Teleost fishes use osmoregulation to keep internal ion concentration constant.
However, it is not known whether the anadromous subpopulations of pike differ in salinity tolerance, or whether they harbour sufficient standing genetic variation or have capacity for phenotypic plasticity enabling them to cope with changes in salinity associated with seasonality or longer term climate change.
Spawning can occur directly in brackish waters along the coast, where they spend the main part of the year living sympatrically with other subpopulations of anadromous and brackish spawning pikes.
Previous studies suggest that freshwater spawning pike are unable to produce offspring in brackish waters over 7 ppt.
We compared salinity tolerance between two anadromous subpopulations of pike (Esox Lucius) that utilize freshwater spawning sites with different salinity regimes.
Eggs from each population were artificially fertilized and incubated in a salinity gradient (0, 3, 5, 7, and 9 psu) using a split-brood design.