Cod versus shrimp dominance in West Greenland waters: Can climate change reverse the regime shift from a cod to a shrimp dominated ecosystem off West Greenland?

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Relative warm conditions prevailed at Greenland from the beginning to the mid of the 20th century and in this period a self-sustaining and very abundant cod stock existed in West Greenland offshore waters. A prolonged period of decline in stock biomass was observed from 1950 to 1975 at intense fishing. The West Greenland cod stock collapsed completely in the beginning of the 1990s when colder conditions prevailed and mean size at age declined drastically. Air and ocean temperature increased again above average in the end of the 1990s but first in 2005 an initial sign for a rebuilding of the stock has been seen. However, a self-sustaining spawning stock has yet not been re-established in Greenland offshore waters. An offshore fishery for Northern shrimp began in the 1970s and a threefold increase in stock biomass at West Greenland occurred from 1997 to 2003 at moderate fishing levels. In the most recent years, shrimp disappeared from Southwest Greenland where relative high temperatures were recorded, and the stock became more concentrated in the northern areas. Further, recruitment and subsequently stock biomass have decreased considerably in the past and this has raised concerns that the current level of exploitation of the shrimp stock may not be maintained in the future. The cod stock has actually a pronounced southern distribution at West Greenland and spatial overlap with the shrimp stock is therefore quite limited. However, the current temperature conditions and recruitment from a growing spawning stock notably off East Greenland may alter this in the coming years