The invasive blue crabs that made their way to Tunisia from the Indian Ocean via the Suez Canal were not welcome at first but since have turned into a new export. Another species of blue crab that originated in America is causing its share of problems for fisherman right now in Italy.
The Callinectes Sapidus, the blue crab, the Atlantic blue crab, or the Maryland blue crab is threatening Italy’s clam-farming and fishing industries. The Italian government has allocated about $3 million USD to fund the capture of as many blue crabs as possible.
As a past researcher on invasive species, working for CAB Biosciences in Switzerland, I am pretty certain that offering a bounty to catch these crabs will have no impact in the long run. The species, as invaders do, will only be balanced when a natural predator finds a way to keep them in check. Remember when the mayor of Hebron offered a $20 bounty for a truck of dead dogs?
At the same time, the blue crab is the fifth most popular crab in the world market. It is especially sought out in the Asian, United States and Australian markets where it is featured on the menus of many restaurants.
According to Nature, the blue crab in Italy was first observed in the Mediterranean Sea in 1949, where it was probably transported in the ballast waters of transoceanic ships.
“The colonisation took some time, it is a slow process,” says Gianluca Sarà, marine ecologist at the University of Palermo. Before invading the Po River Delta, Atlantic blue crabs have been spotted in other locations in Italy. Established populations were first detected in 2014 in the lagoon of Lesina and Varano, in Apulia.
Climate change is suspected to be one of the reasons the blue crab was able to slide into Italy from the Adriatic Sea. Researchers are now looking on how their colonisation will impact other aquatic sea life and shores.
Invasive species like the Portunus segnis from the Indian Ocean or Callinectes Sapidus, the Atlantic blue crab, lived in ecosystems that that developed over thousands, maybe millions of years. The Suez Canal changed this separation between seas fast and is the reason why the Mediterranean is over-run with jellyfish every summer, making it impossible to swim in places like Israel and Lebanon for fear of getting stung during the hottest times of the year.
Two blue crabs invade. Let’s get those crabs straight
Portunus segnis, is the scientific name for the African blue swimming crab. It is a crustacean, and a swimming crab belonging to the family Portunidae. It is native to the western Indian Ocean, but invaded the Mediterranean Sea via the Suez Canal in Egypt. In 2015 it invaded the Gulf of Gabes, in southern Tunisia. Now the country has dozens of crab-processing plants. “At first fishers wanted this species to disappear, but now they are asking the authorities for regulations to protect it,” says one fisherman.
Another invasive blue crab, the one invading Italy currently is Callinectes sapidus, the Atlantic blue crab, or regionally known in the US as the Maryland blue crab. It is a species of crab native to the waters of the western Atlantic Ocean and the Gulf of Mexico, and it is now introduced internationally. It is also known as the Chesapeake blue crab.
Global shipping industry to blame for invaders
According to The Revelator, “global shipping is moving invasive species around the world.”
They report that “in July 2021 federal agents in New Orleans abruptly ordered the 600-foot cargo ship Pan Jasmine to leave US waters. The ship, which had sailed from India, was preparing to offload goods when inspectors noticed fresh sawdust on the cargo deck and discovered non-native beetles and ants boring into wooden packaging materials. The unwelcome insects included an Asian longhorn beetle, a species that was introduced into New York 25 years ago, where it has killed thousands of trees and cost $500 million in control efforts.
“The crew of beetles aboard the Pan Jasmine is not an isolated incident. That same month bee experts north of Seattle were scouring forest edges for Asian giant hornet nests. These new arrivals, famously known as “murder hornets,” first turned up in the Pacific Northwest in 2019, also likely via cargo ship. The two-inch hornets threaten crops, bee farms and wild plants by preying on native bees. Officials discovered and destroyed three nests.
“And this past autumn Pennsylvania officials urged residents to be on the lookout for spotted lanternflies, handsome, broad-winged natives of Asia discovered in 2014 and now present in at least nine eastern states. Believed to have arrived with a shipment of stone from China, the lanternfly voraciously consumes plants and foliage, threatening everything from oak trees to vineyards.”
Can world governments agree on necessary preventative measures?
