Assessment of the Other Flatfish Stock Complex in the Bering Sea and Aleutian Islands
The Bering Sea/Aleutian Islands “other flatfish” group have typically included those flatfish besides northern rock sole, yellowfin sole, arrowtooth flounder, Kamchatka flounder and Greenland turbot. Flathead sole (Hippoglossoides elassodon) were part of the other flatfish complex until they were removed in 1995, and Alaska plaice was removed from the complex in 2002, as sufficient biological data exists for these species to construct age-structured population models. In contrast, survey biomass estimates are the principal data source used to assess the remaining other flatfish. Although over a dozen species of flatfish are found in the BSAI area, the other flatfish biomass consists primarily of starry flounder, rex sole, longhead dab, Dover sole and butter sole. A full list of the species in the other flatfish complex is shown in Table 11.1. With the exception of Dover sole and rex sole, most of the species inhabit shallower continental shelf waters and are also found in other management areas. At present, no evidence of stock structure is evident for these species in the Bering Sea/Aleutian Islands region, although no formal genetic or tagging study has been conducted on these species in this region.
The miscellaneous species of the other flatfish species category are listed in Table 11.1, and their catches from 1995-2015 are shown in Table 11.2 (with historical ABC and TAC). These species are not pursued as fishery targets but are captured in fisheries for other flatfish species and Pacific cod. Catch from 1995- 2003 were obtained from the NMFS Regional Office “blend” data, and the catch for some species are reported by species and in an aggregate flatfish group. The catch estimates for these years were produced by applying the proportional catch, by species, from fishery observer data to the estimated total catch for the aggregate other flatfish group, and adding this total to the catch that was reported by species. In the current catch accounting system (in use since 2003), catches of other flatfish are reported only in an aggregate group, and the catch estimates for these years were produced by applying the proportional catch, by species, from fishery observer data to the estimated total catch of the aggregate group. In recent years, starry flounder (Platichthys stellatus) and rex sole (Glyptocephalus zachirus) account for most of
the harvest of other flatfish, contributing 94% of the harvest of other flatfish in 2015. The 2015 catch of 2,367 t through mid-October is well below (18%) the ABC of 13,250 t.