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Population (Abundance) Estimates

Estimates of current population size, known as abundance estimates, are derived from a combination of fieldwork and computer modelling.  Vessel-based and aerial sighting surveys, acoustic monitoring, and analysis of individual animal markings are techniques used independently or in conjunction with each other to count whales.  The information gathered from this fieldwork is used as the basis for population modelling which produces an abundance estimate.  

In 2017, the IWC Scientific Committee established a new expert group to review and agree all the Abundance Estimates submitted to the Scientific Committee.  This new process ensures quality and consistency across all the estimates used by the IWC. 

Click here to read more about the establishment and work of the Scientific Committee’s Working Group on Abundance Estimates (ASI). 

It is impossible for cetacean abundance estimates to be completely precise and IWC estimates are presented as a ‘best estimate’ figure, accompanied by a 95% Confidence Interval, showing the highest and lowest figure within which the actual abundance figure is believed to sit.  As an example, the abundance estimate for Southern Hemisphere blue whales is 2,300 with a 95% confidence interval of 1,150 - 4,500.  This means that there is a 95% chance that the true number lies somewhere between 1,150 and 4,500.

Increases or decreases in population are indicated within the table, where these have been identified.

At present the IWC has agreed estimates only for some species/areas.  With the establishment of the ASI group it is planned to update this table and fill in the gaps where possible.

The IWC’s most recent Abundance Estimates


MINKE WHALES

 

Year(s) to which estimate applies ‘Best’ estimate Approximate 95% CI

Southern Hemisphere

1985/86-1990/91

720,000

510,000 – 1,010,000

 

1992/93-2003/04

515,000

360,000  –   730,000

North Atlantic

 

 

 

- Northeastern

1989

65,000

44,000 – 95,000

 

1995

112,000

91,000 – 138,000

 

1996-2000

80,000

59,000 – 108,000

 

2003-2007

81,000

 51,000 – 128,000

 

2008-13

90,000

62,000 – 128,000

- Central

2005-2007

50,000

30,000 – 83,000

- West Greenland

2007

  9,100

4,300 – 19,000

 

2015

  5,100

2,100 – 12,000

North Pacific

     

- North West Pacific and Okhotsk Sea

1990-91

28,000

17,000 – 45,000

 

2003

 20,000

13,000 – 30,000

- Sea of Japan

2004-6

4,200

2,700 – 6,300

 



BLUE WHALES

  Year(s) to which estimate applies Approximate point estimate Approximate 95% CI

Southern Hemisphere

(excluding pygmy blue)

1997/98
2,300
1,150 – 4,500
The estimated rate of increase of Southern Hemisphere Blue whales is 8.2% (95% confidence interval 3.8-12.5%) per year between 1978/79 and 2003/04

North Pacific

 
 
 

- Eastern

2008
2,500
1,700 - 3,600

 



FIN WHALES

 

Year(s) to which estimate applies

‘Best’ estimate

Approximate 95% CI

North Atlantic

 

 

 

- East Greenland to Faroes

1987-9

14,800

11,000 – 20,000

 

1995

21,900

16,000 – 30,000

 

2001

25,800

20,000 – 33,000

 

2007

21,900

16,000 – 30,000

 

2015

40,800

28,000 – 59,000

- West Greenland

2007

16,000

4,500 – 57,000

 

2015

2,200

1,000 – 4,900



GRAY WHALES

 

Year(s) to which estimate applies

‘Best’ estimate

Approximate 95% CI

North Pacific

 

 

 

- Eastern

1997/98

21,100

18,400 – 24,200

 

2000/01

16,400

14,500 – 18,500

 

2001/02

16,000

14,000 – 18,400

 

2006/07

20,800

18,800 – 23,400

 

2007/08

17,800

16,100 – 20,000

 

2009/10

21,200

19,400 – 23,300

 

2010/11

21,000

19,200 – 22,900

 

2014/15

28,800

23,600 – 39,300

 

2015/16

27,000

24,400 – 29,900

- Pacific Coast Feeding Group

2007

121

 

- Western

1995

74

66 – 81

 

2015

200

187 – 211


BOWHEAD WHALES

 

Year(s) to which estimate applies

‘Best’ estimate

Approximate 95% CI

North Pacific

 

 

 

- Bering-Chukchi-Beaufort Seas stock

2001

10,500

8,200 – 13,600

 

2004

12,600

7,800 – 20,400

 

2011

16,800

15,200 – 18,700

The net rate of increase of the BCB stock since 1978 has been estimated as about 3.2% per year (95% confidence interval 1.4% - 5.1%)
- Okhotsk Sea

2016

218

142 –  348

North Atlantic

     

- West Greenland feeding area

2012

1,300

900 – 1,600

- East Canada - West Greenland

2013

6,400

3,700 – 11,200

- Svalbard

2015

340

100  – 900

 

HUMPBACK WHALES

 

Year(s) to which estimate applies

‘Best’ estimate

Approximate 95% CI

Southern Hemisphere

     

- Partial coverage of Antarctic feeding grounds

1997/98

42,000

33,000 – 52,000

- Eastern South America

2005

6,300

4,300 – 8,600

 

Rate of increase of around 7%

- Western South America

2006

6,500

4,200 – 10,000

- Western Africa: Gabon

2005

6,800

4,300 – 10,500

- West South Africa

2001

 *300

200 – 400

                                      

*This estimate may represent the resident component of the population

- Eastern Africa: Mozambique

2003

6,000

4,400 – 8,400

- Eastern Africa: Madagascar 

2004

7,400

2,100 – 12,800

- East Australia

2010

14,500

12,700 – 16,600

- Oceania

2005

4,300

3,300 – 5,400

North Atlantic

 

 

 

- Western North Atlantic

1993

11,600

10,000 – 13,500

- Iceland / Faroe Islands

2007

18,000

7,000 – 46,000

 

2015

10,000

4,900 – 20,300

- East Greenland

2015

4,200

1,800 – 9,700 

- West Greenland

2007

2,700

1,400 – 5,300

 

2015

1,000

400 – 2,300

 

Rate of increase of around 9% 1984-2007

North Pacific

2007

22,000

19,000 – 23,000

Arabian Sea

2007

80

60 – 110


RIGHT WHALES

 

Year(s) to which estimate applies

‘Best’ estimate

Approximate 95% CI

Southern Hemisphere

2009

12,000

 

- Southwest Atlantic

2009

3,300

 

 

Rate of increase around 7%

- Southern Africa

2009

3,900

 

 

Rate of increase around 7%

- Sub-Antarctic New Zealand

2009

2,700

 

- South central and Western Australia

2009

2,000

 

 

Rate of increase around 7%

North Atlantic

2010

490

 


SEI WHALES

 

Year(s) to which estimate applies

‘Best’ estimate

Approximate 95% CI

North Pacific

 

 

 

- Central and Eastern

2010-2012

29,600

18,500 - 47,300


BRYDE’S WHALES

 

Year(s) to which estimate applies

‘Best’ estimate

Approximate 95% CI

North Pacific

 

 

 

- Western

1988-1996

32,200

19,000 – 55,000

 

1998-2002

32,200

15,000 – 66,000

 

2008-2015

41,000

24,000 – 68,000


PILOT WHALES

 

Year(s) to which estimate applies

Approximate point estimate

Approximate 95% CI

Central & Eastern North Atlantic

              1989

780,000

 430,000 – 1,390,000


BELUGA (WHITE WHALES)

 

Year(s) to which estimate applies

Approximate point estimate

Approximate 95% CI

North Pacific

 

 

 

- Okhotsk Sea

2010      

~12,000

 

- Eastern Chukchi Sea (part of)

2017      

13,300

5,100 – 34,300


HARBOUR PORPOISES

 

Year(s) to which estimate applies

Approximate point estimate

Approximate 95% CI

North Atlantic

 

 

 

- Western Baltic, Belt Sea & Kattegat

2012

40,000

25,000 – 65,000


HECTOR'S DOLPHINS

 

Year(s) to which estimate applies

Approximate point estimate

Approximate 95% CI

South Island, New Zealand

            2016

       14,800

 11,900 – 18,500


MAUI DOLPHINS

 

Year(s) to which estimate applies

Approximate point estimate

Approximate 95% CI

North Island, New Zealand

           2016

        57

 48  –  71