Variation in the distribution of yellowfin sole Limanda aspera larvae in warm and cold years in the eastern Bering Sea

Multiyear periods of relatively cold temperatures (2007-2013) and warm temperatures (2001-2005 and 2014-2018) altered the eastern Bering Sea ecosystem, affecting ocean currents and wind patterns, plankton community, and spatial distribution of fishes. Yellowfin sole Limanda aspera larvae were collected from the inner domain (<= 50 m depth) of the eastern Bering Sea among four warm years (2002, 2004, 2005, 2016), an average year (2006), and three cold years (2007, 2010, 2012). Spatial distribution and density of larvae among those years was analyzed using generalized additive models that included timing of sea-ice retreat, areal coverage of water <= 0 degrees C, and water temperature as covariates. Analyses indicated a combination of temperature effects on the location and timing of spawning, and on egg and larval survival, may explain the variation in larval density and distribution among years. During warm years, higher density and wider spatial distribution of larvae may be due to earlier spawning, an expansion of the spawning area, and higher egg and larvae survival due to favorable temperatures. Larval distribution contracted shoreward, and density was lower during cold conditions and was likely due to fish spawning closer to shore to remain in preferred temperatures, later spawning, and increased mortality. Predicted drift trajectories from spawning areas showed that larvae would reach nursery grounds in most years. Years when the drift period was longer than the pelagic phase of the larvae occurred during both warm and cold conditions indicating that settlement outside of nursery areas could happen during either temperature condition.

Automated summary

Multiyear periods of cold and warm temperatures in the eastern Bering Sea altered the ecosystem, affecting ocean currents, plankton community, and fish distribution. The distribution and density of yellowfin sole larvae varied among warm and cold years, with temperature playing a key role in spawning location, timing, and larval survival. Warm years showed higher density and wider distribution of larvae due to earlier spawning and more favorable temperatures, while cold conditions led to lower density and contraction of distribution likely caused by fish spawning closer to shore and increased mortality.