There are 35 ecologically important areas for sharks, rays and chimaeras in the polar seas – but fishing activity can be detected in 30 of them. This is shown by a new study in Global Change Biology, which for the first time evaluates Important Shark and Ray Areas (ISRAs) in the Arctic and Antarctic together with fishing effort, sea ice trends and existing marine protected areas.
The 35 areas cover around 397,739 square kilometers. That’s only 0.75 percent of the polar region examined. 27 ISRAs are in the Arctic, eight in the Antarctic. An ISRA is not a legally protected zone, but a scientifically demarcated area that meets certain criteria for vulnerability, limited distribution or important life phases.
86 species – but sufficient area data for only 15
The researchers recorded 86 cartilaginous fish species: 42 sharks, 36 rays and eight chimaeras. 28 species or 32.6 percent are considered globally threatened. Nevertheless, the evidence was only sufficient for 15 species to delineate at least one ISRA. These qualifying species include seven sharks, seven rays and one chimera.
The Greenland shark was the most frequently represented species, qualifying for ten Arctic ISRAs. The basking shark and spiny dogfish also supported area delineations. Most ISRAs were identified from evidence of reproductive areas or aggregations of an unspecified type. Detailed descriptions of each area are available in the ISRA e-Atlas.
The data gap is itself an important finding. 72.1 percent of the regional cartilaginous fish fauna lives in the deep sea. For 13 of the 15 qualifying species, delineation was based on scientific survey catches or commercial fishing. For ten species and 20 ISRAs, these catch data were the only evidence. In Antarctica this applied to six of the eight areas.
Fewer fishing hours can still mean a wider footprint
The study compares AIS-based apparent fishing effort from 2013 to 2018 with that from 2019 to 2024. In the Arctic, recorded trawl hours increased by 17.8 percent, while their spatial extent increased by 26.1 percent. On longlines, hours fell by 2.2 percent, but the area fished grew by 34.7 percent.
Antarctica shows a similar pattern: trawl hours increased by 24.7 percent and spatial extent by 22.6 percent. The number of longline hours registered fell by 2.3 percent, while at the same time their area increased by 39.8 percent. Less time at sea does not automatically mean less spatial pressure.
Fishing signals overlapped with 22 of the 27 Arctic and all eight Antarctic ISRAs. In the Arctic, the highest trawling intensity was in Skagerrak; 90.8 percent of this ISRA area overlapped with trawl activity. For the Greenland shark, 12.7 percent of its range overlapped with trawling activity and 5.4 percent with longline activity.
In the Arctic, 91.8 percent has no MPA overlap
Only 8.2 percent of the Arctic ISRA area overlapped with marine protected areas; only 0.8 percent were in strict no-extraction zones. This means that 91.8 percent had no overlap with a recorded marine protected area. In Antarctica the overlap was larger at 43.8 percent, but there too only 14.8 percent of the ISRA area was in No-Take zones.
Percentages measure spatial overlap, not the effectiveness of controls. Partially protected areas may allow fishing. Conversely, some fishery closures and other effective area-based protection measures are missing from the global protected area database used. The study mentions the Canadian Disko-Fan protected area, which overlaps an ISRA for Greenland sharke.
AIS does not capture all fishing activity
The dataset used by Global Fishing Watch estimates fishing hours from AIS signals. Small ships without AIS, transmitters switched off and journeys not correctly classified remain incompletely recorded. A spatial overlap also does not prove how many sharks or rays were caught there. First, it shows that fishing takes place in or near an important habitat.
The direct combination of falling sea ice concentration and simultaneously growing fisheries was also spatially small in the period examined. The authors therefore primarily describe an increasing future risk: less ice opens up new access points, while species and fisheries can shift polewards or to greater depths.
ISRAs are a planning tool, not a protected status
The researchers recommend incorporating ISRAs into existing instruments – including the global 30 percent protection target, the high seas treaty and the fisheries organizations NAFO, NEAFC and CCAMLR. In the short term, the maps could prioritize observer programs, electronic monitoring, bycatch rules and targeted spatial measures where fisheries already overlap with critical habitat.
- Species: 86 cartilaginous fish species in polar regions, of which 28 are globally threatened.
- Key areas: 35 ISRAs on 0.75 percent of the examined sea area.
- Fishing: Overlap with 30 ISRAs; the spatial extent of trawls and longlines increased at both poles.
- Strict protection: 0.8 percent of the Arctic and 14.8 percent of the Antarctic ISRA area in No-Take zones.
- Uncertainty: AIS and fishing-dependent data do not fully capture utilization and species occurrence.
The study does not provide a complete map of all important polar shark and ray habitats. Rather, it shows where the evidence is already sufficient today – and how large the unknown area remains. Precisely because science and conservation planning could lag behind the spatial expansion of human use, the 35 areas should be understood as precautionary priorities.
