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 a range of plausible values for the population's actual abundance. As an example, the table below shows that the 1991/92-2003/4 abundance estimate for Southern Hemisphere blue whales is 2,300 with a 95% confidence interval of 1,150-4,500. This means that the range 1,150-4,500 was computed using a method that has a 95% chance of including the population's actual abundance.
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.
|
Year(s) to which estimate applies | estimate | Approximate 95% CI |
---|---|---|---|
Southern Hemisphere |
1985/86-1990/91 |
720,000 |
510,000 – 1,010,000 |
|
1991/92-2003/04 |
515,000 |
360,000 – 730,000 |
North Atlantic |
|
|
|
- Northeast & Central |
2014-2019 |
150,000 |
112,000 –201,000 |
- Northeast |
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 |
2008-2013 |
90,000 |
62,000 – 128,000 |
|
2014-2019 |
104,700 |
75,200 –145,750 |
|
- Central |
2005-2007 |
50,000 |
30,000 – 83,000 |
|
2015-2016 |
64,000 |
43,000 –93,000 |
- 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 |
2004-2006 |
4,200 |
2,700 – 6,300 |
Year(s) to which estimate applies | Approximate point estimate | Approximate 95% CI | |
---|---|---|---|
Southern Hemisphere (excluding pygmy blue) |
1978/79-1983/84 | 450 |
200 – 1,000
|
1985/86-1990/91
|
560
|
200 – 1,400
|
|
|
1991/92-2003/04
|
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
|
|
Year(s) to which estimate applies |
‘Best’ estimate |
Approximate 95% CI |
---|---|---|---|
North Atlantic |
|
|
|
- East Greenland to Faroes |
1987-89 |
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 |
2005 |
9,800 |
3,230 – 29,750 |
|
2007 |
16,000 |
4,500 – 57,000 |
|
2015 |
2,200 |
1,000 – 4,900 |
Year(s) to which estimate applies |
‘Best’ estimate |
Approximate 95% CI |
|
---|---|---|---|
North Pacific |
|
|
|
- East |
1997/1998 |
21,140 |
18,500 – 24,140 |
|
2000/2001 |
16,370 |
14,530 – 18,450 |
|
2001/2002 |
16,030 |
14,010 – 18,350 |
|
2006/2007 |
20,640 |
18,570 – 23,990 |
|
2007/2008 |
18,450 |
16,410 – 21,490 |
|
2009/2010 |
20,960 |
19,200 – 23,060 |
|
2010/2011 |
20,820 |
19,040 – 22,710 |
|
2014/2015 |
23,440 |
21,260 – 26,060 |
|
2015/2016 |
27,450 |
24,880 – 30,180 |
|
2019/2020 |
20,630 |
18,840 – 22,710 |
|
2021/2022 |
17,430 |
15,800 – 19,220 |
|
2022/2023 |
14,530 |
13,230 – 15,960 |
|
2023/2024 |
19,260 |
17,400 – 21,300
|
|
|
|
|
- Pacific Coast Feeding Group |
1998 |
127 |
110 – 150 |
|
1999 |
147 |
120 – 180 |
|
2000 |
148 |
120 – 180 |
|
2001 |
179 |
150 – 210 |
|
2002 |
196 |
180 – 220 |
|
2003 |
209 |
180 – 250 |
|
2004 |
215 |
180 – 250 |
|
2005 |
220 |
170 – 280 |
|
2006 |
199 |
160 – 250 |
|
2007 |
198 |
150 – 260 |
|
2008 |
212 |
180 – 250 |
|
2009 |
214 |
180 – 260 |
|
2010 |
205 |
170 – 250 |
|
2011 |
210 |
180 – 250 |
|
2012 |
224 |
200 – 260 |
|
2013 |
243 |
220 – 270 |
|
2014 |
251 |
210 – 290 |
|
2015 |
253 |
220 – 290 |
|
2016 |
255 |
210 – 310 |
|
2017 |
228 |
190 – 280 |
|
2018 |
215 |
170 – 270 |
|
2019 |
212 |
180 – 250 |
|
2020 |
207 |
170 – 250 |
|
2021 |
210 |
160 – 270 |
|
2022 |
202 |
170 – 240 |
|
|
|
|
- Western Feeding Group |
1995 |
74 |
66 – 81 |
|
2015 |
200 |
187 – 211 |
|
Year(s) to which estimate applies |
‘Best’ estimate |
Approximate 95% CI |
---|---|---|---|
North Pacific |
|
|
|
- Bering-Chukchi-Beaufort Seas stock |
2001 |
10,500 |
8,200 – 13,500 |
|
2004 |
12,600 |
7,900 – 19,700 |
2011 |
16,800 |
15,200 – 18,700 |
|
2019 |
14,000* |
8,900 - 22,000 |
|
2019 |
17,200* |
11,000 – 27,000 |
|
The net rate of increase of the BCB stock from 1978- 2011 has been estimated as about 3.7% per year (95% confidence interval 2.9% - 4.6%) | |||
- Okhotsk Sea |
2016 |
218 |
140 – 350 |
North Atlantic |
|||
- West Greenland feeding area |
2012 |
1,300 |
900 – 1,600 |
|
2022 |
888 |
300 – 2,200 |
- East Canada - West Greenland |
2013 |
6,400 |
3,700 – 11,200 |
- Svalbard |
2015 |
340 |
100 – 900 |
*there are 2 estimates for the BCB stock derived through different methods, an ice based visual survey (14,000) and an aerial survey (17,200)
|
|
Year(s) to which estimate applies |
‘Best’ estimate |
Approximate 95% CI |
---|---|---|---|
Southern Hemisphere |
|||
- Partial coverage of Antarctic feeding grounds |
1985/86-1990/91 |
10,230 |
5,700 – 18,300 |
|
1991/92-2003/04 |
42,000 |
33,000 – 52,000 |
- Eastern South America: Brazil |
2005 |
6,300 |
4,300 – 8,600 |
|
Rate of increase of around 7% |
||
- Western South America: Ecuador |
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 |
1999-2005 |
4,300 |
3,300 – 5,400 |
North Atlantic |
|
|
|
- Western North Atlantic |
1993 |
11,600 |
10,000 – 13,500 |
- Norwegian & Barents Seas |
2002-07 |
9,750 |
4,950 – 19,200 |
|
2008-13 |
12,400 |
6,850 – 22,500 |
|
2014-18 |
10,700 |
4,900 – 23,400 |
- Iceland / Faroe Islands |
2007 |
18,000 |
7,000 – 46,000 |
|
2015 |
10,000 |
4,900 – 20,300 |
- Iceland |
1995 |
14,600 |
5,100 – 41,500 |
- East Greenland |
2015 |
4,200 |
1,800 – 9,700 |
- West Greenland |
2005 |
1,160 |
600 – 2,250 |
|
2007 |
2,700 |
1,400 – 5,300 |
|
2015 |
1,000 |
400 – 2,300 |
|
Rate of increase of around 9% 1984-2007 |
||
- Newfoundland and Labrador Sea |
2016 |
10,500 |
3,800 – 28,500 |
North Pacific |
2004-6 |
21,000 |
19,000 – 23,000 |
Arabian Sea |
2007 |
80 |
60 – 110 |
|
Year(s) to which estimate applies |
‘Best’ estimate |
Approximate 95% CI |
---|---|---|---|
Southern Hemisphere Total |
2009 |
12,000 |
|
- Southwest Atlantic |
2009 |
3,300 |
|
|
2019 |
4,600 |
3,840 – 5,690 |
|
Rate of increase around 7% |
||
Southern Africa |
1990 |
1,230 |
1,120 –1,330 |
|
2000 |
2,330 |
2,180 – 2,480 |
|
2009 |
4,400 |
4,000 – 4,900 |
|
2010 |
4,400 |
4,100 – 4,700 |
|
2012 |
5,000 |
4,600 – 5,600 |
|
2020 |
6,470 |
5,910 – 7,030 |
|
Rate of increase around 7% |
||
- Sub-Antarctic New Zealand |
2009 |
2,760 |
2,100 – 3,680 |
|
2020 |
4,480 |
2,480 – 7,030 |
- South central and Western Australia |
2009 |
2,400 |
|
|
Rate of increase around 7% |
||
North Atlantic |
|
|
|
- West |
1990 |
263 |
260-270 |
|
2000 |
308 |
307-311 |
|
2010 |
476 |
470-480 |
|
2019 |
370 |
350-380 |
- East |
Sightings are extremely rare |
|
Year(s) to which estimate applies |
‘Best’ estimate |
Approximate 95% CI |
---|---|---|---|
North Pacific |
|
|
|
- Central and Eastern |
2010-2012 |
29,600 |
18,500 - 47,300 |
|
Year(s) to which estimate applies |
‘Best’ estimate |
Approximate 95% CI |
---|---|---|---|
North Pacific |
|
|
|
- Western |
1988-1996 |
32,000 |
19,000 – 55,000 |
|
1998-2002 |
32,000 |
15,000 – 66,000 |
|
2008-2015 |
41,000 |
24,000 – 68,000 |
Year(s) to which estimate applies | Approximate point estimate | Approximate 95% CI | ||||
---|---|---|---|---|---|---|
Central & Eastern North Atlantic |
1989 |
780,000 |
430,000 – 1,390,000 |
|
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 |
- Eastern Bering Sea |
2017 |
12,270 |
9,700 – 15,500 |
|
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 |
|
|
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 |
2001 |
96 |
62 – 147 |
|
2016 |
57 |
48 – 71 |
||
FRANCISCANA |
|
|
|
|
|
|
Year(s) to which estimate applies |
Approximate point estimate |
Approximate 95% CI |
- Franciscana Management Areas (FMA) Ia |
2018 |
1,183 |
200 – 5,300 |
|
- Franciscana Management Areas (FMA) Ib |
2011 |
1,590 |
500 – 4,500 |
|
2017 |
1,521 |
600 – 3,900 |
||
- Franciscana Management Areas (FMA) II |
2009 |
9,284 |
5,300 – 16,100 |
|
- Franciscana Management Areas (FMA) III |
2022 |
43,150 |
23,400 – 79,400 |
|
For map of (FMA's) see link Here |
|
|
|