When I interviewed Todd Gardner last month while researching an article on lionfish, he told me he had not seen any of the invasive fishes in New York waters over the past three years. That’s what made last week’s find of a tiny post-larval lionfish* clinging to one of the concrete bridge pilings on the Ponquogue Bridge in Hampton Bays so interesting. Gardner was diving with Noel Heinsohn of the Long Island Aquarium and first reported the sighting publicly in a blog post at Reefs.com.
Gardner, a professor of marine biology at Suffolk County Community College in Riverhead, New York, is well-known for collecting some pretty unexpected post larval and juvenile fishes in his local waters. Spotfin butterflyfish, crevalle jacks, blue and French angelfishes–these are tropical and subtropical species most people don’t associate with New York, but Gardner has collected all of them. These fishes appear to get caught in the strong currents of the Gulf Stream and are swept north, where some may survive until ocean temperatures cool sufficiently in the autumn.
In 2006, Gardner was featured in a New York Times article titled “A Spiny Invader Proliferates in L.I. Waters, and Scientists Wonder About Its Impact.” That summer hundreds of the “alien tropical species” were collected by divers in New York and there were serious questions about what that might mean. Gardner is quoted in the 2006 New York Times piece saying, “For us to be finding that many, there must be thousands and thousands more out there. It’s a population explosion.”
Now he’s not so sure of the correlation between mass sightings in New York and the population levels to the south.
“It seemed, in 2006, like the inundation of lionfish to Long Island waters must be an indication of the state of their population in the Atlantic,” Gardner told me in a June 2014 interview, “but now, eight years later, we haven’t seen anything like those numbers since.” Despite a lot of diving, he’s seen no more than a couple lionfish a year and reports seeing none over the past three years. At the same time, research clearly shows that the population of invasive lionfishes off the Southeastern United States, the Bahamas and the Caribbean continues to grow. “The fact that the Atlantic population seems to keep growing, but sightings in New York have remained pretty scarce, makes me believe that there is not much of a correlation.”
Gardner says it’s probably too early to say whether or not this summer will be like the summer of 2006. “Given how early in the season they have appeared,” he says, “I wouldn’t be surprised if this turns into a year that we see a lot of them.” Even if 2014 does end up like 2006 with hundreds of lionfish sighted in New York waters, Gardner cautions against making any sweeping statements about what it means. According to Gardner, the occurrence or abundance of lionfish on any single year probably doesn’t mean much. “If there comes a time that we start to consistently see them,” Gardner says, “that could be indicative of the overall health or range of the invasive population.”
So why would the numbers of lionfish reaching New York fluctuate so dramatically from year-to-year? Gardner speculates a “lionfish bomb” is the likely explanation. He explains that a lionfish egg mass stays clumped together for much of its development. “This means that a single mass of water carrying a single spawn worth of eggs could deposit in a single bay.” The result? A lionfish explosion in a small geographical area having nothing at all to do with the Atlantic population as a whole.
Overall Gardner says it’s looking like an interesting year for tropicals on Long Island. “The grey triggerfish appeared about three weeks early,” he says, and someone sent him a photo of a not-at-all common glasseye snapper the other day, “The tropical fish abundance and diversity usually peaks around Labor Day, so I will have a much better idea towards the end of August.”
*The lionfish specimen collected last week is probably Pterois volitans, although tissue samples will confirm the species. The closely related P. miles is also established and considered invasive in the western Atlantic, but there have yet to be any confirmed P. miles sightings in New York.