If you are familiar with New England Ocean Odyssey, you know we love Cashes Ledge, a majestic 25-mile undersea mountain range and biological hot spot in the Gulf of Maine.
You know that this natural laboratory offers scientists the chance to explore a relatively pristine and unique ecosystem, to discover and observe rare and endangered species, and to hypothesize about what the greater Gulf of Maine looked like before the commercial fishing industry existed.
You know that Ammen Rock, the highest peak in the mountain chain, rises from a depth of 460 feet all the way up into the photic zone (exposure to sunlight), just 40 feet below the ocean’s surface. And you know that Ammen Rock disrupts the dominant Gulf of Maine current, swirling nutrient- and oxygen-rich waters from the seafloor to the top of the water column, providing ideal conditions for a huge array of marine life including sponges, corals, anemones, predatory fish, sharks, whales, and more.
But what specific special species reside at Cashes Ledge, and what migratory visitors stop by throughout the year? Let’s dive a little deeper and find out!
1. (Unclassified) Blue Sponge
This species is so incredibly rare, it hasn’t even been sighted anywhere apart from the rocky walls of Cashes Ledge, let alone taxonomically classified. Needless to say, we have a lot to learn about this species. Cashes is also home to a variety of bright red, orange, and yellow sponges, including mounding sponges as big as footballs!
Cod swim under a wall of sponges and other invertebrates. Image via NOAA/ONMS
Sponges are primitive creatures that latch on to hard surfaces anywhere from the intertidal zone to the deep ocean floor. They filter feed by absorbing tiny organisms through incurrent (think “inbound”) pores and excreting waste through excurrent (“outbound”) pores. Many sponges can reproduce either sexually or asexually.
2. Red Cod
You’ve read about, seen, and probably eaten Atlantic cod…but have you ever heard of red Atlantic cod? While genetic testing has yet to determine if this variation is a distinct species, Graham Sherwood, Research Scientist at the Gulf of Maine Research Institute in Portland, Maine, hypothesizes that it is not. All cod eat high levels of carotenoids (natural pigments found in organisms such as crabs and worms), so it’s no surprise that some cod are red in color. But why are some red while most are olive-colored?
An olive cod (top) and a red cod (bottom) swim through kelp forests at Cashes Ledge. Images via Brian Skerry for New England Ocean Odyssey.
Sherwood’s theory is that the red coloring is an adaptive advantage. Red cod typically permanently reside in shallower kelp forests, while olive-colored cod roam around deeper waters in the North Atlantic. The red coloring may be a U/V protectant or a form of camouflage for shallower waters. We’ll have to stay tuned to find out if red cod are a separate species, or if they are just a colorful variation of olive-colored Atlantic cod.
Check out more Brian Skerry photos of red and olive-colored cod at Cashes Ledge.
3. Christmas Anemone
Urticina crassicornis, the Christmas anemone, resides on rock faces at depths up to about 100 feet and may grow to be a foot tall and 8 inches in diameter. It feeds on crabs, urchins, mussels, gastropods, chitons, barnacles, and fish by stinging and stunning prey with venomous cells found in the anemone’s tentacles.
The candy-striped shrimp, Lebbeus grandimanus, is immune to the Christmas anemone’s sting; the two organisms live in a commensal relationship whereby the anemone provides shelter for the shrimp, and the shrimp does not affect the anemone.
A Northern red anemone on a rock wall at Cashes Ledge. CLF/Brett Seymour.
Porbeagle, Lamna nasus. Credit NMFS/E. Hoffmayer, S. Iglésias and R. McAuley.
No, that’s not a white shark – it’s the great white’s lesser known relative, the porbeagle, Lamna nasus. The porbeagle can be easily distinguished from a white shark by its second dorsal fin (that tiny second bump on the shark’s back before its tail). These big guys can grow up to 11 ½ feet long and are highly migratory throughout the Northwest Atlantic. They tend to stay out of shallow waters along the coast, preferring pelagic waters from the surface to depths of 1000 feet. In the Gulf of Maine, they feed on mackerel, herring, other small fish and sharks, and squids.
NOAA listed the porbeagle as a “Species of Concern” for the Northwest Atlantic stock in 2006, the same year that the International Union for the Conservation of Nature listed the subpopulation as endangered. Since the 1960s, overfishing has been a major threat to porbeagles, which are slow-growing with low productivity rates, making it difficult for populations to recover. In the U.S., the species is managed by the Highly Migratory Species Fishery Management Plan. NOAA’s National Marine Fisheries Service is currently reviewing two 2010 proposals to list the porbeagle on the Federal List of Endangered and Threatened Wildlife under the Endangered Species Act.
5. North Atlantic Right Whale
The waters off the coast of New England get some magnificent, gigantic visitors. Endangered North Atlantic Right Whales, Eubalaena glacialis, hang out around New England and the Bay of Fundy in the summer and fall to feed on zooplankton and raise their young. They move about the Gulf of Maine in a regular pattern, often stopping at Cashes Ledge, where regular circulation of the water column produces plankton-rich waters. In the winter months, the whales typically migrate to birthing grounds in the coastal waters off the southeastern United States.
The North Atlantic Right Whale was subject to intensive whaling from the 1500s through 1935; populations off the east coast of North America are still struggling to recover, due in large part to boat collisions and entanglement in fishing gear.
A North Atlantic Right Whale in Cape Cod Bay in front of Provincetown, MA. Image via Brian Skerry for New England Ocean Odyssey.
6. Bubble Gum Coral
Deep-water coral colonies thrive in the cold, nutrient-rich waters of Cashes Ledge. Paragorgia arborea, nicknamed bubble gum coral for its pink color, is a fan-shaped coral (aka “sea fan”…creative, right?) that typically inhabits exposed locations at depths of 600 to 4,300 feet. It can grow up to six meters tall, making it a real treasure for divers to spot. At Cashes Ledge, Paragorgia inhabits the hard-bottom basalt substrate.
Deep sea corals grow slowly and may live to be thousands of years old, making them extremely susceptible to lasting damage from bottom trawlers. One sweep of a trawl net can destroy centuries of growth – a problem not only for the corals, but also for the marine species that use the corals as a nursery and refuge habitat.
Paragorgia colonies in the New England Seamount chain. Image via NOAA Ocean Explorer.
These are just six of the marvelous, charismatic species that depend on the nutrient-rich waters of Cashes Ledge. If we are to protect them, we must start by protecting Cashes Ledge.