The native trout population originally inhabiting the Biferno and Volturno rivers basin (correspondents respectively to the Adriatic and Tyrrhenian drainages) in the Molise region (South Italy) is the Mediterranean brown trout species. It is listed by the annex II of Habitat Directive, and reported as critically threatened and endangered under the taxonomical term Salmo cettii by the International Union for Conservation of Nature (IUCN). The distribution range of native Mediterranean brown trout has suffered a gradual reduction over the last few centuries. This could be largely attributed to the detrimental effects of anthropogenic disruptions, such as dam building, river straightening and local pollution. Moreover, the hybridization introduction of domesticated Atlantic strains of brown trout for recreational purposes has caused genetic introgression of autochthonous population. Hybridization by non-native genes is considered to be one of the most serious threats to the long-term conservation of diversity within the species. The native Mediterranean brown trout population inhabiting the Molise rivers basin is characterized by migratory life-history, is threatened by genetic introgression and the loss of suitable reproductive sites as a result of high density antropic actions at spawning grounds. After distinctive migratory patterns, the native breeders reach the few suitable and available spawning sites resulting in high densities caused by the loss of other optimal reproductive sites due to pollution, water captations and anthropogenic barriers. Thus, the high breeder densities in the spawning grounds cause a strong male competition for females which strongly influences the individual and population fitness. In this regard, thank to the project “LIFE” Nat.Sal.mo, recently funded by the EU, aiming to the recovery and the conservation of native Mediterranean trout (Salmo macrostigma) in the Molise river basins, has many specific objectives one of which is to produce eggs from wild breeders by artificial reproduction ensuring the genetic variability of the offspring. Supporting breeding in the management of salmonids is discussed at a global level, where it is not strictly necessary due to the need to select native breeders and decrease the degree of population introgression. The main problem derives from the possibility to produce thousands of eggs from a few breeders, causing loss of genetic variability. Moreover, if fry are released, there is a risk of domestication. The restoration of genetic integrity of native Mediterranean brown trout during the LIFE Nat.Sal.Mo Project will occur using a strategy of fertilization schemes that uses frozen semen in artificial reproduction, increasing the number of genetically typed males always available (frozen semen) and crossing the individual males into a scheme designed to increase the breeding pairs. Eggs will be released in nature by artificial nesting, directly on the river grounds, increasing thus the genetic variability of the offspring and avoiding domestication.
The schemes of fertilization in combination with frozen semen as a strategy to increase the genetic variability of native Mediterranean brown (Salmo macrostigma) in Molise region (South Italy)
Iaffaldano N.;Pilla F.;Belliggiano A.;Letizia F.;
2019-01-01
Abstract
The native trout population originally inhabiting the Biferno and Volturno rivers basin (correspondents respectively to the Adriatic and Tyrrhenian drainages) in the Molise region (South Italy) is the Mediterranean brown trout species. It is listed by the annex II of Habitat Directive, and reported as critically threatened and endangered under the taxonomical term Salmo cettii by the International Union for Conservation of Nature (IUCN). The distribution range of native Mediterranean brown trout has suffered a gradual reduction over the last few centuries. This could be largely attributed to the detrimental effects of anthropogenic disruptions, such as dam building, river straightening and local pollution. Moreover, the hybridization introduction of domesticated Atlantic strains of brown trout for recreational purposes has caused genetic introgression of autochthonous population. Hybridization by non-native genes is considered to be one of the most serious threats to the long-term conservation of diversity within the species. The native Mediterranean brown trout population inhabiting the Molise rivers basin is characterized by migratory life-history, is threatened by genetic introgression and the loss of suitable reproductive sites as a result of high density antropic actions at spawning grounds. After distinctive migratory patterns, the native breeders reach the few suitable and available spawning sites resulting in high densities caused by the loss of other optimal reproductive sites due to pollution, water captations and anthropogenic barriers. Thus, the high breeder densities in the spawning grounds cause a strong male competition for females which strongly influences the individual and population fitness. In this regard, thank to the project “LIFE” Nat.Sal.mo, recently funded by the EU, aiming to the recovery and the conservation of native Mediterranean trout (Salmo macrostigma) in the Molise river basins, has many specific objectives one of which is to produce eggs from wild breeders by artificial reproduction ensuring the genetic variability of the offspring. Supporting breeding in the management of salmonids is discussed at a global level, where it is not strictly necessary due to the need to select native breeders and decrease the degree of population introgression. The main problem derives from the possibility to produce thousands of eggs from a few breeders, causing loss of genetic variability. Moreover, if fry are released, there is a risk of domestication. The restoration of genetic integrity of native Mediterranean brown trout during the LIFE Nat.Sal.Mo Project will occur using a strategy of fertilization schemes that uses frozen semen in artificial reproduction, increasing the number of genetically typed males always available (frozen semen) and crossing the individual males into a scheme designed to increase the breeding pairs. Eggs will be released in nature by artificial nesting, directly on the river grounds, increasing thus the genetic variability of the offspring and avoiding domestication.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
