How do fishers respond to changes in fish distribution caused by climate change?

Climate change profoundly affects oceanographic conditions and the future distribution of many fishes. Climate change thus affects fisheries that are assumed to follow fish displacement. In a study published in npj Ocean Sustainability (Abe et al. 2024), we evaluate this assumption by analyzing a long-term, large-scale yet high-resolution dataset of Atlantic cod (Gadhus morhua) fishery in Norway combined with a detailed oceanographic model.

Map of coast of Norway with geographical data distribution

Figure 1. Overview of the study area and the data. The boxes in the map show the spatial resolution of the commercial landings data used in the study and the dotted line is the 180 m depth contour.

By Øystein Langangen, Joël Durant (ed)

Published Aug. 8, 2024

Climate change is affecting the marine environment profoundly. One important aspect of climate change is that species tend to change their distribution according to the local climate velocities (Pinsky et al 2013, 2020, but see post). Wild-caught fish is an essential part of the food security in the world and fisheries is a significant economic activity worldwide. It is therefore imperative to assess how fishers respond to changes in fish distributions. In a recent study (Abe et al. 2024), we investigated how the fishery for Atlantic cod (Gadus morhua) responds to the climate-associated change in the cod distribution. This investigation relied on an extensive data set of commercial landings data (Sletten Hopland & Aasheim 2024), (Figure 1) and an advanced oceanographic model archive Lien et al. 2013.

Image may contain: Slope, Font, Rectangle, Parallel, Map. — **Figure 2.** Yearly centroids of spawning suitability (orange diamonds) and the number of vessels (blue circles).

The oceanographic model was used to estimate the locations and times expected to be suitable for cod spawning. As a first step, to evaluate these estimates, a comparison between the suitability and the amount of catch per trip (a proxy for the catch per unit effort: CPUE) in the landings data was performed. We concluded that the suitability of spawning could satisfactorily explain the catch per trip. This test was important and since it was positive the model could be used for the overarching question of how fishers respond to climate-related shifts in the distribution of Atlantic cod. As a next step in the analysis, the suitability was compared to the number of fishing vessels in the areas (Fig. 2). The suitability for spawning was not able to predict the number of vessels very well. These results indicate that fishers do not fully follow the fish as the fish change its distribution with climate change. This is important for projects of climate change, as these should incorporate the rich and nuanced human behaviour as demonstrated in the recent work by Abe et al. 2024.

References

Abe K, Diekert F, Melsom A & Langangen Ø (2024) Do fishers follow fish displaced by climate warming? npj Ocean Sustainablity 3, 27.

Pinsky ML, Selden RL & Kitchel ZJ (2020) Climate-Driven Shifts in Marine Species Ranges: Scaling from Organisms to Communities. Ann Rev Mar Sci 12, 153–179.

Pinsky ML, Worm B, Fogarty MJ, Sarmiento JL & Levin SA (2013). Marine Taxa Track Local Climate Velocities. Science 341, 1239–1242.

Sletten Hopland R & Aasheim T (2023) Samansette Driftsdata for Fangst (Setel) Og Fartøy (In Norwegian). https://www.fiskeridir.no/Tall-og-analyse/AApne-data/Fangstdata-seddel-koblet-med-fartoeydata.

Lien VS, Gusdal Y, Albretsen J, Melsom A & Vikebø FB (2013) Evaluation of a Nordic Seas 4 km numerical ocean model hindcast archive (SVIM), 1960-2011. Fisken og Havet 7, 1–80.