commercial swim programs with dwarf minke whales on ... - CiteSeerX

COMMERCIAL SWIM PROGRAMS WITH DWARF MINKE WHALES ON THE NORTHERN GREAT BARRIER REEF, AUSTRALIA: SOME CHARACTERISTICS OF THE ENCOUNTERS WITH MANAGEMENT IMPLICATIONS R.A. BIRTLES, P.W. ARNOLD AND A. DUNSTAN Birtles RA, Arnold PW and Dunstan A, 2002.Commercial swim programs with dwarf minke whales on the northern Great Barrier Reef, Australia: some characteristics of the encounters with management implications. Australian Mammalogy 24: 23-38. Commercial swim programs with the dwarf minke whale Balaenoptera ?acutorostrata occur seasonally (primarily June - July) within the Cairns and Far Northern sections of the Great Barrier Reef (GBR) Marine Park. Observations of whale-swimmer interactions over five seasons indicate that initiation and maintenance of contact with vessel and swimmers is largely voluntary and thus the swim programs can comply with the general principle that the whales control the initiation and nature of interactions. Preliminary data on within-season (13 whales in 1999) and between year (four whales from 1999 in 2000, 2001) re-sightings within the study area suggest that any impacts from swim programs may affect a particular subset of the population. The extent of possible cumulative effects can be assessed by continuation of the existing photo and video-ID program. No signs of aggression have been documented but some behaviour (bubble blasts, jaw gape) could be considered as threat display. More detailed analysis of behaviour is necessary to monitor such behaviour. A risk analysis is given for aspects of the interactions, with suggested research to monitor such risks. Key words: minke whale, Balaenoptera acutorostrata, ecotourism, whale-watching, swimwith-whales programs, management, behaviour. R.A. Birtles, Department of Tourism, James Cook University of North Queensland, Townsville, Qld 4811, Australia. Email: Alastair.Birtles@ jcu.edu.au. P.W. Arnold, Museum of Tropical Queensland, 70-102 Flinders St, Townsville, Qld 4810, Australia. Email: [email protected]. gov.au. A. Dunstan, Undersea Explorer, Port Douglas, Qld 4871, Australia. Email: [email protected]. Manuscript received 17 July 2001; accepted 12 June 2002. WHALE-watching caters to a clientele of nature enthusiasts enamoured, largely through extensive positive media coverage, with cetaceans in general and the ‘great whales’ in particular. Based on surface observations, primarily from shore or vessels, such operations can attract large numbers of participants, with significant economic flow on effects to local communities in which such whale-watching operations are based (Hoyt 2000). Swim-with-wildcetacean programs (N.B. when we discuss swim programs, it is only swim-with-wild-cetaceans, not the swim-with-captive-dolphin programs) represent a specialised activity which may, however, attract a wider clientele, including whale-watchers as well as sport divers who desire in-water encounters with such charismatic megafauna as sharks, manta rays, cetaceans and pinnipeds. Both types of operation present management problems. Swim-with-wild-cetacean programs are perceived to present particular problems associated with the close proximity of both vessels and

swimmers to the cetaceans (IWC 1997). The assumption is that this entails a greater risk to both cetaceans and humans involved in in-water encounters. It has led to bans on swim programs with whales in various countries (e.g., United States of America, New Zealand, South Africa). A review of swim programs by the Scientific Committee of the International Whaling Commission (IWC) noted that “the available evidence indicated that swim-with programmes in the wild could be considered as being highly invasive” (IWC 2000). The Whale and Dolphin Conservation Society (WDCS 2000) clearly highlighted specific concerns, i.e.; 1. initiation and maintenance of encounters are not under the control of cetaceans, with risk of harassment and stress to cetaceans 2. disruption of ‘normal’ behaviour, e.g. feeding, calving, mating, socialising 3. displacement from normal habitat 4. cumulative effects of swim program activity 5. risk of injury to whales 6. risk of injury to humans

24

AUSTRALIAN MAMMALOGY

The IWC Scientific Committee also noted, however, that “the impact of swim-with programmes in the wild will vary among species, populations and locations and, therefore, that the impacts of such programmes should be assessed on a case by case basis” (IWC 2000). Studies to date have been almost exclusively on odontocetes; a recent review (Frohoff 2000) included data on 17 species, 15 within the family Delphinidae. In this paper, we present some preliminary results from our study of a small but growing industry, based on swims with a baleen whale, the dwarf minke whale Balaenoptera ?acutorostrata (Best 1985; Arnold et al. 1987), on the northern Great Barrier Reef (GBR). Since the taxonomic status of this species is unresolved, it is hereafter referred to by its common name. In this paper, we concentrate on points 1, 2, 5 and 6 raised by the WDCS, with some discussion of changes to certain behaviours and the potential for cumulative effects. A more general discussion of behaviour, acoustic profiles of the vessel and the potential for displacement from normal habitat are subjects of separate studies which will be reported elsewhere.

METHODS Commercial dive vessels run regular live-aboard cruises from 3 - 6 days long, which primarily visit the outer Ribbon Reefs or patch reefs just to the west (leeward). Sites used vary from vessel to vessel and depend on their ability to anchor in deep water (over 30 m) off the reef or moor at specially constructed mooring sites on particular reefs. These live-aboard cruises operate throughout the year but dwarf minke whales are sighted in the period March - October. Arnold (1997) noted that about 80% of the sightings were in June and July; these figures were based on early records from dive vessels at a time when encounters with dwarf minke whales were primarily opportunistic. Since then, advertised dwarf minke whale trips have been run during this 5 - 6 week midwinter period and our observations have focused on that period. Observations were made from a 25 m commercial dive vessel, Undersea Explorer, primarily in the Cairns section of the GBR Marine Park (Fig. 1), from 1996 - 2001. In this area the continental shelf is usually less than 50 km wide. Along the edge of the shelf is an almost continuous series of Ribbon Reefs usually 5 - 10 km (but up to 25 km) long and usually less than 500 m across. The reefs rise from the sea floor 30 – 50 m deep; they are separated by channels usually less than 1 km wide (Hopley 1984). The edge of the shelf plunges steeply to the deep water of the Coral Sea. All observations from Undersea Explorer were made in a 5,000 km2 area stretching from just south of Opal Reef (16° 15’ S, 145° 52’ E; approximately 50 km ENE of Port

Douglas (Fig. 1) to ‘One and a Half Mile Opening’, northwest of Hicks Reef (14° 25’ S, 145° 26’ E; approximately 25 km north of Lizard Island) (Fig. 1). There were a few observations outside the outer barrier reefs in about 500 m depth but the vast majority of sightings were within 10 km of the back edge of the reefs in water 20 - 40 m in depth. We particularly focussed our observations on a 500 km2 area running 50 km north from the three plug reefs at the southern end of Ribbon Reef 10 (Fig. 1) to Day Reef. Direct observations of whale-swimmer interactions were carried out on Undersea Explorer. A watch was kept during daylight hours (0630-1800) both while the vessel was moored at a reef and during transits between reefs, except when weather conditions (Beaufort 4 or above; rain squalls) limited observations. Committed searches for whales were carried out especially in the area to the west of Ribbon Reef 10. The number of observers varied from 1 - 4 in open water; there was usually a single observer at reefs. Passengers could also act as observers but did so only episodically. Cruising speed was 8.5 - 9 knots. If whales were spotted at a distance greater than 100 m, the vessel maintained course until it was in the general area where whales had been seen (dwarf minke whales are relatively small (maximum recorded length 7.8 m: Best 1985), rarely show an obvious blow, and generally surface only once, making it impossible to predict their direction of travel). The engines were put in neutral and the vessel drifted with the wind. If the whales were seen at a distance estimated as less than 100 m, the vessel was stopped and allowed to drift. If whales were not seen again within 15 min, the vessel resumed course. If whales approached the vessel, two 50 m ropes were trailed upwind from the bow and stern respectively. One researcher (usually RAB) and one crew member (usually the videographer, M. Matthews) took up positions at the end of each rope. Subsequently, passengers would take up positions on the bow or stern line as spaces became available. One observer would monitor the encounter from an observation point on top of the wheelhouse, as well as co-ordinate data recording by crew. Topside information was recorded in a notebook, using codes for behavioural events and diagrams of the layout of vessel and ropes. Basic behaviours are documented in Birtles and Arnold (2002). Data were transcribed to data sheets at the end of each day. Distances were estimated; visual cues included the length of the lines, marked out in 5 m intervals, and the size of swimmers, as well as distance between the ropes so that estimates close to the vessel were more accurate than those in the distance. Underwater observations were recorded on plastic film attached

24

BIRTLES ET AL.: COMMERCIAL SWIM-WITH-WHALE PROGRAMS

25

Fig. 1. Study area showing Ribbon Reefs within the Cairns section of the Great Barrier Reef Marine Park.

to a slate; underwater photographs were taken with a Nikonos V. Underwater video was taken, primarily with a Sony mini-DV camera. The extensive video and photo documentation needed for photo-IDs was only possible from 1999, with funding from Environment Australia; more detailed results from this time period are presented in this paper. When an encounter was terminated, an observer was always stationed topside to monitor positions of whales before the engines were put in gear. Initially the vessel was run at no wake speed, increasing in speed when whales were no longer approaching closely (though whales could still be within 100 m of the vessel).

Terminology An ‘encounter’ is defined as a session with minke whale(s), from the first sighting by a passenger/crew member/researcher to the end of the vessel’s contact with the whale(s). Encounters could include whale(s) seen at a distance but only if they could be identified

as a minke whale. Where whale(s) approached the vessel, the session was described as an ‘interaction’. This could (and usually did) lead to an ‘in-water interaction’. Thus all interactions were encounters but not all encounters led to an interaction. Encounters are numbered in the format year.month.day. encounter number, e.g., 99.6.20.1 is the first encounter on June 20, 1999.

RESULTS Characteristics of encounters Encounter rates Total number of encounters per year (Table 1) varied from 11 in 1996 (5.5 encounters/week of field season) to 60 in 2000 (10 encounters/week), with rates of 7.5 - 8.2 encounters/week in seasons 1997 1999.

Interaction rates Dwarf minke whales were encountered both while moored at a reef and while steaming in open water,

25

26


except in 1996 when whales were only encountered in open water. In all cases, not only were there more open water encounters (probably reflecting the greater area searched) but these contained higher percentages of approaches by the whales leading to an interaction (Table 2): 73% to the vessel drifting in open water (n = 85) vs 46% to the vessel while moored on a reef (n = 45). A higher percentage of the open water, drifting encounters led to interactions lasting longer than an hour: 47/85 (55.3%) with the drifting vessel; 12/45 (26.7%) with the vessel moored at a reef. There was, however, considerable variation from year to year for both open water and reef encounters.

Length of encounters Mean length of reef encounters varied from 0.5 hr (in 1997) to 1.1 hr (in 1999); the value for 2000 was 1.0 hr (Table 1). Mean length of open water encounters ranged from 1.3 hr (1997) to 2.1 hr (1999) with a value of 1.8 hr in 2000. Encounter lengths in open water may be underestimated as many (e.g., 59% in 1999) were broken off by the vessel (e.g., to allow mooring at a reef in daylight hours or to undertake a reef dive). Combining reef and open water encounters, the mean length of encounter ranged from 1.3 hr (1996) to 1.8 hr (1999); the corresponding figure for 2000 was 1.4 hr. This compares with a mean of 1.2 hr recorded from a survey of live aboard dive vessels during 1991 - 1995 (n = 35). It was not always possible to separate those encounters into reef and open water encounters, however about 90% of the encounters appeared to be on a reef (Arnold 1997). About half (21/41) of the encounters during 1999 exceeded 1 hr contact time (Table 3), however this could vary from week to week (Table 3), with 5/6 encounters during July 11 Dates of field trips

16 being extended, while only 1/7 encounters exceeded 1 hr during the following week.

Numbers of whales in encounters The average number of whales for reef encounters in 1999 was 2.3 (range 1 - 12, n = 10), however this value was elevated by a single encounter at Pixie Reef (99.7.5.1) at which 10 - 12 animals were seen. The average number for open water encounters was 5.7 (range 1 - 25, n = 25). Most of these counts are based on maximum counts at any one time. Those interactions in which underwater observations and underwater video have been analysed reveal, however, that new whales may add in throughout an encounter. Thus the total number of whales in an encounter may exceed the maximum counts of whales at any one time, either from the surface or underwater. During open water encounters, the vessel drifted under the influence of wind, waves and tidal currents. Mean drift during encounters in 1999 was 8.9 km (range 2.8 - 18.5 km, n = 15; Fig. 2), during which time whales had to maintain position with the vessel for periods up to 6 hr. Only 1 - 2 whales were seen during the shortest drifts (2.8, 4.6 km); best estimates for the total number of whales per encounter ranged from 5 to 7 - 12; (represented by mean = 9.5 in Fig. 2) for drifts of 5.2 - 15.3 km, with no clear correlation of numbers and length of drift over that range (Fig. 1 ). The largest numbers in an encounter (20 - 25) occurred in the two longest drifts (17.3, 18.5 km).

Presence of cow-calf pairs A cow-calf pair was seen in encounters 99.7.5.1, 99.7.5.2, 00.7.9.1 and 00.7.18.2. This represents 2/41 encounters (4.8%) in 1999, 2/60 encounters (3.4%) in 2000.

Duration of field season (weeks)

On reef encounters (moored)

Open water encounters (drifting)

June 29 - July 12, 1996 (UE)

2

-

July 6 - July 30,1997 (UE)

4

June 27- July 31,1998 (UE)

5

June 20 - July 23, 1999 (UE)

5

June 13- July 21, 2000 (UE)

6

0.5 (0.02-4.3) n=12 0.7 (0.01-2.3) n=14 1.1 (0.02-4.5) n=13 1.0 (0.02-4.85) n=20

1.3 (0.1-3.2) n=11 1.8 (0.02-10.7) n=17 1.8 (0.01-6.3) n=26 2.1 (0.02-6.1) n=28 1.8 (0.02-5.0) n=40

June-July 1991-1995

Combined reef and open water encounters 1.2 (0.1-5.5) n=35 1.3 (0.1-3.2) n=11 1.3 (0.02-10.7) n=29 1.4 (0.01-6.3) n=40 1.8 (0.02-6.1) n=41 1.4 (0.02-5.0) n=60

Table 1. Statistics for duration of encounters between dwarf minke whales and vessels (mean, in hr; range in parentheses; n = sample size). First row is the mean encounter time over period 1991 - 1995 as collated in Arnold (1997) and Arnold and Birtles (1999) from dive charter operators. Subsequent rows are from our encounters on Undersea Explorer (UE).

26

BIRTLES ET AL.: COMMERCIAL SWIM-WITH-WHALE PROGRAMS Open water % >1 hr 70.6 8/17 85.7 17/28 65.0 22/40 72.9 47/85

I/E 12/17 24/28 26/40 62/85

1997* 1999 2000 Total

% 47.1 60.7 55.0 55.3

I/E 4/12 8/13 9/20 21/45

% 33.3 61.5 45.0 45.5

Reef

>1 hr 2/12 4/13 6/20 12/45

27

% 16.7 30.8 30.0 26.7

Table 2. Encounter data for open water and reef locations. For each category, the first column indicates the number of interactions (I), representing a voluntary approach to the vessel lasting 10 min or more (0.17 hr), relative to the number of encounters (E). The percentage of I/E is indicated in the second column. The third column indicates the number of interactions which lasted longer than 1 hour, which is expressed as a percentage in the fourth column. * from Arnold and Birtles (1999).

30

total number of whales

25

20

15

10

5

0 0

2

4

6

8

10

12

14

16

18

20

drift (km) Fig. 2. Numbers of dwarf minke whales seen during an open water encounter for which length of drift (in km) was available (all data from 1999 field season, n = 15). For three encounters the number of animals was given as a range (e.g., 7 - 9); in such cases a mean value is shown in the figure.

Date June 20 - June 25 June 27 - July 2 July 4 - July 9 July 11 - July 16 July 18 - July 23 Total

Number of encounters 7 10 11 6 7 41

Number of interactions exceeding 1 hr contact time 4 5 6 5 1 21

Table 3. Number of encounters within each week of the 1999 field season and those leading to interactions exceeding 1 hr contact time.

‘Friendly behaviour’ The behaviour of the dwarf minke whales around vessels and swimmers in some respects mirrors the so-called ‘friendly’ behaviour of gray whales Eschrichtius robustus as documented by Jones and Swartz (1984). Of the 15 features listed by those authors, seven are in common: 1) participation by

whales of different size classes (though apparently less participation by cow-calf pairs in dwarf minke whales (see above); 2) bubble blasts in the general vicinity of the vessel and swimmers (see below); 3) approach and maintenance of contact with an anchored vessel, as well as drifting vessels in the case of dwarf minke whales (see above); 4) an apparent accumulative affect resulting in large groups (20 in

27

28


case of E. robustus; at least 25 in case of dwarf minke whales); 5) ‘chronic’ curious behaviour of individual whales, including from year to year in both E. robustus and dwarf minke whales (see below); 6) following of slow moving vessels and 7) attempts to follow vessels departing at speed (up to 6 knots for E. robustus; 12 knots for dwarf minke whale).

Occurrence of feeding We have documented 181 encounters, with 266 contact hours during 1996 - 2000 but have not seen any evidence that the whales are feeding over the continental shelf. In 1999 - 2000, we recorded cases of engulfment behaviour (such as encounter 99.6.20.1). Whales were observed underwater (and video and photographs taken) opening their mouth, exposing the baleen plates and inflating the throat to varying degrees. No aggregations of food were visible and we can not consider the behaviour seen as evidence of feeding. On 3 July 2001, during an encounter on another vessel at Lighthouse Pinnacle (near Ribbon Reef 10), video was taken of defecation by a single whale, however this is the only instance we have seen in six field seasons.

Re-sighting within years Since 1998, we have concentrated our search effort in an area to the west of Ribbon Reef 10, where dwarf minke whales have been regularly reported (see Methods), in order to maximise chances of resightings. We are still analysing images (both underwater photographs and video) and the animals recognised so far are those with the most conspicuous scar and/or colour patterns. So far thirteen individuals have been recognised as re-sightings in the 1999 season data; re-sightings occurred either once (10 animals) or twice (3 animals) (Table 4). Animal 99.6.21.2.1 (SCRATCHY) was re-sighted 16 days later in the same location it was first seen. By contrast, animal 7.5.2.9 (SHARK ATTACK) moved 40 km to the north within two days. The short-term movements indicated by re-sightings (20 - 40 km) exceeded the length of the longest drift tracks and could be either to the north or south, suggesting that whales might be encountered almost anywhere within the region searched. Re-sightings indicate that groups associated with vessels are unstable in their composition through a period of days to weeks. During encounter 99.6.30.2, 25 whales were sighted over a drift track of 18.5 km. Six of these were re-sighted (Table 4). Whale 99.6.30.2.20, (SCRATCH) was seen with whales 4, 5, 7, 8 and 9. It was re-sighted 12 days later (Encounter 99.7.12.1) with three new whales (11,12,13). Next day (Encounter 99.7.13.1) SCRATCH was with two

whales (4,5) from the June 30 encounter and two whales (12,13) from the previous day. Whale 9 (99.6.30.2.32, DIVIDED NAPE STREAK SPOT) was seen on 30 June with whales 4 - 8. It was sighted five days later, 20 km to the south of the first sighting, by itself. The mean time between first and last sightings of the 13 animals identified in the 1999 field season (35 days long) was 8.6 days. The longest separation between sightings was 16 days (see above). Whales that were re-sighted did not necessarily remain in the area between sightings. Animal 99.6.30.2.20 (SCRATCH) was seen on 30 June, then again on 12 July. The re-sighting revealed a new oval scar on the back, probably from the open ocean dwelling cookiecutter shark Isistius sp. The appearance of a fresh oval scar would suggest that the whale had been in open water between the sightings on 30 June and 12 July (see Discussion).

Re-sighting between years Three of the whales re-sighted in 1999 were subsequently re-sighted in the same general area during the 2000 field season (Table 4). A fourth animal (99.6.30.2.35, WIGGLY NAPE STREAK) was resighted after 2 years during the 2001 field season. Three of the re-sighted whales were females, while the fourth (MULTI MULTI MULTI SCAR C) is of unknown gender. No year to year re-sightings have been confirmed from the 1996 - 1998 seasons, however the quality of images for those earlier seasons are not as high as the 1999 - 2001 seasons and analysis is also incomplete.

Risk analysis Risk of injury to whales As indicated above (Length of encounters), encounters on the reef are with a moored or anchored vessel. In open water the engine is stopped, thus the vessel is drifting, to allow safe entry and exit of snorkellers from the stern. Under these circumstances, the risk of injury to the whales, either from vessel strike or from propeller gashes, is minimised despite the extended length of the encounter and the close proximity of whales to the vessel and swimmers. We have not seen scars that can be unequivocally attributed to vessel activity (e.g., propeller scars, signs of vessel strike), however one animal (CHOMPED, encounter 99.7.7.2) had massive scars of unknown origin looking as if much of its back had been peeled back. We have seen black blotches appear where a whale rubbed along the aluminium keel of a dinghy, as well as other markings associated with nudging the duckboard of the vessel or brushing against a chain hanging in the water.

28

Table 4. Documented dwarf minke whale re-sightings from 1999 season (as at 27 May 2000) and re-sightings in 2000 (as at 28 May 2001). Ten animals were seen twice and three were seen three times in 1999. Re-sighting intervals range from one to sixteen days and distances vary from nothing (same location) to 40 km. Direction of movement (under Distance column) was both north and south. The three bolded animals were re-sighted in the 2000 field season. Unique Encounter Codes (EC) are recorded in full as year_month_day_encounter number (of the day). Animals are named when first seen underwater and subsequently given a unique identifying (ID) code based on their Encounter Code plus a number reflecting the number of different animals identified in that encounter after examining the video footage (the total number for an encounter may include a number of un-linked left and right sides). The original ID code is used when they are re-sighted. All encounters were from Undersea Explorer except for a where the initial sighting came from video footage (shot on the Lighthouse bommie) supplied from Super Sport.

BIRTLES ET AL.: COMMERCIAL SWIM-WITH-WHALE PROGRAMS 29

29

30


Risk of injury to humans By their nature the interactions with whales, especially in open water, involve risks. these can be divided into at least three categories: injuries from the whales themselves, either

through deliberate aggression or by accident; difficulties involved in being in open water in moderate seas; possible injury from other wildlife, e.g., sharks or sea snakes.

Aggressive acts by whales. We have documented 181 encounters during 1996 - 2000 (Table 1); 55% of open water (n = 85) and 26% of reef encounters (n = 46) involved extended interactions between snorkellers and whales (Table 2). In 1999, one of us (RAB) spent over 58 hr in the water with about 100 individually recognisable dwarf minke whales over a period of five weeks and in 2000 the research team spent over 89 hr over a period of six weeks with about the same number of individually recognised whales. We have not seen any signs of aggression to any swimmer, even in the few instances where there was a cow with a calf. There have been, however, behaviours which might represent threat display and thus represent at least agonistic behaviour. These included fast swimming, bubble blasts or bubble trails and jaw gape or engulfment behaviour. The clearest example occurred when one of us (RAB) was in the water with animal 99.6.30.2.20 (SCRATCH) in a series of encounters in 1999. When re-sighted on 12 July 1999 after 12 days (Table 4), the animal first appeared ascending vertically under RAB, blew a large bubble blast and broke the surface in a high head rise about 2 m away. Surface observations during the encounter, which involved 6 - 7 whales and lasted for 5.9 hr, recorded 15 bubble blasts, however these could not be linked with a particular animal. The following day, within a few minutes of entering the water in encounter 99.7.13.1, RAB experienced a fast head on approach down the line by the same animal which culminated in a wide (> 1 m) jaw gape from about 6 m to about 3 m distance (with partial throat inflation). SCRATCH closed its jaws as it passed at about 2 m distance to one side. Passengers entered the water about 12 min later and the encounter, lasting a further 5.9 hr and involving 7 - 9 whales, progressed without further incident. Main behaviours (other than routine surfacing) noted from the surface included an additional bubble blast, head rises (5), belly rolls (11), spyhop (1), fast surface rolls (3), synchronous swimming of five animals (1), hovering (2) and prolonged surface swims near the videographer (2). Accidental injury by whales. We can not rule out the possibility of accidental injury from the whales. However, dwarf minke whales are highly manoeuvrable and give the impression in their agility and speed more of dolphins than other baleen whales.

Concern has been expressed about injury from calves, which in the larger baleen whales may be more cumbersome in their approaches. Sightings of cow-calf pairs are rare; in the in-water encounters there were no close approaches by the calf. Arnold and Birtles (1999) reported a case where a small animal (estimated length 3 m) closely approached swimmers but then departed so rapidly the swimmers left the water. The potential for injury increases if whales become de-sensitised to the presence of humans and make closer approaches. Animals 99.7.5.2.16 (MULTI MULTI MULTI SCAR C), 99.6.30.2.7 (OLD PUCKER) and 99.6.30.2.17 (BLACK BLOTCH/COCKATOO) were all highly interactive when they were re-sighted in the second year, making repeated close passes. OLD PUCKER ultimately made physical contact with her snout against a video camera after 2.25 hr of interaction during encounter 00.6.21.1. Injury from sea conditions. During the minke whale season, sea conditions are moderate; Arnold and Birtles (1999) noted that for 77.4% of hourly weather recordings (n = 146) sea state was estimated as Beaufort 4 or 5. Entry and exit from the stern can be challenging and potentially dangerous. Once swimmers are in the water, they hold on to one of two ropes. This not only ensures that their position becomes predictable for the whales but also overcomes the problems of individual swimmers drifting off and becoming rapidly separated from the vessel (and increasingly difficult to see). As the vessel is blown along, trailing the ropes, swimmers are literally dragged through the water. This can produce both fatigue and seasickness, in addition to chills in the winter sea temperatures. This imposes an upper limit on the time passengers spend in the water at any one time, although usually passengers have several ‘turns’ on the line. Injury from other wildlife. We have seen dwarf minke whales with healed shark bites. We can not yet link any of these to particular species of sharks although, from the size of the bites, great white Carcharodon carcharias, tiger sharks Galeocerdo cuvier and oceanic white-tip sharks Carcharhinus longimanus are possibilities. We can not say whether such attacks have occurred over the continental shelf or in open ocean. If the former, this suggests that swimmers spending prolonged periods of time in the water with the whales may also be at risk of attack. During 1999, sharks were seen in at least four open water encounters, being recorded in 6.27.3, 6.30.2, 7.14.1 and 7.18.1. Three of the encounters involved silver-tip whaler sharks Carcharhinus albimarginatus which approached swimmers, especially those at or near the end of the ropes. Other carcharhinid sharks have approached swimmers and one encounter was terminated because of close approaches by a bull

30

BIRTLES ET AL.: COMMERCIAL SWIM-WITH-WHALE PROGRAMS shark Carcharhinus leucas. G. cuvier do occur in the area and may be expected in the open water encounters, although we have not yet seen one with minke whales. Sea snakes (family Hydrophidae) have been seen on various occasions during open water encounters (e.g., 99.7.5.2), usually as they surface to breathe. In none of the encounters were the snakes aggressive. We can not rule out the possibility of accidental bites if a snake swimming at the surface is intercepted by a swimmer being dragged along by the rope. However, usually swimmers can be alerted to the presence of a snake by observers monitoring swimmer-whale interactions from the vessel.

DISCUSSION Characteristics of swim program Initiation and maintenance of encounters A general principle of whale-watching agreed by the IWC Scientific Committee is that cetaceans be allowed “to control the nature and duration of ‘interactions’” (IWC 1997, p. 250: Principle 3). This principle underlies Australian policy documents such as GBRMPA (2000) and ANZECC (2000). The perception that swim-with-wild-cetacean programs can not fulfil this principle, with the consequent possibility of stress to the whales, is a concern raised by organisations such as the WDCS. The initiation of dwarf minke whale encounters on reefs, where the vessel is moored, is necessarily voluntary. These encounters have been occurring since at least the mid 1980s (Arnold et al. 1987; Arnold 1997; Arnold and Birtles 1999), with an increasing frequency of records in the Cairns and Far Northern sections of the GBR Marine Park. This increase is at least partly associated with the development of an intensive liveaboard dive industry since the mid 1980s, in which vessels visit the Ribbon Reefs each week throughout the year. It may also be associated with a greater time spent at particular sites at which whales have been encountered regularly in previous years. Although there is an active search for whales in open water, in-water interactions depend ultimately on the whales approaching a drifting vessel. This occurred in 73% of the open water encounters (n = 85) and 46% of reef encounters (n = 45) during 1997, 1999 and 2000 (Table 2). Gedamke et al. (2001) gave an additional indication of these voluntary approaches. As part of a study on vocalizations conducted in parallel with our studies, six ‘control’ sessions were undertaken in which the hydrophones were placed in the water after searches revealed no whales in the area. In four of the six cases, dwarf minke whales subsequently approached Undersea Explorer, after a period of 15 min to 1 hr. All these

31

observations show that dwarf minke whales regularly approach slowly moving or stationary vessels and that interactions with vessels and/or swimmers are initiated by the whales. This is consistent with the behaviour of other populations of minke whales (both B. acutorostrata and the Antarctic minke whale Balaenoptera bonaerensis) which are generally recorded as approaching slow moving or drifting vessels (Stewart and Leatherwood 1985). Given that in open water the vessel was stopped in the vicinity of whales when they were first seen, it could be argued that operators were ‘eliciting’ an interaction. However, the variability from year to year (Table 2) and within season (Table 3) in the percentage of encounters leading to a prolonged interaction shows that whales do not automatically approach a vessel and underscores the fact that the approach is voluntary. The length of reef encounters is totally under the control of whales as the vessel is moored. The extent of open water encounters is also largely under the control of the whales, as the vessel drifts, using its engines only if it is being blown towards a reef – a rare occurrence in the study area given the linear arrangement of Ribbon Reefs along the shelf edge and infrequency of reefs in this area of the GBR lagoon. These encounters may last over 6 hr, (Table 1; the encounter of 10.7 hr involved both drift and slow motoring of the vessel, due to problems with the engine) with a drift of over 18 km (Fig. 2). In such open water encounters, whales must actively maintain contact by swimming with the drifting vessel and thus control the length of the interaction. On a smaller scale, where passengers hang on to surface ropes running from the boat, the whales have control over how close and how often the approaches occur. This method should not be confused with the ‘around boat’ placement of swimmers documented by Constantine (2001) for swim-with-dolphin operations in New Zealand. In that case, swimmers appear to be more directly placed among the dolphins, which are forced to make a choice of staying or avoiding swimmers. The use of lines with minke whale swim programs is more comparable to Constantine’s (2001) ‘line abreast’ placement of swimmers in that, with both techniques, the dolphins or whales can make the choice whether or not to approach. In our data set, mean encounter length (combining both reef and open water encounters) ranged from 1.3 hr (1996, 1997) to 1.8 hr (1999), compared with a mean encounter length of 1.2 hr for encounters during 1991 - 1995 (Table 1). Open water encounters were more frequent in 2000 than 1999 but percentage of encounters leading to an interaction was lower, as was percentage of prolonged

31

32


interactions (Table 2). Part of the increase in number of encounters may be attributed to the longer field season in 2000 (6 weeks vs 5 weeks in 1999) but another factor may relate to search time available. If there are fewer extended interactions, more time is spent searching and the potential for a larger number of encounters increases. Comparison of encounter statistics for the years 1998 - 2000 (Table 1) suggest, however, a greater similarity between 1998 and 2000, with 1999 being the exception. Examination of a longer time series is necessary but the data do not indicate a consistent decrease in either encounter rates or interaction rates with time. This contrasts with Watkins (1986). That widely quoted paper on whale reactions to vessels in Cape Cod waters was based on opportunistic records over a 25 year period, part of which preceded the development of commercial whale watching in that observation area. He noted that B. acutorostrata changed their behaviour from frequent interest in vessels (in the period prior to commercial whale watching) to uninterested reactions. His time series is much longer than ours but his relatively small sample size needs to be noted (122 records on B. acutorostrata over 25 years; 18 records in the subset of data on which analyses were based). Disruption to normal activity Concerns have been raised about the possible disruptions by swim programs of activities such as feeding, resting, socialising, mating, nursing, as well as possible energetic costs associated with avoidance of whale watching vessels or swimmers. Our own observations over six field seasons and reports from other vessels since the early 1990s (in Arnold 1997) provide no evidence that the area where swim programs are conducted is a feeding ground. It is possible that dwarf minke whales enter the Coral Sea to feed. We have seen dwarf minke whales travelling outwards in the channels between Ribbon Reefs and, despite limited opportunities for observations in the Coral Sea due to the moderate to rough sea conditions outside the reef during the minke whale season, we have seen whales within a kilometre outside Ribbon Reef 10 and Agincourt Reefs. We have further circumstantial evidence (from oval scars - see Re-sightings and Discussion) for short-term movements into the Coral Sea. However, the fact that we have seen only one instance of defecation despite extensive underwater observations over a six year period suggests that feeding, either over the continental shelf or in open water, is restricted. The life history of dwarf minke whales is poorly known. For B. bonaerensis, peak of conceptions is believed to occur around late August - September (Best 1982). With a 10 month gestation period, most births would be around May - June. Apparently

recently born dwarf minke whales (2.2 - 3.2 m) have been recorded in April - July (Arnold 1997), so the limited data available suggests dwarf minke whales may have a similar pattern to B. bonaerensis. Estimates for lactation are 4 - 6 months (north Atlantic B. acutorostrata (Jonsgard 1951); B. bonaerensis (Best 1982)). By analogy, dwarf minke whales would be expected to be suckling at the time the swim programs are run (predominantly June July). The main period of conception may take place after the main minke whale swim-with season. However in other populations of minke whales the periods of births (and thus conceptions) may be extended; if the situation is similar in dwarf minke whales, swim programs may occur when at least some of the population is mating. The available information thus suggests that swim programs could potentially effect dwarf minke whales at key parts of their reproductive season (mating, conception, nursing). Based on our own observations, and those reported by crew on dive vessels, cow-calf pairs are rarely seen: in 3.4% - 4.8% of encounters during 1999 and 2000 (n = 41,60) and 2.6% (4/156) of records in the sighting survey of 1991 - 1995 (Arnold 1997). Whether the small number of cow-calf pairs seen on the northern GBR reflects a reluctance by nursing cows to approach vessels or indicates that the GBR is only a marginal part of a much more extended breeding/nursing area, extending to midlatitudes (24° - 38° S) (Arnold 1997), our preliminary information suggests that the swim programs impact little, if at all, on nursing cows with newborn calves. We have insufficient information on the proportion of mature males and females to assess the potential for disruption of mating behaviour and conception. However, in the 2000 field season, one of us (AD) trialled an underwater videogrammetry technique used successfully on humpback whales (Spitz et al. 2000). Although initial results were highly variable, the technique shows real promise in providing objective length data. The extended nature of the dwarf minke encounters, the ‘friendly’ behaviour, and behaviour of some individual whales which had previously interacted with swimmers (see Results: Accidental Injury) raise issues of de-sensitisation of the whales to human contact. This has implications both for changes in behaviour of the whale and for issues of human safety (see below). We are conducting behavioural studies to address such potential problems. Cumulative effects Although opportunistic encounters with dwarf minke whales have been reported throughout the GBR, they occur predictably in a more restricted area, along and

32

BIRTLES ET AL.: COMMERCIAL SWIM-WITH-WHALE PROGRAMS adjacent to the Ribbon Reefs between Port Douglas and Lizard Island (Arnold 1997; pers. obs.). This contrasts with the case of humpback whales Megaptera novaeangliae which are susceptible to coastal whale watching operations along most of their migration along the east Australian coast (Birtles et al. 2001). Cumulative effects are thus most likely to be on a local level. Within the Port Douglas-Lizard Island area, advertised swim programs are currently carried out by at least four vessels, with opportunistic encounters on an additional two. While the number of vessels is small, individual encounters may be prolonged (on Undersea Explorer, up to nearly 11 hr) and, within heavily trafficked areas, the same group of whales may have extended interactions with more than one vessel within a single day. There is thus potential for localised cumulative effects, the extent of which will depend on the number of whales involved, as well as residency time of the whales. The total number of whales in an encounter differed between reef (moored) and open water (drifting) encounters, with larger numbers in the latter. Over the five week field season in 1999, about 100 animals were identified, primarily from the area between Ribbon Reefs 9 and 10 and Lizard Island. These numbers are significantly higher than in the published photo-ID based studies conducted on B. acutorostrata in the northern hemisphere. In a 5 year study off the Isle of Mull, Scotland, Gill and Fairbairns (1995) recorded 28 identified B. acutorostrata, with 11 - 12 identified individuals seen each season in the years 1991-1994. Dorsey et al. (1990) recorded 30 individually recognised B. acutorostrata during a 10 year study in the San Juan Islands, Washington, with 15 - 19 individuals seen during each of the most extensive field seasons (2 - 6 months) of 1980 - 1984. Resighting data suggest that composition of groups of whales involved in vessel and swimmer interactions changes over a period of days to weeks. More information on group composition is needed to assess the levels of exposure that individual whales have to swim programs. Within the Port Douglas- Lizard Island region, sightings are seasonal, spanning March to October. This does not mean that individual whales remain in the area for that length of time. Preliminary analysis of re-sightings from the 1999 season have identified 13 individuals seen again on either one or two occasions, out of approximately 100 individuals identified during the 1999 season. The fact that the mean time between first and last sighting was 8.6 days (over a 35 day period of sighting effort), with most re-sightings within 7 days after the first sighting, suggests that individual whales may remain in the area (and thus be subject to swim program

33

effects) for periods of days to a few weeks. However, on two whales fresh ‘oval scars’ appeared between sightings (both 12 days apart). Such scars on other species of cetacean have been attributed to pennellid copepods (e.g., Ivashin and Golubovsky 1978) but there was no evidence from the first sightings that a pennellid copepod occurred where the scar appeared. Lamprey wounds have been implicated in some wounds on cetaceans (Pike 1951), but lampreys only occur in southern Australia, at latitudes beyond 30° S (Paxton et al. 1989) and can not be responsible for the fresh scars on these dwarf minke whales. The oval scar is consistent with that attributed to a bite from a cookie cutter shark Isistius brasiliensis (see Jones 1971). Despite a recent record of the largetoothed cookie-cutter shark Isistius plutodus over the continental shelf (McGrouther 2001), all other records are from the open ocean (Jahn and Haedrich 1987). Best (2001) used the presence of similar oval scars to differentiate offshore populations of Bryde’s whale (Balaenoptera edeni complex) from inshore populations in southern African waters. Their presence on the dwarf minke whales suggests that these animals had been in the open ocean. Thus these individuals left the area for an unknown time between sightings, suggesting that even the ‘resident’ whales may not be subject to swim program interactions throughout their stay. Nonetheless, 13/100 whales were re-sighted throughout the five weeks of observation in 1999. Three of these dwarf minke whales which we first recorded in 1999 were re-sighted a year later in the same general area of the northern GBR , while a fourth whale was re-sighted two years later in the same area. Three of these four animals were female (the gender of the fourth is unknown). These data suggest the potential for geographical structuring of the population, with the possibility of several discrete breeding areas rather than a single diffuse area along much of the eastern Australian coast. Thus the swim programs may impact on a particular subset of the population which may need to be treated as a distinct management unit. Documentation of cumulative effects on known individual whales thus becomes particularly important in assessing management options. Risk assessment 1. Risk of injury to whales Vessel strikes. A recent review of collisions between vessels and whales (Laist et al. 2001) included two instances in which B. acutorostrata were struck, one apparently killing the whale. Estimated vessel speeds at the time were 25 and 30 knots respectively. Vessels presently used in the live aboard dive industry have a lower cruising rate (approximately 9 12 knots). With increasing size and speed of vessels carrying tourists to reefs in the Cairns section of the

33

34


GBR, the potential for vessel strikes must be considered. This problem, however, is not specific to swim programs. One of the perceived greater risks of swim programs is the close proximity, particularly of vessels, to cetaceans with the attendant risk of injury. This assumes that vessels are being manoeuvred to maintain close contact with the cetaceans. In the present case, maintenance of the encounter is largely under the control of the minke whales. The engine is normally off and the vessel is rarely manoeuvred, except for safety. This situation contrasts markedly with some surface based whale watching activities and with at least some dolphin swims in which vessels are repeatedly manoeuvred to place swimmers in close proximity to the cetaceans (Constantine 2001). The need to address diver safety (e.g., mother ship with propeller disengaged while swimmers are in the water; dive tender legally required to have a propeller guard) is likely to further minimise vessel risks to whales as compared to surface based whale watching endeavours. We do not address acoustic impacts in this paper but the noise levels can be determined from a parallel project on vocalisations of dwarf minke whales carried out on Undersea Explorer by J. Gedamke (University of California, Santa Cruz). The procedure of stopping the vessel and putting engines in neutral when in the vicinity of whales, minimising any manoeuvring when with whales and slowly building up speed at the end of the encounter follow the recommended procedures in McCauley et al. (1996: pp. 19-20) to minimise acoustic impacts. In almost 60% of the cases in 1999, the interaction was terminated by the vessel. It is at this time that great vigilance needs to be taken to avoid the possibility of injury to whales. We have found that dwarf minke whales behaviour changes as soon as the vessel starts moving; whale’s may abort a downwind run towards the vessel; others continue past the bow but at increased speed. Dwarf minke whales are active and highly manoeuvrable; we have seen one repeatedly circle the vessel while it was cruising at 8.5 - 9 knots. Particular attention has to be paid, however, to the position of whales around the boat before the propeller is engaged. Strict adherence to the existing guidelines for vessel manoeuvring in the presence of whales (e.g., no wake speed) and the presence of a lookout, keeping track of whales as the vessel motors away, are essential to avoid accidents. Deliberate injury. Frohoff (2000) documented cases in which sociable, wild dolphins were deliberately injured or killed. We have seen no evidence of such injury in the scars on dwarf minke whales but continue to examine scars which could be of human origin. An additional concern involves the possibility

that whales become de-sensitised to vessels and are thus more susceptible to hunting activities. At present, this seems less of a threat given that there are no directed hunts for dwarf minke whales and they have not been recorded in the Japanese scientific whaling statistics since 1993. Disease. Simmonds (2000) noted the increasing opportunities for cross-infection of disease between humans and cetaceans associated with humanwildlife interactions. An activity such as swim programs, which involves particularly close encounters, may represent a higher risk of disease transmission to cetaceans. It is important, however, to consider the mode of transmission. Transmission through sullage from the vessel is a possibility although, with swimmers in the water through the encounter, release of sullage occurs only by accident. Any such incident is subject to immediate negative feedback from swimmers in the water. Thus for any pathogen transmitted through faecal contamination, swim programs may represent less of a risk than other whale watching operations. Touching cetaceans is illegal under Environment Protection and Biodiversity Conservation Act 1999 and this is strongly enforced in the dwarf minke whale swim programs. We have found that once the reasons for the policy (potential harassment, risk of disease transmission) are properly explained to passengers, and that they have been properly prepared for the experience in pre-swim briefings, that compliance is almost total. Aerosol transmission has been suggested for at least some dolphin morbillivirus epidemics although other in-water transmission routes can not be ruled out (Geraci and Lounsbury 2002). Given that minke whales may surface to breathe near the swimmers breathing through snorkels, there is a possibility of aerosol human to whale transmission of disease although it is impossible to assess the probability. Although we can not assess the risk of disease transmission, we are in a position to monitor for signs of skin disease or prevalence of external parasites (Pennella, Xenobalanus). External parasite burden has been used in other cetacean species as an indicator of poor condition (e.g., Aguilar and Raga 1993). 2. Risk of injury to humans Although this is not of concern in the management of whale populations, human safety is raised as an issue in almost all legislation controlling (or banning) swim programs. In the present case, there are potential risks from close proximity to the whales, the challenging sea conditions that prevail in open water during the minke whale season and from other marine wildlife such as sharks. These risks are

34

BIRTLES ET AL.: COMMERCIAL SWIM-WITH-WHALE PROGRAMS largely unquantifiable, but passengers do need to be aware that they are present. Injury from whales. Human injuries (and even a fatality) have been recorded from odontocetes (Frohoff 2000). However, we have not seen aggressive actions by dwarf minke whales despite extensive in-water observations. The potential for aggression should be reduced in interactions where the whales are in control of the duration and nature of encounters. Behaviours such as jaw gape and bubble blasts that could be considered threat displays have been documented during the whale-swimmer interactions although these behaviours are seen in a variety of contexts (pers. obs.) and can not be automatically considered as threat display. Such behaviour does, however, need to be closely monitored. More frequent interactions with vessels and swimmers, however, could lead to a change in behaviour (e.g., de-sensitisation of individual whales to humans, leading to close contacts with swimmers and an increased potential for accidental injuries). We are already seeing some signs of closer approaches in certain whales which have previously interacted with vessels and swimmers (see Results). This behaviour needs to be carefully monitored. Elsewhere we have outlined some similarities between ‘friendly behaviour’ of E. robustus and dwarf minke whales. In the case of E. robustus, this has resulted in occasional incidents where skiffs have been lifted by a whale or jostled hard enough to knock a passenger overboard (Jones and Swartz 1984). Only a few opportunistic in-water encounters with E. robustus have been reported. A recent account (Hall 2000) indicates, however, that even apparently friendly behaviour of E. robustus could result in injury. Similarly an anecdotal account (Nolan 1996) of snorkelling with Eubalaena australis in Argentina included an instance where one swimmer was held underwater by a calf and another rammed into a boat. Neither action was considered aggressive but still could have caused injury. Dwarf minke whales are smaller and more manoeuvrable than E. robustus or Eubalaena spp so that there may not be exact parallels with the examples presented above. Nonetheless pre-swim briefings need to clearly alert passengers that, despite their name, dwarf minke whales are powerful, wild animals which may weigh several tonnes and can accelerate very rapidly. Passengers have to be aware, therefore, of the potential risk of injury. Caution should be exercised and interactions constantly monitored for overly forceful or exuberant behaviour by the whales, especially with animals which have previously interacted with vessels and swimmers, and which therefore may be more likely to make particularly close approaches.

35

Disease. Higgins (2000) reviewed bacteria and fungi known from marine mammals. The bacteria Abiotropha balaenopterae and a Brucella sp., a potential zoonotic infectious agent, have been isolated from minke whales. In assessing the probability of disease transmission, one again has to consider the mode of transmission. The most frequently suggested route, through bites, may be relevant to dolphins and other odontocetes (Simmonds 2000) but would seem less of a risk with mysticetes such as the dwarf minke whale. Aerosol transmission as a whale breathes near groups of swimmers using snorkels can not be ruled out.

Management implications & research needs The swim program which we describe is based on the dwarf minke whale, a poorly known taxon which has not been formally named (Rice 1998). It is considered ‘Insufficiently Known’ in Bannister et al. (1996) and the chances of getting information on population size or rate of increase are at present minimal. There is, moreover, little information on other minke whale forms or species at low latitudes (Winn and Perkins (1976), Mitchell (1991) and van Waerebeek et al. (2000) for north Atlantic B. acutorostrata; Williamson (1975) and Singarajah (1984) for B. bonaerensis off Brazil) to consider in the absence of data on the dwarf minke whales themselves. There are unresolved issues with potential changes in behaviour and possible cumulative effects of the interactions. Nonetheless we feel that banning the dwarf minke whale swim programs, as has been done with swim-with-whales programs in other countries, is not an option. This applies in particular to interactions which occur while a vessel is moored at a reef. The Ribbon Reefs ,where most of the interactions take place, contain many of the prime dive sites on the GBR. Moorings are placed at particular reefs because of their importance as dive sites and vessels will continue to use these moorings on a weekly basis. Unless there is a change in the behaviour of the whales, they will continue to interact with vessels and swimmers at those sites. While a ban may not be appropriate, specific management policies are clearly needed. In the absence of information on biological effects, our initial efforts have concentrated on producing guidelines (Arnold and Birtles 1999, revised 2002 Code is available on www.reef.crc.org.au/ aboutreef/wildlife/minkewhalecode.html) which aim to manage swimmer behaviour. By managing swimmer behaviour, the goal is to ensure that the interactions are as much as possible controlled by the whales themselves. Direct observations of interactions based on the guidelines and analysis of the experiential data provide the means to assess how successfully this goal is being achieved and, if

35

36


necessary, how procedures can be improved. Given the extended area covered by live-aboard vessels, with attendant problems in surveillance and policing of legislation, industry co-operation and selfregulation is crucial. Further work needs to address effectiveness of the guidelines, levels of compliance with the guidelines and ways of enhancing compliance through interpretive material for operators and passengers.

thus of limited relevance to the dwarf minke whale program documented here. On the other hand, certain of the procedures which we advocate, such as the use of lines which swimmers hold on to, may be inappropriate for larger, less manoeuvrable species such as humpbacks and right whales, especially where calves are present, or for those species which do not undertake repeated voluntary approaches to vessels.

There are operational matters which need to be considered. Table 3 indicates week to week variability in the number of prolonged interactions (over an hour), during a six day period. This variability can be accommodated to a certain extent in the existing situation where advertised swim programs occur on an extended trip, lasting from 3 6 days. Shorter trips (and especially day trips) can be expected to have a lower encounter rate, even at the height of the season. This in turn could lead to greater pressures to ‘elicit’ an interaction with any group of whales encountered - hence a deviation from the principle that whales control the nature of the interaction. For this reason, attempts to expand the industry to include advertised swim programs from day boats should be treated with caution.

ACKNOWLEDGEMENTS

The Australian National Guidelines for Cetacean Observation (ANZECC 2000) are divided into Tier 1 (general) and Tier 2 recommendations, the latter to cover “additional requirements to be considered on a regional basis as necessary”. Tier 2 requirements include assessment of the need for limits on number of swimmers per day, maximum interaction time with a pod, maximum cumulative interaction time with a pod/population, time required between successive swim attempts and need for a closed season. In order to apply these Tier 2 requirements to the dwarf minke whale swim programs, much more information on cumulative effects is needed. Such information is also necessary in establishing critical response thresholds to biologically significant effects, as advocated by a recent workshop on assessing long term effects of whale watching (IWC 2000). PhotoID studies offer considerable promise in providing a first estimate of numbers of dwarf minke whales within the area used for swim programs, site fidelity, residence time and thus the potential exposure time of individual whales to swim programs. As a more general point, we would endorse the recommendation of the IWC Scientific Committee (IWC 2000) that management decisions on swim programs (including whether they should even be allowed) should be on a species by species and case by case basis. Much of the existing literature on swimmer/cetacean interactions is based on odontocetes rather than mysticetes and involve quite different operational procedures. These studies are

We thank our colleagues on Undersea Explorer, particularly M. Matthews and J. Rumney, our research assistants M. Curnock and V. Lukoschek, co-worker P. Valentine (James Cook University) and R. Fitzpatrick (Digital Dimensions) for their help in collection of the data. We are grateful to crew and office staff of other live-aboard dive operations in the Cairns section for providing additional sightings and other information on dwarf minke whales. Logistical and financial support in the 1996 - 1999 seasons has been provided by Undersea Explorer. We acknowledge CRC Reef Research Centre for use of the base map and A. Edwards (James Cook University) and Z. Richards (Museum of Tropical Queensland) for help in modifying its format. We also acknowledge financial support from 1999 by Environment Australia, through the Marine Species Protection Program of Coastal and Clean Seas, managed by the CRC Reef Research Centre at James Cook University. Field research in 1999 was conducted under Environment Australia Research Permit P1999/02 and the Great Barrier Reef Marine Park Authority Research Permit G99/169. This is an expanded version of a paper (SC/52/WW13) presented to the Scientific Committee at the IWC meeting in Adelaide (June 2000).

REFERENCES AGUILAR RA AND RAGA JA, 1993. The striped dolphin epizootic in the Mediterranean Sea. Ambio 22: 524-528. ANZECC (AUSTRALIAN AND NEW ZEALAND ENVIRONMENT AND CONSERVATION COUNCIL), 2000. Australian national guidelines for cetacean observation and areas of special interest for cetacean observation. Environment Australia: Canberra. ARNOLD PW, 1997. Occurrence of dwarf minke whales (Balaenoptera acutorostrata) on the northern Great Barrier Reef, Australia. Reports of the International Whaling Commission 47: 419424. ARNOLD PW AND BIRTLES RA, 1999. Towards sustainable management of the developing dwarf

36

BIRTLES ET AL.: COMMERCIAL SWIM-WITH-WHALE PROGRAMS minke whale tourism industry in northern Queensland. CRC Reef Research Technical Report 27. CRC for Reef Research Centre: James Cook University of North Queensland, Townsville.

37

FROHOFF TG, 2000. Behavioural indicators of stress in odontocetes during interactions with humans: a preliminary review and discussion. Unpublished paper SC/52/WW2 presented to the IWC Scientific Committee, 52nd meeting of the International Whaling Commission: Adelaide, June 2000.

ARNOLD PW, MARSH H AND HEINSOHN G, 1987. The occurrence of two forms of minke whales in east Australian waters with a description of external characters and skeleton of the diminutive or dwarf form. Scientific Reports of the Whales Research Institute, Tokyo 38: 1-46.

GEDAMKE J, COSTA DP AND DUNSTAN A, 2001. Localisation and visual verification of a complex minke whale vocalisation. Journal of the Acoustical Society of America 109: 3038-3047.

BANNISTER JL, KEMPER CM AND WARNEKE RM, 1996. The action plan for Australian cetaceans. Australian Nature Conservation Agency: Canberra.

GERACI JR AND LOUNSBURY V, 2002. Health. Pp. 562-570 in Encyclopedia of marine mammals ed by W.F. Perrin, B. Wursig and J.G.M. Thewissen. Academic Press: Sydney.

BEST PB, 1982. Seasonal abundance, feeding, reproduction, age and growth in minke whales off Durban (with incidental observations from the Antarctic). Reports of the International Whaling Commission 32: 759-786.

GILL A AND FAIRBAIRNS RS, 1995. Photoidentification of the minke whale Balaenoptera acutorostrata off the Isle of Mull, Scotland. Pp. 129-132 in Whales, seals, fish and man ed by A.S. Blix, L. Walloe and O. Ulltang. Elsevier Science B.V: London.

BEST PB, 1985. External characters of southern minke whales and existence of a diminutive form. Scientific Reports of the Whales Research Institute, Tokyo 36: 1-33. BEST PB, 2001. Distribution and population separation of Bryde’s whale Balaenoptera edeni off southern Africa. Marine Ecology Progress Series 220: 277-289 BIRTLES RA AND ARNOLD PW, 2002. CRC Reef Research Centre current state of knowledge. Dwarf minke whales in the Great Barrier Reef. CRC Reef Research Centre; James Cook University of North Queensland: Townsville. BIRTLES RA, VALENTINE P AND CURNOCK M, 2001. Tourism based on free-ranging marine wildlife: opportunities and responsibilities. Wildlife Tourism Research Report No. 11, Status assessment of wildlife tourism in Australia series. CRC for Sustainable Tourism: Gold Coast, Queensland. CONSTANTINE R, 2001. Increased avoidance of swimmers by wild bottlenose dolphins (Tursiops truncatus) due to long-term exposure to swimwith-dolphin tourism. Marine Mammal Science 17: 689-702. DORSEY EM, STERN SJ, HOELZEL AR AND JACOBSEN J, 1990. Minke whales (Balaenoptera acutorostrata) from the west coast of North America: individual recognition and small-scale site fidelity. Reports of the International Whaling. Commission (Special Issue) 12: 357368.

GLADSTONE W, 1984. Meeting minke whales. Geo 6: 80-81. GBRMPA (GREAT BARRIER REEF MARINE PARK AUTHORITY), 2000. Whale and dolphin conservation in the Great Barrier Reef Marine Park: policy document. Great Barrier Reef Marine Park Authority: Townsville. HALL H, 2000. Wildlife photography. Natural History 109: 107. HIGGINS R, 2000. Bacteria and fungi of marine mammals: a review. Canadian Veterinary Journal 41: 105-116. HOPLEY D, 1984. The greatest reef on earth. Pp. 6475 in Readers Digest book of the Great Barrier Reef ed by F. Talbot and R. Steene. Readers Digest: Sydney. HOYT E, 2000. Whale watching 2000. Worldwide tourism numbers, expenditures and expanding socioeconomic benefits. Report to International Fund for Animal Welfare: Crowborough, United Kingdom. IVASHIN MV AND GOLUBOVSKY YU P, 1978. On the cause of appearance of white scars on the body of whales. Reports of the International Whaling Commission 28: 199 IWC (INTERNATIONAL WHALING COMMISSION), 1997. Report of the whale watching working group. Reports of the International Whaling Commission 47: 250-256.

37

38


IWC (INTERNATIONAL WHALING COMMISSION), 2000. Report of the Scientific Committee, 52nd meeting of the International Whaling Commission: Adelaide, June 2000. JAHN AE AND HAEDRICH RL, 1987. Notes on the pelagic squaloid shark Isistius brasiliensis. Biological Oceanography 5: 297-309. JONES EC, 1971. Isistius brasiliensis, a squaloid shark, the probable cause of crater wounds on fishes and cetaceans. Fishery Bulletin 69: 791798. JONES ML AND SWARTZ SL, 1984. Demography and phenology of gray whales and evaluation of whale-watching activities in Laguna San Ignacio, Baja California Sur, Mexico. Pp. 309-374 in The gray whale ed by M.L. Jones, S.L. Swartz and S. Leatherwood. Academic Press: Sydney. JONSGARD A, 1951. Studies on the little piked whale or minke whale (Balaenoptera acutorostrata Lacépède). Report on Norwegian investigations carried out in the years 1943-1950. Norsk Hvalfangst Tidende (The Norwegian Whaling Gazette) 40: 209-232. LAIST DW, KNOWLTON AR, MEAD JG, COLLET AS AND PODESTA M, 2001. Collisions between ships and whales. Marine Mammal Science 17: 35-75. MCCAULEY RD, CATO DH AND JEFFERY AF, 1996. A study of impacts of vessel noise on humpback whales in Hervey Bay. Final report to Queensland Department of Environment and Heritage: Maryborough. MCGROUTHER MA, 2001. First record of the largetooth cookie-cutter shark Isistius plutodus from Australian waters. Memoirs of the Queensland Museum 46: 442. MITCHELL ED JR, 1991. Winter records of the minke whale (Balaenoptera acutorostrata acutorostrata Lacépède, 1804) in the southern North Atlantic. Reports of the International Whaling Commission 41: 455-457. NOLAN M, 1996. My encounters with right whales in beautiful Argentina. (accessed on 26.11.2000 at http://fp.premier1.net/iamdavid/nolan.html). PAXTON JR, HOESE DF, ALLEN GR AND HANLEY JE, 1989. Pisces. Petromyzontidae to Carangidae. Zoological catalogue of Australia, vol. 7. Australian Biological Resources Study: Canberra.

PIKE GC, 1951. Lamprey marks on whales. Journal of the Fisheries Research Board of Canada 8: 275-280. RICE DW, 1998. Marine mammals of the world: Systematics and distribution. Special Publication No. 4. The Society of Marine Mammalogy: Lawrence: Kansas. SIMMONDS MP 2000. Emergent and introduced diseases – a growing threat to cetacean populations. Unpublished paper SC/52/E11 presented to the IWC Scientific Committee, 52nd meeting of the International Whaling Commission: Adelaide, June 2000. SINGARAJAH KV, 1984. Observations on the occurrence and behaviour of minke whales off the coast of Brazil. Scientific Reports of the Whales Research Institute, Tokyo 35: 17-38. SPITZ SS, HERMAN LM AND PACK AA, 2000. Measuring sizes of humpback whales (Megaptera novaengliae) by underwater videogrammetry. Marine Mammal Science 16: 664-676. STEWART B AND LEATHERWOOD S, 1985. Minke whale. Pp. 91-136 in Handbook of marine mammals. Vol. 3. Sirenians and baleen whales ed by S. Ridgway and R. Harrison. Academic Press: Sydney. WAEREBEEK K VAN, ANDRE M, SEQUERIA M, MARTIN V, ROBINEAU D, COLLET A, PAPASTRAVROU V AND NDIAYE E, 2000. Spatial and temporal distribution of the minke whale, Balaenoptera acutorostrata (Lacepede, 1804), in the southern northeast Atlantic Ocean and the Mediterranean Sea, with reference to stock identity. Journal of Cetacean Research and Management 1: 223-237. WATKINS WA, 1986. Whale reactions to human activities in Cape Cod waters. Marine Mammal Science 2: 251-262. WHALE AND DOLPHIN CONSERVATION SOCIETY (WDCS), 2000. Policy on swim-with-cetacean programs. (accessed on 6.2000 at www.wdcs.org.uk/wdcs2/conserve/watching/swi mming.html) WILLIAMSON GR, 1975. Minke whales off Brazil. Scientific Reports of the Whales Research Institute, Tokyo 27: 37-59. WINN HE AND PERKINS PJ, 1976. Distribution and sounds of the minke whale with a review of mysticete sounds. Cetology 19: 1-12.

38