John Pappalardo, the Fishermen’s Alliance’s CEO.
Since you cannot see micro-plastics with the naked eye, Widing takes the contents of the stomach and empties it into sieves. “We put each sieve into water and the micro-plastics float to the surface. We then put them under a microscope,” he explains.
Plastics in the ocean suffer severe weathering so he cannot always tell what the source might be. “But we can usually tell what type of plastic it is without lab analysis,” he says.
The good news is that of the 17 fish he has already dissected only two have shown evidence of micro-plastics in their systems, with one, a bonita, having a significant amount in its gut.
Widing is more than happy to witness the lack of plastics in our local fish, but it was still shocking to see the amount in the bonita. “You hear about plastic pollution but until you open up a fish and see it there it’s hard to conceptualize,” says Widing.
So far, Widing has dissected 15 fish and hopes to examine 30 to 50 fish before he graduates in June. He plans to create a formal presentation and possibly a research paper to submit for publication.
His project is already collaborative. “While Charles uses the gut, other students are taking tissue samples and sending them to Northeastern University for their Ocean Genome Legacy bank,” says Cassista.
Cassista is proud of the work Widing has done: “My greater interest is that students like Charles are able to publish real research at a high school level. He has the opportunity to catapult a significant understanding of micro-plastics as a real thing.”
Widing expects to continue his studies in biology, and potentially marine biology. Meanwhile, he wants his research to make people aware of what is in the ocean, which unfortunately is not just fish.
“I would say small things do matter,” he says, “and anything you can do locally to not let stuff - like plastic straws or bottles - get into the ocean helps. Ultimately it is about gaining consciousness and being a good global citizen.”