engleski

Brown Trout Salmo cf. trutta L. – a Case Species for Fishery- and Aquaculture-Vectorized Invasiveness

Use of the control region (CR) of mitochondrial DNA (mtDNA) as a molecular marker revealed occurrence of 18 haplotypes in brown trout Salmo trutta from four (Danubian Da, Atlantic At, Adriatic Ad and marmo- ratus MA) phylogeographic lineages in the Danube basin of Western Balkans. Brown trout of the Da lineage aboriginal for the area in concern has a prominent overall diversity Hd = 0.987 ± 0.0097 (SE). Assessment of over 60 brown trout samples revealed that majority (55.7%) is still pristine, with brown tout with only one Da haplotype. The importance of brown trout for fishery has lead to introductions of non- indigenous and domesticated At1, Da2 and Adcs1 haplotypes into nearly 20% of trout streams that are mainly attractive for, and strongly subject to angling pressure. Uncontrolled stockings lasting over a century threatened the mostly streams which hold exclusive, either primitive, i.e., ancient (Da*Vr, Da*Dž, Da-s6), or advanced, i.e., derived haplotypes (e.g., Da*Vl, Da22, Da23c). In addition to widely distributed and indigenous Da1 haplotype, domesticated haplotypes with the long stocking history and of wide distribution were detected. All of them pose a great risk to indigenous brown trout in the recipient area, with the aquaculture and environmental sectors detected as the mostly affected. In addition to adverse effects in conservational sense, those in environmental (e.g., increase in competition and predation), population structure (e.g., loss of co-adapted gene complexes), fishery management (e.g., increase in fishing efforts) and aquaculture (e.g., introduction of diseases) senses should not be neglected. The setting of network for development of a common policy in precautionary trout fishery management and its implementation would stop further deterioration of the conservational status of all brown trout populations, without affecting the trout fishery in Western Balkans. That would lead to the effective control of the trade with brown trout stocking material in the Western Balkans region, with the reliable genotyping of brown trout hatchery brood stocks using both mitochondrial and nuclear genetic markers.

Molecular diversity ; Brown trout ; Non-indigenous strains ; Regional networking ; Invasiveness ; Conservation

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