Humpback Whale Distribution and Abundance in the Near Shore SW

Field Report A Description of Humpback Whale and other Mega fauna Distribution and Abundance in the Western Pilbara Using Aerial Surveys – 2009/2010

Prepared by Curt and Micheline Jenner Centre for Whale Research (WA) Inc. PO Box 1622 Fremantle WA 6959 [email protected]

1. Abstract

Aerial surveys were conducted across a 12 month period in the coastal region of the proposed Anketell Point Iron Ore Port facility in order to determine mega fauna distribution and abundance for development purposes. A total of 1069 humpback whales were sighted in 22 aerial surveys over the western Pilbara offshore region during mid August 2009 to late July 2010. The aerial surveys also reported regular sightings of dolphins, manta rays and turtles throughout the survey. A useful humpback whale baseline dataset has been established prior to establishment of the new port facility so that managers and key stakeholders can proceed with an understanding of where potentially important areas to humpback whales may be monitored.

2. Objective

The primary purpose of this study is to determine the seasonal distribution and relative abundance of humpback whales and other mega fauna along the western Pilbara coast near Anketell Point during a 12 month seasonal cycle. Aerial surveys were considered the most effective means of detecting spatial and temporal species clusters in the time window assigned and which could be used for preliminary environmental assessment purposes. This report describes a 12 month dataset collected at approximately two week intervals during the predicted peak whale period (June to November) and at 3 week intervals during off-peak periods(December to May).

3. Introduction

The Centre for Whale Research (CWR) was commissioned by API Ltd in October 2009 to design, conduct and analyse, a series of aerial surveys that would best compliment existing datasets and fill knowledge gaps in great whale and other mega fauna distribution and abundance along the inshore and offshore western Pilbara coastline (Figure 1). This is the final report which documents the complete 12 month monitoring programme (in total 22 aerial surveys) and provides contextual interpretation of the results for future management purposes. It forms the first step in a systematic process to address the question: Does Anketell Point and the surrounding off-shore area represent a biologically important area for humpback whales?

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3.1 Survey Relevance

CWR has been conducting independent studies into the population dynamics and migratory habits of humpback whales in Western Australia since 1990. CWR has confirmed Chittleboroughs’ (1953) theory that Exmouth Gulf, 325 km to the southwest of the study area (2-4 days swim-time, based on speeds of 2.4 – 4.6 km/hr, Dawbin (1956) and Chittleborough (1965)), is a nursery area for humpback whales (Jenner et. al. 2001). As such, Exmouth Gulf represents the closest known biologically important area for humpback whales to the study site and here is used as a comparison basis for this study program.

The understanding of Exmouth Gulfs’ role for humpback whales is more advanced than that at Anketell Point. CWR has conducted a variety of boat-based (including photo-id, genetic, behavioural and satellite tracking) and aerial survey studies in Exmouth Gulf since 1995. Humpback whales are expected to be the most frequently encountered protected species in the Anketell study area although direct study programs have not been conducted in this general area since 1994 (at Dampier, Jenner and Jenner( 1994)).

Chittleborough (1953) first described Exmouth Gulf as a possible “nursery” for humpback whales based on aerial surveys over the area in 1951 and 1952. These flights were a regular part of an exploratory process designed to maximise returns for the commercial whaling industry. A whaling station operated at Norwegian Bay near Pt Cloates (Lat S 22˚ 36’) from 1912 to 1916 and then from 1922 to 1928, and finally from 1949 to 1955. By 1963, when a moratorium on humpback whaling commenced, there was thought to be less than 800 whales left in Breeding Population “D”, or the Western Australian population (Chittleborough 1965).

Now, over forty years on since the cessation of whaling, this population of whales is thought to have been recovering at an annual rate of between 7 and 12% (Hedley et al., 2009; Salgado Kent et al., 2010). By extrapolating this recovery rate forward to 2010, the population could reach 30-35,000 individuals. If, as suggested, approximately 10% of this population is represented by cow/calf pairs, then as many as 3,500 pairs could use nursing areas like Exmouth Gulf by 2010. How this population increase is progressing and how it relates to other nursing or resting areas is of great interest to industry and regulatory managers.

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Figure 1. Aerial survey flight paths for the Anketell 2009/2010 study period showing proximity to the 2000–2009 CWR aerial survey flight paths near North West Cape and the Exmouth Gulf series from 2004/2005.

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3.2 Background Research – Humpback Whales at Exmouth Gulf/North West Cape

Exmouth Gulf is the nearest area on the WA coast to Anketell Point that detailed migration data for humpback whales exists. Timing of migration and off-shore distribution patterns of whales from the two adjacent, but separate, study sites will be compared.

The migration of humpback whales both north and south past Exmouth Gulf follows predictable but complicated patterns each season. The northern migration of this species near Albany, Western Australia, has been described by Chittleborough (1965) as being segregated by age and sex class. It is likely that this same pattern, where subadults and mature females terminating lactation are in the vanguard of the northern migration, followed by mature males and females and then later pregnant females (carrying near-term foetuses), is present off North West Cape and the broader south western Pilbara offshore region.

The southern migration follows a similar order, with addition of cows and their newly born calves at the tail end of the migration. The cow/calf portion of the migration congregates in greatest numbers inside Exmouth Gulf, but their spatial/temporal distribution has not previously been described near the Anketell study area.

Spatially, the northern migratory path is consistent for all age and sex classes off North West Cape and centres on about the 250 m depth contour (Figure 2). Whales rarely enter Exmouth Gulf during the northern migration (June to early August), perhaps due to the 3˚C or more temperature difference between the open ocean and the shallow Gulf during June to early August. A transition phase between the northern and southern migrations occurs from early August to early September (Figure 3). This time period coincides with peak numbers of whales each season (Figure 5) and results in the migratory path spreading spatially to include a much wider depth range than is observed during the northern or southern migration. Sightings of whales inside the northern warmer part of the Gulf increase during early September and by mid-late September the main southbound migratory peak passes by west of North West Cape with some animals entering the Gulf (Figure 4).

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Northern Migration (June to early August)

Exmouth Gulf

Figure 2. Aerial survey sightings of humpback whales during the northern migratory period (June to early August) in 2000 and 2001. Data from CWR aerial surveys in Woodside Energy EIS Document (2002) section 2.3.2.5.

Peak of Migration (mid August to early September)

Exmouth Gulf

Figure 3. Aerial survey sightings of humpback whales during the Transition Phase (mid August to early September) in 2000 and 2001. Data from CWR aerial surveys in Woodside Energy EIS Document (2002) section 2.3.2.5.

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Southern Migration (mid September to December)

Exmouth Gulf

Figure 4. Aerial survey sightings of humpback whales during the southern migratory period (mid September to December) in 2000 and 2001. Data from CWR aerial surveys in Woodside Energy EIS Document (2002) section 2.3.2.5.

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120 106 100

60 45.5 40 32 32.5 24 17 15 16 20 9.5 12.5 5 7.5 9 6.5 6.5 2 0.5 1.5 0 Jul 4-13Jul Oct 2-11Oct Aug3-12 Sep2-11 Mean number of pods / 10 day block Jul 14-23Jul 1-10Nov June4-13 12-21Oct 22-31Oct Aug13-22 Sep12-21 Nov 11-20Nov 21-30Nov June14-23 Jul 24-AugJul 2 Sep22-Oct 1 June24-Jul 3 Aug23-Sep 1 Sample period

Figure 5. Mean number of humpback whale pods recorded during aerial surveys in 10 day sample blocks per sampling season during the months of June to October ( X  1 SE). Data from CWR aerial surveys west of, and not including, Exmouth Gulf for Woodside Energy 2000/2001, Woodside Energy EIS Document (2002) section 2.3.2.5.

It is likely that water temperature plays a role in determining when whales, particularly cow/calf pairs trying to minimise metabolic expenditures, enter Exmouth Gulf, however it is also possible that

6 | P a g e the northward facing opening to the Gulf acts to trap whales migrating southwards along the coast. Cow/calf numbers inside the Gulf peak during the first two weeks of October (Figure 6), at a similar time annually that the sea surface temperature inside the Gulf becomes equal to that found offshore at the same latitude (Figures 7 & 8).

Number of Calves of Number 5

Figure 6. Numbers of cow/calf pod sightings from 2005 aerial surveys inside Exmouth Gulf (CWR unpubl. data).

Figure 7. Sea surface temperature map for late August 2004 (Transition phase, peak numbers of whales offshore) showing the cooler water inside Exmouth Gulf and the inshore south western Pilbara region.

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Figure 8. Sea surface temperature map for mid-October 2004 showing the increase in temperature inside Exmouth Gulf during the period when peak numbers of cow/calf pods rest in the Gulf and inshore south western Pilbara Region.

Expansion of the existing knowledge base for humpback whale spatial and temporal distribution from the North West Cape area and Exmouth Gulf is a logical and necessary first step for this current study program.

4. Materials and Methods

4.1 Aerial Surveys

The offshore area to approximately 60m depth off-shore from Anketell Point has been systematically examined using aerial surveys for mega fauna from August 2009 to August 2010. Transects have been designed to be consistent and comparable with other CWR transects in different study areas along the NW coast, and were intended to include the main humpback whale migratory body, both spatially and temporally (Jenner et al. 2001). A total of 22 samples of all transects were collected at 14-21 day intervals with the precise dates within these time blocks (intervals) dependant on “good” weather conditions (winds less than 18 knots or Beaufort Sea State 5) for detecting humpback whales (the primary target species).

The design of the survey followed protocols defined in the Distance ver. 5.1 software programme (Buckland et al. 2001, Buckland et al. 2004). This programme specifically designs and analyses biological line transect sampling projects for the purpose of estimating density and abundance. Using the principles of this system, parallel transects were constructed over the study area in order to maximise coverage probability during a single flight. Although parallel line transect designs are disadvantaged because the time spent in between transects is “off survey”, this technique results in a more even probability of coverage for non-rectangular survey areas such as the current study site (Buckland et al. 2001). Furthermore, this system is consistent with previous CWR aerial surveys from

8 | P a g e both offshore near North West Cape (20 km southwest of the study area) and Exmouth Gulf (325 km southwest of the study area) (Figure 1).

Due to logistical constraints, the timing of the surveys, which began in mid August 2009 and continued until late July 2010, cover part of the 2009 migratory season and part of the 2010 migratory season. However, in order to develop a migratory continuum for future management purposes, this report assumes that basic migratory principles (spatial/temporal) will remain consistent between seasons and therefore the graphed data has been presented in a month-wise- flow from January to December. The authors accept that there may be natural irregularities in humpback whale (and other species) migration patterns between separate migratory seasons that make this assumption less robust, however as a baseline data management system it is more efficient to present the data in this manner.

The first eight surveys in 2009 (mid August to November) were expected to coincide with a crossover or Transition event between the northern and southern migratory phases, but then be dominated by the southern migration (see Figure 9 for the trend in humpback swim direction). Timing for peak numbers of cow/calf humpback whale pods, based on CWR data from Exmouth Gulf, are expected to be in peak numbers in the study area during late September to early October and, along with all other humpback whales, are likely to have decreased in numbers by early November. Peak whale numbers in this region (apart from cow/calf pods) are expected to be in late August (Jenner et al. 2001). The anticipated northern migration period could not be monitored until June/July 2010.

1,2 M IGRATING SOUTH M IGRATING NORTH 1,0

0,8

0,6

0,4

0,2 PROPORTIONOF PODS

0,0

-0,2 June July Aug ust September October November

MONTH

Figure 9. Migratory direction of humpback whale pods at North West Cape from aerial surveys (from Jenner et al,. in prep. showing October/November period as a southern migration period. Non-migrating whales (i.e. resting or milling) are not plotted.

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4.2 Aerial Survey Detail

Aerial surveys were conducted at an altitude of 305 m (1000 ft) and at a speed of 222 km/hr (120 knots) using a twin-engine, over-head wing aircraft (Cessna 337). The plane followed line transects which were surveyed in passing mode (i.e. the plane did not deviate from the flight path) at 10km spacing’s. Surveys were only initiated in wind speed less than 33 km/hr (18 knots) which has been shown to be adequate for spotting whales (Jenner et al. in prep). Each flight was of approximately 6.5 to 7 hours duration and take-off times varied between 8:40 and 10:55 so that the mid-day period was consistently sampled and glare would be a consistent factor for all flights. Flights during the expected southern migration period were flown from east to west to minimize the possibility of double counting pods of whales on successive transects. Similarly, the flights during the northern migration period were flown from west to east.

Personnel for each survey included four people; two pilots and two observers. The observer team consisted of four trained personnel. One person (Lyn Irvine) flew nineteen flights, and one person flew twelve flights (Jennifer Thompson), one person flew 11 flights (Jane Kennedy) and Emily Wilson flew one flight. The pilot and co-pilot were not responsible for spotting, and were separated acoustically from the two observers. The co-pilot was responsible for recording the planes’ angle of drift on each transect, so that angles reported from the compass boards could be corrected relative to the flight path. The observers were linked via a separate intercom system which was logged to a time coded Sony Mini Disk Recorder NH900 which allowed the observers to search continuously and voice record all sightings to a time code which was synchronized to the Global Positioning System (GPS) before each flight. A Garmin III Pilot aeronautical GPS was used to log sightings (as waypoints) and coordinates of the flight path, including altitude, for every second of the flight.

Observers sighted and recorded positions of whales by measured vertical and horizontal angles from the aircraft to the whales (using Suunto PM-5/360PC clinometers, and a compass board, respectively). The location (latitude and longitude) of each sighted whale was later plotted by projecting a new GPS waypoint from the waypoint recorded at the time of sighting (using Oziexplorer ver 3.95 GPS software) from the calculated angle and distance of the aircraft to the whale. The angle was calculated with the following formulae: Angle to starboard = AC + (MHA + DA), and Angle to port = AC + (MHA - DA), where AC was the aircraft course, MHA was the measured horizontal angle and DA was the angle of drift of the aircraft. Distances were calculated using formulae in Lerczak and Hobbs (1998).

No vertical or horizontal angles were recorded for any other species (i.e. dolphins, dugongs, rays sharks or turtles) and it was assumed for plotting purposes that sighting positions were the same as the waypoint marked (i.e. directly under the plane). This allowed more detailed information to be reported for whales in often busy conditions and does not falsely assume that smaller species (less than 3m in length) can be sighted across the width of the effective search strip (5km). For example, Marsh (1995), used only 200m as the effective search strip width for transects designed specifically for dugongs.

The sighting information that was recorded for whales included the direction of migration (north, south, resting/milling, or undetermined) of each pod observed. Southbound whales were those sighted swimming parallel to the coast in a southerly direction. Pods reported as “milling” were swimming perpendicular to the coast (not northbound or southbound) or surface lying at the time of

10 | P a g e sighting with no obvious signs of swimming (i.e. resting whales). Pods recorded as “undetermined” were sighted too far from the aircraft, or for too short a time period, to assess swim direction.

The level and direction of glare (scale 1-3) for each observer was recorded for each transect as well as environmental variables such as Beaufort sea-state (scale 0-12), associated wind speed (estimated in knots) and direction (from wave patterns), cloud cover below 1000 feet (percentage) and overall visibility (scale 1-3).

4.3 Relative Density Calculations

The GIS programme Arcview 3.2, with extensions Spatial Analyst and Animal Movement (Hooge and Eichenlaub 1997), was used to analyse the distribution of cetaceans and all other encountered marine fauna. Complete spatial randomness (CSR) of cetacean sightings was tested to determine if sightings data were spatially structured (i.e. whether sightings were clustered, random or uniformly distributed). Nearest neighbour routines were run in Arcview to test for CSR and a Kernel “home range” estimator was used to compute locations of clusters (indicating higher relative densities and possible migratory corridor or resting area) for cetaceans within the study area. The mean distance of whale pods on each flight from the nearest section of the proposed shipping channel was measured using a GIS “Spider Distance” tool to establish spatial and temporal patterns in clustered data. Probability contour maps were generated that display relative density contours across surveys reporting humpback whales.

A smoothing factor (“h” statistic) controls the size of the home range reported and has been shown to be inconsistent for different sample sizes (Hooge and Eichenlaub 1997). For this reason, a second technique, the minimum convex polygon (MCP) method, was used to first confirm sightings range extent. The MCP was considered to be the minimum extent of the sightings range and the smoothing factor was adjusted until the area of an unbroken 95% kernel contour for the entire dataset completely included the area of the MCP. This provides an objective method for selecting the smoothing factor (Hooge and Eichenlaub 1997) and creates a baseline for relative density comparisons between flights.

The “h” statistic was used to calculate 50%, 75% and 95% probability density contours where the 50% contour represents the highest density of whale pods (not whales) and the 95% contour represents the likely extent of all pods.

5. Results

5.1 General Description – Aerial Surveys

A total of 22 flights at both two and three week intervals from 13 August 2009 to 29 July, 2010, totalling 141.7 survey hours over the western Pilbara offshore region resulted in 3678 mega fauna sightings (Table 1) and 794 vessel sightings (Appendix 1). Besides the target species, humpback whales, Bryde’s whales (total of 8) and false killer whales (total of 4)were the only other positively identified large whale species sighted in the study area. Dugongs (total of 36) were sighted on eight of the flights and a single whale shark was sighted on March 2, 2010. Dolphins and turtles were the most commonly sighted mega fauna, totalling 1281 and 1194 individuals, respectively. Krill balls (identified as amorphous grey to pink clouds of animals and often associated with jumping fish and diving birds) were sighted on three consecutive flights during March to mid April.

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Table 1. Mega fauna and vessel sightings during the first eight flights of a twenty flight series. Peak values are highlighted.

False Flight Humpback Bryde's Unid Flight Date Killer Manta Whale Krill Number Whale Whale whale whale Dugong Dolphin Turtle Ray Shark Ball 1 13/08/2009 172 0 0 0 0 19 19 2 0 0 2 22/08/2009 191 0 0 0 1 14 9 3 0 0 3 08/09/2009 120 0 0 0 0 0 2 0 0 0 4 24/09/2009 131 0 0 0 0 143 25 0 0 0 5 06/10/2009 52 0 0 0 0 0 2 1 0 0 6 18/10/2009 65 0 0 0 1 80 93 2 0 0 7 03/11/2009 15 0 0 0 0 45 53 2 0 0 8 19/11/2009 0 0 0 0 0 0 2 0 0 0 9 06/12/2009 0 0 0 0 0 5 4 6 0 0 10 04/01/2010 0 0 0 0 0 46 14 4 0 0 11 17/01/2010 0 2 0 0 0 56 175 13 0 0 12 05/02/2010 0 0 0 0 0 58 32 0 0 0 13 02/03/2010 0 2 0 2 7 144 81 8 1 2 14 22/03/2010 0 4 0 0 0 58 54 15 0 15 15 13/04/2010 0 0 0 0 2 57 34 0 0 1 16 01/05/2010 0 0 0 0 6 101 170 1 0 0 17 21/05/2010 0 0 0 0 3 210 147 0 0 0 18 04/06/2010 0 0 0 0 0 0 5 1 0 0 19 17/06/2010 7 0 0 0 0 124 164 1 0 0 20 07/07/2010 5 0 0 0 0 0 0 0 0 0 21 17/07/2010 186 0 4 0 13 59 76 3 0 0 22 29/07/2010 125 0 0 0 3 62 33 3 0 0 TOTAL 1069 8 4 2 36 1281 1194 65 1 18

5.3 Humpback Whales

A total of 702 humpback whale pods containing 1069 individual whales were sighted during the August 13, 2009, to July 29, 2010, study period (Table 2). The majority of humpback whale sightings occurred between mid July and late September. A total of 73 calves were sighted. As expected, no humpback whales were sighted during 11 consecutive flights from November 19, 2009 to June 4, 2010. Humpback whales were present in the study area during the months of June to November with peak numbers present during late August (Figure 10). A small majority (52%, 365/702) of pods sighted were resting/milling (surface lying or swimming perpendicular to the coast) while 32% (225/702) were swimming (migrating northbound or southbound) and 16% (112/702) were undetermined in their swim behaviour (whales sighted only once and/or too far away to determine swim direction). Humpback whale sightings decreased significantly after late September (Table 2).

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Table 2. Humpback whale sightings during the August 13, 2009, to July 29, 2010 study period.

Number Pods Flight Number Pods Pods Pods Flight Date of with # of Pods Swimming Resting/Milling Undet. Whales Calves 1 13/08/2009 112 172 4 38 52 22 2 22/08/2009 128 191 4 31 65 32 3 08/09/2009 91 120 16 28 49 14 4 24/09/2009 83 131 12 30 45 8 5 06/10/2009 35 52 13 15 11 9 6 18/10/2009 44 65 15 4 38 2 7 03/11/2009 9 15 5 4 5 0 8 19/11/2009 0 0 0 0 0 0 9 06/12/2009 0 0 0 0 0 0 10 04/01/2010 0 0 0 0 0 0 11 17/01/2010 0 0 0 0 0 0 12 05/02/2010 0 0 0 0 0 0 13 02/03/2010 0 0 0 0 0 0 14 22/03/2010 0 0 0 0 0 0 15 13/04/2010 0 0 0 0 0 0 16 01/05/2010 0 0 0 0 0 0 17 21/05/2010 0 0 0 0 0 0 18 04/06/2010 0 0 0 0 0 0 19 17/06/2010 4 7 0 4 0 0 20 07/07/2010 4 5 0 3 1 0 21 17/07/2010 106 186 0 68 38 0 22 29/07/2010 86 125 4 0 61 25 TOTALS 702 1069 73 225 365 112

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Figure 10. Numbers of humpback whales sighted per flight during the August 13, 2009, to July 29, 2010, study period (data presented in monthly order, January to December). No humpback whales were sighted during eleven of the twenty-two flights (red circles).

As a means of initially exploring the spatial datasets, tests for Complete Spatial Randomness (CSR) of humpback whale pod distribution were conducted to test the hypothesis that distribution within the study area was random. The nearest neighbour analysis function in Animal Movement (v.2.0) was used to test for CSR using a polygon encompassing the flight path area as a boundary.

Assumptions for the test are as follows;

1) If the resulting value of R from the nearest neighbour analysis equals 1 for an observed data set then the data is randomly distributed, since the observed distribution does not deviate from the expected random model. 2) If R < 1, the data is clustered where the observed mean nearest neighbour distance is less than what is expected with the random model, thereby resulting in clusters. 3) If R > 1, the data is uniformly distributed because the mean observed nearest neighbour distance is greater on average than the expected.

Complete Spatial Randomness analysis using the nearest neighbour technique resulted in the data points on all flights being designated “clustered” (R values all less than 1, Table 3).

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Table 3. Values of R indicating clustered distribution of humpback whale pods during each flight (* - Sample size too small for analysis)

Flight Number Flight "R" Value 1 13/08/2009 0.8684 2 22/08/2009 0.8454 3 8/09/2009 0.9294 4 24/09/2009 0.8201 5 6/10/2009 0.7914 6 18/10/2009 0.6760 7 3/11/2009 0.6887 8 19/11/2009 - 9 6/12/2009 - 10 4/01/2010 - 11 17/01/2010 - 12 5/02/2010 - 13 2/03/2010 - 14 22/03/2010 - 15 13/04/2010 - 16 1/05/2010 - 17 21/05/2010 - 18 4/06/2010 - 19 17/06/2010 * 20 7/07/2010 * 21 17/07/2010 0.7439 22 29/07/2010 0.7753

Having established that there is clustering of the data points, the next step in spatial analysis was to determine if there is any evidence of site fidelity in each flight, bearing in mind variables such as date which may influence migratory direction and therefore spatial distribution.

Dates for separating the season into migratory direction categories (northern or southern phases) were identified using the proportion of whales sighted swimming either northbound or southbound during each flight for the core humpback whale usage period of this study area (mid July to mid October, see figure 10). Pods of whales listed as “Undetermined” were allocated proportionately to either Northbound, Southbound or Resting/Milling categories. Northerly migrating whales were prevalent in the study are during June/July while Southerly migrating whales were more common during August to November (Figure 11). A Transition period where all whales sighted were Resting/Milling (not migrating north or south) occurred in late July.

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Northbound Southbound Milling

100

40 Proportionof Pods 30

0 Jul_17 Jul_29 Aug_13 Aug_22 Sep_08 Sep_24 Oct_06 Oct_18

Figure 11. The Proportion of pods sighted swimming either Northbound, Southbound or Milling during the core of the humpback whale migratory season (mid July to mid October).

Separating the seasonal sightings data into a northern and southern migratory phase, using the July 29 flight as the dividing point, the GIS tool Animal Movement 2.0 (Hooge et al., 1997) was next used to calculate probabilistic contours of equal utilization distributions. This tool is also known as a kernel home range calculator. The kernel home range is considered one of the most robust of the probabilistic techniques for spatial analysis of point data (Worton 1989). The kernel is essentially a grid of equal utilisation areas that has smoothed edges. The smoothing can be done automatically by the GIS program or adjusted manually, using an “h” statistic, which is fit to the dataset with a Minimum Convex Polygon (MCP). For the current dataset, points from flights prior to July 29 were combined to form northern migration dataset and the data points from flights post July 29 were combined to form a southern migration dataset. For each migration phase a maximum boundary for the MCP was created. An “h” value of 0.025 was fit to the Northern Migration dataset and an “h” value of 0.042733 was automatically generated for the Southern Migration (Figure 12 and 13).

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Figure 12. The Minimum Convex Polygon used to fit the smoothing factor for the Northern Migration dataset. Smoothing factor “h”=0.025 and the resulting 95% kernel contour.

Figure 13. The Minimum Convex Polygon used to fit the smoothing factor for the Southern Migration dataset. Smoothing factor “h”=0.042733 and the resulting 95% kernel contour.

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Ranked kernel density polygons (highest to lowest) for the Northern Migration period (June/July) using the same “h” value (0.025), are presented in Figure 14. A similar plot for the flight on July 29, the transition between the Northern and Southern migration when all pods sighted were resting/Milling is shown in Figure 15. Ranked kernel density polygons for the Southern Migration (August to November, “h”= 0.042733) are shown in Figure 16.

Distribution of all humpback whale pods during the Northern Migration was off-shore of Nickol Bay and was similar to that observed during the flight (July 29, 2010) identified as a transition between the northern and southern migration periods. The distribution of whales during the southern migration was focused further inshore in shallower waters but also contained a component of off- shore pods as well. Overall, higher numbers whales were sighted in the study area during the southern migration than during the northern migration.

Given the lack of humpback whale sightings in the Nickol Bay area and in particular near the proposed port Infrastructure during the Northern and Transition migratory periods, further analysis is focussed on the Southern migration period (August to November).

Spatial patterns for Milling/Resting whales and cow/calf pods were next examined. Milling and Resting whales were widely dispersed, however a discreet concentration of this migratory category were sighted approximately 20km west of the proposed shipping channel in Nickol Bay in water depths averaging 10m (Figure 15 and 17). Cow/calf pods were found in highest densities inside Nickol Bay (Figure 16) and the highest proportion were resting/milling (57%, 37/65) (Figure 18).

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Figure 14. Positions of humpback whale pods sighted during the Northern Migration period (June and July) with relative density distribution polygons.

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Figure 15. Positions of humpback whale pods sighted during the Migratory Transition period (late July) with relative density distribution polygons.

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Figure 16. Positions of humpback whale pods sighted during the Southern Migration (August to November) with relative density distribution polygons.

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Figure 17. Milling and Resting humpback whale pod density plot during the August 13 to November 3, 2009, flights. Note: migratory direction is assumed based on actual swim direction and is assigned based on sections of the compass rose in the upper right corner of the figure.

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Figure 18. Distribution and swim direction of Cow/calf pods during the August 13 to November 3, 2009, flights. Note: migratory direction is assumed based on actual swim direction and is assigned based on sections of the compass rose in the upper right corner of the figure.

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The mean distance of humpback whale pods from the proposed shipping channel during the Southern Migration was measured using the perpendicular Spider distance tool (Arcview 3.2a). Distances remained consistent for all flights, ranging from 18 km to 24 km away (Figures 17 and 18).

Figure 19. “Spider distance” measurements from each pod during the Southern Migration to the nearest section of channel.

40000 35000 30000 25000 20000 15000 10000 Distance (metres) (metres) Distance 5000 0

Figure 20. Mean perpendicular Spider distance results for all humpback whale pods during the Southern Migration. Error bars are + 1SD.

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5.4 Other Mega Fauna

5.4.1 Other Large Whales

Bryde’s whales (Balaenoptera edeni) were the most commonly sighted other large whale with a total of eight sightings clustered in the January to March time period (Table 1, Figure 21). A pair of unidentified whales were sighted on March 2, 2010, the same day as two Bryde’s whales. It is considered likely that these unidentified whales were also Bryde’s whales although a positive identification could not be made from the distance the whales were spotted. Sightings of Bryde’s whales coincided with peak numbers of krill swarms and manta rays. A group of four false killer whales (Pseudorca crassidens) were sighted at the northern most extent of the off-shore transects on July 17, 2010.

False killer whale Bryde's whale Unidentified whale

4.5 4 3.5 3 2.5 2 # Whales # 1.5 1 0.5 0

Figure 21. Numbers of other large whale species sighted during the 22 flight series between August 13, 2009 and July 29, 2010.

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Figure 22. Location of Bryde’s whale sightings in relation to krill swarm sightings during 3 flights across mid January to late March, 2010.

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5.4.2 Dugongs

A total of 36 Dugongs were sighted during eight of the twenty-two flights with two calves sighted (Table 1, Figure 23). Dugong sightings were in predominantly shallow water in an embayment in the eastern section of the study area (depths less than 10 m, Figure 24). Peak numbers were sighted during mid-July, however there were too few dugongs sighted to calculate a density plot.

Dugongs Calves

14 12 10 8 6

# Dugongs # 4 2 0 Jul_07 Jul_17 Jul_29 Jan_04 Jan_17 Jun_04 Jun_17 Oct_06 Oct_18 Apr_13 Feb_05 Sep_08 Sep_24 Dec_06 Aug_13 Aug_22 Nov_03 Nov_19 Mar_02 Mar_22 May_01 May_21

Figure 23. Numbers of Dugongs sighted during the 22 flight series between August 13, 2009 and July 29, 2010.

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Figure 24. Distribution of Dugongs sighted during the 22 flight series between August 13, 2009 and July 29, 2010.

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5.4.2 Dolphins

Dolphins are likely to be inshore species including Tursiops spp. or Sousa chinensis, or offshore species, Stenella spp., ( Jenner and Jenner, unpublished data from vessel surveys) however dolphins were not able to be identified to species level due to difficulties with identification from the aircraft. A total of 1281 dolphins (178 pods) were sighted with peak numbers observed during the May 21, 2010 flight (Figure 25). Dolphins were sighted in all ranges of water depths in the study area (Figure 26).

Dolphins

250

200

150

# Dolphins # 100

Figure 25. Numbers of dolphins sighted during the 22 flight series between August 13, 2009 and July 29, 2010.

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Figure 26. Distribution of dolphin pods sighted during the 22 flight series between August 13, 2009 and July 29, 2010.

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5.4.3 Turtles, Manta Rays and Whale Sharks

Turtles were not able to be identified to species level at the time of sighting. Boat based sightings by CWR from previous surveys suggest that the principal turtle species in the nearshore Dampier Archipelago region is the green turtle (Chelonia mydas), although loggerhead turtles (Caretta caretta) and flatback turtles (Natator depressus) have also been sighted in the area. Hawksbill turtles (Eretmochelys imbricata) are also frequently sighted in mangrove creeks. Turtles were sighted during each of the 22 flights except July 7, 2010 when sea state conditions made sightings difficult (Table 1, Figure 26 and Appendix 2). Turtles were predominantly located inside the 30m bathymetry (Figure 25).

Turtle spp.

200 180 160 140 120 100

# Turtles # 80 60 40 20 0

Figure 26. Numbers of turtles sighted during the 22 flight series between August 13, 2009 and July 29, 2010.

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Figure 26. Distribution of turtle species sighted during the 22 flight series between August 13, 2009 and July 29, 2010.

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Manta rays (Manta birostris) were distinguished from other rays by their distinctive shape although it is possible that other species of bottom dwelling rays were mistaken for Mantas along the mangrove creek areas. Manta rays were more broadly and sparsely distributed and were not “clumped” sufficiently to allow accurate density contours to be constructed (Figures 27 and 28)

Whale sharks (Rhincodon typus) are large, wide headed sharks easily distinguished from other sharks from the air. One whale shark was sighted during the 22 flight series on March 2, 2010, when krill swarms and other filter feeding predators (manta rays) were relatively abundant.

Manta Ray Whale Shark

16 14 12 10 8 6 # Individuals # 4 2 0

Figure 27. Numbers of manta rays sighted during the 22 flight series between August 13, 2009 and July 29, 2010.

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Figure 28. Distribution of manta rays and whale sharks sighted during the 22 flight series between August 13, 2009 and July 29, 2010.

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5.4.4 Vessels

A total of 794 vessels were sighted during the 22 flight series between August 13, 2009 and July 29, 2010 (Appendix 1). The majority of vessels were sighted in water depths less than 30m and focussed around the Cape Lambert area immediately to the east of Anketell Point where an iron ore loading and storage facility are located (Figure 29).

Figure 29. Distribution of vessels plotted during the 22 flight series between August 13, 2009 and July 29, 2010.

6. Discussion

This report summarises a study programme carried out between August 13, 2009, and July 29, 2010, in the offshore western Pilbara region using aerial surveys at a combination of 14 day and 21 day intervals. Two week intervals were planned to provide consistent monitoring during the humpback whale migratory season (June to November) while three week intervals were planned for the off- season period (December to May). This document is intended to provide baseline spatial and temporal data for humpback whales and other mega fauna species for the purpose of planning the Anketell Port development.

Of particular interest to this development are the movements of humpback whales. No previous studies have been conducted in this area despite awareness that coastline usage by this species is

35 | P a g e becoming an important management issue due to an expanding and recovering whale population. Exmouth Gulf 325km to the south of the study area is recognised as an important resting and nursing area for this population of whales at this latitude (Jenner et al. 2001). Similarities between Exmouth Gulf and the Anketell Point/Nickol Bay area are explored below to begin to put this new study area into biological perspective for this species.

Establishing the temporal and spatial boundaries of humpback whale core usage areas are the first parameters to consider in establishing humpback whale usage of the Anketell Point/Nickol Bay area.

Temporally, peak numbers of whales were sighted in the study area during late August and the highest numbers of cow/calf pods were sighted during a six week period from early September to late October. These timings are consistent with Exmouth Gulf which is expected to be only 2-3 days away for a steadily migrating whale. Previous studies in Exmouth Gulf (Jenner and Jenner 2005) have identified the mid-September to mid-October period, and water depths between 10 and 20 m, as temporal and spatial boundaries for the cow/calf portion of the population.

Spatially, the migration path in mid-August was the most widely dispersed, with high densities of whales sighted up to 50km off-shore in 40m depth. The flights from late August onwards showed a shift in migratory path preference to inshore waters, and highest densities for the remainder of the migratory season were found in depths less than 35m and less than 30km off-shore. A consistent high density core of sightings was observed approximately 20km west of Anketell Point in Nickol Bay in 10-20m depths, similar to Exmouth Gulf. A similar shift inshore of the migratory body has been reported for several areas along the Western Australian coast (Jenner et al. 2001). For example Exmouth Gulf is not used by humpback whales during the northern migration (June/July) when the migration is centred off-shore near the 250m dept contour, however, during the August to November southern migratory period, whales tend to follow the coastline inside the 50m depth contour and large numbers of whales enter Exmouth Gulf.

This study has established timing and spatial distribution patterns for the southern migration of humpback whales at Anketell Point/Nickol Bay which appears to be consistent with patterns shown at Exmouth Gulf. The northern migration past this region appears to completely by-pass the Nickol Bay area and it is likely that , considering the comparatively low numbers sighted (versus the southern migration), a large and unmeasured component of the northern migratory body was undetectable and passed by this area further off-shore than the aerial surveys sampled (85 km). Given this finding, future surveys and management decisions could be more efficiently focussed on the southern migration time period (August to November) only.

The relatively large number of resting and milling whales reported during the August to November flights raises the possibility that Nickol Bay, in particular its north western sector, may be a resting area for south migrating whales. The highest numbers of cow/calf pods were also sighted in this area of the embayment. Aerial surveys at two week intervals are limited in their ability to detect fine scale behavioural usage patterns that would help to determine whether the Bay is indeed an important resting area, or simply a natural barrier that temporarily condenses and focuses the migratory body as a result of natural topographic features.

At the time of this report a 20 day vessel based behavioural study has just been completed that aimed to test the hypothesis that Nickol Bay represents a resting area for humpback whales. A

36 | P a g e report is pending that will add behavioural detail (swim vs. rest duration, length of stay, frequency of active behaviours, etc.) to the baseline spatial/temporal dataset reported here. This behavioural study system will form part of a larger long term study and planning process that is aimed at establishing whether a growing Western Australian humpback whale population (Breeding Population D) may have undiscovered or previously unused resting areas along the Pilbara coastline. Furthermore, the study can be used by managers to assess behavioural change/impact as a result of planned human activities.

Interactions between other large whale species and the proposed port facility appear to be unlikely as a result of the current survey. Bryde’s whales are an interesting and little studied species in Australian waters and their presence in the study area may stimulate future independent study, however it seems unlikely that the proposed port facility itself will have any impact on this species. However it is important to consider increasing shipping movements as a future collision risk, especially given the cumulative increase in shipping movements in the Pilbara region as a whole. If this species is feeding seasonally in this area, as evidenced by the proximity to krill balls during this study, mitigation such as speed restrictions or defined shipping lanes maybe necessary.

Dugongs do not appear to use the area surrounding Anketell Point and Nickol Bay in high densities during any month of the year and, as a result, are not discussed further in this report.

Dolphins appeared to be widely dispersed in the area, spatially and temporally, as is typical of the Pilbara near coastal region, and no unusually high numbers of these animals were sighted in the near shore study area, including Nickol Bay. In comparison, Jenner and Jenner (2005) have shown that there are significant year round populations of both dolphins and dugongs that use Exmouth Gulf, however, from this limited dataset it appears that the Anketell/Nickol Bay region does not offer similar suitable or sufficient habitat for high densities of these species.

Turtles and manta rays were found in the study area year round, with higher numbers sighted during the January to June period. Both species may pose a risk for vessel collisions management however it should be noted that the Port of Dampier, which the authors of this report are very familiar with, is one of the busiest ports in Australia and has few reports of large ship collisions with either of these frequently sighed species. Risk of collisions is likely to increase for small fast vessels which may increase as a result of increasing population base. Similarly, small fast (<7m, >20 knots) vessels are considered a collision risk for inshore dolphin species as well.

Interpretation of the temporal/spatial patterns shown in this report for animals less than three metres in length (i.e. dolphins, dugongs, turtles, manta rays) should consider wind speed and sea state which appears to have had a significant influence, as expected, on the sight-ability of animals that are small and/or submerged for long periods. There appears to be a direct correlation between sea state (Appendix 2) and numbers of these species sighted (Table 1). For example, the best three weather days were 24 September, 18 October and 3 November 2009. These three days also have the highest counts of dolphins, turtles and manta rays. Conversely, November 11, 2009 and July 7, 2010, have sea states of 4 and corresponding low turtle, dolphin and manta ray counts. As such, sightings of other mega fauna reported here are of limited use in determining absolute population densities of these species and should rather be used to infer presence (not absence, nor density) during a particular flight/time of the year.

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Vessel distribution appears to be related to the Cape Lambert iron ore loading facility immediately to the east of Anketell Point, or to other off-shore production or shipping activities. There is no historical basis from which to correlate present distribution and abundance of species reported in this document with their presence.

7. Conclusion

While this study provides essential baseline data for mega fauna distribution across an entire twelve month period for this area, it must be recognised that “snap-shot” samples at two and three week intervals may either over emphasize, or under emphasize, the amount of time particular species utilise this area. However, temporal and spatial clusters of animals of management interest that have been identified from this survey will form the basis of ongoing studies in order to provide managers with more complete datasets.

Specifically the western side of Nickol Bay, where high concentrations of resting/milling humpback whales have been observed, will be monitored in greater detail (during 2010/2011/2012) such that a detailed behavioural understanding of humpback whale habitat usage in the immediate vicinity of the proposed port facility is achieved. Quantitative measures of cow/calf activity levels, both inside and outside of the identified core usage area in the western Bay, will be compared to similar data, including length of stay, from Exmouth Gulf, a known resting area.

Establishing whether the clusters of humpback whales sighted in the western Bay represent whales using a biologically important habitat, is the next priority of this ongoing study program.

8. Summary

Information to be used for management purposes from this report can be summarised as follows:

 Humpback whales were present in the study area during June to November.  Near shore waters (< 35m depth) during the southern migration period had higher densities of humpback whales than offshore waters.  Humpback whales do not use the near shore Nickol Bay area during the northern migratory period (June/July).  It is likely that a large component of the northern migratory body passed further off-shore than the northern extent of these aerial surveys.  Peak numbers of northbound whales passed outside Nickol Bay during mid-July.  Peak numbers of southbound whales arrived, or passed by, during late August and were found both inside and outside Nickol Bay.  Cow/calf humpback whale pods were in highest numbers inside Nickol Bay during the early September to mid October period.  There was a distinct Transition from the northern migration phase to the southern migration phase in late July.  Swim direction data suggests that humpback whales, particularly cow/calf pods, may use western Nickol Bay to rest for an as yet undetermined periods of time.  The Burrup Peninsula may form a natural barrier to the southern migration of humpback whales along the Pilbara coastline and therefore increase the likelihood of whales stopping migration before navigating out of the embayment.

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 Bryde’s whales may be feeding off-shore of Nickol Bay during summer months.  Dugongs were not present in significant numbers in the study area at any time of year.  Dolphins and manta rays are found widely dispersed off-shore to at least the50m contour (off-shore extent of the survey) with detection rates likely linked to sea state.  Turtles are present in significant numbers in the study area and detection rates are also tied to sea state.

9. References

Buckland, S.T., Anderson, D.R., Burnham, K.P., Laake, J.L., Borchers, D.L. and L. Thomas (2001) Introduction to Distance Sampling. Oxford University Press, London.

Buckland, S.T., Anderson, D.R., Burnham, K.P., Laake, J.L., Borchers, D.L. and L. Thomas (editors) 2004) Advanced Distance Sampling. Oxford University Press, London.

Chittleborough, R. G. (1953) Aerial observations on the humpback whale (Megaptera nodosa) (Bonnaterre), with notes on other species. Austr.J. Mar. Freshw. Res.4:219-26

Chittleborough, R. G. (1965) Dynamics of two populations of humpback whale, Megaptera novaeangliae (Borowski). Austr.J. Mar. Freshw. Res. 16:33-128

Dawbin, W. H. (1966)—The seasonal migratory cycle of humpback whales. In : S. Norris (ed) Whales, dolphins and porpoises. University of California Press, Inc., Berkeley, California, USA, 145– 70.

Hedley, S.L., Bannister, J.L. and R.A. Dunlop (2009) Group IV humpback whales: Abundance estimates from aerial and land-based surveys off Shark Bay, Western Australia, 2008. Report of the International Whaling Commission, SC/61/SH23, 17 p.

Hooge, P. N. and B. Eichenlaub (1997) Animal movement extension to Arcview. ver. 1.1. Alaska Biological Science Center, U.S. Geological Survey, Anchorage, AK, USA.

Jenner, K.C.S. and M.-N.M. Jenner (1994) A preliminary population estimate of the Group IV breeding stock of humpback whales off Western Australia. Report of the International Whaling Commission 44,303–07.

Jenner, K. C. S., Jenner, M.-N.M. , Salgado Kent, C. P. and K. Bilgmann (In prep).Migratory Patterns in Distribution, Abundance and Behaviour of Humpback Whales (Megaptera novaeangliae) at North West Cape, Western Australia.

Jenner, K.C.S., Jenner, M.-N.M, and K.A. McCabe (2001) Geographical and temporal movements of humpback whales in Western Australian waters. APPEA Journal 38(1):692-707.

Jenner, K. C. S. and M.-N.M. Jenner (2005) Final Report - Distribution and abundance of humpback whales and other mega-fauna in Exmouth Gulf, Western Australia, during 2004/2005. Report to Straits Salt, 24pp.

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Lerczak, J.A. and R.C. Hobbs (1998) Calculating sighting distances from angular readings during shipboard, aerial, and shore-based marine mammal surveys. Marine Mammal Science, Vol. 14 (3): 590-599.

Marsh, H. (1995) Fixed-width aerial transects for determining dugong population sizes and distribution patterns. Information and Technology Report 1, pp 56 -62.

Salgado Kent, C.P., Jenner, K.C.S., Jenner, M.-.N.M., Bouchet, P. and E. Rexstad (2010) Southern Hemisphere Breeding Stock ‘D’ Humpback Whale Population Estimates from North West Cape, Western Australia. Submitted pp 29.

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Appendix 1 – Vessel sightings for each flight from August 13, 2009, to July 29, 2010.

Flight Date Vessels

13/08/2009 44 22/08/2009 30 08/09/2009 22 24/09/2009 33 06/10/2009 17 18/10/2009 42 03/11/2009 20 19/11/2009 22 06/12/2009 40 04/01/2010 23 17/01/2010 58 05/02/2010 15 02/03/2010 20 22/03/2010 39 13/04/2010 39 01/05/2010 52 21/05/2010 40 04/06/2010 29 17/06/2010 41 07/07/2010 32 17/07/2010 96 29/07/2010 40

TOTAL 794

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Appendix 2 – Beaufort Sea State for all transects during each flight. Colour referenced dark to light (high to low sea state).

Flight Flight Date TRANSECT 1 TRANSECT 2 TRANSECT 3 TRANSECT 4 TRANSECT 5 TRANSECT 6 Number Flight 1 13/08/2009 3 3 3 1 2 2 Flight 2 22/08/2009 2 3 3 3 3 3 Flight 3 08/09/2009 3 3 3 3 2 3 Flight 4 24/09/2009 2 2 2 1 2 1 Flight 5 06/10/2009 3 3 3 3 3 3 Flight 6 18/10/2009 2 1 1 1 2 1 Flight 7 03/11/2009 1 1 2 2 2 2 Flight 8 19/11/2009 4 5 4 4 4 4 Flight 9 06/12/2009 3 2 3 3 3 4 Flight 10 04/01/2010 3 3 2 2 3 3 Flight 11 17/01/2010 1 1 0 1 3 3 Flight 12 05/02/2010 3 2 2 2 2 2 Flight 13 02/03/2010 1 2 1 1 1 1 Flight 14 22/03/2010 2 2 2 3 3 2/ 3 Flight 15 13/04/2010 3 3 3 2 3 2 Flight 16 01/05/2010 2 1 1 2 1 0 Flight 17 21/05/2010 0 0 0 0 0 1 Flight 18 04/06/2010 3/ 4 3/ 4 4 3 3 3 Flight 19 17/06/2010 2 1 1 1 1 1 Flight 20 07/07/2010 3/ 4 3 4 4 4 4 Flight 21 17/07/2010 1/ 2 2 2 2 2 2 Flight 22 29/07/2010 2 2 3 2 3 2

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APPENDIX 3

A Description of Humpback Whale and other Mega fauna Distribution and Abundance in the Western Pilbara Using Aerial Surveys – 2009/2010

Prepared by Curt Jenner & Gabbrielle Cummins Centre for Whale Research (WA) Inc. PO Box 1622 Fremantle WA 6959 [email protected]

2 November 2010

APPENDIX INFORMATION

Preliminary advice is described below on the relative importance of Nickol Bay as a possible resting area for humpback whales, Megaptera novaeangliae based on vessel surveys in the Anketell Port Project area during August 2010 and aerial surveys over August 2009 to 2010. Further research as part of an Honours thesis “Humpback whale distribution and habitat use within Nickol Bay, Western Australia, a potential resting area” (Cummins, 2010) documents preliminary findings from this work and discusses the importance of Nickol Bay in relative context to other embayments along the Western Australian coastline.

A summary of the preliminary findings are:

 although the behaviour patterns recorded for cow/calf pairs in Nickol Bay are almost identical to those seen for cow/calf pairs resting in Exmouth Gulf, it is important to note that the density of whales observed in Nickol Bay during its “peak of season” indicates that it is not likely to be as important to the Stock D population as Exmouth Gulf (Figure 1);  residency time periods would currently indicate that most cow/calf pods spend less than one day in Nickol Bay (during the peak August/September period and based on photographic identification in the 2010 season) verses an average stay in Exmouth Gulf of 2 to 2weeks for cow/calf pods;  Correlations with depth and sea surface temperature (SST) may be real or due to the natural “whale trap” shape of the coastline created by the Burrup Peninsular on the west side of Nickol Bay that happen to coincide with seasonal fluxes in coastal SST. These are issues requiring further investigations over several seasons and it is premature to make definitive statements here.

Data collected thus far show that Nickol Bay is a part of the southern migration, and that cow/calf pods that migrate through Nickol Bay exhibit classic resting behaviour.

However there is no evidence at this stage to show that these cow/calf pods use Nickol Bay for extended periods as occurs for Exmouth Gulf or Camden Sound.

APPENDIX 3

Figure 1. Humpback whale density in Nickol Bay (inner transect) and Exmouth Gulf (east‐west transect).

Reference:

Cummins, G.H. (2010). Humpback whale distribution and habitat use within Nickol Bay, Western Australia, a potential resting area. Manuscript presented for the degree of Bachelor of Science (Honours)”, School of Plant Biology, The University of Western Australia, November 2010.

Cummins, G.H., Meeuwig, J.J., Hanson, C., and Jenner, K.C. (2010). Humpback whale distribution and habitat use in the Nickol Bay region, Western Australia, a potential resting area. Draft Manuscript to be submitted to Journal of Marine Ecological Progress Series.

APPENDIX 3

Humpback whale distribution and habitat use in the Nickol Bay region, Western Australia, a potential resting area.

1 2 3 4 Cummins, G.H. , Meeuwig, J.J. , Hanson, C.E and Jenner, K.C.S

1 School of Plant Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009.

2 Centre for Marine Futures (Oceans Institute) and School for Animal Biology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009.

3 School of Environmental Systems Engineering, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009.

4 Centre for Whale Research Western Australia Inc. PO Box 1622 Fremantle, WA 6959.

ABSTRACT The strong coastal affiliation and wide ranging nature of the humpback whale, Megaptera novaeangliae, makes understanding this species‟ distribution and habitat use patterns critical to their conservation. While global patterns of habitat use in relation to temperature and depth are documented for humpback whales on wintering grounds, little is known of their habitat use in resting areas. Humpback whale breeding stock "D", the largest humpback population worldwide, winter off Western Australia (WA), with an annual southward migration from Kimberly breeding grounds in WA‟s northwest to Antarctic Southern Ocean feeding grounds. Major resting areas identified for Group D‟s southward migration are in the sheltered embayments of Exmouth Gulf, Shark Bay and Geographe Bay. Nickol Bay, located north of Karratha on WA‟s northwest shelf, is an additional potential resting area for this species. To quantify the importance of the Nickol Bay region, humpback distribution, habitat use and behaviour were documented using both aerial surveys (Aug 2009- Aug 2010) and boat surveys (Aug 2010). Humpback whale abundance was higher in comparatively cooler (22.6-23.6˚C), and shallow (< 40 m) waters and their depth preferences were consistent through time. The proportions of active, passive and neutral behaviours were similar to those documented in Exmouth Gulf, suggesting that Nickol Bay may similarly serve as a humpback whale resting area. The strong habitat associations and resting behaviours in the Nickol Bay region highlight the area is important to humpback whale conservation, a key issue given their recovering status and the rapid industrialisation of the region.

Key words: southern migration, sheltered embayment, temperature, depth