With ICES investigative field breaching new frontiers in the marginal Arctic Ocean waters of the Barents Sea and Norwegian Sea, the fish stock assessments and ecosystem analyses carried out by the Arctic Fisheries Working Group (AFWG) during its 54-year history have never been of greater significance. On the back of 2013's gathering of expert members, the ever-changing character of the world's most northerly marine region was once again central to key points of concern involving fish numbers and record-breaking low ice covering.
Since its inception in 1959, the Arctic Fisheries Working Group has, perhaps slightly contrarily to its name, dealt with stocks of cod, haddock, saithe, beaked and golden redfish, Greenland halibut, and capelin exclusively in the northeast Arctic (in this context the Barents Sea, Norwegian Sea, and Norwegian Coast north of 62° N).
Whilst the membership makeup of the group has remained relatively consistent, with Norway and Russia naturally well-represented, one of the oceanographic mainstays of the group's research – sea ice – has been slowly on the decline, paving the way for more open waters.
"The lessening of sea ice is definitely something that has been observed in recent decades," said AFWG Chair Bjarte Bogstad. "Last autumn was at an all-time low. And since in the Barents Sea north of Norway and Russian there is quite a large shelf area, which is now more open and with water area increased, cod and a number of other species have been able to extend their distribution range northwards, which seems to have been beneficial for them."
In this way the gradual liquefaction of sea ice has positively contributed to the abundance of fish. "That (the climate) is one of the reasons behind the recent upswing in cod stock in the area. The climate has been better and there has been good fish recruitment and sensible management."
Historically this is a pattern not entirely alien to fisheries management; indeed, a warm period back in the 1930s also broadened the grounds for grazing cod in the Arctic. Will this current trend impact on the fisheries and their boundaries themselves though? "If the fishermen know that the fish will migrate south again in winter to spawn, then this doesn't mean that the fisheries will automatically move further north," added Bogstad. "So far we haven't seen much of a shift in the spawning areas, just the feeding areas."
In terms of overall influence on fish - and in particular cod - numbers, there are variables other than ice melt to consider, not least the delicate dynamics of ecosystem components and predator-prey relationships. Cod are cannibalistic, for example, which might play a part, and there are the indirect effects of phytoplankton and zooplankton affecting swimming routes. All of which reflects a practical implementation of an ecosystem approach to management.
Bjarte Bogstad and his group, which met at ICES Secretariat 18 -24 April, will also feature heavily in the future development of ICES work on the Arctic and along three lines: commercial stock assessments, identifying the knowledge base for ecosystem components, and integrated assessments.