Implications for introgression: has selection for fast growth altered the size threshold for precocious male maturation in domesticated Atlantic salmon?

Background: Mature male parr (MMP) represent an important alternative life-history strategy in Atlantic salmon populations. Previous studies indicate that the maturation size threshold for male parr varies among wild populations and is influenced by individual growth, environmental conditions, and genetics. More than ten generations of breeding have resulted in domesticated salmon displaying many genetic differences to wild salmon, including greatly increased growth rates.

Influence of depth, time and human activity on detection rate of acoustic tags: a case study on two fish farms.

The detection rates of stationary acoustic transmitters deployed at three depths on two Atlantic salmon Salmo salar cage farms for c. 2 months were investigated. Deployment depth, time of day, day of the year and specific incidences at the farm substantially affected the rate of signal detection by the receiver.

Evaluation of emamectin benzoate and substance EX against salmon lice in sea-ranched Atlantic salmon smolts.

Experimental releases of Atlantic salmon smolts treated with emamectin benzoate (EB) against salmon lice have previously been used to estimate the significance of salmon lice on the survival of migrating smolts. In recent years, the salmon louse has developed reduced sensitivity to EB, which may influence the results of such release experiments. We therefore tested the use of 2 anti-lice drugs: EB was administered to salmon smolts in high doses by intra-peritoneal injection and the prophylactic substance EX (SubEX) was administered by bathing.

Salmon lice increase the age of returning Atlantic salmon.

The global increase in the production of domestic farmed fish in open net pens has created concerns about the resilience of wild populations owing to shifts in host-parasite systems in coastal ecosystems. However, little is known about the effects of increased parasite abundance on life-history traits in wild fish populations. Here, we report the results of two separate studies in which 379 779 hatchery-reared Atlantic salmon smolts were treated (or not) against salmon lice, marked and released.

Salmon lice--impact on wild salmonids and salmon aquaculture.

Salmon lice, Lepeophtheirus salmonis, are naturally occurring parasites of salmon in sea water. Intensive salmon farming provides better conditions for parasite growth and transmission compared with natural conditions, creating problems for both the salmon farming industry and, under certain conditions, wild salmonids. Salmon lice originating from farms negatively impact wild stocks of salmonids, although the extent of the impact is a matter of debate.