Climate Affects Bottom-Dwelling Fish Species

by Sabrina Heerema | Published: 13-Sep-21 | Last updated: 13-Sep-21 | Tags : climate ecoregion Greenland ICES | category: NEWS

The ECOTIP project focuses on understanding and predicting changes (potential tipping points) in Arctic marine biodiversity and implications for fisheries production and carbon sequestration, which in turn affect global climate. The offshore area West of Greenland is one of the main research sites, and also where recent research about Greenland Halibut has been published. The conclusion of the recently published scientific article is that fishery for Greenland halibut in the waters offshore of West Greenland appears to be sustainable at present, which implies that local ecosystem changes have occured due to climate change.

Researchers from Greenland Institute of Natural Resources (GINR), Spain’s University of Vigo, and the American National Marine Fisheries Service have analyzed research survey data for the past 22 years in the important fishing ground of Greenland halibut to understand the effects of both climate and fishing pressure on stocks of bottom-dwelling fish species. They studied data on 156 fish species caught in the period 1997-2019 from different depths: 400-800m, 800-1200m and 1200-1500m.

Bottom temperatures were used as expressions of climate, as they vary between periods with cold and warm water, related to variations in the global deep-water circulation, which are affected by variations in climate. Data on commercial catches of Greenland halibut (number of fishing hours and weight of catch) were used as expressions of fishing pressure. Researchers found a strong correlation between changes in bottom temperatures and changes in the composition of the bottom-dwelling fish communities. They found that changes had happened in the Greenland halibut’s preferred habitats. In the beginning of the offshore fishery, the halibut preferred deeper areas, but in the last two decades they had become more common in shallower and mid-depth waters.

The degree of structural and compositional changes in fish community structure due to temperature variation depends on the depth, such that periods with warmer bottom water result in relatively large changes in the fish community in shallower waters. Stocks of adult Greenland halibut increased over the 22-year period in shallow and medium deep water, while they declined in deep water, despite the adult halibut’s depth and temperature preferences. Increasing stocks of deepwater redfish in shallow and medium deep water may have encouraged the halibut to move into shallower waters. And while catches of Greenland halibut in the sea off West Greenland have been increasing, there has been no noticeable effect on fish stocks, which indicates that offshore fishing for Greenland Halibut is sustainable. Click here to read the full research article in the ICES Journal of Marine Science, or for further information on this research, contact: Adriana Nogueira, Researcher, Greenland Institute of Natural Resources, Department of Fish and Shellfish, Telephone + 299 36 12 00 or e-mail adno@natur.gl.