North Carolina State University engineers have created a non-toxic ship hull coating that resists the build up of barnacles.

Barnacles that colonize the hull of a ship augment the vessel’s drag which in turn increases fuel consumption. After no more than six months in salt water, the fuel consumption of a ship has normally swelled substantially, forcing the ship owner to either spend more money on fuel or to remove the ship from the water and place it in a dry dock where it can be cleaned. Both alternatives are naturally costly, and for many years ship owners fought barnacles by regularly coating ship hulls with substances toxic to barnacles. Unsurprisingly, these substances turned out to be toxic to a wide range of other marine life as well, including fish, which caused most countries to ban their use.

Ships are not the only ones colonized by barnacles. In the wild, it is common to see barnacles attached to a wide range of marine species, such as whales and sea turtles. One type of animal is however usually free of barnacles: the sharks. Unlike the smooth-skinned whales, sharks tend to have rough and uneven skin, and this might prove to be the salutation for ships as well.

The new hull coating created by Dr. Kirill Efimenko, research assistant professor in the Department of Chemical and Biomolecular Engineering, and Dr. Jan Genzer, professor in the same department, contains nests of different-sized “wrinkles” which makes the surface rough and uneven, just like the skin of a shark.

The wrinkly material was tested in Wilmington, N.C and remained free of barnacles after 18 months of exposure to seawater. Flat coatings made of the same material were on the other hand colonized by barnacles within a month.

“The results are very promising,” says Efimenko. “We

are dealing with a very complex phenomenon. Living

organisms are very adaptable to the environment, so

we need to find their weakness. And this hierarchical

wrinkled topography seems to do the trick.”

Efimenko and Genzer created the wrinkles by stretching a rubber sheet, exposing it to ultra-violet ozone, and then relieving the tension, causing five generations of “wrinkles” to form concurrently. After that, the coating was covered in an ultra-thin layer of semifluorinated material.

“We are not asking fishermen to stop fishing, only asking them to start releasing their catch,” says marine scientist Edd Brooks.

Brooks is a scientific advisor for the not-for-profit Company Shark-Free Marina Initiative, SFMI, who has just instigated a new strategy for preventing the deaths of millions of sharks belonging to vulnerable or endangered species.

The Shark-Free Marina Initiative works by prohibiting the landing of any caught shark at a participating marina. The initiative is based on the Atlantic billfish model which banned the mortal take of billfish in the 1980’s to give severely depleted populations a chance to recover.

By promoting catch-and-release and working closely with marinas and game fishing societies, SFMI hopes to win over the fishing community. Other important allies in the endeavour are competition sponsors and tackle producers.

Collaborating with the Fisheries Conservation Foundation in the USA and the Cape Eleuthera Institute in the Bahamas, SFMI has already gained the attention of marinas and non-profits nation-wide.

Enlisting the aid of anglers
By practising catch-and-release, sport fishers can not only decrease their impact on shark species; they can also actively aid ongoing research studies by collecting valuable data.

“Although the number of sharks killed by recreational fishermen each year is dwarfed by commercial catches, the current crisis facing shark stocks requires action wherever possible.” says Brooks.

During the last five years, the average number of sharks harvested annually by sport- and recreational anglers in the United States exceeded half a million. The outlook for these shark populations seem even graver when you take into account that many of the sharks targeted by fishermen are large, breeding age specimens belonging to endangered or vulnerable species. Removing so many sexually mature specimens from a population each year naturally has a major impact on its chances of long-term survival.

“Shark-Free Marinas is a necessary response to the culture of mature shark harvest” says SFMI’s Board Director, Marine Biologist Luke Tipple “Our effect will be immediate, measurable and, together with saving millions of sharks, will establish a new global standard for responsible ocean management. There’s a lot of talk about the atrocity of shark fining and fishing worldwide, but not a lot of measurable action towards reversing the damage. The time has come to stop simply ‘raising awareness’ and start implementing sensible management techniques to protect vulnerable species of sharks from inevitable destruction.”

You can find more information at www.sharkfreemarinas.com.
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