Population Estimates

CONTENTS

Population table	The IWC’s figures for estimated whale populations
Comprehensive Assessment	The comprehensive assessment of current whale stocks
Status of whales	A brief overview of the ‘status’ of whale populations
PDF Translations of this page:	French	Note on translations

ESTIMATES

Good conservation and management requires and understanding of the status of populations. A key component of this is, of course, an estimate of present abundance (and ideally trends in abundance) against which possible threats can be evaluated.

Estimating the abundance of animals that spend most of their time below the surface is difficult. The Scientific Committee has developed guidelines on how to best estimate abundance of whales from ships and aeroplanes for use in the RMP. Other methods include a combination of visual and acoustic techniques (e.g. bowhead whales off Alaska) or mark- recapture techniques using the natural marks found on some species that allow individuals to be identified (e.g. humpback whales in the North Atlantic). Because of the considerable scientific uncertainty over the numbers of whales of different species and in different geographical stocks, the International Whaling Commission decided in 1989 that it would be better not to give whale population figures except for those species/stocks which have been assessed in some detail. This does not mean that there are not other published estimates of some species or populations or areas.

At present, these are the best estimates (and associated confidence intervals) for some species and areas.

TOP

Population	Year(s) to which estimate applies	Approximate point estimate	Approximate 95% confidence limits
MINKE WHALES
Southern Hemisphere	1982/83 – 1988/89	761,000	510,000 – 1,140,000
	Current	The Commission is unable to to provide reliable estimates at the present time. A major review is underway by the Scientific Committee.

North Atlantic (Central & Northeastern)	1996-2001	174,000	125,000 – 245,000

West Greenland	2005	10,800	3,600 – 32,400

North West Pacific and Okhotsk Sea	1989-90	25,000	12,800 – 48,600

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

FIN WHALES
North Atlantic (Central & Northeastern)	1996-2001	30,000	23,000 – 39,000

West Greenland	2005	3,200	1,400 – 7,200

GRAY WHALES
Eastern North Pacific	1997/98	26,300	21,900 – 32,400
The population was increasing at a rate of 3.2% (95% confidence interval 2.4% – 4.3%) over the period 1967/68 – 1987/88 with an average annual catch of 174 whales.
Western North Pacific	2007	121	112 – 130

BOWHEAD WHALES
Bering-Chukchi- Beaufort Seas stock	2001	10,500	8,200 – 13,500
The net rate of increase of this population since 1978 has been estimated as about 3.2% per year (95% confidence interval 1.4% – 5.1%).
Off West Greenland	2006	1,230	490 – 2,940

HUMPBACK WHALES
Western North Atlantic	1992/93	11,600	10,100 – 13,200
A rate of population increase of 3.1% (SE=0.005) was obtained from the Gulf of Maine for the period 1979-1993
Southern Hemisphere south of 60S in summer (i.e. incomplete)	1997/98	42,000	34,000 – 52,000
Rates of increase. East Australia: 1981-96 12.4% (95%CI 10.1-14.4%). West Australia: 1977-91 10.9% (7.9-13.9%)
North Pacific	2007	at least 10,000	not yet available
Rates of increase of about 7% have been reported for the eastern North Pacific, 1990-2002.

RIGHT WHALES
Western North Atlantic	2001	about 300	not available

Southern Hemisphere	1997	about 7,500	not available
There is evidence of increase rates of 7-8% for populations of Argentina, Australia and South Africa

BRYDE’S WHALES
Western North Pacific	1998-2002	20,501 (CV=0.337)	not available

PILOT WHALES
Central & Eastern North Atlantic	1989	780,000	440,000 – 1,370,000

TOP

THE COMPREHENSIVE ASSESSMENT

When, at its 1982 meeting, the IWC agreed to a pause in commercial whaling (or to use popular terminology, a ‘moratorium’) from 1986, the amendment to the regulations included a clause that ‘the Commission will undertake a ‘comprehensive assessment’ of the effects of this decision on whale stocks and consider modification of this provision and the establishment of other catch limits’.

The term ‘Comprehensive Assessment’ had not been defined by the Commission and eventually the Scientific Committee defined it to be:

‘an in-depth evaluation of the status of all whale stocks in the light of management objectives and procedures… that … would include the examination of current stock size, recent population trends, carrying capacity and productivity’.

To date the Committee has completed or is still undertaking such in-depth analyses of:

Antarctic minke whales – Southern Hemisphere;
Common minke whales – North Atlantic; western North Pacific
Fin whales – North Atlantic
Humpback whales – Southern Hemisphere and North Atlantic
Bryde’s whales – western North Pacific
Bowhead whales – Bering-Chukchi-Beaufort Seas