Thünen-Institute of Sea Fisheries

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1 Federal Research Institute for Rural Areas, Forestry and Fisheries Thünen-Institute of Sea Fisheries Palmaille 9, Hamburg Telephone Telefax Az.: Dr.Ko./v.S./3594 Bericht über die Teilnahme am Survey zur Erfassung von Walen im Bereich der Süd Shetland Inseln/Antarktische Halbinsel vom 25. Januar bis 11. März 2013 Helena Feindt-Herr 1), Karl-Hermann Kock 2), Carsten Rocholl 1) 1) Institut für Terrestrische und Aquatische Wildtierforschung, Stiftung Tierärztliche Hochschule Hannover Werftstraße 6, D Büsum, Germany 2) Thünen Institut für Seefischerei, Palmaille 9, D Hamburg, Germany Abstract The Institute for Terrestrial and Aquatic Büsum of the Technical University of Hannover and the Institute for Sea Fisheries, Hamburg conducted an aerial cetacean survey from board RV Polarstern in the South Shetland Islands/Antarctic Peninsula region from 25 January to 11 March 2013 by means of a helicopter. The survey is part of the contribution of Germany to the work of the Scientific Committee of the International Whaling Commission. The survey was part of a series of cetacean surveys conducted by Germany in the Atlantic Ocean sector since 2006/07. The survey suffered from poor weather conditions in particular in the north eastern Weddell Sea. 669 individuals in 265 groups of six species were observed (blue whale, fin whale, humpback whale, minke whale, southern bottle nose whales, killer whales and hourglass dolphins). By far the most abundant species were fin whales and humpback whales. 68 whales remained unidentified. Kurzfassung Das Institut für Terrestrische und Aquatische Wildtierforschung Büsum der TU Hannover und das Institut für Seefischerei, Hamburg führten gemeinsam einen Walsurvey im Gebiet der Süd Shetland Inseln/Antarktische Halbinsel vom 25. Januar bis 11. März 2013 durch, Survey Plattform war der bordeigene BO 105 Hubschrauber. Der Survey ist Teil des Beitrages Deutschlands zum Wissenschaftsausschuss der Internationalen Walfangkommission. Er ist Teil einer Serie von Walsurveys, die Deutschland seit 2006/07 im atlantischen Sektor der Antarktis durchführt. Der Survey litt deutlich unter den schlechten Witterungsbedingungen, besonders im nördlichen Weddell-Meer, die auch die Krilluntersuchungen in diesem Gebiet behinderte, so dass nur gut 50% der Flüge durchgeführt werden konnten, die gute Witterungsbedingungen erlaubt hätten. 669 Wale in 265 Gruppen von sechs Walarten wurden identifiziert (Blauwal, Finnwal, Buckelwal, Zwergwal, Südlicher Entenwal, Schwertwal und Stundenglas Delphin wurden identifiziert. Die mit Abstand häufigsten Arten waren Finn- und Buckelwal. 68 Wale konnten nicht identifiziert werden. Verteiler: Thünen-Institut für Seefischerei per BMELV, Ref. 614 BMELV, Ref. 613 Bundesanstalt für Landwirtschaft und Ernährung, Hamburg Präsidialbüro (Michael Welling) Thünen-Institut für Fischereiökologie Thünen-Institut für Ostseefischerei Rostock FIZ-Fischerei Thünen-Institut - PR MRI - BFEL HH, FB Fischqualität Dr. Rohlf/SF - Reiseplanung Forschungsschiffe Bundesamt für Seeschifffahrt und Hydrographie, Hamburg Mecklenburger Hochseefischerei GmbH, Rostock Deutscher Fischerei - Verband e. V., Hamburg Leibniz-Institut für Meereswissenschaften IFM-GEOMAR H. Cammann-Oehne, BSH Institutsleiter: Dr. Gerd Kraus Institut für Seefischerei Palmaille Hamburg Fon Fax sf@ti.bund.de

2 Itinerary RV Polarstern left Punta Arenas (Chile) in the morning of 22 January 2013, one day later than intended, due to additional repair work on the latches of one of the holds. The scientific programme started on 25 January with several hydrographical stations north of King George Island (South Shetland Islands). Weather conditions permitting we flew up to 6 hours per day with the helicopter (BO 105) along pre-described transect to count the number of whales. RV Polarstern started a number of west-east transects in the northern part of Bransfield Strait on 26 January to investigate hydrographical conditions and the distribution and abundance of krill (see report Siegel). Large parts of the north eastern Bransfield Strait and the northern Weddell Sea were found to be covered in drifting annual and multiannual ice. The area to Elephant Island in the north and to 58 W (easternmost stations of transect) was almost completely covered in ice (80-99% coverage) which was sometimes difficult to penetrate even for an ice-breaker such as Polarstern and slowed down the survey substantially. As a consequence of the unusual ice conditions, Polarstern was unable to cover the whole survey area leaving gaps in our coverage of some parts of the northern Weddell Sea (Figure 1). When it became obvious that Polarstern was unable to penetrate further south into the Weddell Sea to fulfil its initial cruise plan and conduct the main body of its research in front of the collapsed Larsen A and B glaciers and in front of the Larsen C glacier, an alternative research programme was set in place. Polarstern left the northern Weddell Sea on 22 February in the direction of Bransfield Strait. Investigations in Bransfield Strait and in front of the South Shetland Islands were intensified. Weather conditions were still far from suitable but improved slowly which made it possible to survey almost all of Bransfield Strait and the South Shetland Islands for cetaceans. The cetacean survey was completed on 11 March RV Polarstern completed her programme on 13 March The cruise ended in Punta Arenas in the morning of 18 March Objectives Knowledge on the distribution, density and abundance of cetaceans in the Southern Ocean is still limited. Even less research has been conducted in the pack-ice region, as only few vessels are ice-strengthened enough to be able to penetrate into the ice. Macro-scale investigations on the distribution and abundance of Antarctic minke whales (Balaenoptera bonaerensis) have been conducted during three circum-antarctic surveys by the International Whaling Commission s (IWC) IDCR Programme from 1978/79 to the second half of the 1990s. Estimated minke whale abundance declined from the second to the third circum-antarctic survey by approximately 30% (IWC 2012). However, if their number has really declined, or to what extent minke whales have reacted to changing sea ice conditions in some areas, by changes in distribution and abundance on various scales, is unknown. The distribution and density of whales in the pack-ice could not be estimated by the IWC surveys, because survey vessels were not ice-strengthened and unable to penetrate into the pack-ice. It remained a matter of great debate in the IWC, to what extent minke whales inhabit the pack ice, and if they have moved into the pack-ice in larger numbers than hitherto thought (e.g. Kelly et al. 2012) in response to changing ice conditions. Polarstern as one of the few ice-breaking vessels in the Southern Ocean offers the opportunity to study the distribution and abundance of minke whales in the pack-ice (Scheidat et al., 2007a, b, Kock et al., 2009). Aerial cetacean surveys conducted in the pack-ice provide the possibility to test the hypotheses to what extent minke whales utilize the pack-ice as habitat. In continuation of the work conducted during cruises ANT 23-8, ANT 25-2, 27-2, and 28-2, we collected

3 3 systematic sighting data of cetaceans in and out of the pack-ice following standard line transect methodology. These data will be linked to ecologically relevant biotic and abiotic parameters, such as sea ice cover, collected simultaneously, in order to obtain information on habitat use. Results will allow for habitat modelling and density estimates of whales in and out of the pack-ice. Work at sea We conducted aerial surveys following standard line-transect distance sampling methodology (Buckland et al. 2001) with the two helicopters (BO 105) of Polarstern between January 25, 2013 and March 11, A total of 47 flights were accomplished, resulting in 74 hours of flying time. Seven of the flights, however, could not be used for data acquisition, as due to unfeasible weather conditions they had to be terminated within 20 minutes after take-off. The remaining 40 flights had an average duration of 1 hour and 48 minutes, ranging from 54 minutes to 2 hours and 21 minutes. All surveys were planned in an ad-hoc manner. Track lines were designed in a way that they could be surveyed depending on the current position and track of Polarstern as well as on weather conditions, aiming to achieve a good coverage of the survey area and applying basic principles of good survey design following Buckland et al. (2001). All survey flights were conducted at an altitude of 600 feet and a speed of knots. Two observers were positioned in the back of the helicopter and observed the area to the right and to the left side of the helicopter, respectively, concentrating on the area below the helicopter. The third observer was seated in the port front seat of the helicopter observing the area to the front, focusing on the transect line. The observer in the front seat of the helicopter used the VOR software (Hiby & Lovell 1998), running on a laptop computer, to continuously store GPS data, data on environmental conditions (sea state, cloud cover, glare, ice coverage, sighting conditions) and data on all sightings of marine mammals. For each sighting of a marine mammal in the water, the following data were collected: species, distance to transect (via declination angle), group size, group composition, behavior, cue, swimming direction and potential reaction to the helicopter. Inclinometers were used to measure the declination angle to each sighting when abeam the helicopter, in order to later calculate the distance of the sighting to the transect line. This information is crucial for later estimation of the effectively covered strip width. If a sighting occurred and species could neither be identified nor group size be determined immediately, the survey was halted in order to approach the sighting for closer inspection (closing mode). After identification, the helicopter returned to the transect line and the survey was continued. Digital photography was used to aid in species identification and for Photo-ID purposes. Preliminary results A total of 40 successful surveys were conducted, covering km on effort (i.e. in observing mode). During these surveys, a total of 267 cetacean sightings of 669 individuals were recorded. Seven species were identified. Table 1 provides an overview of the number of sightings and individuals by species encountered. Figure 1 presents all tracklines covered and positions and species of all sightings recorded. Data Publication in scientific journals in the fields of marine biology and zoology and presentation on scientific conferences will make the data obtained available for science and public. Survey results will be presented to the Scientific Committee of the International Whaling Commission. Data will be stored in the Antarctic Marine Mammal Survey Database of the Institute for Terrestrial and Aquatic Wildlife Research, Büsum, Germany.

4 4 Acknowledgement We would like to thank Captain Pahl and the entire crew of Polarstern for their neverending support throughout the whole survey. Our survey would not have been possible without the excellent work and support of the helicopter crew, Klaus Hammrich, Lars Vaupel, Carsten Möllendorf and Thomas Müller. We are grateful to the meteorological office onboard, Manfred Gebauer and Hartmut Sonnabend. Their weather forecasts made it possible to conduct this survey in very variable weather conditions. This project was funded by the German Federal Ministry of Food, Agriculture and Consumer Protection within the project: Modellierungen zu Populationsgrößen und räumlicher Verteilung von Zwergwalen im antarktischen Packeis auf der Grundlage von See- und luftgestützten Tiersichtungen (Förderkennzeichen 2811HS002). References Buckland ST, Anderson DR, Burnham KP, Laake JL, Borchers DL, Thomas L (2001) Introduction to distance sampling: estimating abundance of biological populations. Oxford University Press, Oxford Hiby AR, Lovell P (1998) Using aircraft in tandem formation to estimate abundance of harbour porpoise. Biometrics 54: Kock K-H, Scheidat M, Boebel O, Bräger S, Herr H, Lehnert K, Lehnert LS, Verdaat H, Williams R (2009) The occurrence of cetaceans along two transects from 57 S to Atka Bay ( S/ W). Paper SC/61/IA/11, International Whaling Commission, Cambridge, UK. Scheidat M, Kock K-H, Friedlaender A, Lehnert LS, Williams R (2007a). Preliminary results of aerial surveys around Elephant Island and the South Shetland Islands SC/59/IA21, International Whaling Commission, Cambridge, UK. Scheidat M, Kock K-H, Friedlaender A, Lehnert L, Williams R (2007b). Using helicopters to survey Antarctic minke whale abundance in the ice. SC/59/IA20, 15 pp., International Whaling Commission, Cambridge, UK. Table 1: Cetacean sightings by species from the aerial surveys during ANT XXIX 3 Species Number of groups Number of individuals Antarctic minke whale (Balaenoptera bonaerensis) Humpback whale (Megaptera novaeangliae) Fin whale (Balaenoptera physalus) Southern bottlenose whale 1 2 (Hyperoodon planifrons) Killer whale 7 73 (Orcinus orca) Blue whale 1 1 (Balaenoptera musculus) Hourglass dolphin 2 9 (Lagenorhynchus cruciger) Unidentified beaked whale 1 3 Unidentified baleen whale Total

5 Fig 1: Cetacean sightings and tracklines covered on effort during the aerial cetacean survey of ANT