Colleen Harpold

The dataset consists of zooplankton abundance estimates from an ecosystem survey in the Bering Sea. The survey follows the 70 m isobath along the middle shelf. At each station, a bongo net array is towed to within 10 m of the bottom depth at a speed of approximately 1.5 knots. The bongo net consists of two nets of 60 cm diameter equipped with a 505 um mesh net and two nets of 20 cm diameter equipped with 153 um mesh net. The net is also equipped with General Oceanics flowmeters to estimate the volume of water filtered by each net.

In 2014, the Bering Sea shifted back to warmer ocean temperatures (+2 oC above average), bringing concern for the potential for a new warm stanza and broad biological and ecological cascading effects. In 2015 and 2016 dedicated surveys were executed to study the progression of ocean heating and ecosystem response. We describe ecosystem response to multiple, consecutive years of ocean warming and offer perspective on the broader impacts. Ecosystem changes observed include reduced spring phytoplankton biomass over the southeast Bering Sea shelf relative to the north, lower abundances of large-bodied crustacean zooplankton taxa, and degraded feeding and body condition of age-0 walleye pollock. This suggests poor ecosystem conditions for young pollock production and the risk of significant decline in the number of pollock available to the pollock fishery in 2-3 years. However, we also noted that high quality prey, large copepods and euphausiids, and lower temperatures in the north may h...