Scup and grasshoppers

A mild winter has been hard on some.

A recent shot of a brown-morph Chortophaga viridifasciata nymph. —Courtesy Matt Pelikan

Thanks to Cynthia Aguilar of West Tisbury for providing a delightful follow-up on my Jan. 26 “Wild Side” column on a massive die-off of scup in the Lagoon. The column detailed the death of hundreds or thousands of scup that succumbed to a sudden drop in water temperature. Such events seem to be just common enough so that everybody knows they happen, but just rare enough that nobody can recall a specific instance. But Cynthia gleaned a historical reference from a quirky little history of the peninsula now known as Hines Point, self-published in 1907 by C.G. Hine. (The text of this short document is available here.)

The story goes back to the time of Grey’s Raid on Sept. 10, 1778, during the American Revolution. British Major-General Charles Grey, seeking provisions to support British troops in the New York area, visited the Vineyard (as well as Fairhaven and New Bedford) with a powerful fleet and demanded tribute of livestock. From the Vineyard, Grey extracted some 10,000 sheep and more than 300 head of cattle — surely a high percentage of the animals Islanders depended on for income and for food through the winter. Isolated to start with, and especially vulnerable because British naval power blocked the Island’s usual supply line from the mainland, the Vineyard faced a winter of hunger.

But the situation was eased somewhat, according to Hine’s history, by a massive kill of scup, “a shower of manna in the shape of frozen fish [that] saved the people of the Island from starvation.” As with the scup kill this past January, it sounds as though the mortality in 1778 was concentrated on the Lagoon. No date is given for the event, but since such kills depend on a sudden plunge of water temperatures into the 30s, it presumably occurred some weeks after General Grey absconded with the Island’s livelihood.

After my scup column appeared in late January, I received a voicemail from my friend Jim Feiner, an able fisherman living in Chilmark. Jim reminded me that scup is one of his favorite fish for eating, and asked if I thought the dead scup on the Lagoon were suitable for salvage. Clearly ancestral Islanders once had the same thought, which is not a bad one: scup meat is noted for deteriorating somewhat less quickly than the flesh of many fish, and since the fish died of cold and then were beached in temperatures around freezing, they may have stayed edible for quite a while.

I got Jim’s message, though, some 10 days after the fish had died, and despite the cold, they must surely have been in dubious condition. Moreover, Nelson Sigelman, fisherman-in-residence at the Times, had mentioned to me that the Massachusetts scup season closed on Dec. 31, making the harvest of scup in January, even if they died of natural causes, probably illegal. In any case, Jim’s question was moot by the time I got it, since a high tide had washed the fish corpses away.

It feels a bit like tempting fate to speak of the winter of 2015-2016 in the past tense. But if this season was a rough one for scup, it appears to have been benign from the perspective of many other wild species. The conditions of this winter — generally mild temperatures (despite a couple of nights of exceedingly low temperatures) and relatively little snow cover — will no doubt affect wildlife populations in complicated ways as the breeding season approaches.

One example might be the grasshopper population in my yard in Oak Bluffs. Regular readers will know that I’m a bit obsessed with these insects, a particular species (Chortophaga viridifasciata) that overwinters as semi-active, partially developed nymphs (rather than as eggs, like most grasshoppers). As March began, numbers of nymphs in our yard were larger than I had ever seen them at this point in the season: On recent warm days, I’ve quickly tallied 50 or more individuals in just a small portion of the yard.

But if the milder-than-normal season has helped these tiny grasshopper nymphs survive, the benefit has not been evenly distributed within the population. Chortophaga occurs in two distinct color forms, or “morphs”: brown and green. In early January, I was finding roughly equal numbers of the two variants. But as March began, the green form was almost absent, and the robust population consisted almost entirely of brown individuals.

My guess is that the shift resulted indirectly from the relative lack of snow cover this winter. Our yard is visited occasionally by flocks of birds: fish crows, starlings, and now that the first migrants have returned, grackles and red-winged blackbirds. My grasshoppers figure prominently on the menu, and my guess is that green ones are much more visible than the brown ones against a background of dead vegetation. Limited snow cover, in other words, exposed the population to unusually high, but also highly selective, levels of predation.

The scup and the grasshoppers both found out that a mild winter comes with certain perils. It will be interesting to see how the coming spring unfolds.