Joint species distribution modeling reveals a changing prey landscape for North Pacific right whales on the Bering shelf

The eastern North Pacific right whale (NPRW) is the most endangered population of whale and has been observed north of its core feeding ground in recent years with low sea ice extent. Sea ice and water temperature are important drivers for zooplankton dynamics within the whale’s core feeding ground in the southeastern Bering Sea, seasonally forming stable fronts along the shelf that give rise to distinct zooplankton communities. A northward shift in NPRW distribution driven by changing distribution of prey resources could put this species at increased risk of entanglement and vessel strikes. We modeled the abundance of NPRW prey, Calanus glacialis, Neocalanus, and Thysanoessa species, using a dynamic biophysical food web model of nine zooplankton guilds in the Bering shelf zooplankton community during a period of warming (2006–2016). This model is unique from prior zooplankton studies from the region in that it includes density dependence, thereby allowing us to ask whether species inte..., Zooplankton species abundance (ind. m-3) were obtained from fall NOAA cruises (mid-August – early October) on the Bering shelf from 2006 to 2016. Data collection is led by the NOAA EcoFOCI program. Zooplankton were collected using oblique tows of paired bongo nets (20 cm diameter frame with 153 μm mesh, and a 60 cm diameter frame with 333 or 505 μm mesh). These oblique tows spanned from ~10 m of the bottom to the surface from a boat moving at ~1.5 knots. Net depth was determined using a SeaCat or FastCat conductivity, temperature, and depth (CTD) sensor (Sea-Bird Electronics), and the volume filtered was estimated using a General Oceanics flowmeter mounted inside the mouth of each net. Onboard, zooplankton samples were preserved in formalin for later laboratory sorting and identification. Plankton were processed using an established splitting and subsampling protocol and were identified to the lowest taxonomic level and stage possible at the Plankton Sorting and Identification Center (S...,