Density-dependent migratory waves in the marine pelagic ecosystem.
The migration of large aggregations of animals that sweep through the landscape is a phenomenon with large consequences in many ecosystems. It has been suggested that such migrations are mediated by resource depletion. Under this hypothesis it has been shown that simple foraging rules may generate density-dependent migratory waves (DDMW) in which the speed and amplitude increase with animal abundance. We tested these predictions on a 32-year data set of the spatial distribution of the two youngest age groups of a small pelagic schooling fish, the capelin (Mallotus villosus), by the end of their annual feeding migration in the Barents Sea. Our data suggest that the two age groups divided the Barents Sea by forming migratory waves that moved in opposite directions. The aggregation and spatial displacement of these waves increased with increasing age-specific abundance. However, possibly through social interactions, migratory pattern was modified by the abundance of the other age group.
Fauchald
Per
P
Norwegian Institute for Nature Research, Department of Arctic Ecology, Polar Environmental Center, N-9296 Tromsø, Norway. per.fauchald@nina.no
Mauritzen
Mette
M
Gjøsaeter
Harald
H
D000367:Age Factors; D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D003710:Demography; D017753:Ecosystem; D008386:Marine Biology; D009792:Oceans and Seas; D011156:Population Density; D012044:Regression Analysis; D017858:Salmoniformes / Q000502:physiology*; D013696:Temperature; D013997:Time Factors