SC/62/IA15

A short review of recent Scientific Committee issues relating to large whalesin the North Pacific that might assist in setting priorities for a co-operative seriesof cruises
K. Matsuoka, L. A. Pastene, R. Brownnell, T. Kitakado and G. Donovan

ABSTRACTAt the 2009 IWC Scientific Committee (SC) meeting, a mid- to long-term research programme involving sighting surveys toprovide information for cetacean stock management in the North Pacific was presented. To assist in the development of thisresearch programme the IWC SC established an intersessional group. One of its tasks was to ‘review the SC issues in the North
Pacific and circulate a paper before the next Annual Meeting’. A document responding this TOR was presented by the first twoauthors to the informal intersessional meeting (IM) held in Tokyo in September 2009. The present paper updates the information
presented to the IM. It focuses primarily on stock structure and abundance of sei, common minke, Bryde’s and right whales. Since
the Scientific Committee has spent little time on blue, humpback and fin whales in recent years, we have attempted to suggest
some areas of research.

INTRODUCTION
At the 2009 IWC Scientific Committee meeting, a mid- to long-term research programme involving sighting surveys toprovide information for cetacean stock management in the North Pacific was presented. The Committee recognised thatan important starting place for the planning process of this programme was (1) to review key recent issues in the
Scientific Committee discussions relevant to large whales in the North Pacific issues on large whales within the SC thatare relevant to the proposed mid- long-term research programme and (2) a careful examination of available informationand identification of gaps in knowledge (IWC, 2009a). An informal intersessional meeting (IM) was held on 27-28
September in Tokyo. A paper summarizing the SC issues on North Pacific sei, common minke and Bryde’s whales waspresented to the meeting (Matsuoka and Pastene, 2009). The IM recommended that the paper should be revised andupdated to incorporate SC issues on other large whales in the North Pacific (IWC, 2010). This paper responds to thatrecommendation from the IM.

SEI WHALE
Distribution
Sei whales were widely distributed in the western, Central and Eastern North Pacific according to the Japanese catch
data by Masaki (1976), (Fig 1). The Soviet catch data are still incomplete for the North Pacific. The previous studies ofsei whale distribution were based on the Japanese commercial catch record (1952-1972), the Japanese Scouting Vessel(JSV) data (1965-1996), and the US sighting data (1986-2006) in the North Pacific. The most recent distribution study
was based on JARPN and JARPNII sighting data (1994-2007) in the western North Pacific as well the British Columbia
sighting data (2004-2005) in the inshore waters.
The SC is planning an in-depth assessment of the North Pacific sei whale. Several data sources for thisassessment were identified in Appendix 4 of the IA Sub-Committee this year (IWC, 2009b, see Appendix of this reportattached). Regarding stock structure and abundance the following needs have been identified.

1

SC/62/IA15

Fig.1. Summer distribution of accumulated number of sei whales caught by Japan from 1952 through 1972 seasons (Masaki, 1976).

Fig.2. Sampling locations of sei whales in the North Pacific. Triangle: JARPNII, Square: commercial whaling. (Kanda et al., 2009a).

Need for sighting surveys for abundance estimation
Offshore parts of the central and eastern North Pacific (north of 35°N, east of 170°E) have not have been surveyed inrecent years and thus there are no estimates of current abundance in these areas. Although the Committee has not
identified specific areas/months for the sighting survey of sei whale abundance estimation, it is clear that any surveys
undertaken should focus, at least initially on areas closest to recently surveyed areas.
Need for surveys for investigation of stock structure
The most recent studies of stock structure were based on JARPN samples in the western North Pacific and pastcommercial samples in the central and eastern North Pacific. These studies suggested a single stock of sei whales.

2SC/62/IA15
However there are some important data gaps (Fig 2). As for other baleen whales, stock structure should be much moreeasily elucidated if the breeding grounds are known and sampled, but these grounds remain unknown.
Collection of the following new data would assist in resolving stock structure issues:Collection of additional biopsy samples (and sightings data) from areas away from the western North Pacific toinvestigate possible additional structure:oin the eastern North Pacific, along the coast the North Americaoin the central North Pacific particularly in the longitudinal sector 170°E -170°W.

Sighting surveys in low latitude to investigate location of breeding grounds (telemetry work would be valuable
in locating appropriate areas to cover)

COMMON MINKE WHALE
Distribution
Based on the JSV data in July and August, common minke whales are widely distributed in the Sea of Okhotsk and Seaof Japan (Miyashita et al. 1996). Common minke whales are also distributed in the western North Pacific as showed by
JARPN & JARPNII catches west of 170°E (Fig 3). They also occur in the eastern North Pacific although sighting effort
there is more limited .

Fig.3. Sighting positions of the collected Common minke whales during the JARPN and JARPNII surveys during 1994 to 2007 seasons. Both theoffshore and coastal component samples are included (Kanda et al., 2009b).

Several meetings associated with the RMP Implementation completed in 2003, as well as discussions in workshops
considering the JARPN and ongoing JARPNII programmes and the more recent work on an in-depth assessment ofwestern North Pacific have all considered common minke whales and research needs. The primary identified needs withrespect to abundance estimations and stock structure are summarised below.
Need for sighting surveys for abundance estimation3

SC/62/IA15
As was the case for sei whales, offshore parts of the central and eastern North Pacific have not have been surveyed inrecent years and thus there are no estimates of current abundance in these areas. Although the Committee has not
identified specific areas/months for additional sighting surveys for this species, it is clear that any surveys undertaken
should focus, at least initially, on areas closest to recently surveyed areas.
Need for surveys for investigation of stock structure
The four stock structure hypotheses for the western North Pacific were considered during the 2003 RMP
Implementation (IWC, 2004) and subsequent discussions have resulted in further hypotheses (e.g. IWC, 2010). Figuresdescribing these can be found in IWC (2010 p.31 and p.215, respectively).
Collection of the following new data would assist in resolving stock structure issues related to the western North Pacificand elsewhere:collection of additional biopsy samples (and sightings data) to further elucidate stock structure:oas a high priority, collection of additional samples throughout the Okhotsk Sea, to investigate theproportions of different stocks (e.g. ‘O’ and ‘J’ on those feeding grounds)

oin the central North Pacific particularly to the east of 170°E (especially with respect to possible ‘W’stock)collection of additional biopsy samples at different times of the year in areas of suspected mixing (telemetrywork would be valuable in examining migration timing and routes and thus appropriate sampling)sighting surveys in low latitude to investigate location of breeding grounds (telemetry work would be valuable
in locating appropriate areas to cover)

BRYDE’S WHALE
Distribution
Bryde’s whales are widely distributed in summer in the western North Pacific south of 40ºN (e.g. Fig. 4 based on recent
Japan/NRIFSF and US/NOAA sighting data (Shimada, 2008; Jackson, 2003 ) and JARPN/JARPN II catches (Fig. 5;Pastene et al., 2009, respectively). They also occur in the eastern North Pacific but the sighting effort is more limited,but data are available from the eastern Tropical Pacific. Wade and Gerrodett 1993, Jackson 2003).

Fig.4. Primary sighting positions of Bryde’s whale and the predetermined cruise track lines on effort in the Bryde's whale sighting survey in Augustand September, 1998-2002 (Shimada, 2008).

4

SC/62/IA15

Fig.5. Bryde's and unidentified Sei/Bryde's whale sightings, STAR03 (Jackson, 2003).

Fig.6. Catch distribution of Bryde’s whales in the western North Pacific. Red corresponds to catch by pelagic whaling operations conducted between
1971 and 1979; blue corresponds to catch by JARPN II between 2000 and 2005 (Pastene et al., 2009).

The RMP Implementation for western North Pacific Bryde’s was completed in 2007. The following research needs onabundance and stock structure remain (IWC, 2008).
Need for sighting surveys for abundance estimation
As for sei whales, offshore parts of the central and eastern North Pacific (east of 155°W) have not have been surveyed
in recent years and thus there are no estimates of current abundance in these areas. Although the Committee has not
identified specific areas/months for additional sighting surveys for this species, it is clear that any surveys undertaken
should focus, at least initially, on areas closest to recently surveyed areas.
Need for surveys for investigation of stock structure
Four stock structure hypotheses were considered during the RMP Implementation (IWC, 2008). Not all were assigned
high plausibility and thus clarification of stock structure remains a priority. The primary questions relate to: (a) whether
or not sub-stocks occur in sub-area 1 and (b) whether or not a different stock occurs in sub-area 2.

5

SC/62/IA15

Collection of the following new data would assist in resolving stock structure issues related to the western North Pacificand elsewhere:collection of additional biopsy samples (and sightings data) to further elucidate stock structure:in the central North Pacific particularly to the east of 180°Esighting surveys in low latitude to investigate location of possible breeding grounds for Bryde’s whales(telemetry work would be valuable in locating appropriate areas to cover)

telemetry work in sub-area 1 to investigate mixing of whales between sub-areas 1W and 1E

RIGHT WHALES, BLUE WHALESThe Committee has considered North Pacific right whales a number of times for conservation purposes, and inparticular during the Workshop held in 1998 on the worldwide status of right whales (IWC, 2001). There is a paucity ofrecent information on right whales in the North Pacific although they were one widespread. Even in areas where there
have been surveys, it is clear that densities are low (apart from, perhaps, from some areas of the Sea of Okhotsk). The
eastern North Pacific population is critically endangered and is being studied inter alia by US scientists (Wade et al.
2010).
The situation is similar for the blue whale i.e. there is a paucity of recent information on right whales in the North
Pacific although they were one widespread. Even in areas where there have been surveys, it is clear that densities are
low, except in waters off California and Baja California, Mexico. The current abundance is estimated for the easternside at 1,548 (Barlow and Forney, 2007) or 2,000 to 3,000 (Calambokidis and Barlow, 2004)
For both these species, it would not be practical (except perhaps for right whales in the Okhotsk Sea) to dedicate acruise to abundance or biopsy sampling. However, given their rarity, then it would seem appropriate to allocate highpriority to obtaining photo-id and biopsy data when encounteredFig.7. Distribution of right whales in the North Pacific between 1966 and 1990 seasons. Top : July, Bottom: August. (Miyashita et al., 1995).

6

SC/62/IA15

Fig.8. Right whale distribution of the Density Index (number of primary sightings of individuals / 100 n.mile ) during JARPN and JARPN II from1994 to 2007 surveys by Lat.1°× Long.1°square (Matsuoka et al., 2009).

Fig.9. Positions of within-year and between-year resightings of North Pacific right whales in the Bering Sea from 1996-2008 (Clapham et al., 2009).

7SC/62/IA15
REFERENCESBarlow, J. and Forney, K.A. 2007. Abundance and population density of cetaceans in the California Current ecosystem. Fishery Bulletin 105:509-526.
Calambokidis, J. and Barlow, J. 2004. Abundance of blue and humpback whales in the Eastern North Pacific estimated by capture-recapture and linetransect methods. Marine Mammal Science 20:63-85.
Clapham P.J, Zerbini, A.N, Kennedy A., Rone, B. and Berchok, C., 2009. Updated on North Pacific Right Whale Research. SC/61/BRG16. 9pp.
IWC, 2003. Report of the workshop on North Pacific Common minke whale, J. CETACEAN RES. MANAGE. 5 (SUPPL.) 457p.
IWC, 2004a. Report of the Scientific Committee, Annex D, p.75-184.
IWC, 2004b. Report of the Scientific Committee, Annex D, Appendix 10, p.123.
IWC, 2008. Report of the Scientific Committee, p.106-107.
IWC, 2009a. Report of the Scientific Committee, Madeira, IWC/61/Rep1. 108pp.
IWC, 2009b. Report of the Scientific Committee, Madeira, IWC/61/Rep1. Annex G, Appendix 4.
IWC, 2010. Report of the Intersessional meeting on the North Pacific Survey Programme. Tokyo, 27-28 September, 2009. 9pp.
Jackson, A. Gerrodette, T. Chivers, S. Lynn, M. Olson, P. and Rankin, S. 2003. Marine mammal data collected during a survey in the Eastern
Tropical Pacific Ocean aboard the NOAA ships McARTHUR II and DAVID STARR JORDAN, July 29 - December 10, 2003. NOAA-TMNMFS-SWFSC-366. 104pp.
Kanda, N., Goto, M., Yoshida, H. and Pastene, L.A. Stock structure of sei whales in the North Pacific as revealed by microsatellite and mitochondrial
DNA analyses. SC/J09/JR32. 14pp.
Kanda, N., Goto, M., Kishiro, T., Yoshida, H., Kato, H. and Pastene, L.A. 2009. Microsatellite analysis of minke whales in the western North Pacific.
SC/J09/JR30. 14pp.
Masaki, 1976. Biological studies on the North Pacific sei whal. Bull. Far Seas Fish. Res. Lab., No.14. pp1-104.
Matsuoka, K., Kiwada, H., Fujise, Y. and Miyashita, T., 2009. Distribution of blue (Balaenoptera musculus), fin (B. physalus), humpback (Megapteranovaeangliae) and North Pacific right (Eubalaena japonica) whales in the western North Pacific based on JARPN and JARPN II sighting surveys(1994 to 2007). SC/J09/JR35. 12pp.
Matsuoka and Pastene, 2009. A brief review of some Scientific Committee’s issues in the North Pacific. Paper NP/09/WP4, presented to theintersessional planning meeting on the North Pacific Survey Programme. Tokyo, September 27. 14pp.
Miyashita,T., Kato, H. and Kasuya, T., 1995. World wide Map of Cetacean Distribution based on Japanese Sighting data (Volume 1), National
Research Institute of Far Seas Fisheries. 140pp.
Shimada, 2004. Abundance estimate of the western North Pacific stock of Bryde’s whales using sighting data from 1998 to 2002. SC/56/PIF6. 8pp.
Pastene, L,A., Hatanaka, H., Fujise, Y., Kanda, N., Murase, H., Tamura, T., Miyashita, T. and Kato, H., 2009. The Japanese Whale Research Program
under Special Permit in the western North Pacific Phase-II (JARPN II): origin, objectives and research progress made in the period 2002-2007,
including scientific considerations for the next research period. SC/J09/JR1 (Rev 1). 73pp.
Wade, P. R. and Gerrodette, T. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific. Reports International Whaling
Commission 43:477-493.

8

SC/62/IA15
Appendix(from 61 SC report, Annex G, Annex 4)
st9

SC/62/IA1510