Hybrids with brown trout are fish with an Atlantic Salmon parent and a brown trout parent.[1][2]
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Life cycle
Hybrids have reduced fertility.[2] The salmon has 58 chromosomes and the brown trout 80. Genes pass from one species to the other only through fish with three sets of chromosomes, and very few of these offspring survive.[3] Offspring survival was 24.4% in salmon-trout crosses against 30.3% in crosses within a species.[2]
Origin and change
The two species have always lived side by side and share the same spawning times and places, so they cross at low levels in both directions.[1] In a study of 10 southern European rivers, the salmon was the mother in most crosses.[2] Escapes of farmed salmon increase the chance of crosses.[1]