Driftnetting continues in several countries with an estimated 600 boats working in the
Mediterranean despite a ban on the fishery. This sperm whale off the southern coast of Turkey was
found and disentangled in 2002. Many others are not as fortunate.
Watch a short video of this sperm whale entangled in a driftnet and the efforts of scientist Dr. Bayram Ozturk to
release it with the assistance of the Turkish Navy.
Language - Turkish with English subtitles
Photo & Video courtesy of Bayram & Ayaka Ozturk of TUDAV
October 18, 2004
'Walls of Death' - Driftnetting in the Mediterranean
Real Audio Report
This is Genevieve Johnson speaking to you from the Odyssey in the Mediterranean Sea.
As we discuss extensively in previous Odyssey reports, an estimated 300,000 cetaceans (whales, dolphins and porpoises) are killed around the world each year as a result of entanglement in fishing gear. The Mediterranean Sea is no exception.
Historically, driftnets were the most significant source of entanglements for cetaceans. Driftnets are large, floating nets made of a mesh of monofilament or multifilament line, deployed in the open ocean. They are designed primarily to trap and entangle large fish such as tuna and swordfish. They can be up 50 kilometers (30 miles) long and hang vertically 20-30 meters from the surface. Left to drift freely, the design of the nets means they are not selective in what they catch, resulting in a high level of bycatch - the catch of non-target species.
Because driftnets are generally deployed in the open ocean, they are likely to entangle large pelagic species, including whales, dolphins, sharks, turtles, rays and seabirds. Populations of these animals are particularly vulnerable to excessive losses, as they are generally long-lived and reproduce slowly.
The propensity for driftnets to kill so many large animals earned them the nickname "walls of death". At the peak of driftnetting activity, there were cumulatively thousands of miles of driftnets fishing the oceans at any one time - reportedly more than enough to circle the earth. As fleet and net sizes increased this highly indiscriminate fishing method gained notoriety and was widely considered a threat to the effective conservation of living marine resources, particularly of highly migratory species.
Beginning December 31, 1992, the United Nations banned the use of large-scale driftnetting operations on the high seas. Many nations followed suite, banning the use of driftnets in their own waters. Also in 1992, the (then) European Economic Community declared it illegal to use driftnets greater than 2.5 km in length in European waters. When this did not solve the problem, the European Union further banned driftnets of all sizes beginning January 1, 2002.
Despite their illegal status, almost twelve years after the UN ban on driftnetting, these nets are still in use in the Mediterranean Sea and continue to kill numerous sperm whales, dolphins, sharks, rays, and turtles, each year.
Dr Antonio Di Natale, a fisheries biologist who is Scientific Director of the Genoa Aquarium in Italy, Assistant Director of the International Commission for the Conservation of Atlantic Tuna (ICCAT), and an expert in cetaceans who regularly disentangles sperm whales caught in driftnets, comments on the ban.
Dr. Antonio Di Natale:
"It was not so easy to do this [ ban the fishery ] because this was a traditional fishery and it was necessary for fisherman to use long nets because they were targeting swordfish, which is not a schooling species so they only have a few opportunities to catch enough specimens to survive."
Within the Mediterranean, driftnet fishing continues to take place illegally by fishermen from a number of nations. Efforts by countries such as Italy to subsidize fishermen to decommission their boats were only marginally successful.
This sperm whale in the Mediterranean has a driftnet around its tail.
According to a summary of records from the waters of Spain, France and Italy between 1971-2003,
229 sperm whales were reported as stranded, entangled in fishing gear or carrying entanglement scars.
Photo courtesy of Dr. Alexandros Frantzis and the Pelagos Cetcean Research Institute
Dr. Antonio Di Natale:
"From our research it was pointed out that below 7 or 8 kilometers [in net length], this fishery is not economically valid. So even imposing [a limit of] 2.5 kilometers that was stated by the UN resolution in the beginning was not valid at all. Then there was a decision not to carry on any other observer program but to try to ban this fishery without any further understanding. That's a pity because we never tried to manage this fishery, in reality, and from my point of few it was possible to try to manage this fishery, reducing the net length, certainly reducing the fleets and setting up a good observer program just to provide good scientific data."
According to some scientists if the fishery was managed there could be more effective control. Because driftnets are illegal, states will not admit formally to their use, or are unable to monitor the practice within their waters, and therefore no data on the targeted catch rates or the associated bycatch rates are available for driftnet fisheries. Bycatch rates in driftnets can for the most part be determined only from animals that wash ashore, and as few individuals taken as bycatch actually make it ashore, these only represent a fraction of the actual bycatch rates. The capture of marine mammals has been a particularly sensitive issue, and fishermen who accidentally catch whales or dolphins are unlikely to report it. It is even controversially suggested that the impact on cetaceans is almost as devastating now that the fishery is completely illegal.
Researcher Barbara Mussi of Delphis, a cetacean conservation organization based in Naples, Italy recently reported seeing 22 different driftnetting boats off the island of Ischia, Italy within a 24-hour period. Ocean Alliance President Dr. Roger Payne observed driftnetting boats docked in the harbor of Sorrento, Italy earlier this year while the meeting of the International Whaling Commission took place in the city - during which the mortality of cetaceans through entanglement in fishing gear was extensively discussed.
Driftnetting practices, whether legal or illegal, have historically had devastating consequences for both large and small cetaceans in the Mediterranean Sea. Between 1986 and 1990, 83% of all cetacean strandings could be attributed to driftnets. At the peak of driftnetting, an annual bycatch of over 8,000 cetaceans was estimated for Italian seas alone. These catch rates were undoubtedly unsustainable for the species most affected, including striped and common dolphins, and sperm whales. Between 1986 and 2000, 64 sperm whales in Italy were killed as a result of entanglement in fishing gear, and probably most if not all of these were from driftnets.
Dr. Antonio Di Natale:
"Of course the main problem is with sperm whales.
For the fin whales we don't have this problem -we know of only a few cases of fin whales entangled in the Med - because the shape of the body is completely useful for the fin whale to escape from a driftnet. It is a pointed shape so they can pass over or below the driftnets. It is not like this for sperm whales. Sperm whales are like a wall crashing against another wall. The head is so big, it crashes against the net and the net then goes around the body and gets the sperm whale entangled in a few seconds. The second movement then makes the situation much worse. It becomes worse and worse, minute-to-minute. So, very often when we find sperm whales, we find them completely entangled in the nets, sometimes with hundreds of meters of nets around their body so it is a difficult duty to release them.
Personally I have rescued 14 sperm whales and assisted in the operation in 18 occasions. This year we had 8 sperm whales entangled in Italy, all in the same area, the southern Tyrrennean Sea. One of these animals died, and it died almost immediately, within the same day, possibly due to the stress."
This ariel view of a fin whale shows the shape of its head
making it easier to pass above or below a driftnet.
However, the large, blunt square head of
a sperm whale, shown here from a frontal perspective, can crash against the wall of net,
entangling the animal almost immediately.
Photos : Chris Johnson
While no one knows exactly how many sperm whales are resident in the Mediterranean Sea, most estimates number in the hundreds. With such a small number of animals there are concerns over the impact of this illegal fishery on this isolated population.
Dr. Antonio Di Natale:
"As far as we know there is still illegal activity going on by several countries in the Med. There is still a huge Moroccan fleet, an important fleet in Turkey, another one in France, still vessels carrying on with this illegal fishery in Italy and maybe a few vessels still fishing in Spain and other countries, including Monaco.
Right now we strongly suspect that the total number of illegal fishing boats all over the Med is over 600 vessels with nets having an average length between 7 and 9 kilometers.
Most of the concentration is around the Strait of Gibraltar which is a very sensitive area for the migration of most marine mammals and the biggest fleet right now is still in Morocco."
Fortunately, the press and the public are starting to pay attention to the fact that driftnetting still occurs following a few high-profile entanglements of sperm whales in the Mediterranean Sea. However, it will take public pressure, governmental will and alternatives for fisherman before any significant change will take place. Meanwhile, for the whales' unfortunate enough to encounter a driftnet,
In our next Odyssey log, Dr. Tony Di Natale discusses his personal experience with disentangling sperm whales.
- Giuseppe Notarbartolo di Sciara, Giovanni Bearzi, Ana Canadas, Alexandros Frantzis -
High mortality of sperm whales in the north-western Mediterranean, 1971-2003 (2004).
- Biodiversity Impact of the Moroccan Driftnet Fleet Operating in the Alboran Sea (SW Mediterranean). WWF Mediterranean Program Office. October 2003.
- Lauriano, G., Fortuna, C.M., Romeo, T., Canese, S., and Greco, S. - An update on sperm whale status in the Southern Tyrrhenian Sea:
Overview from stranding report. Journal of Cetacean Research and Management.
- A. Miragliuolo , B. Mussi and G. Bearzi - Observations of driftnetting off the island of Ischia, Italy,
with indirect evidence of dolphin catch.
- Silvani, L., Gazo, M., and Aguilar, A. - Spanish driftnet fishing and incidental catches in the Western Mediterranean.
Biological Conservation (90). 1999.
Log written by Genevieve Johnson.
Special thanks to Sarah Smith for additional research.