Habitat and infauna prey availability for flatfishes in the northern Bering Sea

Abstract

Yellowfin sole (Limanda aspera), northern rock sole (Lepidopsetta polyxystra), and Alaska plaice (Pleuronectes quadrituberculatus) are valuable flatfishes in the southeastern Bering Sea (EBS) bottom trawl fishery. The northern Bering Sea (NBS) is near their northern distribution limit. We conducted the first assessment of NBS habitat suitability for these benthivorous flatfishes from the perspective of prey availability in 2010. Benthic samples were collected at 12 trawl stations along a meridional transect extending from 60.5°N to 64.5°N east of St. Lawrence Island to characterize the prey environment. Stomach contents from the flatfishes were concomitantly collected to relate diets to prey fields. The diet compositions did not correspond spatially with the infauna communities. The flatfishes elected a prey group regardless of its relative availability. The spatial mismatch between diet and infauna compositions suggests that prey availability was high in the NBS. The flatfishes generally have versatile diets, but they were more selective of their prey here than in the EBS. The biomass and the abundance of the infauna along the transect were comparable with the EBS. Although niche overlap was high in the NBS, competition for food was likely lower than in the EBS because of the lower density of flatfish. The bottom temperatures in the NBS were in the same range as the EBS during the summer of 2010. The NBS appears to be suitable flatfish habitat at least during the summer ice-free period. The effects of climate warming on the prey environment and on the production and distribution of flatfish are complex and difficult to predict, but if the NBS were to shift over time toward milder winter conditions that more resemble the EBS, its suitability as flatfish habitat would presumably increase based on the present prey availability.

Depth gradient in the resource use of a fish community from a semi‐enclosed sea

“…In this area, bivalves dominated flatfishes' diet on the inner shelf (shore to 50 m), while polychaetes were the main prey on the middle shelf (∼ 50–100 m). In this case, diet changes were associated with estimated trends in prey abundance (Yeung and Yang ). The authors however emphasized the possible mismatch between diet composition and infauna abundance in regions with high prey availability, where endobenthos‐feeding fish preferentially feed on polychaetes even when they are not the dominant prey.…”

Otolith biochronologies reveal latitudinal differences in growth of Bering Sea yellowfin sole Limanda aspera

“…As a result, there are regional differences in the yellowfin sole diet even within the southeastern Bering Sea; polychaetes are associated with the muddier middle shelf and thus are more prevalent in the diet of yellowfin sole collected there, whereas clams are more dominant in the diet of yellowfin sole collected from the sandier inner shelf . In contrast to the southern Bering Sea, where the diet of yellowfin sole corresponds directly with local prey species composition , yellowfin sole in the northern Bering Sea appear to selectively prefer amphipods, which are relatively nutritionally rich (Yeung and Yang 2014). Given that yellowfin sole population density is lower in the northern Bering Sea (Nichol 1997;Lauth 2011), the benefit of energy-rich prey and reduced competition, along with possible transient habitat usage, may explain the apparent reduced sensitivity of yellowfin sole in that region to climate variability.…”

“…Primary prey items in the yellowfin sole diet are polychaetes, bivalves, gammarid amphipods, brittle stars, and sand dollars Yeung and Yang 2014). Temperature is less important in explaining polychaete assemblages than seafloor sediment texture and composition (Yeung et al 2010).…”