Catch statistics
Prior to 1972, Bryde’s whales were not distinguished from sei whales in International Whaling Statistics, but in some cases the pre-1972 species breakdown of “sei” whale catches can be determined from original records, or approximated, based on current knowledge of the geographical and seasonal occurrence of sei and Bryde’s whales, or from the compositions of later catches in the same area and season (IWC 1997, 2006b). Bryde’s whales are distinguished from sei whales in Japanese national catch statistics from 1962, but in sighting records only from 1972 (Ohsumi 1978a).

Stock divisions
In the North Pacific region, the International Whaling Commission (IWC) Scientific Committee (SC) recognises the following stocks: Western North Pacific Stock (west of 150°W, down to 2°S), Eastern Tropical (east of 150°W down to 10°S), East China Sea, and Gulf of California (IWC 1996). The region of the South China Sea, and the Philippines and Indonesian and Solomon archipelagos are considered habitat of small-type Bryde’s whales and Omura’s whale, and not included in any putative stocks for ordinary Bryde’s whales, although the latter probably also occurs there (see above).

The IWC SC has not assessed Southern Hemisphere Bryde’s whales in recent times, but the IWC Schedule lists the following stocks, based on recommendations from the IWC Scientific Committee in 1980: western South Pacific (west of 150°W, but excluding Solomon Islands area), eastern South Pacific (south of 10°S), southern Indian Ocean, northern Indian Ocean, South African Inshore, and South Atlantic.

Western North Pacific
The currently accepted abundance estimate for the western North Pacific is 26,000 (CV=24%) based on surveys conducted during 1998-2002. Catches of Bryde’s whales from coastal stations in Japan are thought to have begun in 1906 and continued uninterrupted until 1987 when Japan adhered to the IWC’s commercial whaling moratorium. Pelagic catches were taken by Japanese fleets during 1971-79 and by Soviet fleets during 1966-79. Bryde’s whales were also caught from Taiwan during 1976-80 from the Bonin islands (Japan) during 1946-52 and 1981-87, and offshore whaling from the Philippines during 1983-1985 (IWC 2006a). Japanese pelagic catches resumed in 2000 under scientific permit (50 per year).

An annual catch series totalling over 20,000 whales for the period 1911-87 was estimated by the IWC SC in 1996 (IWC 1997). Since then, some new information has come to light: for example, Kondo and Kasuya (2002) reported that catches of Bryde’s whales by Japanese operations in the Bonin Islands during 1981-87 had been falsely reported as 2,659, in order to keep within catch limits, but that the true total was 4,162. According to a 1995 population assessment by the IWC SC, the population was reduced, in the worst case, by 49% during 1911-96 (IWC 1996). Work on a revised catch series and assessment is in progress (IWC 2007).

Eastern tropical Pacific
Wade and Gerrodette (1993) estimated 13,000 (CV= 20%) Bryde’s whales for the eastern tropical Pacific (in an irregularly-shaped area of 19 million km² between about 15°S and 25°N) from data collected during 1986-90.

An IWC/International Decade of Cetacean Research (IDCR) —later Southern Ocean Whale and Ecosystem Research (SOWER) — survey of the eastern equatorial Pacific (10°S-10°N, 80°-110°W) in December 1982 yielded an estimate of 17,000 (CV=32%) Bryde’s whales (IWC 1984), but the estimate should be recalculated using current methodology.

Bryde’s whales were distinguished from sei whales in Peruvian catch statistics from 1973, and 3,589 are recorded caught during 1973-83 (IWC 2006a). Of the “sei” whales reported caught during 1968-72, an estimated 1,953 were Bryde’s whales, to give a total Bryde’s catch of 5,542 during 1968-83.

Other North Pacific stocks
The most recent accepted estimate for the East China Sea Stock is 137 (variance not calculated), and for the Gulf of California stock 235 (173-327) (IWC 1996). The East China Stock was subject to whaling in southwestern Japan until the early 1970s, and may have been depleted (Omura 1977).

Southern Hemisphere
The Southern Hemisphere stocks of Bryde’s whales have not been re-assessed during the past 25 years, but the abundance estimates accepted at the time were: southern Indian Ocean − 13,854; western South Pacific − 16,585; and eastern South Pacific – 13,194 (IWC 1981). These were not based on what are currently accepted methods of survey design and analysis. Based on a majority recommendation of the Scientific Committee, the IWC subsequently reset the classification of these stocks to “zero catch limit pending a satisfactory estimate of stock size” (IWC 1983).

Of 1,705 “sei” whales reported taken off Chile during 1932-79 (IWC 2006a), an unknown proportion were Bryde’s whales (Gallardo et al. 1983).

The South African Inshore stock was estimated at 582 (±184) in 1983 (Best et al. 1984). Over 2,000 Bryde’s whales are recorded caught by modern whaling during 1911-67 in Cape Province, South Africa, including 1,300 during 1947-67 (IWC 2006a) of which most were from the inshore stock (IWC 1980).

No population estimates are available for the remainder of the South Atlantic. Of 2,536 “sei” whales taken by the pirate whaling ship Sierra in the South Atlantic during 1969-76, the majority are believed to be Bryde’s whales (IWC 1980). Of the over 5,000 “sei” whales recorded caught off Brazil during 1948-77, at least some were Bryde’s whales, but possibly only 8% (Omura 1962, Williamson 1975).

North Atlantic
Apart from a population estimate for the Southern Gulf of Mexico of 40 (13-129) animals (Mullin and Fulling 2004) there are no abundance estimates for the North Atlantic. Some of the “sei” whales recorded around the Straits of Gibraltar in the first half of the 20th century may have been Bryde’s whales (Aguilar 1984).

Small-type Bryde’s whales
No population estimates exist, and are unlikely to become available until methods are developed to identify them at sea and their range is better known.

Unknown