Manipulation of Salmon Eggs

The relationship between stonefly nymphs of the genus Alloperla and developing pink and chum salmon embryos was studied in Harris River, Alaska, from August, 1965, to April, 1966. Polyethylene containers with alternating layers of salmon eggs and washed gravel and containers with washed gravel only were buried in sections of an upstream spawning riffle and were removed and examined in three sampling periods. Correlation and linear regression analysis of numbers of missing embryos, dead embryos, and stonefly nymphs in the containers supported the hypothesis that the nymphs were scavengers but failed to support the hypothesis that they were predators.Some of the beneficial effects to living embryos of scavenging by nymphs is discussed, as well as the likelihood of occurrence of predation by stonefly nymphs in general.

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Sperm motility and offspring pre- and post-hatching survival in hybridization crosses among a landlocked and two anadromous Atlantic salmon populations: implications for conservation

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2020-0158 ◽

2020 ◽

Author(s):

Aslak Tiuna Eronen ◽

Jukka Kekäläinen ◽

Jorma Piironen ◽

Pekka Hyvärinen ◽

Hannu Huuskonen ◽

...

Keyword(s):

Genetic Diversity ◽

Sperm Motility ◽

First Generation ◽

Hybrid Vigor ◽

Outbreeding Depression ◽

Genetic Rescue ◽

Low Genetic Diversity ◽

Salmon Eggs ◽

Salmon Population ◽

Lake Saimaa

The landlocked salmon (Salmo salar m. sebago) endemic to Lake Saimaa, Finland, is critically endangered and severely threatened by low genetic diversity and inbreeding. To explore the possibility of increasing the genetic diversity of threatened salmon populations by controlled hybridization (genetic rescue), we studied sperm motility and offspring pre- and post-hatching survival in hybridization crosses of landlocked salmon with two geographically close anadromous salmon populations (Rivers Neva and Tornio) relative to the pure-bred populations. While some degree of gametic incompatibility between landlocked and Tornio salmon cannot be ruled out, there were no indications of outbreeding depression in survival traits in these first-generation hybridizations. Instead, pre-hatching survival of landlocked salmon eggs fertilized with Neva salmon sperm and post-hatching survival of anadromous salmon eggs fertilized with landlocked salmon sperm were higher than in pure-bred landlocked salmon. These differences might imply genetic rescue effects (hybrid vigor), although there were also strong maternal effects involved. Our results on early viability point to the possibility of applying genetic rescue to the landlocked salmon population by hybridization with an anadromous population.

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