From Practical Fishkeeping:
Possible new pike species discovered
Researchers at the University of Perugia in Italy are calling for a ban on the relocation of pike from countries north of the Alps into Italian fisheries, after they discovered native fish were likely to be a different species.
The Northern pike, Esox lucius … is a widely distributed species, found throughout much of Europe, North America and Eurasia and has also been introduced to many other countries, often with damaging impact to native fish populations.
Until now it had been assumed that fish from south of the Alps were the same species, but the Italian teams research into the differing DNA of the two populations supports their theory that these southern fish are actually a entirely new species, and not simply a geographical variant, as samples from Northern European fish show them to be genetically more similar to American or Chinese populations than fish from Southern Europe.
The taxonomy of Esox lucius has remained unchanged since it was first described by Linnaeus in 1758, but as a result of this new insight which shows that the Italian pike are significantly different at phenotypic, genotypic and geographical levels, the new species Esox flaviae, the Southern pike has been proposed.
This discovery is not only a major coup for the researchers due to the rarity of new fish discoveries in Europe, but also has major implications for the management of fisheries. The pike is a extremely popular target for recreational anglers, and dwindling populations in some areas as a result of this has led to the introduction of juvenile fish from healthy populations in other areas to bolster numbers. Worryingly this practice could lead to hybridisation between the two species, so for this reason the team are calling for a ban on the introduction of Northern pike.
For more information see the paper; Lucentini L, Puletti ME, Ricciolini C, Gigliarelli L, Fontaneto D, et al. (2011) Molecular and Phenotypic Evidence of a New Species of Genus Esox (Esocidae, Esociformes, Actinopterygii): The Southern Pike, Esox flaviae. PLoS ONE 6(12): e25218. doi:10.1371/journal.pone.0025218
The richness in native fish of Mediterranean rivers can be improved with simple measures: here.
Dutch pikes cannot survive in salt water: here.