Bering Sea canyons unique habitats within the eastern 1 Bering Sea ?

5 Some of the largest submarine canyons in the world incise the eastern Bering Sea shelf break, 6 including Bering, Pribilof, Zhemchug, Pervenets and Navarin canyons. In 2012, the North 7 Pacific Fishery Management Council (NPFMC) received testimony from environmental 8 organizations to protect coral, sponge and other benthic habitat of fish and crab species in two of 9 these canyons (Pribilof and Zhemchug). In response to this testimony, the NPFMC requested that 10 the NOAA Alaska Fisheries Science Center analyze the distribution of fishes and benthic 11 invertebrates and the vulnerability of their habitat to fishing activities. We compiled data from 12 the eastern Bering Sea that included trawl survey data on fish and invertebrate distributions and 13 observations of ocean conditions and benthic habitat. These data were analyzed using 14 multivariate techniques to determine if the two canyons are distinguishable from the adjacent 15 continental slope. The potential for fishing effects on coral and sponge was assessed with spatial 16 modeling of historical fishing effort, coral and sponge distributions and an index of their 17 vulnerability to physical damage. Pribilof and Zhemchug canyons do show some distinguishing 18 physical characteristics from the adjacent slope such as lower oxygen and pH and higher 19 turbidity, but none based on biological characteristics (i.e., fish, coral and sponge distributions). 20 These analyses imply that Pribilof and Zhemchug canyons are not biologically unique. Instead 21 the major variables structuring the communities of fish and invertebrates on the eastern Bering 22 Sea slope appear to be depth and latitude rather than submarine canyons. Corals were predicted 23 to occur predominantly along the eastern Bering Sea slope, whereas sea whips were predicted to 24 occur predominantly along the outer continental shelf. Sponges were mixed, with about two25 DRAFT FOR REVIEW BY NORTH PACIFIC FISHERY MANAGEMENT COUNCIL C-7(a) 2 thirds of their habitat predicted for the outer shelf and the remainder for the slope. One unique 26 feature of the focal canyons is that about one third of the coral habitat predicted for the eastern 27 Bering Sea slope occurs in Pribilof Canyon, an area that comprises only about 10% of the total 28 slope area. Although apparently concentrated there, the average density of coral for Pribilof 29 Canyon (0.28 colonies m) is much less than the density for the Aleutian Islands (1.23 colonies 30 m). The physical and biological characteristics of Zhemchug and Pribilof canyons are spatially 31 heterogeneous; coral habitat was more common in some sections of Pribilof Canyon. Higher 32 vulnerability indices were found both within and between canyons and were not unique to 33 Pribilof and Zhemchug canyons. Pelagic trawl, longline and pot gear but not bottom trawl gear 34 overlapped some coral and sponge habitats of the slope including canyons. Substantial overlap 35 does not explain whether effects of fishing were light, medium or high, just that effects likely 36 were greater in overlap areas compared to other areas. Further, the effect for the pelagic trawl 37 fishery will depend on how often and where fishing occurs on bottom. 38