Assessment of Stocking Activities on the Native Brown Trout Populations from Nestos River (Southern Balkans) Inferred by mtDNA RFLP and Sequencing Analyses

Ioannis A Giantsis,Emmanouil Koutrakis,Argyrios Sapounidis,Apostolos P Apostolidis

doi:10.3390/app11199034

Ioannis A Giantsis, Emmanouil Koutrakis + Show 2 more

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https://doi.org/10.3390/app11199034

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Abstract

Alien fish introductions, conducted towards the ichthyofauna enhancement in local drainages, have been occasionally proved harmful for the indigenous freshwater fish populations. The present study was designed to assess the impact of stocking activities, carried out in the past decades with fingerlings originating from Acheloos river hatcheries, on the native trout (Salmo sp.) populations of Nestos River, Greece. Trout specimens collected from several tributaries of Nestos River and were analyzed by means of PCR-RFLP and sequencing targeting the mitochondrial ND5-ND6 genes and the entire control region, respectively. It should be mentioned that trouts from Acheloos mainly belong to the marmoratus mitochondrial DNA (mtDNA) lineage, while the autochthonous trouts from Nestos belong to the Adriatic lineage. Both methodologies demonstrated that most samples from the three tributaries located at the lower part of Nestos constitute offspring of the fingerlings transferred from Acheloos hatcheries. Therefore, these tributaries have been strongly affected by stocking activities with a potential complete loss of their autochthonous trout. On the other hand, it seems that trout populations from higher altitude tributaries have not been affected by stockings. Hence, efforts should be undertaken in order to prevent the prevalence of the non-indigenous translocated Salmo in higher altitude tributaries, in conjunction with a management plan designed for the total trout populations from the area, speaking of which it has been recently included to the National Park of Rodopi Mountains.

Highlights

Intentional introductions of alien fish species, or translocations of fish populations belonging in the same species, genus or family, to different ecosystems, have been taken place in Greek inland waters for nearly one hundred years, aiming to the enhancement of the ichthyofauna of several local drainages [1]
As a result of these stocking activities, the non-indigenous populations or species have hybridized with the local ones putting in danger their unique genetic profile [4]
It must be noted that Nestos River together with its tributaries in the area, in the last decade, have been included in the protected area of the National Park of Rodopi Mountains, Administrative Region of Eastern Macedonia and Thrace, Greece

Summary

Introduction

Intentional introductions of alien fish species, or translocations of fish populations belonging in the same species, genus or family, to different ecosystems, have been taken place in Greek inland waters for nearly one hundred years, aiming to the enhancement of the ichthyofauna of several local drainages [1]. These actions have been proved unnecessary, and harmful for the indigenous freshwater fish populations [2]. Such incidents, include the numerous, still debatable, Salmo taxa described in Greece, which exhibit considerably high levels of phenotypic and genetic variation [3]. The Nestos (Mesta) River in north-eastern Greece represents such a case, where the local populations of trout, inhabiting the tributaries of the river, have been affected by stocking activities conducted many times in the past. It must be noted that Nestos River together with its tributaries in the area, in the last decade, have been included in the protected area of the National Park of Rodopi Mountains, Administrative Region of Eastern Macedonia and Thrace, Greece

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