SC/53/E8

 

PRELIMINARY REPORT ON IWC-SO GLOBEC COLLABORATIVE RESEARCH IN THE WESTERN ANTARCTIC PENINSULA STUDY AREA MARCH – JUNE 2001

 

Deborah Thiele1, Eileen Hofmann2, Ari Friedlaender3, Sue Moore4, Mark McDonald5

 

1 Marine and Migratory Wildlife Ecology Group, School of Ecology and Environment, Deakin University, GPO Box 423, Warrnambool, Victoria, Australia 3280

 

2 Center for Coastal Physical Oceanography, Crittenton Hall, Old Dominion University, Norfolk, VA 23529, USA

 

3 Duke Marine Lab., Beaufort, North Carolina, USA

 

4 NOAA/National Marine Fisheries Service, National Marine Mammal Laboratory, 7600 Sand Point Way NE, Seattle, Washington 98115, USA

 

5 2535 Sky View Lane, Laramie, Wyoming 82072, USA

 

Abstract

The first three cruises in the ‘year round’ Southern Ocean GLOBEC series for 2001-2002 were conducted from March – June 2001. International Whaling Commission researchers participated in all three cruises (Gould LMG 01-03 USA mooring cruise, Polarstern AntXVIII5b ship and helicopter based studies Germany, Nathaniel B Palmer NBP 01-03 USA survey cruise). A combination of ship, zodiac and helicopter based visual survey, tissue biopsy, and photo identification techniques were used on the vessels by the IWC. Passive acoustic moorings and expendable sonobuoys were deployed by the US passive acoustic team. The most frequently recorded and abundant baleen whale species in the study area were minke and humpback whales. An initial overview of oceanographic data shows strong patterns of correlation between autumn and early winter baleen whale distribution, the inshore cold Antarctic coastal current, and upwelling of this cold water produced by intrusions of the Antarctic Circumpolar Current into Marguerite Bay. Confirmation of krill autumn migration into inshore waters associated with complex bathymetry (ie. dense aggregations in deep pools or holes) was made on these surveys. This indicates that baleen whale prey is available throughout all seasons. Baleen whales were observed in Marguerite Bay as late as June, and it is likely that both humpback and minke whales overwinter in this region. These preliminary associations will be tested during the winter NB Palmer cruise (July – September) and through modelling and analysis planned between IWC and SO GLOBEC in 2001. The 2002 series of cruises will further test these and other physical and biological associations.

Note: all figures/maps are in colour and are available from the Secretariat as reference copies. A full set of images can be copied for individuals on request.

Introduction

The International Whaling Commission’s interest in participating in international multidisciplinary research programs such as CCAMLR and SO GLOBEC has been extensively documented in IWC Scientific Committee reports, Resolutions of the Commission and papers (ie. SC/46/O18, SC/47/O20, SC/50/Info.14, SC/52/E22). At IWC 51 plans for collaboration on CCAMLR surveys in the Antarctic Peninsula were developed for the 1999-2000 austral summer. These surveys were successfully conducted and initial results were presented in SC/52/E21 (Reilly et al 2000).. Detailed analysis of krill and baleen whale data sets are currently being conducted by CCAMLR and IWC scientists.

 

At IWC 52 preparations were made for participation in the 2001 – 2002 ‘year round’ series of SO GLOBEC survey and process cruises. A budget was developed to include purchase of essential equipment; participation by Thiele (IWC-SO GLOBEC steering group Chair) in planning meetings and relevant GLOBEC workshops; and to fund IWC participation in the initial cruises planned for March – June 2001. Due to urgent funding requirements for the POLLUTION 2000+ initiative, it was agreed at IWC 52 that funds for the IWC-SO GLOBEC collaboration would need to be limited to equipment purchases and planning activities, with participation to be delayed until after IWC53 unless funds could be acquired outside the IWC SC budget. Thiele secured funding from the Australian Government to support initial IWC participation in the first three SO GLOBEC cruises. Equipment for the collaboration approved in the IWC 52 budget was purchased by the IWC.  Items of equipment not covered in the IWC 52 budget were lent from Thiele’s SOCEP program. Although the opportunity to biopsy appeared unlikely prior to the initial cruises, we determined that it would be prudent to be prepared, and two sets of crossbows with associated biopsy sampling gear were kindly contributed by the Southwest Fisheries Science Center in return for any skin samples obtained. This meant that participation by the IWC could begin in the first phase of the program, and the opportunities provided by the substantial research effort in the first half of 2001 would not be lost.

 

A range of national research programs had been identified, some tentatively, to contribute to studies during 2001 – 2002 in the SO GLOBEC study area. However, by far the greatest effort came from the US National Science Foundation funded cruises. This effort includes five cruises in 2001 in the austral autumn and winter, all of which will be repeated at exactly the same time in 2002.

 

The overall goal of the US SO GLOBEC effort in this study is to elucidate shelf circulation processes and their effect on sea ice formation and Antarctic krill survivorship and availability to higher trophic levels, including seals, penguins and whales (Hofmann et al 2000 – draft plan in SC/52/E22 Appendix 1). The central Western Antarctic Peninsula (WAP) continental shelf area is characterised by unusually high krill production. The US SO GLOBEC research program structure has been developed around a central hypothesis: that a unique combination of physical and biological factors contribute to enhanced krill growth, reproduction, recruitment and survivorship throughout the year in the central Western Antarctic Peninsula (WAP) continental shelf area; and that in particular this region provides physical conditions that are especially favourable to winter survival of larval and adult krill.

 

The presence of krill predators in the study region, particularly in winter, is central to the main hypothesis of the research program. Seal and penguin studies are a strong component of the process study cruises in the US program. Clearly this program provided an unprecedented opportunity for the IWC to obtain data and conduct multidisciplinary analyses towards its objectives regarding associations between baleen whales, their prey and the physical environment. SO GLOBEC will benefit from the collaboration through an additional, and essential top predator component in their investigations of the dynamics of krill in these ecosystems.

 

Berths for IWC visual surveys were provided on the mooring cruise (L M Gould) and both survey cruises (NB Palmer) by the passive acoustic team led by John Hildebrand. The IWC team and this team have worked collaboratively throughout the US surveys. Process study cruises on the L M Gould run simultaneously with the N B Palmer survey cruises and although no berths were available for IWC on the LMG process cruises, the seal teams on board were trained to use Wincruz Antarctic by the IWC observers, and provided with equipment to record cetaceans whilst on watch. This approach further increased the cetacean coverage at a time of year when relatively few cetaceans are likely to be present.

 

Other national programs (ie. Germany, Brazil, UK) operating in the study region will contribute to the study by conducting complementary research in addition to the major US effort.

 

Here we:

1.      Provide summaries from individual cruises on research conducted;

2.      Make recommendations for IWC participation and involvement in the SO GLOBEC analysis process.

1. Summaries from individual cruises

 

The SO GLOBEC study by the USA and other national programs in the Marguerite Bay area of the Western Antarctic Peninsula (Figure 1.) commenced in March 2001. A range of cetacean research options were opportunistically pursued on each of these multidisciplinary cruises. Visual surveys were conducted on all cruises, passive acoustic studies were conducted (NSF Moore and McDonald) on the Gould and Palmer cruises; helicopter surveys were conducted from the Polarstern; and photo identification and biopsy sampling of minke and humpback whales was made possible from the Gould and Palmer cruises through the allocation of dedicated ship time for IWC studies by the US SO-GLOBEC program (five days on LMG and one day on NBP).


Figure 1. Survey and process study area SO GLOBEC Marguerite Bay WAP.

RV Laurence M Gould 18 March – 13 April

The L M Gould departed Punta Arenas on 18 March 2001 with the objective of deploying a series of cetacean passive acoustic and oceanographic moorings in the area off the year round SO GLOBEC study site at Marguerite Bay (Figure 2).

 

Figure 2. LMG01-3 cruise track

 

 

 

Methods – visual survey, biopsy and photo identification

Visual survey for cetaceans was conducted on LMG 01-03 during daylight hours on all days when weather conditions allowed. Searching was conducted by the IWC observer (D Thiele) and Sue Moore with assistance from the rest of the acoustic mooring team. Sightings were recorded on a laptop based Wincruz[1] Antarctic program which also logged gps position, ship course and speed automatically. Seals, seabird concentrations, ice concentration, sea surface temperature, marine debris, sonobuoy deployments, depth and other events were also recorded on the program. Survey effort generally commenced at first light from the outside bridge wings and/or inside the bridge (weather dependent) and ceased at dark. All times noted here, and in cruise records refer to UTC/GMT not local time.

 

Results – visual survey, biopsy and photo identification

Visual surveys alone were conducted from 19 March to 2 April during the oceanographic and acoustic mooring components of the cruise. Many humpback whales (Megaptera novaeangliae) were observed during the afternoon transit across the Bransfield Strait on 23 March. Five days of ship time were allocated to conduct cetacean survey (including closing on sightings, biopsy, photo identification and sonobuoy deployment) from first light on Tuesday 3 April to end of day Saturday 7 April. The weather improved markedly for this part of the survey. During this time the ship traversed the inside channels from the northern end of Renaud Island, Grandidier Channel, Crystal Sound, Matha Strait and passages to the east of Adelaide Island and the north-eastern section of Marguerite Bay (Figures 2 and 4). Figure 4.a, b show the Western Antarctic Peninsula and Marguerite Bay study area with LMG 01-03 cetacean sightings.

 

In Matha Strait two large feeding groups of the dark shouldered minke whale (Balaenoptera acutorostrata bonaerensis) were sighted (total of 80 animals). Photographs were obtained and biopsies of four minkes from the largest group were taken. On entering the northern end of Marguerite Bay, just near Rothera Station (UK), a large group (30) of killer whales (Orcinus orca) were sighted. The killer whales broke into sub-groups and travelled north past the ship with many accompanying fur seals, and a minke whale (Balaenoptera acutorostrata). One humpback (Megaptera novaeangliae) was also seen in the vicinity. The ship took a south west course to Neny Island and then headed across the bay and towards Palmer Station on a course close to the coast and inside the islands from Matha Strait onwards. Two pairs of humpbacks were located late in the afternoon of the 7th April, with photo identification and biopsy obtained from one pair. Total biopsies taken: 5 minke (one from a group of 7, and 4 from the feeding group of 50) and 5 humpback (one from one pair and both animals from another two pairs). A summary of the biopsy samples is included at Table 2.

 

Methods and sonobuoy recordings - passive acoustics

The long-term nature of seafloor recorder deployments allows for a statistically significant number of acoustic encounters, even with a widely dispersed whale population, assuming whales call roughly ten to fifty percent of the time.  The recordings will likely also include sounds from minke, right, fin and humpback whales.  Mysticete whales will be detected via reception of their calls on passive, bottom-mounted acoustic recorders.  Detection of whale calls via moored passive acoustic recorders has proven quite effective during recent studies, especially for blue and fin whales.  New technology, that of long-term deployments of autonomous low power recorders makes an acoustic survey of mysticete whales in remote locations practical.  Deep water is desirable partly because the ambient noise, which largely is produced at the surface, is reduced at depth and also because acoustic travel paths will interact less with the seafloor which absorbs acoustic energy.  The long-term nature of seafloor recorder deployments allows for a statistically significant number of acoustic encounters even with a widely dispersed whale population, assuming whales call roughly ten to fifty percent of the time. 

Given the great uncertainty in the numbers of blue whales in the Southern Ocean, and in the subspecies to which they belong, we believe the minimum census estimates which can be provided by acoustic monitoring is a key goal of the proposed project. Application of the techniques of point transect theory to the results of the survey where each acoustic contact is assigned a range should allow a minimum census estimate, the primary factor which will remain to be answered from other combined visual and acoustic data being the percent of whales calling during a time constant. The second fundamental goal of this work will be minimum population estimates and seasonal occurrence profiles for fin whales and humpback whales.  Other species such as minke whales and sperm whales may be detected, but are expected to be so infrequent as to make population density estimates unreliable. Perhaps the most important overall result of this work will be to establish an acoustic detection baseline from which to measure future changes in relative abundance of Southern Ocean mysticete whales. 

 

We deployed eight seafloor acoustic recorders (Figure 3.), each with a hydrophone that  is floated about 5 m above the seafloor.  These instruments will record continuously at 500 samples per second for fifteen months, writing the data to 36 Gb of computer hard drive in each instrument.  The recorders have a 16 bit dynamic range and are powered by lithium double D size batteries, which are placed inside high tensile aluminum pressure cases.  The seafloor recorders use a system of drop weights, Benthos glass balls and an acoustic release for recovery. Throughout the cruise we deployed and recorded 36 directional sonobuoys and two broadband sonobuoys both randomly and when whales were sighted, as a means to record and thereby `groundtruth’ mysticete whale calls in this remote region. Recordings were obtained from humpback, minke and fin whales during the cruise.  No blue or right whales were sighted or heard during this cruise.

 

MATLAB Handle Graphics

Figure 3. Locations of the moorings and drifters deployed on LMG01-3 (SIO moorings are passive acoustic recorders).

 


Figure 4.a  LM Gould 01-03 Mooring cruise - all cetacean sightings

 

 

 

Figure 4b L M Gould 01-03 minke and humpback sightings

 

General

This cruise was primarily an oceanographic and passive acoustic mooring cruise. A series of oceanographic and passive acoustic moorings were deployed on the shelf region off the Marguerite Bay study area (Figure 3.). These moorings will be retrieved during the 2002 mooring cruise and will provide important contextual data for the survey and process study cruises on ocean current dynamics and cetacean presence/absence and distribution throughout the period March 2001 to March 2002. IWC participation was included on this cruise due to the opportunity to conduct visual surveys in the area of mooring deployments. Expendable sonobuoys were also used in conjunction with ship and zodiac based visual surveys, biopsy and photo identification studies by the IWC team. During the cruise a block of five days was allocated for the IWC work. Unlike the N B Palmer survey cruise, the research on the L M Gould did not include an oceanographic and biological sampling program (Limeburner et al 2001). However associations between cetaceans and physical and biological features in this area will be determined from existing models and data series held by the US program. Generally, the location of baleen whales was similar to that observed on the N B Palmer, where comprehensive multidisciplinary sampling revealed associations between the Antarctic Coastal Current, fronts between major water bodies and upwelling zones.  In addition, survey of the passages between the continent and Western Peninsula Islands to the north of and inside Marguerite Bay also revealed associations between baleen whales and cold water fronts likely to be the result of mixing between warm and cold water as noted in the N B Palmer summary (Figure 12.).

 

Polarstern AntXVIII5b 14 April – 7 May 2001

The Polarstern departed on cruise AntXVIII5b on 14 April 2001 and headed directly for the SO GLOBEC study site (Figures 5. and 6.).

 

 

Figure 5. Polarstern AntVIII5b cruise track and sampling stations

 

Most research work on the Polarstern has occurred in the Weddell Sea, however some research has been conducted in the Western Peninsula and Bellinghausen Sea regions. Generally top predator studies on the Polarstern have been conducted by J. van Franeker (with a focus on seabird abundance and associated cetacean records), and some surveys have included cetacean visual surveys (Pankow and Kock 2000). J. van Franeker conducted seabird census from the upper bridge flying deck on the April – May cruise, whilst the IWC observer worked from the inside bridge. Helicopter surveys reported here were conducted with JvF as he kindly shared his dedicated helicopter flight time for the voyage with the IWC observer.

 

Weather conditions on this cruise were not conducive to visual surveys, and few whales were sighted from the vessel. Most sightings were made on the helicopter surveys (which were conducted in good weather only) and on the one sunny day within the ice to the south of Marguerite Bay. The survey area was reached on 18 April and line transect sampling began on a northern transect placed between those soon to be occupied by the N B Palmer. The ship remained working in the survey area until 21 April, and then steamed to the oceanic fast ice edge well to the south of Marguerite Bay.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Figure 6. Polarstern AntVIII5b cruise track and inset of Figure 8&9 with all cetacean sightings. Species codes: 7=humpback – yellow circle; 13&59=Lagenorhynchus sp. – green diamond; 4,91&92=minke – black star; 9,64,65,67=unidentified whale – yellow triangle

 

 

Hourglass dolphins (1:10), like fin (1:2) and an unidentified whale were recorded in the transect area. The ship proceeded well within the ice to locate sea ice sampling stations. At the first station on 23 April in a small lead near an iceberg a group of four dark shouldered minke whales were sighted, and spent the whole afternoon around the vessel whilst on station. This area, and the area traversed through ice to reach it had 10/10 ice coverage and extensive algal deposits on the underside of floes. On 24 April  two groups of minke whales (six animals were observed in the ice near the vessel). On 25 April a series of helicopter flights were conducted to deploy sea ice buoys and search for penguins, seals (JvF) and whales (DT). On take off the usual 10/10 ice coverage could be seen to include a network of leads and breathing holes similar to that reported in Thiele and Gill (1999). Two groups consisting of three undetermined minke whales were sighted on the survey routes mapped in Figure 7. Also depicted in this figure are the sightings of minke and probable minkes recorded on a visual survey along the cruise track whilst JvF conducted a helicopter survey ahead of the vessel. The helicopter survey recorded only one minke, while the ship based visual survey recorded 29 whales. These whales, either confirmed as minke whales, or as like minke whales, were spread evenly over the shelf area within 10/10 ice and were spaced fairly evenly throughout. Minke whale presence stopped abruptly once the swell affected region of ice was reached, coinciding with the shelf break.

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Figure 7. Polarstern AntVIII5b in ice cetacean sightings – In ice helicopter surveys and ship based visual survey 25 & 26 April 2001. Black star=minke; yellow triangle=probable minke. Bold red line = cruise track. Fine red lines = helicopter surveys. Yellow line = oceanic fast ice edge.

 

On 27 April the vessel left the ice and headed for the GLOBEC study site to resume line transect survey and sampling. The IWC observer was provided with helicopter time to conduct two further whale flights whilst in the vicinity of Adelaide Island (Figure 8.) and Anvers Island. The first of these surveys (1 May) covered an route from the vessel on the western side of Adelaide Island, around the southern coast and then north to Rothera Station. The helicopters then landed (to take equipment to Rothera). One helicopter was then used to conduct a survey of the area to the south of the station. Large numbers of humpback whales (20 in 10 pairs) were observed near Jenny Island, a location where we had previously biopsied a humpback pair from the L M Gould platform. One pair of humpbacks observed on the helicopter flight was confirmed as a biopsied pair from the L M Gould cruise. Some minke whales were also observed on this flight, and a pair of humpbacks were seen feeding less than 1nm from the ship on the return flight. The final helicopter survey was conducted on 2 May off Anvers Island to the north of the GLOBEC study site (near Palmer Station). On this short (due to adverse weather) flight we surveyed the south western bays of Anvers Island, observing pairs of humpbacks, and one group of four (with a large calf) close inshore in separate bays. The humpbacks appeared to be spread along these bays, and as this habitat extends to the north for some considerable distance, it is likely that many more groups inhabited the unsurveyed bays.

 

The areas of concentration of both minke and humpback whales coincide with those recorded on the N B Palmer cruise.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Figure 8. Polarstern AntVIII5b cetacean sightings – Adelaide Island/Rothera helicopter survey 1 May 2001. Yellow circle=humpback, black start=minke. Bold red line = ship cruise track. Fine red lines = helicopter survey tracks.

 

 

Nathaniel B. Palmer 01-03 24 April – 6 June

The N B Palmer departed Punta Arenas on 24 April directly to the SO GLOBEC study area in order to commence the survey cruise at the same time as the L M Gould (LMG 01-04) conducted process studies in that area (Figure 1 a and b). The NB Palmer commenced survey at the northern end of the line transect series shown in Figure 1.).

 

Methods – visual survey, photo identification and biopsy

During this cruise, observations were made from the ice tower or the bridge level by a single observer (AF).  When conditions permitted, the observer was outside along the cat-walk of the ice tower, otherwise, observations were made from inside.  Effort was focused 45° to port and starboard of the bow ahead of the vessel, while also scanning to cover the full 180° ahead of the vessel. °. In ice the method was adjusted to include searching in behind the vessel track as well, in order that cetaceans and seals hidden by ice would be detected more readily. The observer used a combination of eye and binocular (7x50 Fujinon) searching.  Effort would commence when the following conditions allowed: appropriate daylight, winds less than 20 knots or Beaufort Sea State less than or equal to 5, visibility greater than 1 mile (measured in the distance a minke whale blow could be seen with the naked eye as judged by the observer) and the ship actually steaming. Sightings were recorded on a laptop based Wincruz Antarctic program which also logged gps position, course, ship speed, and a suit of other environmental and sighting conditions automatically.  Visual observations were made both during the station-transect portion of the trip, as well during transit.  When possible, photographic and/or video documentation was made of each sighting for later use in individual identification, species confirmation, and habitat description. A second component to the IWC work is biopsy sampling from small boats.  On the occasion that weather conditions, daylight, timing, and whales were present, biopsy sampling was attempted from Zodiacs.  Samples were obtained with a Barnett Wildcat Crossbow equipped with custom made floating bolts, and screw-on hollow point biopsy plugs. 

 

Results – visual survey

Generally, sighting conditions during the cruise were poor. However, nearly 80 hours (79:33) of sighting effort were made during the entire cruise.  Of this time, 45:30 was made during the survey grid.  In Antarctic waters (south of 60°S), 43 cetacean sightings of 67 animals were made (Figure 9).

 

Figure 9.  NBP 01-03 Cetacean Survey Effort Lines and Sightings in Antarctica (below 60°S)

 

These include 19 sightings of 30 humpback whales, Megapatera novaeangliae, 22 sightings of 33 minke whales, Balaenoptera acutorostrata, 1 sighting of 3 ‘like’ humpback whales, and 1 sighting of 1 unidentified whale (Table 1). More specifically, within the study area as defined by the survey grid, 18 sightings of 27 humpback whales (Figure 10.), 19 sightings of 30 minke whales (Figure 11.), 1 sighting of 3 ‘like’ humpback whales, and 1 sighting of 1 unidentified whale were made (Table 1.).

 

Figure10.  NBP 01-03 Cetacean Survey Effort and Humpback Whale Sightings

 

Results – sonobuoy, photo identification and biopsy

On the evening of 24 May, sonobuoys recorded several humpback whales relatively close to the ship (C. Berchock pers. comm.), and whales were seen in the ship’s lights as the RVIB Nathaniel B. Palmer traveled north along the west coast of Alexander Island.  At first light the ship was approximately 2 miles north of where the whales were seen.  Ship’s time was dedicated to biopsy sampling for the day in the area where the whales were seen the previous day.  At 0930 whales were sighted in an area with bands of brash ice several miles off the coast.  Weather conditions were optimal for surveying and small boat work.  In the area of the ship (68.75S, 71.35W) were 3 pairs of humpback whales and one single humpback whale, one group of 2 minke whales and one group of 3 minke whales.  The whales appeared to be tracing back and forth, perpendicular to the coast in a 2-3 mile area.  Photo-ID pictures were taken of  each of the whales in the area, except 2 minkes and one humpback that were not approached.  Video footage of the approach, biopsy shot and behaviour were taken.  Biopsy samples were obtained from 3 humpback whales and 1 minke whale.  Only one sample was taken from each group of animals approached.  Skin samples were taken from all 4 whales, while blubber samples were taken from 2 of the humpbacks and the minke whale (Table 2).

 

 

General

A primary research objective of the cetacean studies within SO GLOBEC is to determine the winter distribution and foraging ecology of baleen whales in relation to the characteristics of the environment and the distribution of their prey. Sightings data from this cruise recorded only humpback (Megaptera novaeangliae) and minke (Balaenoptera acutorostrata) whales present in the study region in the austral fall and winter, suggesting that both over-winter around Marguerite Bay.  Correlation of cetacean distributions with concurrent hydrographic distributions (Figures 9., 10., 11., 12.) show whales associated with: 1) the southern boundary of the Antarctic Circumpolar Current, 2) the frontal boundary between intrusions of warm Upper Circumpolar Deep Water and continental shelf water, and 3) the frontal boundary between inner shelf coastal current (Antarctic Coastal Current) and continental shelf waters (E. Hofmann pers. Comm., Figure 13.).  Cetacean sightings were particularly numerous along the frontal boundary formed as the coastal current exits the southern end of Marguerite Bay.  Humpback whales were associated with all three frontal boundaries while minke whales were found only along the continental shelf and coastal frontal boundaries.  The correspondence between the cetacean sightings and hydrographic features suggests that the austral winter distribution of cetaceans along the west Antarctic Peninsula is not random, but rather is determined by the structure of the physical environment, which in turn determines prey distribution.  Continued analyses and collection of cetacean sightings data in conjunction with concurrent prey and hydrographic distributions will allow determination of the causal relationships underlying austral winter cetacean distributions in the Antarctic Peninsula region. This survey cruise included a comprehensive suite of physical and biological programs and an extensive range of scientific equipment in order to carry out both fine and larger scale studies (ie. biomapper, ctd, echosounders, net sampling, ROV, primary productivity etc..). It is one of the most comprehensive multidisciplinary cruises ever conducted in the Southern Ocean and provides the IWC with access to a well planned cruise and analysis process of enormous scope and potential.

 

 

Figure 11. NBP 01-03 Cetacean Survey Effort and minke whale sightings

 

 

 

Preliminary results from NB Palmer 01-03 on adult krill distribution and migration in Antarctic autumn with implications for baleen whale winter strategies and feeding ecology

One of the major objectives of all krill related studies in the Southern Ocean has involved the determination of over wintering strategies for this species which at present are unknown. In 1986 Kawaguchi et al. suggested that krill were benthopelagic animals which probably migrated to the sea floor during autumn and winter. However, they had no quantitative data to support this hypothesis. Siegel and Kalinowski (1994) speculated on a seasonal migration of krill across shelf areas, with this autumn/winter migration possible related to the food gradient across the shelf (ie. that benthic food sources may be the key to overwinter survival). Later, Gutt and Siegel (1994) reported benthopelagic krill aggregations at the shelf edge in the southeastern Weddell Sea which they observed directly along transects using a video camera mounted on a ROV. The observations were made at depths of 480 and 416m from a distance of up to 200cm above the bottom. At one station a swarm was observed to reach densities of several tens to several hundreds of specimens per m3, maximum density exceeded 230 specimens per m3.

was then followed up by observations by Gutt and Siegel (1994).

 

During the N B Palmer survey cruise (and on Polarstern line transects) predominantly larval krill were found on the outer shelf and oceanic regions of the study area. Adult krill were for the most part only observed in near-shore shoal areas with widely varying (complex) topography (refer to Fig 28.US SO GLOBEC Technical Report #2, Wiebe et al. 2001). Basically the adult krill were observed aggregated in holes among the peaks in a complex sea floor. These areas of krill concentration occurred off the northern portion of Alexander Island and the southern end of Adelaide Island. These coincide with baleen whale concentration sites recorded in autumn and early winter on the 2001 cruises. The presence of aggregations of adult krill inshore from the shelf is interesting because, if this autumn – winter pattern is shown to be widespread in Marguerite Bay and similar areas, then an overwinter food source is potentially available to baleen whales. In the past it has been reported that all baleen whales (except minkes as reported in Thiele and Gill, 1999) migrated out of the Antarctic once the summer ‘feeding’ season ended. The July to September 2001 winter survey by the N B Palmer (NBP 01-04) and data from the passive acoustic moorings will help determine whether baleen whales remain in this region of the Antarctic; whether they are feeding during the autumn and winter; and what prey they are consuming. It may well be that while the majority of baleen whales depart the rich Antarctic feeding grounds in early autumn, in some areas some portion of populations of baleen whales may remain throughout the winter, supported by adult krill concentrations which appear to be located in direct association with well defined oceanographic and bathymetric features.

2. Recommendations for IWC participation and involvement in the SO GLOBEC analysis process

The initial plans for a complete year round study of the Marguerite Bay region included cruises by a large number of nations. Unlike the US program, many of the other national programs were tentative. Since IWC 52, where at least six nations were expected to run SO GLOBEC collaborative cruises, it has become clear that the majority will not now be participating. There are plans for a UK cruise in 2002, which will cover both the SO GLOBEC study site and the area around South Georgia, however this cruise is best evaluated for IWC participation at IWC 54, by which time more details of the cruise will be available. 

 

As a result, only the US SO GLOBEC cruises will take place in the latter half of 2001 and from March through September in 2002. This effort comprised five cruises in 2001 in the austral autumn and winter, all of which will be repeated at exactly the same time in 2002. The US cruises on their own provide an extraordinary opportunity for the IWC to gain valuable insights into baleen whale ecology in this region, and in the Antarctic in general. We have been provided with berths and dedicated ship time already, and there is every indication that this will continue on subsequent cruises. The NSF costs for these cruises is in excess of US $20 million. The cost to the IWC of participating is minimal, particularly given the unprecedented scope of the program; the comprehensive suite of data being simultaneously collected by scientific programs on each of the survey and process cruises; and the benefits of dedicated ship time provided so far.

 

We highly recommend that the Scientific Committee approve the continuation of IWC participation in these cruises, and that a budget be developed to cover participation of observers on cruises; the trial incorporation of VHF tagging on the autumn and winter 2002 cruises; the continuation of participation in all planning and analysis milestones in the SO GLOBEC process; and funds for modelling and other data analysis as outlined in the attached timetable (Appendix A). We highly recommend that the Scientific Committee approve the continuation of IWC participation in these cruises, and that a budget be developed to cover participation of observers on cruises; the trial incorporation of VHF tagging on the autumn and winter 2002 cruises; the continuation of participation in all planning and analysis milestones in the SO GLOBEC process; and funds for modelling and other data analysis as outlined in the attached timetable (Appendix A).

 

A comprehensive review of the current status of knowledge on biological and physical features and processes in the study area (Marguerite Bay and nominally IWC Area I) is currently under compilation by the authors. The review will cover: top predators; oceanography, krill/other zooplankton, sea ice; phytoplankton/primary productivity; and bathymetry. The review will identify ecological questions from a top predator viewpoint to assist in fine tuning of field experiments in the 2002 season using data collected on surveys in 2001 and other data sets (LTER time series – Franklin et al 1990; SOCEP cetacean time series – SC/52/E9; and oceanographic, sea-ice, primary productivity and krill models as described in Haskell et al 2001, Hoffman et al 1996, Hoffman and Lascara 2000, Prezelin et al 2000, . It will also provide a template for a series of journal articles and presentations and modelling as part of the ongoing SO GLOBEC research and analysis process (as noted in the Timetable – Appendix A). The timetable for cruises, the analysis process with SO GLOBEC, manuscript deadlines and IWC and GLOBEC specific conference and workshop presentations is attached as Appendix A.

Acknowledgements

We are extremely grateful to Captain Warren Sanamo; his crew; Skip, Jenny, Jonnette and Andy from the Raytheon marine support team; and the oceanographic science team from the L M Gould, all of whom were responsible in some way for providing us with five days of ship time and the opportunity to conduct biopsy and photo identification from zodiacs throughout that period. We also thank them for their enthusiasm and happy, professional attitude. All of the above applies equally to the Captain, crew, marine support and science teams on the N B Palmer, who provided similar opportunities and support on the major survey cruise. Thanks also to Mark Christmas, National Geographic Society for providing video footage of whale biopsy approaches on the NB Palmer. We are extremely grateful to Eileen Hofmann, who has driven much of the effort to have the IWC included in the SO GLOBEC effort; and to John Hildebrand who included the IWC in the berth allocations for his program, long before our participation could be assured. Thanks must also go to the Captain and crew of the Polarstern, the cruise leader – Uli Bathmann, the Alfred-Wegener Insititute, and to Jan van Franeker and Martin Doble for sharing their helicopter time with the IWC, sharing data and helping with mapping.


References

Franklin, J. F., Bledsoe, C. S., Callahan, J. T. 1990. Contributions of the Long-Term Ecological Research Program. Bioscience 40 (7): 509 – 523.

Gutt, J. , Siegel, V. 1994. Benthopelagic aggregations of krill on the deeper shelf of the Weddell Sea (Antarctic) Deep Sea Research I Vol 41 No. 1: 169 – 178.

Haskell, A. G. E., Hofmann, E. E., Klinck, J. M., Lascara, C. M. 2001. Lagrangian modeling studies of the spatial dynamics of Antarctic krill (Euphausia superba). Submitted to Journal of Marine Research April 2001.

Hofmann, E. E., Klinck, J. M., Lascara, C. M., Smith, D. A. 1996. Water mass distribution and circulation west of the Antarctic Peninsula and including Bransfield Strait. Foundations for Ecological Research West of the Antarctic Peninsula, Antarctic Research Series 70: 61 – 80.

Hofmann, E. E., Lascara, C. M. 2000. Modeling the growth dynamics of Antarctic krill Euphausia superba. Marine Ecology Progress Series 194: 219 – 231.

Hofmann, E. E., Reilly, S. 2000. An invitation for the IWC to participate in Southern Ocean GLOBEC. SC/52/E22. Unpublished paper submitted to IWC SC 52.

Kawaguchi, K., Matsuda, O., Ishikawa, S., Naito, Y. 1986. The overwintering strategy of Antarctic krill under the coastal fast ice off the Ongul Island in Lutzow-Holm Bay, Antarctica.  Memoirs of the National Institute of Polar Research Tokyo Special Issue 44: 67-85.

Limeburner, D. et al. 2001. RV Laurence M Gould Cruise 0103 to the Western Peninsula of Antarctica US SO GLOBEC Report available on web site.

Pankow, H., Kock, K-H. 2000. Results of a sighting survey in the Antarctic Peninsula region in November – December 1996. SC/52/E23. Unpublished paper submitted to IWC SC 52.

Prezelin, B. B., Hofmann, E. E., Mengelt, C., Klinck, J. M. 2000. The linkage between Upper Circumpolar Deep Water (UCDW) and phytoplankton assemblages on the west Antarctic Peninsula continental shelf. Journal of Marine Research 58: 165 – 202.

Reilly, S., Hedley, S., Hewitt, R., Leaper, R., Thiele, D., Pitman, R. L., Naganobu, M., Watkins, J., Holland, R. 2000. SOWER 2000: initial results from the IWC-CCAMLR program to study whales and krill in the Southern Ocean. unpublished paper submitted to IWC SC 52.International Whaling Commission Scientific Committee June 2000, Adelaide, SC/52/E21.

Siegel, V., Kalinowski, J. 1994 in Southern Ocean Ecology: The Biomass Perspective. El-Sayed, S. Z. (ed.) Cambridge University Press.

Thiele, D., Gill, P. C. 1999. Cetacean observations during a winter voyage into Antarctic sea ice south of Australia. Antarctic Science 11 (1), 48-53.

 

Thiele, D., Chester, E. T. 2000. Ecological research and baleen whale management: a case study from the Southern Ocean. Unpublished paper submitted to the International Whaling Commission Scientific Committee June 2000, Adelaide, SC/52/E9.

Wiebe, P. et al. 2001. RVIB Nathaniel B. Palmer Cruise 0103 to the Western Peninsula of Antarctica US SO GLOBEC Report available on web site.

Reports:

LMGould 01-03 1stcruise (mooring cruise) - US Southern Ocean GLOBEC Report No.1

NBPalmer 01-03 1stcruise  (survey cruise)- US Southern Ocean GLOBEC Report No.2

LMGould 01-04 2ndcruise (process cruise) - US Southern Ocean GLOBEC Report No.3

Web site for IWC cetacean summaries by cruise, cruise reports, and technical US SO GLOBEC reports:

http://www1.npm.ac.uk/globec/ this site provides a direct link to the CCPO site by clicking on SO GLOBEC

Table 1. Total cetacean sightings and number of animals in Antarctic waters (south of 60°S) for 2001 SO GLOBEC cruises  LMG 01-03 18 March – 13 April 2001, Polarstern AntXVIII5b 14 April – 7 May 2001, and NBP 01-03 24 April – 6 June

 

 

Species – scientific name

Species code

Total sightings:animals

LMG 01-03

Total sightings:animals

Polarstern AntXVIII5b

Total sightings:animals

NBP 01-03

Species – common name

Balaenoptera physalus

2

1:3

 

 

Fin whale

Balaenoptera acutorostrata bonaerensis

4

9:91

5:13

 

Minke (ordinary – dark shoulder)

Like Balaenoptera acutorostrata

92

5:14

27:30

 

Like minke

Lagenorhynchus cruciger

13

1:4

1:10

 

Hourglass dolphin

Unidentified cetacean

16

1:1

 

 

Unidentified cetacean

Undientified large baleen whale

64

 

 

 

Unidentified large baleen whale

Unidentified large whale

67

3:5

1:1

 

Unidentified large whale

Orcinus orca

10

4:53

 

 

Killer whale

Ziphiidae

11

2:5

 

 

Ziphiid

Like Megaptera novaeangliae

71

 

 

1:3

Like humpback whale

Megaptera novaeangliae

7

38:81

16:38

19:30

Humpback whale

Megaptera novaeangliae – and like Balaenoptera physalus (mixed group)

7 and 91

1:12

 

 

Humpback whale and like fin whale (mixed group)

Undetermined Balaenoptera acutorostrata

91

18:40

7:11

22:33

Undetermined minke whale

Like Balaenoptera physalus

66

1:3

1:2

 

Like fin whale

Unidentified small baleen whale

65

 

1:1

 

Unidentified small baleen whale

Unidentified whale

9

4:4

 

1:1

Unidentified whale

Total

 

88:316

59:106

43:67

Total

 


Table 2. Cetacean biopsy samples LMG 01-03 and NBP 01-03 cruises

 

Date

3 April 2001

4 April 2001

4 April 2001

5 April 2001

7 April 2001

25 May 2001

25 May 2001

25 May 2001

25 May 2001

Latitude (S)

66 02.15

66 40.41

66 41.38

67 42.90

65 34.44

68.75

68.75

68.75

68.75

Longitude (W)

65 46.27

67 24.53

67 26.27

68 09.19

64 54.99

71.35

71.35

71.35

71.35

Unique

Id (WS#)

LMG 01-03#51

LMG 01-03#57

LMG 01-03#60

LMG 01-03#73 A + B

LMG 01-03#85 A + B

NBP 01-03#34

NBP 01-03#35

NBP 01-03#37

NBP 01-03#36

Species

2

1

1

2

2

2

2

2

1

Group size

2

7

50

2

2

2

2

2

3

No. animals sampled

1

1

4

2

2

1

1

1

1

photo id

Y

Y of group

Y of group

Y

Y

Y

Y

Y

Y

Species 1 = minke dark shoulder form

Species 2 = humpback


APPENDIX A

-

SO-GLOBEC/IWC COLLABORATION

2001 - 2003

CRUISE, MEETING AND PAPER TIMETABLE

Last updated 11October 2001

Light grey denotes completed tasks

 

DATE

COUNTRY

VESSEL/MEETING NAME

 

Funding source

2001

 

 

 

 

8 - 10 January

USA

SOGlobec Planning Meeting, Arlington, Virginia

All US SO-Globec and Korea and UK present

1 (DT)

 

18/3 - 13/4

USA

Gould - mooring deployment/passive acoustics

Hildebrand team to be part of cetacean survey

1 (DT)

 

19/4

Punta Arenas

Joint Palmer-Gould cruise planning meeting

Conference room RV Palmer

DT

 

14/4 - 7/5

Germany

Polarstern - Globec survey

1 (DT)

 

20/4 to 6/6

USA

Gould – process cruise

0

 

23/4 - 6/6

USA

Palmer - Globec survey cruise

1 (AF)

 

 

July

UK

Annual IWC SC meeting

Preliminary report on cruises conducted so far

DT

 

9-10/7

USA

Globec science steering committee meeting

NSF

Arlington

Hofmann

 

21/7 - 1/9

USA

Palmer - Globec survey cruise

(2) AF RP

 

21/7 - 1/9

USA

Gould - Globec process studies predator/prey group cruise

0

 

October

Argentina

Input to Costa for GLOBEC presentation

 

 

 

28 Nov - 3 Dec

Vancouver

Vancouver Marine Mammal Biennial - joint poster presentation

AF

 

Sept - Jan

 

Review template – oceanography, krill, whales, sea ice etc

DT and others

 

July - Dec

na

Cetacean model development

EH/JK

 

Nov

 

Abstracts due for presentations at Dec plannng meeting and Ocean Science Meeting

 

 

Dec-Feb

Norfolk, USA

Sea Ice biology meeting SO GLOBEC and Mini investigator workshop – krill and whales - Model refinement

EH, JK, AF, DT etc

 

Dec 10-12

USA

Series of presentations at Planning meeting for 2002 cruises

DT/AF

 

2002

 

 

 

 

Date ?

 

IWC Fisheries interactions workshop presentations

?

 

2002

na

Paper on 2001 cruises to J.C.Res.M

all

 

January

Honolulu

Ocean Science Meeting

Includes many Globec sessions for planning for 2002 season

DT/AF

 

 

 

 

 

 

Date to be determined

?

IWC whale research methods workshop

?

 

March - June

 

Journal article Ecological Applications submitted

 

 

March

USA

Gould - mooring recovery/deployment passive acoustics

1 (DT)

 

Apr - 6 June

USA

Gould - Globec process cruise - predator prey group headed by Costa

0

 

Apr - 6 June

USA

Palmer

Palmer - survey cruise

 2 (AF/DG)

 

 

April

Shiminoseki-Japan

IWC 54

Report on cruises and progress (DT/SM)

(SO GLOBEC mini symposium to be held at IWC55)

DT

 

Jul - Sept

USA

Gould - Globec process cruise - predator prey group headed by Costa

0

 

Jul - Sept

USA

 

Palmer - survey cruise

1 AF

 

October

 

Deep Sea Research papers to be ready for Special Issue on SO Globec

DT/AF

 

October

 

Tentative SCAR workshop on sea ice (includes predators)

DT/AF

?

 

2003

 

 

 

 

Jan - Feb 2003

UK

BAS - James Clark Ross

Large scale frontal cruise

2 IWC visual plus 2 IWC acoustics

 

April/June

USA

US Globec synthesis workshop to outline a collaborative paper

DT/AF

 

April-July?

?

IWC 55

SO GLOBEC mini symposium

DT/AF

 

Sept/Oct

International

2nd GLOBEC Open Science Meeting targeting Southern Ocean programs

China

DT/AF

 

 

 

 



[1] Wincruz Antarctic is a free software program developed by Robert Holland at the Southwest Fisheries Science Centre, La Jolla, USA for cetacean surveys in the Antarctic. The software is available at http://mmdshare.ucsd.edu/software.html