Offshore and deep-water, spawning flatfish species in the Gulf of Alaska, such as arrowtooth flounder and Pacific halibut, have juvenile nurseries that are inshore, in bays, or at the mouths of bays. Larvae must emigrate from their spawning areas along the continental slope and outer shelf towards inshore bays, in a direction normal to the prevailing Alaskan Stream. Using a 20-year time series of data from ichthyoplankton surveys in the Gulf of Alaska, we examined patterns of variability in larval halibut and flounder distributions that may reflect processes resulting in successful recruitment to nursery areas. Several patterns can be observed in these data. Eggs and the smallest sized larvae are located along the outer shelf and slope.
Larger larvae tend to be located farther inshore over the continental shelf.
Larger larvae are also associated with deep-sea valleys and troughs that penetrate the shelf. Larvae of these flatfish species live in deep water, and literature reports indicate that bottom water flows up the sea valleys. Thus, these topographic features may serve as transport pathways to juvenile nursery grounds. Variability in larval transport as related to ENSO and other events that enhance onshore advection, may play an important role in recruitment of flatfishes to their nursery grounds.