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Swimming with Whales: Humpback Analysis
Introduction
Whale watching tours are run in 119 countries with an estimated 13 million participants
generating in excess of 2.1 billion dollars annually. Each year in Queensland tens of thousands
of people take part in commercial whale watching tours or see humpback whales from their own
boats. With the increasing Humpback whale (HW) population, there are now more HW
swimming within sight of Queensland’s coastline and an even greater number of people
watching (QLD Department of Environment and Heritage Protection, 2017).
The swim-with Dwarf Minke Whale (DMW) industry in the Great Barrier Reef (GBR) has
adopted a Code Of Practice with all stakeholders involved, which is now considered Worlds
Best Practice and has won several awards. This industry has demonstrated that while
maintaining vessel approach distances of 100m to whales, a reduction in the distance that
swimmers and divers can enter the water from less than 100m (but not closer than 30m) from
DMW has allowed the industry to flourish. However, research and monitoring by scientists,
operators, passengers and managers continues with DMW encounters to characterize safety
risk in terms of whale behavior and diver/snorkeler distance.
Current vessel guidelines for whale observations identify a caution zone within 300m and limits
vessel and swimmer approaches to 100m of a whale. However, Tier 2 of the Australian National
Guidelines for Whale and Dolphin Watching 2005 contains provisions for vessels and swimming
that allow for special authorized whale watching operations where scientific evidence supports
different management arrangements. The guidelines also allow for closer interactions than
those specified in Tier 1 for authorised swim programs.
The aim of this report is to outline the possible benefits and identify scientific evidence that
support a request for a temporary reduction trial period in the minimum HW vessel and swimmer
approach distance from 100m to 30m. The purpose of this request is to enable further research
related to swim-with-whales commercial viability, human and whale safety, and HW behavior.
All data collected for this report was carried out by untrained crew aboard “Main Event” during
their normal duties, and this report was commissioned by Lady Musgrave Experience.
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Swimming with Whales: Humpback Analysis
Scientific
Evidence
Summary
Previous work with DMW has characterized safety risk in terms of whale behavior and
diver/snorkeler distance. This report analysis examines HW sighting data from a single vessel
during the 2016 whale watching season in the southern Great Barrier Reef.
DMW research has identified specific behaviors as potential risks if they occur within 6m of a
diver or vessel (Birtles et al, 2014). These include three that were observed in this study with
Humpback whales: breaching, belly presentation, and spyhop/headrise. Another behavior
considered here is identified by The Australian National Guidelines for Whale and Dolphin
Watching 2005 as a possible indication of whether a whale is disturbed. That is, who departed
the area first, the whale(s) or the vessel.
There is no whale-diver distance information in the data supplied for this analysis as no in-water
interactions took place. Further, only a small subset of this data (33 of 311 observations)
supplies any whale-vessel distance information. Consequently, in addition to exploring the
relationships between behavior and whale-vessel distance, this analysis also considers
relationships between behavior and social (whale) conditions, associations between behaviors,
behavior and external conditions and encounter duration and departure. The purpose of these
additional assessments is to identify factors related to behaviors that may be predictable by
context and/or indicate whale distress.
Of the Whale Sighting Sheet (WSS) data (n=34), encounter durations ranged from four to 135
minutes with a mean of 23 minutes; closest approach by the whales ranged from 2m to 100m
with a mean of 39.6m; and pod size ranged from two to nine whales with a median pod size of
3. All encounters reported, with one exception that began while steaming and ended while
drifting, took place while the vessel was drifting.
Whale-vessel distance of first sighting in this study ranged from 0.5 nm to 5 nm with a mean of
3.7 nm (n=29). Closest approach distance by a whale to the vessel in this data ranges from 2 m
to 100 m with a mean of 39.6 m (n=29). The data available suggests weak to moderate
associations of closest approach with belly presentation, breaching and blows. It also
suggests weak associations between 1st sighting distance with fin slapping and playing.
Social conditions included number of whales observed in a pod, size of whales in a pod, and
whether one or more calves were present. Number of whales in pod was moderately associated
with belly presentation. Pod number was also weakly associated with breaching, fin
slapping, and who ended the encounter first; the whale(s) or the boat. There was also evidence
that breaching and tail slapping are associated with the size of whales a given pod. Calf
presence was weakly associated with the likelihood of playing but otherwise not with other
behaviors or pod characteristics (n=311). Of the combined WSS and WST observations, 30%
included the presence of a calf.
Behavior associations examined whether specific behaviors occurred in clusters or particular
sequences. These analyses suggest a moderate association of breaching with playing and
swimming.
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Swimming with Whales: Humpback Analysis
External conditions included wind, wave, visibility, date, and time of day information. There is
some evidence suggesting that wave height and wind speed may be associated with breaching
and belly presentation. There is also weak evidence that time of day (AM or PM) may be
associated with breaching and playing.
Encounter duration and departure assessments identified no significant associations for how
an encounter ended. However, encounter duration was found to be negatively associated
with wind speed, presence of calves and closest approach distance. Encounter duration
was also found to be positively associated with belly presentation, breaching, swimming,
and pod size. It is suggested that encounter duration may be a useful indicator of whale
pleasure and/or distress.
Methods
Data collection
All data was collected by untrained onboard
crew of the vessel “Main Event” (Lady
Musgrove Experience tour company, Southern
Great Barrier Reef). The collected data was
supplied in one of two formats: the Whale
Sighting Sheet (WSS) or the Whale Sighting
Table (WST) created by Main Event crew. The
WSS was developed by the Minke Whale
Project. The WST is a subset of the WSS and
represents the majority (278/311) of
observations recorded. WSS and WST form
samples and a summary table of variable
descriptives are appended in the
Supplementary Information section at the end
of this report.
Figure 1 indicates the areas (black dots) where Figure 1
observations were made.
Statistical methods
The R statistics package (ver. 3.4.0) was used to analyze these observations. As noted in the
descriptive data of these variable sets, the small number of observations and/or tests of skew
and kertosis do not support the assumption of a normal distribution for the variables reviewed.
Consequently, only non-parametric methods are used in these analyses. Complimentary
methods are applied for any given test in order to help validate results and provide additional
insights. Finally, because of the small number of records available for many of these variables,
unless otherwise noted the cut-off p-value used was 0.05.
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Swimming with Whales: Humpback Analysis
Overview of Data
Table 1
Table 1 shows a summary of the raw data. Data descriptions in bold are explored in this
analysis. Data identified here as NaN (Not a Number) has been otherwise parsed. That is,
defined by parts.
Parsed data includes times, dates, and encounter descriptions. Time of first and last sightings
have been used to define encounter duration. The free-text descriptions of encounters have
been used to identify categories of behavior, most of which were not listed in the WSS check
box behaviour selections.
Whale size was defined by three categories: large (> 6m), medium (4m – 6m), and small (< 4m).
Encounter end indicates whether the whale left first (W) or the boat left first (B).
Page 4Swimming with Whales: Humpback Analysis Table 2 Table 2 shows the rounded means and medians of encounter duration, closest approach and pod size when calves were and were not present from data collected with the WSS reports (n=29). Table 3 Table 3 shows the frequency of Humpback whale behaviors observed for the WSS and WST reports as well as those observed for Minke whales (Curnock, 2010; Birtles et al, 2014). These data suggest that for HW, breaching and blows were most frequently observed. It also suggests that the frequency of behaviours observed for the HW are quite different from those of the MW. The behaviours observed in this study that have been previously identified as a potential risk because they were observed to occur within close range (
Swimming with Whales: Humpback Analysis
Analysis
Overview
Kruskal-Wallis rank sum tests were used to identify whether there were significant differences in
conditions when a given behaviour was observed to be present versus when it was not.
Table 4
Table 4 lists findings for variable pairs with p-values ≤ 0.5. Elements identified in red are those
that were collected with the WSS only. These suggest that for ten different conditions there are
significant differences in the likelihood of belly presentation, breaching, playing, fin slapping, tail
slapping and how an encounter ended (e.g. who left first, the whale or the boat).
Page 6Swimming with Whales: Humpback Analysis
Table 5
Table 5 shows multilevel analyses (Pedhazur, 1997; R psych package, statsBy function) for the
bimodal conditions time of day (AM or PM), the absence or presence of calves, and how the
encounter ended (whale or boat left first). Unlike other methods for the complex analysis of
hierarchical (multilevel) data structures, this test is a much simpler function that gives basic
descriptive statistics for two level models. The results indicate a weak AM-PM level effect for
breaching (ηρ2 = 0.03, intraclass correlation = 6%). Calf presence suggests a weak effect for
playing (ηρ2 = 0.03, intraclass correlation = 4%). For encounter end (who left first) there was a
moderate effect for belly presentation (ηρ2 = 0.06, intraclass correlation = 15%).
Page 7Swimming with Whales: Humpback Analysis
These tests suggest that breaching has a moderate association with time of day and wave
height; belly presentation has a moderate association with pod size; and play has a weak to
moderate association with the presence of calves. Other relationships, while statistically
significant, are negligible.
Table 6
Table 6 shows complimentary correlation tests using Kendall’s tau and Spearman’s rho. These
results suggest that the number of large, medium and/or small whales in a given pod is
associated with the occurrence of breaching and tail slapping. It also suggests that the closer
the approach during a given encounter, the more likely belly presentation, breaching and
possibly fin slapping will be observed and the less likely blowing will be observed. Finally, it
suggests that the encounter duration is associated with belly presentation, breaching and fin
slapping.
The following sections examine these associations in more detail by category.
Whale-‐vessel
distance
Whale-vessel distance of first sighting reported in the WSS data ranged from 0.5 nm to 5 nm
with a mean of 3.7 nm (n=29). Closest approach distance by a whale to the vessel in this data
ranges from 2 m to 100 m with a mean of 39.6 m (n=29).
As noted above, 1st sighting distance is weakly associated with playing and fin slapping while
closest approach is associated with belly presentation, blowing, breaching and possibly fin
slapping.
Page 8Swimming with Whales: Humpback Analysis
Social
conditions
and
behaviors
Figure 2 illustrates the distribution of pod sizes for all
observations. This data suggests that most observed
pods were composed of two to three whales.
Figure 2
Page 9
Figure 3Swimming with Whales: Humpback Analysis
Figure 3 shows two visualizations using correspondence analysis (Venables & Ripley, 2002; R
MASS package, corresp function) that gives a graphical representation of cross tabulations. The
first (red) analysis of whale size and behaviour suggest that calves are most closely associated
with blowing and spyhoping; small whales with belly presentation, and large whales with how
the encounter ends. The second (blue) analysis indicate that smaller pod sizes are generally
more likely to be associated with most of the behaviours observed in this study indicating that
smaller groups display more surface behaviors.
Associated
behaviors
Table 7 shows complimentary
correlation tests between behaviours. It
suggests that there are negative but
weak associations of breaching with
playing and swimming.
Table 7
Figure 4
Page 10Swimming with Whales: Humpback Analysis
External
conditions
and
behaviors
Figure 5
Figure 5 suggests that wave height and wind speed are negatively associated with the likelihood
of both belly presentation and breaching. However, as identified in table 4 of the analysis
overview, with the exception of breaching and wave height, these effects are weak.
Page 11Swimming with Whales: Humpback Analysis
Encounter
duration
and
departure
Figure 6
Figure 6 shows a histogram of encounter durations which
ranged from 4 - 135 minutes, with a mean of 23.2 and
median of ten minutes (n=28).
Figure 7 summarizes how encounters ended for the WSS
reports (n=30). In 43% of encounters, the vessel left first,
in 57% of cases the whale(s) left first.
Figure 7
Page 12Swimming with Whales: Humpback Analysis
Although no significant associations of how an encounter ended were found, encounter
duration was found to be negatively correlated with wind speed (rho=-0.4; tau=-0.3),
presence of calves (rho=-0.2; tau=-0.3), and closest approach distance (rho=-0.2; tau=-0.3).
Encounter duration was also found to be positively correlated with swimming (rho=0.2;
tau=0.3), belly presentation (rho=0.3; tau=0.3), breaching (rho=0.3; tau=0.4), and pod size
(rho=0.3; tau=0.4).
Figure 8
The bar charts in figure 8 show the positive relationships between encounter duration and the
absence or presence of belly presentation, breaching and swimming.
Page 13Swimming with Whales: Humpback Analysis
Discussion
The aim of this analysis is to support a request by Lady Musgrave Experience for a decrease in
approach distance for swimmers/snorkelers from 100m to no less than 30m of HWs in order to
conduct further research to identify the viability of this change in regulations. It aims to identify
behaviours, whale-human safety, and indicators of whale distress in order to justify this.
Safe interactions between DMW and humans have previously been defined by relative distance
and specific behaviours (Birtles, 2014). Other work has identified a number of behaviours as
possible indicators of whale distress. In both cases, these guidelines are broad and generally
non-specific. This discussion outlines why further research into HW encounters is needed to
determine the triple bottom line sustainability potential of a reduction in swimmer/snorkeller
approach distances.
This study observed and assessed several behaviours and conditions. These included three
behaviors that prior research has associated with safety (breaching, belly presentation,
spyhop) and one with distress (encounter departure). Most of the associations found were
weak to moderate. However, these findings suggest that some HW behaviours are more
frequent and/or extended in particular conditions. Specifically breaching, belly presentation,
playing and the duration of an encounter.
Breaching was found to be one of the most frequently observed behaviours, occurring in 48%
of the observations. It was found to be significantly and directly associated with playing and
indirectly associated with swimming and blowing.
Previous work suggests that this behaviour is an important social and physiological activity. It
has been suggested that whales are more likely to breach when they are in groups (Cetacean
surfacing behaviour, 2017). Although this analysis shows weak and mixed associations with
group composition and size, breaching associations with swimming and playing indicate a social
motive.
Breaching is often also seen in rough seas. Consequently it has been suggested that a breach
allows the whale to breathe in air that is not close to the surface and full of spray (Cetacean
surfacing behaviour, 2017). This data does not supports this view; although there is a significant
difference in wave height when breaching is present or absent, breaching was found to be less
frequent in the presence of larger waves. Wind speed had very little impact on breaching
behaviour. More research is needed to determine the distance of breaching, and fin slapping,
from the vessel, and whether they are related to other factors, as these are the two behaviours
most likely to pose significant risk to swimmers and snorkellers.
Spyhoping was infrequent, occurring in 3% of encounters. Although there is some indication
that this behaviour is weakly associated with the presence of calves, significant relationships
with other behaviours or conditions were not found.
Belly presentation was also infrequent, occurring on during only 5% of encounters. However, it
had a significant association with increased encounter duration and decreases in closest
approach suggesting it is a positive social indicator.
Page 14Swimming with Whales: Humpback Analysis
Encounter departure by the whale(s) occurred in slightly more than half, 57%, of the
observations. No significant associations were found for how the encounter ended leaving no
indication of why they may have left. However, encounter duration was found to have a
number of associations with social (calf presence & pod size), physical conditions (wind speed)
and other behaviours (closest approach distance, belly presentation, breaching, and swimming).
It is suggested that this measure may be an additional indicator of whale emotional response to
a given encounter.
The scientific evidence presented here identifies several areas for further study that would be
enabled by permission to reduce swimmer approach distance regulations from 100m to no less
than 30m. It suggests that HW behaviour is distinct from DMW behaviour. It also Identifies
specific HW behaviors previously linked with safety that are significantly associated with social
and external contexts.
Given the notion that HWs are approaching the vessel, often with calves, for sometimes
extended periods, and exhibiting social behaviour, suggests a degree of relaxed and confident
behaviour on behalf of the HWs. With no swim-with HW data to compare any of these results we
suggest that further detailed and ongoing research into HW and vessel/human encounters is
needed and justified to properly assess any change in possible regulations regarding the swim
with HW industry.
References
Birtles, A. et al. (2014). Report to the Great Barrier Reef Marine Park Authority on the dwarf
minke whale tourism monitoring program (2003-2008). Research Publication 112, GBRMPA,
Townsville.
Commonwealth of Australia. (2016). Draft Australian National Guidelines for Whale and Dolphin
Watching 2016. Retrieved from
http://www.environment.gov.au/system/files/consultations/a7cd15ae-3226-495d-b3e9-
146d0b310471/files/draft-revised-australian-national-guidelines-whale-and-dolphin-watching.pdf
Curnock, M.I. (2010). Mechanisms for assessing the sustainability of swimming-with-whales
tourism in the Great Barrier Reef. James Cook University PhD Thesis.
Mangott, A. (2010). Behavioural studies on dwarf minke whales (Balaenoptera acutorostrata
subsp.) associated with the swim-with industry in the northern Great Barrier Reef. James Cook
University PhD Thesis.
Natural Resource Management Ministerial Council. (2005). The Australian National Guidelines
for Whale and Dolphin Watching 2005. Retrieved from
https://www.environment.gov.au/system/files/resources/fed9ff86-0571-43ff-bb18-
32205fc6a62c/files/whale-watching-guidelines-2005.pdf
O’Connor, S., Campbell, R., Cortez, H., & Knowles, T. (2009). Whale Watching Worldwide:
tourism numbers, expenditures and expanding economic benefits, a special report from the
International Fund for Animal Welfare. Yarmouth MA, USA, prepared by Economists at Large.
Page 15Swimming with Whales: Humpback Analysis
Pedhazur, E.J. (1997). Multiple regression in behavioral research: explanation and prediction.
Harcourt Brace.
QLD Department of Environment and Heritage Protection. (2017). Whale watching. Retrieved
from http://www.ehp.qld.gov.au/wildlife/watching/marine-
mammals/whales.html#new_marine_mammal_legislation
Strasser, H. and Weber, C. (1999). On the asymptotic theory of permutation statistics.
Mathematical Methods of Statistics, 8, 220–250.
Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth edition.
Springer.
Supplementary
information
Whale Sighting Table (WST)
Page 16Swimming with Whales: Humpback Analysis
Whale Sighting Sheet (WSS)
MINKE WHALE PROJECT WHALE SIGHTING SHEET 2016
We are interested in all of your whale sightings, but are particularly keen on hearing about minkes (dwarf minke whale pictured above left).
Please fill out this sheet as best you can to help our sightings records.
Part A: Fill in immediately when whales are seen:
1. Time of initial sighting:………………………….. 2. Date: _______ / _______ / 2016
3. Location: Coordinates at start: Lat:………………..……...…….(S) Long:………………..……….(E)
4. Approx. distance from vessel when first sighted: ……..… 5. Time of first approach (to within 30m) ….……
Part B: Fill in immediately after end of encounter:
6. Time of last sighting:…………… 7. Vessel:…………….…..………… 8. Your name: ………….………….
9. Coordinates at end (if drifting/steaming): Lat:………………………. (S) Long:…………………………(E)
10. How did the encounter end? (please tick one) …. Whale(s) left the boat Boat left the whale(s)
Part C. Fill in at end of encounter:
11. Type of whale: (please circle one) Minke / Humpback / Other:………………….…………………………..
12. Number of whales: ……………………… Certain / Approx... If approximate, please provide a range, with a minimum estimate
(the most whales seen at one time) and a maximum estimate (number of different whales you think may have been present throughout the encounter).
13. Estimated size(s): (No. of whales): more than 6m: #________; 4m-6m: #_______; less than 4m: #_______
14. Any calves? (2016 calf will be < ½ size of mother, in close proximity to her & breathing more often): # ___________________
If a cow & calf were seen; how long did they stay in the area? (give times) From:_____________ To: ______________
15. Vessel status when whale(s) first sighted: (please circle one) Anchored / Moored / Steaming / Drifting
16. Did the vessel status change during the encounter? (Please explain and give times;; e.g. “dropped mooring to drift at 15:35”)
………………………………………………………………………………………………..………….…….
17. Distance drifted during encounter: ………… naut. miles 18. Average wind speed: ……………. knots
19. Average wave height: ………………..…..… metres 20. Underwater visibility …………… metres
21. Name of nearest reef or dive site:………………...………… 22. Distance to that reef/site:……….. ____
23. Closest approach distance by whale(s) (metres from boat): ………… 24. Rope used?: Y / N (please circle one)
25. Maximum number of divers in at one time: Using snorkel: ……………… Using SCUBA: ………………….
26. Brief description of encounter (e.g. movement of whales, swimmers, etc; use back of page if necessary): ...…………...…..
………………………………………………………………………………………………..…………….….
…………………………………………………………………………………………………...…………….
27. Were any of the following behaviours observed? (Tick where appropriate and write number of times observed)
(For descriptions of behaviours see the CRC Reef brochure, www.minkewhaleproject.org or the Minke Whale Project Interpretive DVD 2007)
□ Breaching? # times:__________ □ Headrise/Spyhop? # ____ □ Bubble blast? #_____ □ Gulping? #:_______
□ Sudden speed up? # _______ □ Sharp veer away? #_____ □ Sudden deep dive? #: _____________________
□ Jaw clap? # _____________ □ Belly presentation? #_____ □ Close approach (You can also read
