Conservation threats to dice snakes (Natrix tessellata) in Golem Grad Island (FYR of Macedonia)

Abstract

Most conservation efforts are channeled toward highly endangered species. However, snake populations decline rapidly worldwide, and many species that are currently classified as not threatened (e.g. LC - least concern, IUCN Red List) may well rapidly fall into the threatened categories. Yet, common species attract little attention. The principle, that it is more efficient to prevent disasters than to cure effects, is not taken into account. Dice Snakes (Natrix tessellata) offer a typical example of this situation. This species is one of the most widespread and polymorphic snake of the planet. Very large populations occur in the Balkans. On Golem Grad Island (the single island of FYR of Macedonia), a remarkable population of Dice Snakes suffers from recent assaults. Thousands of snakes are killed every year in the nets set by poachers, notably gravid females, raising population viability concerns. Protecting Dice Snakes, other reptiles (e.g. tortoises, vipers, and lizards) and the whole eco-system of Golem Grad Island would require moderate efforts: application of official rules, summer attendance, delivery of official permits to local people (including fishermen), and controlling tourism. In this paper, we addressed a central issue: does illegal fishing represent a potential threat to Dice Snakes? Our data suggest that recent increase of illegal fishing correlates with population decline.