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)*	1991/2-2003/4	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	2017	230	180 - 290
- 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 – 13,500
	2004	12,600	7,900 – 19,700
	2011	16,800	15,200 – 18,700
	2019	12,500	7,900 - 19,600
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
- 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	1991/2-2003/4	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	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	2004-6	21,000	19,000 – 23,000
Arabian Sea	2007	80	60 – 110

RIGHT WHALES

	Year(s) to which estimate applies	‘Best’ estimate
Southern Hemisphere Total	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	32,000	19,000 – 55,000
	1998-2002	32,000	15,000 – 66,000
	2008-2015	41,000	24,000 – 68,000