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Satelite tracking of Humpback whales in West Greenland

Rune Dietz et al.

NERI Technical Report No. 411

Summary

Tagging and longevity information
The tagging of 6 humpback whales (Megaptere novaeangliae) off West Greenland was conducted in June 2000. Data were obtained from the tagged whales over a period from 0 to 42 days (Mean = 12.5 days; n = 6), whereas locations were only obtained during 0 to 17 days (Mean = 6.2 days; n = 6). The four whales from which positions were obtained were tracked for a total of 1042 kilometres. The tagging revealed that humpback whales of West Greenland within the month of June, as a minimum, can move between Fiskenæs Banke, Fyllas Banke, Tovqussaq Banke, Sukkertop Banke and up to Lille Hellefiske Banke. The whales showed a preference for the continental slopes with depths less than 200 m. The whales may travel up to 120 nautical miles (220 km) from the shores to water deeper than 1000 m, and they may also visit the Central West Greenland fiord systems.

Depth of dives
The humpback whales primarily are at the surface during the middle of the day, where they spend as much as 83.3 % of the time in the upper 8 m of the water column. This means that noon is the optimal time to count humpback whales of West Greenland during the summer season (June - July). It was documented that the humpback whales use the majority of their time in the upper 4 m (36.7 %) and 4-20 m (24.5 %). The dive categories 20-35, 35-50, 50-100, 100-150, 150-200 and 200-300 m were frequented from 3.0 to 7.5 % of the time, whereas the humpback seldom dived to 300-400 m (0.27 %) and 400-500 m's (0.035 %) depth. No recordings were registered deeper than 500 m.

Dive duration
The length of the dives confirmed the preference for shallow feeding of the humpback whales. Most of the dives (22 %) were recorded in the category of dives lasting less than a minute, representing animals staying close to the surface. The one-minute dive duration intervals between 1 and 7 min represented from 6 to 14 % of the dives and most dives were recorded at a length of 7-8 min (15 %). Dives of 8-9 min were less common (5 %) and dives longer than 9 min were rare (<1 %). No dives lasted longer than 15 min. The average dive duration of the 667 recorded dives was 3.8 min.

Use of the drilling and license area
Two of the tracked whales provided positions within the Fylla licence area but less than 10 % of the positions were obtained within this area. The closest position to Qulleq-1 was 24.3 NM, which means that chances for direct encounter with the drill ship was remote. The exploration drilling was carried out on 1152 m water depth, an area of little or no importance for the feeding of the humpback whales, as no dives below 500 m were recorded. None of the transmitters provided positions beyond the starting day of "West Navions" drilling. From the literature only few sightings have been recorded outside the banks within the license area. This condition is supported by the fact that the West Greenland humpback whales showed a preference for shallow water for their feeding, as 93 % of their time was used at depths shallower than 200 m. In addition the whales observed in this study and in previous studies have mainly shown a preference for the landward slopes of the banks. This means that the banks will reduce noise generated from activities further offshore.

Conclusion
The fact that the humpback whales have been tracked to and re-sighted at other banks along the Greenland west coast, means that the whales have alternatives to the Tovqussaq and Fyllas Banke if they are disturbed. The summering areas in Greenland must be regarded as a critical habitat as the whales are building up their blubber deposits which they are dependant on during the rest of the year, where they are not feeding.

Bibliographic information: Dietz, R., Teilmann, J., Jørgensen, M.-P.H. & Jensen, M.V. (2002): Satelite tracking of Humpback whales in West Greenland. National Environmental Research Institute, Denmark. 40 pp. NERI Technical Report No. 411. Available electronic at www.dmu.dk

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2002-11-15