The 3.3 million km² marine ecosystem around the North Pole, defined as the Central Arctic Ocean (CAO), is a blind spot on the map of the world’s fish stocks. The CAO essentially comprises the permanently ice-covered deep basins and ridges outside the continental shelves, and is only accessible by ice-breakers. Traditional trawling for assessing fish stocks is impossible under the thick pack ice, and coherent hydroacoustic surveys are unachievable due to ice-breaking noise. Consequently, nothing is known about the existence of any pelagic fish stocks in the CAO, although juveniles of Boreogadus saida richly occur at the surface associated with the sea ice and ice-associated Arctogadus glacialis has been reported as well. We here present a first indication of a possible mesopelagic fish stock in the CAO. We had the opportunity to analyse a geophysical hydroacoustic data set with 13 time windows of usable acoustic data over a transect from 84.4 °N in the Nansen Basin, across the North Pole (90.0 °N), to 82.4 °N in the Canada Basin. We discovered a deep scattering layer (DSL), suggesting the presence of zooplankton and fish, at 300–600 m of depth in the Atlantic water layer of the CAO. Maximum possible fish abundance and biomass was very low; values of ca. 2,000 individuals km⁻² and ca. 50 kg km⁻² were calculated for the DSL in the North-Pole area according to a model assuming that all acoustic backscatter represents 15-cm long B. saida and/or A. glacialis. The true abundance and biomass of fish is even lower than this, but cannot be quantified from this dataset due to possible backscatter originating from pneumatophores of physonect siphonophores that are known to occur in the area. Further studies on the DSL of the CAO should include sampling and identification of the backscattering organisms. From our study we can conclude that if the central Arctic DSL contains fish, their biomass is currently too low for any sustainable fishery.

该3300000公里²海洋生态系统围绕北极，定义为中北冰洋（CAO），是世界上鱼类的地图上的盲点。CAO基本上包括大陆架外部永久覆冰的深水盆地和山脊，并且只有破冰船才能进入。在厚冰层下不可能进行传统的拖网捕鱼来评估鱼类资源，由于破冰噪声，无法进行连贯的水声调查。因此，对中非合作组织中尚没有中上层鱼类种群的情况一无所知，尽管婆罗洲虎的幼鱼丰富地存在于与海冰和冰相关的Arctogadus glacialis有关的地表。也有报道。我们在这里提出了CAO中可能存在近中生鱼类种群的第一个迹象。我们有机会分析了一个地球物理水声数据集，该数据集包含一个横断面（从南森盆地的84.4°N，北极（90.0°N）到加拿大盆地的82.4°N）的有效声波数据的13个时间窗。我们发现了一个深散射层（DSL），表明在CAO大西洋水层深300–600 m处存在浮游动物和鱼类。最大可能的鱼类丰度和生物量很低；约值 2,000个人km ^-2和ca. 50公斤公里^-2是根据一个模型假设所有的声学反散射代表15厘米长的计算在北极区域的DSL B.赛达和/或A.glacialis。鱼类的真实丰度和生物量甚至低于此值，但由于该地区已知的physonect虹吸虫的肺炎球菌可能引起反向散射，因此无法从该数据集中进行量化。对CAO DSL的进一步研究应包括对反向散射生物的采样和识别。根据我们的研究，我们可以得出结论，如果北极中心DSL包含鱼类，那么对于任何可持续渔业而言，它们的生物量目前都太低了。