In just two decades, the species makeup of the Mediterranean Sea has changed, with 55 invasive species calling the sea home, according to a research study that was conducted by scientists with the University of Haifa, Hebrew University of Jerusalem and the Israel Oceanographic and Limnological Research Center. This is the largest influx of foreign species of any marine ecosystem, the study said.
Researchers compared trawler catch data from the time periods of 1990-1994 and 2008-2011. The findings show that the makeup of the fish catch in just 20 years has changed dramatically. The invasive species that made up 29 percent of the catch 20 years ago now comprises more than half the catch today, and have now reached 55 percent of the total biomass in the Mediterranean Sea. The researchers also note that of the 55 invasive species that are now established in the Mediterranean, half of the species were introduced in the last 10 years and six of them are now the most common species found in the eastern Mediterranean. All of the invasive species arrived via the Suez Canal.
The introduction of these species has had a detrimental effect on certain native species, according to the study. For example, a type of sea bream called the jarvida has dropped in fishing catches by two-thirds, while the quantities of an invasive species called barbon has increased, presumably at the expense of the jarvida. The researchers say that fishing limits need to be imposed on the native species to give them a chance to compete against the invasive species.