Magnetic map in nonanadromous Atlantic salmon

Abstract

Long-distance migrants, including Pacific salmon (Oncorhynchus spp), can use geomagnetic information to navigate. We tested the hypothesis that a “magnetic map” (i.e., an ability to extract positional information from Earth’s magnetic field) also exists in a population of salmon that do not undertake oceanic migrations. This study examined juvenile Atlantic salmon (Salmo salar) originally from a nonanadromous population in Maine transferred ∼60 years ago to a lake in central Oregon. We exposed juveniles to magnetic displacements representative of locations at the latitudinal boundaries of the Pacific salmon oceanic range in the North Pacific and at the periphery of their ancestral oceanic range in the North Atlantic. Orientation differed among the magnetic treatments, indicating that Atlantic salmon detect map information from the geomagnetic field. Despite no recent history of ocean migration, these fish displayed adaptive orientation responses similar to those observed in native Pacific salmonids. These findings indicate that use of map information from the geomagnetic field is a shared ancestral character in the family Salmonidae and is not restricted to populations with anadromous life histories. Lastly, given that Atlantic salmon are transported throughout the world for capture fisheries and aquaculture, such a robust navigational system is of some concern. Escaped individuals may have greater potential to successfully navigate, and thus invade, introduced habitats than previously suspected.

Anadromy, potamodromy and residency in brown trout Salmo trutta: the role of genes and the environment

“…In passerine birds migration pathways to geographically distinct wintering areas are genetically encoded and specific genes associated with particular migratory phenotypes have been identified for some species (Lundberg et al ., ). However, while salmonines show innate compass orientation in the marine phase (see below), it is not known if the resolution of the magnetic‐field map is sufficient to provide positional information over the more limited scale of a river catchment (Scanlan et al ., ). In some situations, it is not a matter of moving downstream until the feeding destination is reached since, for some allacustrine populations where spawning occurs in a tributary of the outlet, getting to the lake requires downstream migration followed by upstream migration (Figure ).…”

“…Subsequently O. tshawytscha were shown to use an inherited magnetic map that facilitates navigation during their oceanic migration (Putman et al ., ) . Salmo salar , from a long‐standing non‐anadromous population, were shown to be able to orientate in novel magnetic fields (Scanlan et al ., ). As this ability to extract location information from the Earth's magnetic field is present in at least three salmonines species, it seems to be an ancestral state in the sub‐family and thus is very likely to be present in S. trutta .…”

Magnetoreception in fishes: the effect of magnetic pulses on orientation of juvenile Pacific salmon

“…4C,D). Interestingly, salmon are known to possess both a magnetic 'compass' that enables them to use Earth's magnetic field as a directional cue (Quinn, 1980) and a magnetic 'map' that allows them, in effect, to assess their position within an ocean basin (Putman et al, 2014a(Putman et al, , 2020Putman, 2015;Scanlan et al, 2018). In principle, the mechanism underlying the compass, the map or both might have been affected by the magnetic pulse.…”

The Monarch Butterfly as a Model for Understanding the Role of Environmental Sensory Cues in Long-Distance Migratory Phenomena

“…It is possible that monarchs from these populations display directional flight, but the distances of their flights are simply limited by geographical constraints, e.g., living on a relatively small island in the middle of the ocean. Although it is possible that traits associated with migration, e.g., oriented flight behavior, can be quickly selected out to produce populations of migratory species that are non-migratory, such traits might remain in the population due to evolutionary inertia (Alerstam, 2006 ) or exist despite large differences in the movement ecology of populations (Scanlan et al, 2018 ). For instance, translocated nonanadromous Atlantic salmonids with no recent history of migration, can display similar directed responses to local orientation cues as native Pacific salmonids (Scanlan et al, 2018 ).…”