Dolphin Conservation: Fisheries|Bycatch

Scandal: EU introduction of “floating nets” threatens cetaceans in the Mediterranean

A new EU Regulation regarding the Mediterranean fisheries is of great concern to dolphin conservationists. On December 21, 2006, the “Council Regulation concerning management measures for the sustainable exploitation of fishery resources in the Mediterranean Sea“ came into force. Unfortunately, it has little to do with “sustainability”.

Driftnets were banned in 2002 in the Mediterranean because they were held responsible for the deaths of tens of thousands of dolphins. With the new regulation, these nets are now re-introduced through the “back door”. These new “floating gillnets” hardly differ from driftnets. In a clever move, the EU Commission has simply redefined bottom-set gillnets, which are normally fixed to the bottom. Now the term bottom-set gillnets also includes nets that are fixed to the bottom of the sea and float freely in the water column. They constitute death traps for dolphins, sea turtles, sharks, and seabirds. What’s particularly scandalous: the maximum size allowed for “bottom-set gillnets” has been increased to more than double. While previously each ship was allowed to set a maximum of 5 km of nets, with a maximum drop of 4 m, the permitted length now is 4 to 6 km (depending on the number of fishermen on board), with a maximum drop of 10 m. A net of 500 m in length may even have a drop of up to 30 m.

As a member of the EU Commission has explained to us the increase of net size was merely a regulation of what had previously been common practice. GRD considers this to be an after-the-fact legalization of a certain fishing practice. Greenpeace estimates that between 400 and 500 illegal driftnetters operate in the Mediterranean, using nets of 20 km in length and more. This, too, has now been legalized by the EU: on board a fishing vessel, driftnets and “floating gillnets” cannot be distinguished from one another!
Pursuant to the Regulation, the newly defined “bottom-set gillnets” shall not be used to catch pelagic fish such as tuna or swordfish. Unfortunately, the EU has failed to inform these fish species that they are not allowed to swim into these nets! If caught as by-catch they may be sold nonetheless. This is yet another back door for the unfettered overexploitation of fish stocks!

back to top

Reflective nets: A Solution to the bycatch problem?

300,000 marine mammals are dying in fishing nets worldwide each year. In the North and Baltic seas set gill nets pose a threat in particular to harbor porpoises. The development of dolphin-friendly nets could be a hope for the endangered animals. Sven Koschinski and Prof. Boris Culik, German marine zoologists from Kiel, made behavioral studies involving harbor porpoises at the Canadian west coast to find solutions to the bycatch problem. In the summer of 2003, they studied how harbor porpoises react to a new net material consisting of a barium sulfate nylon mixture. This study was financially supported by GRD, WWF, DUH, and other organizations. First findings are promising.

Sven Koschinski reports:
Conventional nylon nets are difficult to be detected by harbor porpoises, which orient themselves by using sonar clicks. The material produces almost no echo so that the animals swim “blindly” into the fishermen’s set and drift gillnets. Heavy barium sulfate particles mixed into the net fiber can act as acoustic reflectors, allowing the animals to detect the net early enough to avoid it. While initial tests with the new nets had yielded a noticeable reduction in the level of bycatch, subsequent studies led to contradictory results. We wanted to know what precisely happens at these nets in comparison with “normal” nylon nets. Is the reduction in bycatch due to the stiffness of the net fiber or can the material really be better detected? To find out we studied the swimming behavior of harbor porpoises in the vicinity of two nets, a barium sulfate net and a standard net, set by turns in the coastal waters off Vancouver Island, using a theodolite (an instrument used in surveying) for our observations. In addition, a click detector was fixed in the net to record the animals’ echolocation sounds.

Sonar Clicks of Harbor Porpoises Vary

Based on the record of the click sounds, we have been able to clearly identify differences in the harbor porpoises’ behavior. The intervals between the individual sonar clicks were longer at the barium sulfate net than they were at the standard net. These longer intervals imply that an animal “looks” at the net from a greater distance than it does around the standard net, because harbor porpoises first wait for the echo of a click to return before emitting another sound. With greater distances, this takes longer. Early echolocation can make sure that the animals detect the net in time to avoid it. We have thus been able to prove that the net can actually be better detected by the harbor porpoises’ biosonar. This has also been confirmed by subsequent acoustic measurements in a tank. Low additional costs are another advantage: barium sulfate nets cost only 10 percent more than conventional nets, according to WWF. Mass production could reduce this difference even more.

However, the factor of improved detectability only applies when harbor porpoises do use their sonar, which, unfortunately, is not always the case. Yet, in another test we could show that the harbor porpoises’ echolocation activities in the research area could be quadrupled with the aid of sine tones at low sound levels. Therefore, another study regarding a combination of these two methods will be carried out this year. A “warning signal” is to stimulate the animals to echolocate so that they can detect the net and safely swim around it. Since these warning signals are not as loud as those of conventional “pingers” –acoustic harbor porpoise deterrents whose use will be obligatory in the EU for certain high-risk fisheries as of 2005– they contribute significantly less to the noise pollution of the oceans.

back to top

EU Regulation spells death to harbor porpoises
in the Baltic Sea

The EU squandered yet another chance to protect small cetaceans, as a thorough GRD analysis of the new EU regulation to curb small cetacean bycatch has revealed. As always, the fishing nations’ economic interests prevailed over nature conservation. Our analysis has revealed some shocking facts.

The draft regulation has been significantly watered down in its final form. Unlike proposed, there will be no restriction in the length of driftnets used in the Baltic Sea. Most of these nets are between 15 and 21 kilometers in length and are primarily used to target salmon. The use of driftnets will be reduced only gradually and a ban will not take effect until 2008, rather than 2007 as originally planned. The use of bottom-set gillnets, which are commonly considered to pose the greatest risk to harbor porpoises, will not be restricted at all.
Moreover, provision is made for an observer scheme to monitor small cetacean and seabird bycatch in certain fisheries. In contrast to the proposal, however, vessels of a length of up to 15 meters and vessels using pingers are exempt. As of next year, the use of pingers is mandatory in the North Sea and the Kattegat for turbot nets and wreck fisheries. In the Baltic Sea, this applies only to set gill net and driftnet fisheries in two small areas off the southern coast of Sweden. As of 2007, the area shall be extended to include the coast of Mecklenburg-Western Pomerania. The drawback with this regulation is that it only applies to vessels of 12 meters and more in length.
“Owing to an absurd catalog of regulations a mere 2 percent, at most, of the German set gillnet fishermen are required to use pingers. And the success of this measure does not even have to be monitored, since fishermen using pingers are not subject to the observer scheme,” says Sven Koschinski, a German marine biologist and expert for harbor porpoises. The acoustic harassment devices have not yet been sufficiently tested for their potentially adverse effects, according to him. The animals might become habituated or be excluded from parts of their habitat. “If the use of pingers is obligatory for only part of the nets, there is a risk of the porpoises being chased from alarmed into non-alarmed nets, which might possibly lead to an increase in bycatch,” says Koschinski.
The population of harbor porpoises in the Central Baltic Sea, estimated at only 600 animals, has been abandoned to its fate because the new regulation fails to protect this highly endangered population. The trawl fisheries, which are implicated in the deaths of thousands of dolphins in the Atlantic, do not have to implement any measures other than an observer scheme.

Worldwide, 300,000 marine mammals are officially estimated to die in fishing gear every year, above all dolphins and harbor porpoises. Alone the set gillnets used in the North and Baltic Seas are responsible for the annual deaths of more than 8,000 harbor porpoises. The self-praised measures agreed by the EU will unfortunately not change much in this respect. Politicians continue to merely sit by and watch. If we only wait long enough we will no longer need any protective measures…

back to top

Home : Magazine : Donation : Fisheries|Bycatch