Ocean transport paths for the early life history stages of offshore-spawning flatfishes: a case study in the Gulf of Alaska

Offshore- and deepwater-spawning flatfish species face the problem of transport of their planktonic stages to shallow juvenile nursery grounds that are often far shoreward in bays or estuaries. We compare life history attributes of four offshore-spawning flatfish species in the Gulf of Alaska: Pacific halibut (Hippoglossus stenolepis), arrowtooth flounder (Atheresthes stomias), rex sole (Glyptocephalus zachirus) and Dover sole (Microstomus pacificus) to examine how their larvae get from a spawning location at the edge or beyond the continental shelf to specific inshore nursery zones. We utilize historical records of survey catches of different life stages to characterize the stage-specific changes in distribution of spawning, planktonic stages and juvenile nursery areas. We infer transport mechanisms based on the shifts in distribution of the life stages and in comparison with local physical oceanography. This comparison provides insight into the different mechanisms marine species may use to solve the common 'problem' of planktonic drift and juvenile settlement.