FishBase 2017: Pauline Snoeijs Leijonmalm
Channel: Fishbase Sweden
Date: 30/10/2017

Pauline Snoeijs-Leijonmalm, Stockholm University, gave a lecture titled "FISH UNDER THE NORTH-POLE SEA ICE: REGIONAL POLITICS AND ACOUSTIC STUDIES"

Abstract: Diplomatic negotiations are going on between ten northern nations (including the EU) with a possible future interest in commercial fishing in the High Seas Area (= the area outside the Exclusive Economic Zones of the five coastal states). This area overlaps to a large extent with the Large Marine Ecosystem called the Central Arctic Ocean (CAO = the deep waters outside the continental shelves). The High Seas Area will become more accessible in the near future with the decrease of the summer Arctic sea ice cover through climate change. The negotiations build on the precedent of the Oslo Accord (2015) in which the five nations with Exclusive Economic Zones adjacent to the High Seas Area agreed to interim measures controlling commercial fishing in the area. Scientific experts from the respective nations have met four times in the FiSCAO group to summarize the available scientific information on fish living in the High Seas Area. Only twelve fish species are known to be established here and published information about their distribution under the ice cover is scarce. 
Recently, acoustic data from the Swedish ice-breaker “Oden” were made available for analysis from surveys carried out in 2016 (data: Martin Jakobsson and Katarina Gårdfeldt). These data - collected with an 18 KHz echosounder - were aimed at locating gas seeps from the seabed and not to monitor fish. The acoustic data analyses are carried out by the Institute of Marine Research in Bergen, Norway (Harald Gjøsæter, Randi Ingvaldsson, et al.). A first exploratory analysis shows that most of the echograms are too noisy to use, probably caused by mechanical noise from breaking ice, propeller cavitation and/or electric noise from other instruments. However, during periods when the vessel was stationary, and after removing noise by running various filters built into the post-processing software, scattering from at least parts of the water column can be assessed.
Preliminary analyses indicate that echoes from pelagic fish (most probably the Arctic cod _Boreogadus saida_) can be recognized in such echograms from several stations north of 85 °N. These data provide a first insight in the distribution of fish under the North Pole ice. We will collect a new - very extensive - data set during the coming one-year MOSAiC expedition with the German ice-breaker “Polarstern” that will be drifting in the Arctic sea ice in 2019-2020.