ABSTRACT

A compilation of 181 sightings from the central and northern Great Barrier Reef, Australia indicates that dwarf minke whales are regularly seen between Cairns (16° 55'S) and Yonge Reef(14° 36'S). Sightings occurred from May to September, with 79.5% of sightings in June and July. Groups of up to 8 animals were recorded, but 53.3% of sightings were of a single whale and 28.9% of a pair of animals. Most sightings north of Cairns (140/156) were of whales which approached boats on a reef. Observations in 1996 suggest, however, that groups of animals may occur in open water on the continental shelf, inshore of the reefs where most whales have been reported. Estimated lengths of animals varied widely between observers and need to be confirmed by an objective technique such as photogrammetry. Records of stranded animals 3 metres or less in length indicate calving can occur at about 24° -38° S in Australia. There were four reports of cow-calf pairs on the northern Great Barrier Reef, between 15° S -16° S, but more information is needed to assess the extent to which the area is a calving/nursery ground.

INTRODUCTION

Since the 'diminutive' form or 'dwarf minke whale' Balaenoptera acutorostrata sensu lato was first documented by Best (1985), there have been scattered records from temperate and tropical waters of Australia (Arnold et al., 1987), New Zealand (Baker, 1990;Dawson & Slooten, 1991), southern Atlantic coast of South America (Zerbini et al., 1996) as well as subantarctic and Antarctic waters to 65° S (Kasamatsu et al., 1993). However distribution remains poorly known, especially at low latitudes during the austral winter months.

Underwater photographs of dwarf minke whales taken on the northern Great Barrier Reef have been regularly published in recent Australian sport diving publications. This prompted me to approach sports divers, divemasters and dive charter boat skippers and to compile their sight records and photographs of dwarf minke whales. The present paper on distribution patterns is based primarily on these records, as well as my field observations in 1996.

METHODS

Reports and photographs were requested through sport diver publications, and by direct approach to dive charter companies. Data sheets were distributed to participating vessels; some divemasters and skippers also kept their own field notes which were made available to me.

A summary of sightings from a spotter plane operated by Mike Ball Dive Expeditions during 1996 was made available. The spotter plane (a twin engine Shrike AC500: Brown, 1996) did not follow a consistent route and effort was directed in particular areas around the dive boat. It did, however, range away from the reefs and thus covered a wider area than the dive vessels which provided most of the sightings.

I observed dwarf minke whales during 29 June-5 July and 6 July-12 July, 1996 on Undersea Explorer, a 25m long dive charter vessel. Sightings for these trips are included here for comparison with results of the compiled sightings.

Additional records from Queensland were compiled from the literature and unpublished records of stranded animals held at the Queensland Museum.

Identification of whales

In this study, information was only requested on the dwarf minke whale, which is readily identifiable by its characteristic colour pattern (in particular, the white shoulder patch and white at base of flipper: Best, 1985; Arnold et al., 1987). In 92/181 of the compiled sightings (50.8% of the total) the whales had been observed underwater; photographs and/or underwater video supported 33 cases (18.2% of the total), with additional photographs and video not matched to particular sightings (total of 103 colour transparencies and 22 colour prints taken underwater; 63 colour prints taken at the surface). All photographs and video submitted by divers were of the dwarf minke whale; the 22 whales I observed on Undersea Explorer in July, 1996 were also all dwarf minke whales. Even when photographs were not available, it was clear from reports by the divers (often including sketches of colour pattern) and subsequent discussions with them that they had seen dwarf minke whales. Respondents were familiar with the appearance of humpback whales Megaptera novaengliae, but could have confused dwarf minke whales seen in the distance with the 'ordinary' southern hemisphere minke whale Balaenoptera bonaerensis or Bryde's whale Balaenoptera edeni. Neither of these species has been confirmed in the study area but the latter, in particular, is likely to occur. The potential for misidentification would occur mainly in the open water sightings, which represent 10.2% of the 156 sightings north of Cairns.

Observers in the spotter plane were not initially familiar with whales, so there is potential for species confusion. However some of the sightings were in conjunction with a dive vessel which confirmed the identification as dwarf minke whales (see Table 2).

Table 2

Summary of spotter plane sightings in 1996 supplied by Mike Ball Dive Expeditions. First figure is the number of groups seen; figures in parentheses are the number of animals in the groups. Potential repeat sightings (same number of animals in the same are seen within 15minutes are marked with an asterisk. Lower values where a range is given assumes that sightings with asterisks are repeats; higher value assumes that all sightings are unique. No animals reported from flights on July 2,3,5 or 6.

Date	Sightings on reefs	Sightings away from reefs
June 25	1(1)#	3(3,4,4)
June 26	1(1)#	3(2,4,2)
July 12	1(2)	6-7(2,1,1,2,2,3*3*)
July 13	2(1,2)2	6-8 (1,2,1,2*,2*,1*,1*,2)
July 16	1(2)	3(3,2,1)
July 17		1-2(2*,2*)

# Early morning sightings from anchored vessel, seen before aerial survey.

Distribution of sighting effort

There was no systematic search pattern. Most sightings north of Cairns came from observers on three dive charter vessels ( Supersport, Taka II, Nimrod III) which visit the Ribbon Reefs along the edge of the continental shelf (Fig.1) each week. Observers on the vessels varied from year to year. The three vessels visited different reefs and even the same charter vessel visited different reefs from year to year. This makes year to year comparisons questionable and the records (all but 17 from the period 1991-1995) were pooled for analysis.

Table 1

Distribution of sighting records of dwarf minke whales on or near reefs north of Cairns, Queensland (n=156), ordered from South to North. Number of sighting totals for the years 1991-1995. Number of visits are the mean number of visits per year by tourists charter vessels, based on the years 1993/1994 and 1994/1995. Figures in the final column were calculated by dividing the number of sightings by the mean vessels visits per year to give a crude estimate of sightings/visit effort.

Reef Name	Lat	Long	Number of Sightings	Number of Visits	Sightings /visits x100
Moore	16.25S	146.14E	1
Opal	16.13S	145.54E	6
Argincourt	16.02S	145.51E	7
Escape	15.53S	145.51E	9
Ruby	15.44S	145.47E	2
Ribbon 1/Lena	15.36S	145.48E	3	91.5	3.2
Ribbon 2	15.33S	145.48E	1	60.5	1.6
Ribbon 3	15.29S	145.48E	42	516.5	8.1
Ribbon 4	15.26S	145.43E	6	81.5	7.4
Ribbon 5	15.22S	145.47E	11	458	2.4
Ribbon 6	15.16S	145.45E	2	14.5	13.8
Ribbon 7	15.12S	145.44E	5	89.5	5.6
Harrier	15.08S	145.41E	11	180.5	6.1
Ribbon 8	15.05S	145.44E	4	55.5	7.2
Ribbon 9	14.59S	145.44E	11	348	3.2
Ribbon 10	14.46S	145.44E	27	1,332	2.0
Lizard Island	14.40S	145.28E	6
No Name	14.39S	145.39	1	285.5	0.4
Yonge	14.36S	145.39E	1	125.5	0.8

Exact cruise paths were not available for the charter vessels which participated in the survey. As an approximate measure of spatial variation in sighting effort, I used the total number of tourist charter vessel visits throughout the year to reefs within the study area at which whales were seen. These statistics have been supplied since 1993 to the Great Barrier Reef Marine Park Authority (GBRMPA) by each commercial operator, and were made available to me. The mean number of vessel visits to a particular reef during the seasons 1993-1994 and 1994-1995 was used as an approximate index of sighting effort at that reef, and was used to calculate a 'sighting rate'.

As an approximate measure of variation in sighting effort throughout the year, I averaged statistics supplied to GBRMPA on the number of visits by tourist charter vessels in each month. These figures were calculated for four reefs in the study area at which whales were recorded (Agincourt Reef 4, Ribbon Reef 3, Harrier Reef, Ribbon Reef 10) during the seasons 1993-1994, 1994-1995 and 1995-1996. On average, 41.7% of the vessel visits in each year occurred during May-September, when minke whales are reported (see below), while an average of 63.4%(range 51.7-70.7%) of vessel visits occurred in the seven months when no whales were recorded.

RESULTS

Records from Queensland (n=190) ranged from Moreton Island (27° 13'S) in the south to Yonge Reef (14° 36'S) in the north. Nine records, mainly from southern Queensland, were of stranded animals while 181 records were based on sightings. 156 of these sightings were between Cairns (16° 55'S) and Yonge Reef (Fig.1).

 

Distribution of sightings

In the northern region, whales were reported at or near 19 reefs or islands ( Table 1, Fig.1), with 42 sightings at Ribbon Reef 3 (15° 29'S) and 27 sightings near Ribbon Reef 10 (14° 46'S). Ribbon Reef 10 averaged 1332 visits each year by tourist charter boats, so the crude sighting rate (2.0, see Table 1) is one of the lowest of the Ribbon Reefs. The high sighting rate for Ribbon Reef 6 of 13.8 (Table 1) is almost certainly spurious. The two sightings listed for Ribbon Reef 6 were of breaching animals and probably occurred near to rather than on the reef. Ribbon Reef 6 is a preservation zone where anchoring is prohibited, which explains the low mean visitation rate (14.5 visits/year). However vessels transitted the area more regularly than the visitation rate would imply; note the high number of visits at the adjacent Ribbon Reef 5. Ribbon Reef 3 had the highest number of absolute sightings and the highest sighting rate (8.1) except for the spurious figure for Ribbon Reef 6. Ribbon Reef 3 appears to be the most consistent site for dwarf minke whales.

In only 16/156 cases were the whales reported in open water away from reefs, in 7/16 cases sightings were west of the reefs over a level sea floor of the continental shelf approximately 30-40m deep. In contrast, despite committed watches totalling 21.5 hours while anchored on reefs, all sightings in 1996 on Undersea Explorer were in open water over the continental shelf, along a cruise tract approximately 1-4km west of the Ribbon Reefs or 0.5-2km west-northwest of the Agincourt Reefs complex. While in transit to Lizard Island, we saw a breaching dwarf minke whale at 14° 44'S, 145° 34'E, in open water approximately 12km due west of Ribbon Reef 10 (Fig.1). This is the most 'inshore' record. On all but the last three days during these trips, winds were 15-25 knots, with sea state Beaufort 3-5. Whales had been spotted at reefs both before and after our trips, when winds were lighter (Table 2). It is possible that the heavier sea conditions kept the whales away from the reefs at this time.

No whales were recorded from the spotter plane during this period of rough weather in early July. However at other times, with better spotting conditions, usually two to three times as many groups of animals were recorded in open water, away from the reefs, as on the reefs themselves (Table 2). Exact details of the locations and search pattern are not available, but the majority of sightings were over level sea floor of the continental shelf up to '5 miles' to the west of the outer Reefs or between the outer and mid-shelf reefs, in the same general area that whales were seen from the Undersea Explorer.

Timing of sightings

Sightings and strandings (n=190) were from March to September, with 37.4% of the records in June and 42.1% in July (Table 3).

Sightings for which time of day was recorded (Table 4, n=98) showed peaks at 1300 hours (17.3% of sightings), 0700 (12.2% of records) and 1700 hours (10.2% of records). One animal was seen in the torchlight during a night dive.

Whereas during sightings at 1300 and 1700 a variety of behaviours (breaching, vessel approach, circling of boats and divers) was recorded, the activities reported at 0600- 0800 were predominantly circling of boats and divers. At this time the boats would still be anchored at overnight sites on the reef.

Table 3

Monthly records of the dwarf minke whales in the Great Barrier reef region (n=190), with percentage of total number of records. The March record is a stranding; 181 of the remaining records are sightings (see text)

Month	Number of Whales	Percentage
March	1	0.05
April	0	0.00
May	12	6.32
June	71	37.37
July	80	42.10
August	22	11.58
September	4	2.10

Table 4

Diel timing of sightings of dwarf minke whales in the Great barrier Reef region (n=98), based on the time that the whales were first sighted. Last column records activities at each time for the subset of cases (n=69). Abbreviations are A: approaching the vessel underway, B: circling the boat, Br: breaching, D: with divers and/or snorkellers, D/B circling the boat and/or divers, T: seen at the surface while vessel travelling between reefs.

Time	Number of Occurrences	Activities
0500-0600	1	D/B
0600-0700	3	D,D,B
0700-0800	12	D,D,B,D,D,D,D,B.B
0800-0900	8	D,B,B,B,Br,T
0900-1000	3	D,T
1000-1100	9	B,D,D,T,B
1100-1200	5	D,D,D,D
1200-1300	9	B,Br,D,D
1300-1400	17	D,B,T,A,Br,Br,Br,B,D,D,D,D
1400-1500	7	B,D,B,D
1500-1600	6	B,D,D,T,D,D
1600-1700	7	D,D,D,Br,T
1700-1800	10	B,D,A,B,Br,Br,T
1800-1900
1900-2000
2000-2100
2100-2200	1	D/B

Numbers of animals

The majority of sightings (Table 5, n=180) contained a single individual (53.3%) or a pair of whales (28.9%). The maximum group size recorded was eight.

On Undersea Explorer, 6/11 sightings were of single animals; other sightings ranged from 3-5 animals (Table 5).

Table 5

Number of animals per sightings in the Great Barrier Reef region. The first figure is based on compiled sightings records between 1991-1995; when a range of abundances (eg 1-2 animals) was given, the lower figure is used in the table. The figures in parentheses refer to observations on the Undersea Explorer in July 1996

Number Animals	Number Records
1	96(6)
2	52
3	17(2)
4	8(2)
5	3(1)
6	1
7	1
8	2

Direction of travel

Direction of travel, primarily in open water, was recorded by spotter plane observers in 23 cases. Movement was variable: north (4 cases), east (9 cases), south (4 cases, including once with whales travelling at speed towards a vessel) and west (6 cases). In an additional six cases, whales were either circling, stationary, or in contact with a boat

.

Estimated lengths of animals

There was considerable variation in size estimates between observers. The majority of observers (n=13) estimated whales at less than 6m in length, with 35/75 whales estimated as 4-5m long. Two observers, however, gave significantly larger estimates; they estimated that 22/40 whales were over 6m long, with one whale estimated at 9m. The last size estimate is about 1m longer than the largest dwarf minke whale actually measured (Best, 1985).

Occurrence of calves

Records of stranded dwarf minke whales 3m long or less were compiled from records of Australian museums (Table 6). These records were supported by photographs or descriptions of body colour pattern, allowing positive identification. Strandings were recorded from May to July at latitudes 24° 07'S to 37° 53'S.

Table 6

Strandings of dwarf minke whales about 3 m long or less from the eastern and western coasts of Australia, based on records of the Queensland Museum, Museum of Victoria and Western Australian Museum. There were no records of dwarf minke whales within the size range at the Australian Museum. Abbreviations are WA: Western Australia, Vic: Victoria; Qld : Queensland.

Locality	Latitude	Date	Length of Animal	Sex
Cervantes Beach, WA	30°30'S.	16.5.73	10' (3m)	Female
Harmelin Bay, Shark Bay, WA	26°22'S.	29.6.69	9'(2.7m) est length - decomposing
Rockingham, WA	32°15'S.	-.6.35	8'(2.4m) est length
Reeve Channel, Lakes Entrance, Vic	37°53'S.	3.6.66	2.2m	Female
Moreton Island. Qld	27°13'S.	11.6.87	2.9m
Fraser Is. Qld	24°47'S.	19.6.87	2.6m	Male
Lady Elliot Island, Qld	24°07'S.	8.6.94	3.2m	Female

There were four sightings of cow-calf pairs on the northern Great Barrier Reef. Two were on 27 June and 8 July, 1996 near Agincourt Reefs 2-4 (about latitude 16° S); the others were at Steve's Bommie, Ribbon Reef 3 (15° 29'S) on 16 June, 1993 and at Great Escape Reef (15° 53'S) on 30 June, 1993. Estimates of calf length in the 1996 sightings were '6-7 feet' (1.8-2.1m); the calves seen in 1993 were estimated as '8-10 feet' (about 2.5-3m).

DISCUSSION

Spatial distribution

The following biases need to be considered when examining the data.

Dive charter and research boats do not regularly visit reefs north of Lizard Island; the absence of records of dwarf minke whales at latitudes less than about 14° S may just reflect the lack of sighting effort in that area. Marsh (1990) reported six 'minke' whales near Ashmore Bank (11° 55'S) during an aerial survey in November, 1985, but the identification must remain unconfirmed. A group of seven feeding rorquals (probably Bryde's whales) was photographed by Queensland Dept of Environment staff in the same general area (Wreck Bay, 12° 06'S) in December, 1993.

There were 25 sight records of dwarf minke whales in the central and southern sections of the Great Barrier Reef (about 18° -22° S), but they are too few and widespread to reveal spatial patterns.

Even within the area of concentrated sightings (14° -17° S), the sighting network did not give total coverage. Two instances of this came to light from contacts made on the Undersea Explorer trips. There were only seven records from the Agincourt Reef complex in 1991-1995 (Table 1), however experienced observers working on a reef platform at Agincourt Reef 3 recorded 14 sightings between 2 May-9 July, 1996 (S. Downs, A. Marshall, pers. comm.). Similarly, dwarf minke whales were seen more regularly at Flynn Reef, off Cairns, than indicated from previous sighting records (M. Collins, pers. comm.).

Best (1985) reported that 10/13 dwarf minke whales harpooned off Durban, South Africa were taken within 30 nautical miles (55km) of the coast, in contrast to the 'ordinary' form which was captured up to 150nm (277km) offshore. Most sightings of dwarf minke whales in the present study were on or near reefs at the edge of the continental shelf, which are approximately 40-45km from the Queensland coast in the Port Douglas sector (Fig.1) and 50-80km offshore in the Ribbon Reef sector. This at least partly reflects the distribution of tourist charter vessels which spend most time on the reefs along the edge of the shelf.

The sightings from Undersea Explorer and the spotter plane of whales over level sea floor to the west of the outer reefs suggest that the dwarf minke whales may be more generally distributed over the Queensland shelf. This is not a surprising result, but contrasts with the small number (16) of records in open water in the 1991-1995 data. Dwarf minke whales which we observed on Undersea Explorer were most commonly alone, surfaced only once giving no indication of direction of travel and occurred in sea conditions which were often sufficiently rough to hamper sightings. The small number of reports of minke whales in open water in the 1991-1995 data may reflect the difficulty in spotting them in open water without a committed search.

Searches on Undersea Explorer and from the spotter plane were concentrated near the edge of the shelf, no more than 12 km inshore of the reefs. A more extensive coverage across the shelf is necessary to determine the onshore-offshore distribution of dwarf minke whales.

Despite the shortcomings of the data, they still show clearly that dwarf minke whales regularly occur on the northern Great Barrier Reef, at least between approximately 14° -17° S. There appear to be particularly consistent sites (e.g. a patch reef called Steve's Bommie on Ribbon Reef 3, Pixie Pinnacle/Pixie Reef on Ribbon Reef 10, Harrier Reef). These are all popular dive sites and sightings may simply reflect this, however all are also in channels between Ribbon Reefs leading to the Coral Sea or at the southwest corner of a Ribbon Reef, near such a channel.

There were no sightings of the 'ordinary' southern minke whale Balaenoptera bonaerensis, nor were they seen from Undersea Explorer. I identified a 5.83m male B. bonaerensis stranded at 19° 20'S on 19 June, 1994; this is the most northerly confirmed record of the 'ordinary' form on the east coast of Australia of which I am aware. Kasamatsu et al. (1995) recorded high numbers of minke whales at 10-20° S in October-December, but it is not evident that their sightings consistently separated dwarf and 'ordinary' southern minke whales. Best (1985) reported that the 'ordinary' form occurred further offshore than the dwarf minke whale off Durban, South Africa. It is possible that the 'ordinary' form occurs off the Queensland shelf, in the adjacent Coral Sea, but few dive vessels regularly work outside the reef in winter months because of the rough sea conditions at that time. Thus the chance of sight records in the Coral Sea is small.

Seasonality of sightings

Sightings north of Cairns indicated a marked seasonality, with all records between May and September. Since, on average, 63.4% of visits to reefs by charter vessels occurred between October and April (see Methods), the lack of sightings at that time can not be attributed to a lack of sighting effort. Nor does it obviously reflect the quality of sighting conditions. Beginning from March to May, the southeast tradewinds dominate in the study area, with winds averaging from 15-35 knots. Winds ease from late July, and the period October to December is generally recognized as having the best diving conditions, with calm seas (Byron, no date). Sightings thus occurred when spotting conditions were worst, on average.

Most (12/13) dwarf minke whales harpooned off Durban (about 30° S) were taken from April to June (Best, 1985). Zerbini et al. (1996) reported that strandings in Brazil (approximately 13° -33° S) occurred between June and February, although it was not always evident how long after death such strandings were recorded. Australian records of freshly stranded dwarf minke whales at between 24° 07'S and 37° 53'S were in May and June (Table 6). At the same time, dwarf minke whales were frequently reported between 14° -17° S, with about 37% of the sight records north of Cairns occurring in June (Table 3). There is insufficient information to determine whether these occurrences in eastern Australia over such a broad latitudinal range are from the same population.

Numbers of animals

Over 50% of the records from 1991-1995 were of a single animal, while 6/11 of the encounters on Undersea Explorer in 1996 were with a single whale. The 13 dwarf minke whales harpooned off Durban were all single animals (Best, 1985), as were the four dwarf minke whales harpooned between 60° 34'S and 65° 04'S (Kasamatsu et al., 1993).

Groups of up to eight dwarf minke whales have been recorded on the northern Great Barrier Reef (Table 5). On 11 July, 1996, even with limited visibility, up to five animals were visible underwater at the same time, while the next day I observed three whales underwater swimming past me as a group. Synchrony of behaviour was exceptional, but the whales did form a cohesive group when close to the vessel.

Estimated lengths of animals

Most of the whales reported by observers were estimated as being less than 6m. This would suggest immature animals, but not young of the year, based on published life history data for dwarf minke whales (Best 1985). Our estimates of lengths on Undersea Explorer included larger animals, at least 6-7m long. However, Best (1984) demonstrated that length estimates in the field could be low even for experienced whalers and we can not claim greater accuracy than previous observers. Length estimates need to be confirmed by objective techniques such as photogrammetry.

Occurrence of calves

Stranding records from the east and west coasts of Australia (Table 6) indicate that immature dwarf minke whales occur in May-June at higher latitudes (about 24° -38° S). Dwarf minke whales 1.92m and 2.54m long stranded in May-July at latitudes 34° 07'S and 34° 09'S in South Africa (Best, 1985). Best (1985) suggested that dwarf minke whales were born at about 2m length. The smallest stranded animals in Australia (2.2m; estimated 8 foot (2.4m)) were at latitudes 37° 53'S and 32° 15'S, both in June. These records indicate that calving may occur at mid-latitudes. The other point from the stranding records is the large spread of lengths (2.2-3.2m) of animals stranded in June. The 2.2m animal stranded at Reeve's Entrance on 2 June was likely a newborn animal. The 2.9m animal stranded on Moreton Island on 11 June was estimated to be 6-8 weeks old, based on dating of presumed perinatal rib fractures (Paterson and vanDyck, 1996). The range of sizes suggests that the calving season may be prolonged in dwarf minke whales, as suggested for other minke whales ( e.g. N. Atlantic minke whale: Jonsgard, 1951; B. bonaerensis: Best, 1982).

The paucity of strandings in northern Australia at least partly reflects the smaller number of population centres there, and thus the smaller likelihood that a stranded whale is noticed and recorded. There were, however, four sight records between about 15° -16° S of animals estimated at about 3m or less, with a larger animal which was thought to be its parent. Reports of protective behaviour by the larger animal (maintaining itself between the presumed calf and observers) or the more active behaviour of the small animal are consistent with a cow-calf pair. Many of the reports from 1991-1995 noted 'larger' and 'smaller' animals. However, given the difficulty in accurately estimating lengths, few of the sight records could be unambiguously interpreted as a cow and calf.

ACKNOWLEDGEMENTS

It is a great pleasure to acknowledge the co-operation and generous support of individual researchers and especially members of the dive industry, who kept records of minke whales and donated photographs and video. These include R. Beaman, J. Brosnan (Taka II), K. Clements, M. Churchward (Mike Ball Dive Expeditions), M. Collins (Prodive, Cairns), S. Downs (Quicksilver, Port Douglas), J. Dryzmulski (Taka II), U. Engelhardt (Great Barrier Reef Marine Park Authority), K. Fabricius, J. Healey, G. Kelly (Queensland Dept of Environment), A. Marshall (Quicksilver, Port Douglas), P. Matthew, M. Maxwell (Mike Ball Dive Expeditions), F. Scott, A. Steffe (Nimrod III), I. Stapleton (Nimrod III), B. Wood & A. Wrigglesworth. M. Ball and W. Williams (Mike Ball Dive Expeditions) provided a summary of their sightings from a spotter plane used in 1996. J. Rumney (Undersea Explorer) provided berths and accommodation on two trips to the northern Great Barrier Reef and additional financial support for the project. I also thank J. Rumney, J. MacGregor, L. Zell, A. Birtles and the crew & passengers on Undersea Explorer for their help during the trips. B. Barnes publicized the project through Dive Log and Sportsdiving in Australia & New Zealand. L. Gibson (Australian Museum), R. Paterson & S. vanDyck (Queensland Museum) and J. Bannister (Western Australian Museum) provided unpublished records of stranded dwarf minke whales on file at their institutions. S. Beck, M. Pickersgill, S. Whitford & F. Yates, volunteers at the Museum of Tropical Queensland, helped collate data and check records. C. Honchin, C. Wood and M. Vanderzee (Great Barrier Reef Marine Park Authority) provided data on tourist charter boat use of selected northern reefs. Leon Jackson and Andrew Elliot (Great Barrier Reef Marine Park Authority) provided the base map used in Fig. 1. Finally, I thank J. Bannister (Western Australian Museum), P. Corkeron (James Cook University) , G. Ross (Australian Biological Resources Study) and an anonymous reviewer for their helpful comments on the manuscript. The observations on Undersea Explorer were made under Scientific Permit P1996/043 from the Australian Nature Conservation Agency.

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Locality Map

Location of sites at which dwarf minke whales were reported. Numbers correspond to the sites listed in Table 1 : 1.Moore Reef; 2.Opal;3.Argincourt;4.Escape;5.Ruby;6.Lena/Ribbon No1;7.Ribbon 2;8.Ribbon 3;9.Ribbon 4;10.Ribbon 5;11.Ribbon 6; 12.Ribbon.7;13.Harrier;14.Ribbon 8;15.Ribbon 9;16.Ribbon 10;17.Lizard Island;18.No Name;19.Yonge Reef

Fig. 1. Location of sites at which dwarf minke whales were reported. Numbers correspond to sites listed in Table 1: 1.Moore Rf; 2.Opal Rf; 3.Agincourt Rf complex; 4.Escape Rf complex; 5.Ruby Rf; 6:Lena Rf/Ribbon Rf1; 7.Ribbon Rf2; 8.Ribbon Rf3; 9.Ribbon Rf4; 10.Ribbon Rf5; 11.Ribbon Rf6; 12.Ribbon Rf7; 13.Harrier Rf; 14.Ribbon Rf8; 15.Ribbon Rf9; 16.Ribbon Rf10; 17.Lizard Is; 18.No Name Reef; 19.Yonge Rf.