A Thorny Problem

Last week, Defenders and our conservation allies submitted a petition to the National Marine Fisheries Service (NMFS), asking the agency to list the thorny skate under the Endangered Species Act (ESA). Back in 2011, the agency found that the skate did indeed warrant protection – but it soon reversed course, stating that no protection was necessary. The result: the species continued to decline. In fact, the population has been in a nosedive for forty years. The science is clear – we are long overdue to protect the thorny skate.

First things first: What is a skate? These animals look similar to stingrays, minus the stinging spine. They lay eggs instead of giving birth to live young, and prefer deep waters. As the name suggests, the thorny skate has large thorns (11 to 19 of them) along its back and tail. The species is also known as the “starry skate” because some of the thorns on the brown fins have star-shaped bases. Females become even thornier than males as they mature, and adult thorny skates can grow to be more than three feet long.

The thorny skate inhabits the Northwest Atlantic, mainly in Canadian waters and the Gulf of Maine, as well as the eastern North Atlantic from Greenland to the English Channel. The expert scientists at the International Union for Conservation of Nature (IUCN) determined the thorny skate is “vulnerable” globally and “critically endangered” in U.S. waters. We are urging the agency to protect the Northwest Atlantic population of thorny skate or at the very least those found in U.S. waters.

Thorny skates live to be about sixteen years old, but don’t reach sexual maturity until they’re eleven years old — almost three quarters into their lifespan (imagine if humans didn’t start having kids until their 50s or 60s!). Female thorny skates lay around forty eggs per year, but only about fifteen hatchlings survive annually. That 38% success rate can be problematic for a species that arrives relatively late to the reproductive game. It becomes even more of a problem when the species’ population starts to decline – as the thorny skate’s has been doing for decades.

Thorny skates live in cooler waters along the ocean floor, skimming over sand, gravel, pebbles, shells, and mud. They’re not picky eaters, with the larger skates preying on squid and fish, while smaller ones prey on worms, shrimp, crabs, and other bottom-dwelling invertebrates.

Because the thorny skate prefers the ocean floor, it’s especially sensitive to a fishing practice called trawling. This is when fishermen drag large nets along the ocean floor to catch a wide variety of fish and other creatures. They may not be intending to catch skates, but the skates will be swept up into the nets along with everything else. Even if they are quickly thrown back into the sea after being brought aboard the ship, thorny skates usually die after being caught because they’re often injured, making them more vulnerable to predators.

In 2003, due to the species’ rapid decline, NMFS banned fishermen from landing or possessing thorny skates. But this measure didn’t have any real impact because fishermen were not required to identify the species of skate they brought to shore until 2014. So for more than ten years, 100% of skates brought to shore were reported as “unclassified.” Thankfully that loophole is now closed, but thorny skates are still caught illegally. When only skate wings are brought to shore, they’re even harder to identify because the species’ unique feature is its thorny spine, not its brown wings.

With population numbers at an historic all-time low, an ESA listing would provide hope for the thorny skate to escape extinction. The species would gain significant legal protections to ensure its survival and recovery, including a focused recovery plan identifying specific management measures that could be taken to help the species recover to healthier population levels. The Atlantic salmon population in the Gulf of Maine was in a similar situation, where NMFS had created a plan to manage the fisheries and had prohibited landing and possession, but the species continued to decline. When the agency finally listed the Atlantic salmon, created a recovery plan, and designated critical habitat, the species slowly started to recover. With our petition to NMFS to list the Northwest Atlantic population of thorny skate, we hope this species can have a similar outcome. From here, the agency has ninety days to decide whether listing the thorny skate may be warranted, so stay tuned for the next development!