Genetic characterization and artificial reproduction attempt of endemic Sardinian troutSalmo truttaL., 1758 (Osteichthyes, Salmonidae): Experiences in captivity

Abstract

Native species of Sardinian brown trout (Salmo trutta) have declined drastically because of the introduction of non-native salmonids, overharvesting, and habitat degradation. One approach to conservation of declining species is to establish new populations through repopulation with genetically certified fish. In this study, samples of brown trout from seven rivers in Sardinia were analysed to look for the presence of pure individuals of the endemic Sardinian trout. Analyses of the mitochondrial DNA control region and the LDH-C1* gene revealed the presence of non-endemic and hybrid individuals in four of the seven rivers analysed. In addition, we reared a stock of native Sardinian trout at the experimental fish farm of Sadali and had them reproduce artificially. This experiment provided more knowledge about the incubation phase, hatching, reabsorption of the vitelline sac and the initial phases of growth, which can be used to develop more optimal management of this resource.

Restoration of native Mediterranean brown trout Salmo cettii Rafinesque, 1810 (Actinopterygii: Salmonidae) populations using an electric barrier as a mitigation tool

“…Considering the genetic analysis reported in previous studies (Sabatini et al 2011) we decided to remove all the trout present in the headwater of Ermolinus stream. The fish were removed using two motor-powered, backpack-mounted electrofisher units (5.2-2.8 Å, 230-400 V, 1300 W).…”

“…The fish used in the experiment were hatchery-reared genetically characterised native brown trout (Sadali fish farm, Sardinia, Italy) (Sabatini et al 2011). After the second eradication, a second phase of stocking activities was conducted in 2014 and 2015 using parr and adults (N = 135, from age 0+ to 3+) obtained from the same fish farm.…”

“…Historic literature was used, as well as information from the Forest Guard, local individuals and fishermen, to assess the current presence and distribution of native trout in the study area (Pomini 1940;Cottiglia 1968;Massidda et al 1996;Orrù et al 2010). A previous study, conducted between 2005 and 2007, analysed the nuclear locus LDH-C1 and mtDNA CR of salmonids and showed that the stream was inhabited by non-native trout and hybrids (Sabatini et al 2006(Sabatini et al , 2011. The hybridisation with domestic Atlantic trout was a consequence of past restocking practices in the Ermolinus stream and other rivers within the Flumendosa basin.…”

“…Sardinian rivers in Italy are home to two introduced, non-native salmonid species, the brown trout (Salmo trutta Linneaus, 1758 -North Atlantic origin) and the rainbow trout ((Oncorhyncus mykiss (Walbaum, 1792) -North American origin)), as well as the native Mediterranean brown trout ((Salmo cettii Rafinesque, 1810 -formerly Salmo (trutta) macrostigma (Duméril, 1858)) (Sabatini et al 2006(Sabatini et al , 2011Kottelat & Freyhof 2007;Massidda et al 2008;Zaccara et al 2015). Non-native trout in Sardinia have replaced native populations over much of their range (Massidda 1995).…”

“…Atlantic brown trout have interbred with local forms, altering their gene pool. Consequently, in many areas of Sardinia, entire populations of native trout have disappeared and have been replaced by hybrid or nonnative trout (Sabatini et al 2006(Sabatini et al , 2011.…”