The Native Mediterranean brown trout (Salmo cettii) populations inhabiting Biferno and Volturno rivers in Molise are decreasing due to poorly regulated fishing activities, river pollution and the introduction of allochthonous strains. This last factor has triggered an overall genetic impoverishment, therefore reducing the original genetic variability. Because of these factors, the conservation status of S. cettii in the Mediterranean area is now considered as ‘critically endangered’ by IUCN Italian Red list. In this regard, the project ‘LIFE’ Nat.Sal.Mo, recently funded by the EU, aims to ensure the recovery and the conservation of native trout in Molise river basins. In particular, the creation of a sperm cryobank is a milestone in the Nat.Sal.Mo project and is an effective strategy for the protection of the biodiversity of the local Mediterranean brown trout populations. The purpose of this work was to depict the results achieved during the first 2 years of the project when it comes to the creation of the first European cryobank and its practical use in the artificial fertilization schemes to safeguard the genetic resources and improve the genetic variability of native trout. Autochthonous specimens were captured using fixed traps allocated in the main attractive spawning sites. Semen was collected by stripping and was extended to reach a final cryoprotectant concentration of 0.15 M glucose and 7.5% methanol and loaded into 0.25 mL plastic straws, obtaining a final sperm concentration of 3 × 109 sperm/mL. The straws were equilibrated for 15 min above ice at a height of 3 cm, then frozen by exposure to liquid nitrogen (LN2) at 3 cm above LN2 level for 5 min and finally placed in LN2. During the first 2 years of activities 1287 semen doses from 93 native individuals were stored. About 25% of these doses were used for artificial fertilization. In total around 90,000 eggs were fertilized with frozen semen, obtaining a yield to eyed eggs of about 70–75%. The creation of the first sperm cryobank of pure Mediterranean trout populations with a high genetic variability will be useful even after the end of the project for Molise river basins as well as for other Italian basins where S. cettii is at risk of extinction. Besides being a supportive tool in ensuring the sustainability of the project in the future, it represents a powerful multiplying effect which will affect other neighbouring areas at a national level and other European river basins.
Cryobanking of native Mediterranean brown trout semen as a tool for the safeguard of genetic resources
IAFFALDANO N.;RUSCO G.;ANTENUCCI E.;TESTA B.;DI IORIO M.
2021-01-01
Abstract
The Native Mediterranean brown trout (Salmo cettii) populations inhabiting Biferno and Volturno rivers in Molise are decreasing due to poorly regulated fishing activities, river pollution and the introduction of allochthonous strains. This last factor has triggered an overall genetic impoverishment, therefore reducing the original genetic variability. Because of these factors, the conservation status of S. cettii in the Mediterranean area is now considered as ‘critically endangered’ by IUCN Italian Red list. In this regard, the project ‘LIFE’ Nat.Sal.Mo, recently funded by the EU, aims to ensure the recovery and the conservation of native trout in Molise river basins. In particular, the creation of a sperm cryobank is a milestone in the Nat.Sal.Mo project and is an effective strategy for the protection of the biodiversity of the local Mediterranean brown trout populations. The purpose of this work was to depict the results achieved during the first 2 years of the project when it comes to the creation of the first European cryobank and its practical use in the artificial fertilization schemes to safeguard the genetic resources and improve the genetic variability of native trout. Autochthonous specimens were captured using fixed traps allocated in the main attractive spawning sites. Semen was collected by stripping and was extended to reach a final cryoprotectant concentration of 0.15 M glucose and 7.5% methanol and loaded into 0.25 mL plastic straws, obtaining a final sperm concentration of 3 × 109 sperm/mL. The straws were equilibrated for 15 min above ice at a height of 3 cm, then frozen by exposure to liquid nitrogen (LN2) at 3 cm above LN2 level for 5 min and finally placed in LN2. During the first 2 years of activities 1287 semen doses from 93 native individuals were stored. About 25% of these doses were used for artificial fertilization. In total around 90,000 eggs were fertilized with frozen semen, obtaining a yield to eyed eggs of about 70–75%. The creation of the first sperm cryobank of pure Mediterranean trout populations with a high genetic variability will be useful even after the end of the project for Molise river basins as well as for other Italian basins where S. cettii is at risk of extinction. Besides being a supportive tool in ensuring the sustainability of the project in the future, it represents a powerful multiplying effect which will affect other neighbouring areas at a national level and other European river basins.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
