Purple Quahog Mystery | CAI

Purple Quahog Mystery

Nov 19, 2020

For hundreds of years, Wampanoag people have relied on quahogs both for food and for making wampum, traditional purple shell beads. But recently, Chuckie Green has been wondering if these two uses are competing. Green is the natural resources department director for the Wampanoag Tribe, and he says native quahogs are changing.

“We didn’t really notice it until I’d say probably the last 15-18 years, that the native quahogs were starting to come up with less and less purple shell.”

Chuckie says he doesn’t know exactly why this is happening. But in recent decades, the town of Mashpee has increased efforts to boost wild native quahog populations with planted hatchery seed. He thinks there’s a chance it could be related.

“We do know there’s been high levels of seeding done to try to support the quahog fishery. Hatchery seed is bred for disease resistance, rapid growth, and longevity.” 

In other words, the purple color is not a priority. Once the hatchery seed is on the flats and in the water, they can cross breed with wild quahogs. So, it’s possible these fast-growing hatchery quahogs do have less purple and they’re outcompeting wild quahogs that have historically had more. Given the importance of wampum and quahog meat to Wampanoag culture, Chuckie decided to investigate. A few years ago he reached out to Dale Leavitt, an aquaculture extension specialist and Professor of Marine Biology at Roger Williams University.

“I had a student that spent about 6-8 months, maybe two semesters, going through a whole sequence of chemical analyses of the shell with the purple color in it versus shell with no purple color in it. We tried a whole host of different chemical analyses from liquid chromatography to raman spectroscopy to just about every protocol that we could think of that might actually allow us to determine exactly what that compound was," Dale said. He added, "and to this day we still don’t have a good understanding.”

Eventually, Dale and his student gave up. Isolating the compound was supposed to be just the first step—from there they would figure out the mechanism causing the purple deposition and that would help them hypothesize as to why it might be disappearing. Without this information, Dale’s just guessing. But he thinks maybe the purple color represents some kind of waste product that builds up in the shell slowly.

“And I have no scientific basis whatsoever to support that. But if it is a—something that is slowly built up in the shell then obviously the age of the animal is something that is going to dictate to a large degree how much is going to be actually showing up in the shell.”

This is where Dale and Chuckie’s observations come together. Most hatchery seed grows quickly and is big enough to harvest within a few years. Maybe if the animals stayed on the flats for longer, like many wild quahogs, they’d accumulate more purple. For Dale, it’s a puzzle he hasn’t been able to pin down. For Chuckie, it’s about protecting a resource that’s been part of his culture for generations.

“The quahog, I have many crafters in my tribe that like to make jewelry and such. Myself I can remember when you could go out take a rake and you’d have two meals of quahogs without spending search time and clams were abundant. So I’d like to be in a place where I can try to get back to our traditions and also to improve the conditions for the animals out there that we use for sustenance."