On Wednesday, on MPBN’s show Maine Calling, the subject was sustainable seafood. While I made an apple pie, I listened with interest because lately I’ve been wondering if there is such a thing as sustainable seafood, and I was curious what the gist of the show would be. The program was hosted by Keith Shortall, and the guests were Jen Levin, Sustainable Seafood Project Manager, Gulf of Maine Research Institute, and Barton Seavor, chef and author of four cook books.

Shortall began the program by acknowledging that we “know some of the most popular fish are in trouble because of overfishing,” and much of the show revolved around encouraging people to turn to “underutilized fish” such as dogfish, Atlantic pollock, and whiting, all species that, according to Jen Levin, are flourishing.

When the question arose of what exactly sustainability meant in terms of seafood, Barton Seavor did recognize that one aspect involved promoting thriving, resilient species. But, and it’s a big but, he went on to state that “ultimately the measure of sustainability must fundamentally be measured by the ability of human beings to thrive.” Levin did add that a growing population needed to live within its means.

Now, I’m distilling an hour show into a post for a blog, and as such, I can only include snippets of what the guests discussed. Readers who are interested in this subject—sustainability and seafood—should listen to the podcast for a longer, more complete version of what Shortall and his guests actually said.  However, not once during that hour-long show did I hear about the importance of abundant fish to the vast, interconnected chain of life in the ocean or of how quickly humans can change abundance to scarcity, even when fish seem to be plentiful.

For this we must turn to Sylvia Earle, author, marine biologist, former chief scientist of NOAA, and “National Geographic explorer in residence.” As Sylvia Earle eloquently puts it, “[T]he ocean is the cornerstone of Earth’s life support system, it shapes climate and weather. It holds most of the life on Earth. It is the blue heart of the planet.” (I must admit that I was surprised to learn that most of the oxygen in Earth’s atmosphere is generated by life in the sea. I thought that trees and plants had a much larger role.)

I am currently reading Earle’s book The World is Blue, where she clearly and beautifully explains the importance of the abundance of fish and other creatures to the health of the ocean and indeed the planet.  Earle writes, “There is no surplus in a natural, healthy system. What appears to be overabundance to human observers is a natural insurance policy against population reduction by diseases, storms, ups and downs of predators and food supply…” and “[S]pecies do not live in isolation. They are integrated into exceedingly complex systems…the first fish to be taken from an unexploited population are the largest…the ‘old timers’…They are also the ones that produce the most offspring.”

So here are my questions: Does anyone know what a truly sustainable harvest of dogfish, Atlantic pollack, and whiting would be? Are we viewing them as so abundant that we think we can eat them on a regular basis? If so, is this a correct assumption?

Sylvia Earle indicates this is not the case at all. On NPR’s The Bob Edwards Show, Earle said that she doesn’t eat fish and instead eats a plant-based diet. In a recent interview in The Guardian, Earle was asked, “What about eating fish sustainably? For instance, trading top predators for smaller fish?”

Earle replied, “I think that’s disastrous, really…. The large fish have to eat the small fish. We have choices; they do not….  And there’s another aspect as well. All fish are critical when you think of them as middlemen, because they consume phytoplankton and zooplankton, the little guys that the big fish cannot access….we shouldn’t take fish on a large-scale basis; there’s simply no capacity left to do this.”

Except for island nations that don’t have much of a choice, Earle believes that fish are wildlife that should be left in the ocean, Earth’s “blue heart,” from which most of our oxygen comes and has developed over hundreds of millions of years.

So, two opposing views. The first, espoused by Keith Shortall’s guests was that even though fish such as cod have been overfished, there are plenty of overlooked and underutilized fish in the sea to eat. And we should do so eagerly. The second, put forth by Sylvia Earle, is that the oceans are in such peril that we shouldn’t be eating fish and seafood on any kind of regular basis. Once in a great while, at the most.

Even though I love seafood and could eat it several times a week, I’m casting my lot with the marine biologist. Sylvia Earle has been studying the ocean for decades and has lived long enough to see the terrible degradation of the world’s oceans as we humans eat our way through the fish and other creatures that live in the sea.

For me and for my husband Clif, it will be mostly plants that we eat.