Electropositive shark repellent Atlantic longlining vessels in 2008. As expected, teleosts (bony fish) are not repelled by the electropositive metal’s cation liberation in seawater. This is because teleosts lack the ampullae of Lorenzini. Teleost response was confirmed using captive Cobia ("Rachycentron canadum") and Pacific halibut ("Hippoglossus stenolepis"). In July 2008 swordfish ("Xiphias gladius") catch was reported on experimental hooks treated with electropositive metal. As with all shark repellents, 100% effectiveness will not be achieved with electropositive metals. The metals are particularly effective when the shark is relying on its electrosense. It is likely that electropositive metals are ineffective for deliberately stimulated (chummed) sharks,
Fish anatomy and various processes which project from the centrum or arches. An arch extending from the top of the centrum is called a neural arch, while the hemal arch or chevron is found underneath the centrum in the caudal (tail) vertebrae of fish. The centrum of a fish is usually concave at each end (amphicoelous), which limits the motion of the fish. This can be contrasted with the centrum of a mammal, which is flat at each end (acoelous), shaped in a manner that can support and distribute compressive forces. The vertebrae of lobe-finned fishes consist of three discrete bony elements.