HUMPBACK DOLPHINS IN THE GREAT SANDY STRAIT &

HERVEY BAY, QLD

Daniele Cagnazzi, Peter Harrison & Graham Ross

Southern Cross University Whale Research Centre

Study Period: 04/04 – 05/05N° surveys: 116N° of pods recorded: 131N° identified: 125 (26 calves)

Group:mean=5.2 (SD=3.97) range= 1-19Adult ID= 3.2 (SD=2.62)Calves = 1.1 (SD=1.29)Sub-A. = 0.9 (SD= 1.17)

Sightings per dolphin: mean: 3.4 (SD=2.68) range: 1-12

STUDY AIMSDistribution and abundance of Sousa in Great Sandy Strait and Hervey Bay

DISTRIBUTION SUMMARY

• 54 dolphins in the analysis-P= 0.78 ± 0.99-Mean HWI= 0.07 (CV=2.21)- 24.2% of recorded associations

Component 1

1,0,50,0-,5-1,0

Com

pone

nt 2

1,0

,5

0,0

-,5

-1,0

hd121

hd115

hd112hd111hd110 hd108

hd105

hd104hd101hd99hd98hd97hd96hd95hd94

hd92 hd87hd83hd82hd79

hd69hd67

hd62

hd60

hd59

hd58

hd55

hd49

hd47

hd40

hd37

hd33

hd31hd28

hd27

hd26

hd25

hd24

hd23

hd22

hd21

hd20

hd19

hd18hd17

hd16

hd14

hd13

hd12

hd8

hd7

hd_5hd4hd3 hd2

hd1

S.G.

N.G.

Northern Community

Southern Community H

D12

1H

D11

5H

D11

2H

D11

1H

D11

0H

D10

8H

D10

5H

D10

4H

D10

1H

D99

HD

98H

D97

HD

96H

D95

HD

94H

D92

HD

87H

D83

HD

82H

D79

HD

67H

D62

HD

61H

D60

HD

59H

D58

HD

55H

D49

HD

47H

D40

HD

37H

D33

HD

31H

D28

HD

27H

D26

HD

25H

D24

HD

23H

D22

HD

21H

D20

HD

19H

D18

HD

17H

D16

HD

14H

D13

HD

12H

D8

HD

7H

D5

HD

4H

D3

HD

2H

D1

Latit

ude

-25,0

-25,2

-25,4

-25,6

-25,8

-26,0

• 2 groups in Great Sandy Strait:- Northern Group- Southern Group

Community distribution and boundaries

Population movement

100 101 1020.012

0.014

0.016

0.018

0.02

0.022

0.024

0.026

0.028

0.03

0.032

Time lag (Day)

Lagg

ed id

entif

icat

ion

rate

Data(1/43.2541)*exp(-td/625.2015)

100 101 1020

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

Time lag (Day)

Lagg

ed id

entif

icat

ion

rate

Data0.024681*exp(-0.0012141*td)

1. Emigration/mortalityAICc=7861.55 p=0.055

2. Emigration/reimmigration/mortality: AICc=7865.49 p = 0.039

3. Emigration/reimmigration AICc= 7881.30 P= 0.007

4. Closed AICc=7878.18 p= 0.009

1. Emigration/mortalityAICc=1052.46 p=0.1631

2. Closed AICc=1052.58 p= 0.063. Emigration/reimmigrationn

AICc=1050.58 P= 0.0144. Emigration/reimmigration/mort.AICc=1052.82 p = 0.026

Population estimates and trends

Northern CommunityPOPAN :Φ(c)p(c)pent(c)• N=71 (71.81, SE = 3.03,

95%CI=68.22, 81.21)Mortality Trend• N=49.89±4.7 (95%CI =

44.1 – 57.5)SE = 0.0007)

• TREND: 0.001 (SE = 0.001)

• Stable population

Southern CommunityPOPAN :Φ(c)p(t)pent(c)• N=54 (54.65 SE= 4.34,

95% CI = 50.06, 69.39)Mortality Trend.• N=31.09 ± 10.8 (95%CI)

23.8 - 44.0• TREND: -0.003

(SE=0.0031)• Declining population

Conclusions

• Great Sandy Strait and Hervey Bay support the largest number of dolphin recorded in Australia.

• Two communities separated by narrow tidal channels resulting in very little interaction (1 mixed pod).

• Transient, short term resident, long term resident.• Northern Community stable, Southern Community slightly

declining.• NC: Immigration for parturition?

0121000020birthsna4460644545404350naN321121187654Month

The End