水産資源管理談話会報

第42号（財）日本鯨類研究所
2008年

資源管理研究センター
8月

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目

次

お知らせ
南極海鯨類捕獲調査（JARPA）の背景とその概要

西脇茂利

・・・

1

クロミンククジラの系群構造の解明

後藤睦夫

・・・

4

資源管理に有用な生物学的特性値の推定

坂東武治・・・ 11

南極海生態系の中で鯨類の果たす役割の解明−オキアミを巡る争いを中心として−田村力

・・・ 17南極海の環境変動が鯨類に与える影響の解明−環境汚染物質について−安永玄太

・・・ 25Contribution of JARPA to the management andconservation of large baleen whalesLuis A. Pastene・・・ 32

田中昌一

・・・ 36【投稿】
鯨資源の動態モデル

第55回資源管理談話会
2007 年 7 月 26 日

Contribution of JARPA to the management and conservation of large
baleen whales
Luis A. Pastene
Institute of Cetacean Research
Toyomi-cho 4-5, Chuo-ku,
Tokyo 104-0055,
Japan
INTRODUCTION
The Japanese Whale Research Program under Special Permit in the Antarctic (JARPA)
started with two feasibility surveys in the austral summer seasons 1987/88 and 1988/89
under the Article VIII of the International Convention for Regulation of Whaling. The
full research program started in 1989/90 and was completed in 2004/05.
The two original research objectives of JARPA were the following:(1) Estimation of biological parameters to improve the stock management of theSouthern Hemisphere minke whale, and(2) Elucidation of the role of whales in the Antarctic marine ecosystem.
Subsequently, as part of the natural evolution of the program and in response todeveloping requirements, two further objectives were added:(3) Elucidation of the effect of environmental changes on cetaceans, and(4) Elucidation of the stock structure of the Southern Hemisphere minke whales toimprove stock management.
Objective (1) of JARPA was the main one and it was established considering the datarequired by the New Management Procedure (NMP), the procedure to manage
commercial whaling used by the International Whaling Commission (IWC) until theadoption of the moratoria. Biological parameters related to growth such as birth rate,natural mortality and age at sexual maturity, were required under the NMP to establish
catch limits. The IWC Scientific Committee (SC) completed the Revised Management
Procedure (RMP) in 1992. Unlike the NMP this procedure needs only reliable andperiodic data on population abundance and accurate catch data. The question waswhether or not information provided by JARPA could still providing important
information for management of baleen whales under the RMP. To respond to thisquestion it is necessary to explain about the Implementation Simulation Trials (ISTs),
which is one of the major works of the RMP.
The ISTs are conducted to guarantee the performance of RMP prior to the actual
application of RMP to calculate a catch limit of whales for commercial purposes. TheISTs showed satisfactory robustness under a wide variety of simulations test whenapplied to a model of a single isolated baleen whale stock. However it is important to32

investigate how this robustness is maintained in situations of multiple stocks and mixing,
and this is investigated through the ISTs. The main purpose of the ISTs then is to allow asustainable exploitation of whale resources by avoiding depletion of individuals stocks.
The ISTs are specific to species/areas. Therefore the hypotheses on stock structure andtheir plausibility are important, as those are the basis for the establishment of Small
Areas, on which catch limits are calculated.
Although the ISTs are based on 100-years projection periods the RMP includes therequirements that Implementation Reviews be conducted every 5 years. The aim of such
review is to check that research conducted since the original Implementation does notreveal that hypotheses used in previous ISTs were not sufficiently broad to encompass
reality or are not longer considered plausible (Punt and Donovan, 2007).
JARPA objective (4) on stock structure above can provide important information if theIWC decides to conduct an Implementation Review for Antarctic minke whales underthe RMP. It is also considered that biological parameters calculated under objective (1)were still being useful in the context of the RMP. For example MSYR data is important
for the ISTs, and this parameter can be estimated based on catch at age data obtained by
JARPA. In more general terms biological parameters are still being useful to understandthe population dynamics of Antarctic minke whales, and therefore important for themanagement of whale resources.
The JARPA has also provided information useful for management and conservation onother large whale species that are not target of the RMP. For example JARPA has
conducted systematic sighting surveys and data obtained in these surveys have beenused to estimate abundance in large whale species. Because sighting surveys are
conducted in different years in a same area, abundance information can be used toinvestigate the abundance trends of species that were heavily exploited in the past.
JARPA has also collected biopsy samples from these large whales, which have beenused in DNA studies on stock structure. Information on stock structure is important foran adequate interpretation of abundance and abundance trends.
Data collected and results obtained under the JARPA program were reviewed by theIWC/SC in a workshop held in December 2006 (IWC, 2007). The objective of thispaper is to summarize the information collected by JARPA that is, or can be, useful formanagement. This is summarized for both information collected from the Antarctic
minke whale useful for the RMP e.g. information collected under Objectives (1) and (4)(stock structure; abundance estimates; MSYR and other biological parameters), andinformation collected from other large whale species that are not target of the RMP(stock structure and abundance of humpback whales). This information was presentedand discussed at the IWC JARPA review workshop (IWC, 2007).
Results of JARPA related to Objectives (2) and (3) and their implications formanagement are given in separate papers.
RESULTS
Stock structure of Antarctic minke whale
The IWC/SC conducted a comprehensive assessment of the Antarctic minke whales in1990. On that opportunity genetic and non-genetic analyses on stock structure based on33

samples and data from past commercial whaling were presented. These analyses failed
to detect unambiguously any biological stock of the Antarctic minke whale in theAntarctic feeding grounds.
The implication of this for management was that the SC in 1993 “agreed that for Small
Areas, as defined in the Draft Specifications for the calculation of Catch Limits in a
RMP for baleen whales, 10 degree longitudinal sectors represented the best present
option although this might require revision as more information is obtained”.
The total JARPA samples obtained in the Antarctic feeding grounds of Areas IIIE, IV,
V and VIW were used in genetic (mitochondrial DNA and microsatellites) and nongenetic (biological parameters and morphometric) analyses on stock structure. Results
were presented to the JARPA review workshop and the conclusion of the workshop was
as follow: “Based on the analyses of the genetics and morphometric data presented, itagreed that there at least two stocks of Antarctic minke whales present in the JARPA
research area. The data also suggest an area of transition in the region around 150º-160ºE across which there is an as yet undetermined level and range of mixing” (IWC,2007). The review workshop recommended several additional analyses to refine thishypothesis.
Therefore JARPA has established a plausible hypothesis on stock structure in theJARPA research area based on a new and comprehensive data set. It is clear that thenew information do not support the Small Areas definition of 10 degree longitudinal
sectors agreed by the SC in 1993. Based on the results by JARPA this definition ofSmall Areas in the Antarctic should be revised if the IWC decides to conduct anImplementation Review of this resource under the RMP.
Abundance estimates of Antarctic minke whale
Abundance estimation of Antarctic minke whale was made based on sighting dataobtained by JARPA in 16 austral summer seasons. Results were presented for Areas IVand V as well for the two stocks hypothesis presented to the review workshop. There isno agreement yet on the abundance of Antarctic minke whales in the JARPA researcharea. The review workshop recognized that considerable progress has been made in
addressing the issues related to abundance and trends and provided that therecommendations offered in the workshop are followed, the SC should soon be able toagree estimates. The abundance estimates will be valuable for any future
Implementation Review under the RMP (IWC, 2007).
MSYR and other biological parameters estimates for Antarctic minke whale
Estimations on several biological parameters were presented to the review workshop
according to the two stock hypothesis presented at the review meeting. These
parameters were length and age at sexual maturity, length and age at physical maturity,
size at age (i.e. generation of a growth curve), percentage of matured females pregnant,foetal sex ratio (male %) and mean litter size. All these parameters are important formodels of population dynamics.
JARPA also provided estimates of natural mortality using two different approaches. The
confidence intervals of natural mortality obtained by one of these approaches spanned awide range (e.g. it had low precision). The other approach (ADAP-VPA) spanned anarrower confidence interval but this estimation relied in part on commercial age data34

where some problems were identified (IWC, 2007). This later approach also provided
estimations of MSYR according to the stock hypothesis presented to the review
workshop. However these estimations also relied in part on the commercial age data.
Stock structure of the humpback whale
JARPA has obtained a substantial number of biopsy samples of humpback whales,
which has been used in genetic analyses on stock structure based on mtDNA andmicrosatellites. The analysis involved a total of 411 samples. Results suggested thathumpback whales in Areas IIIE, IV, V and VIW belong to different stocks. The review
workshop welcomed this study and suggested that DNA data in the feeding groundshould be analyzed together with available DNA data from the breeding grounds.
Abundance estimates of humpback and other large whale species
Systematic sighting surveys conducted under JARPA have allowed the estimation ofabundance and trends in other large whale species such as humpback, fin and blue
whales. The review workshop agreed that a large dataset on distribution and abundance
for these species has been accumulated by sighting surveys conducted under JARPA.
Regarding humpback whales the review workshop agreed that the abundance estimatesprovided represented useful steps forward in working towards acceptable estimates ofabundance (IWC, 2007)
CONCLUSIONSJARPA has generated extensive data that has contributed or potentially can contributefor management and conservation of Antarctic minke and other large whale species in
the research area.
The IWC review workshop agreed that “The results from the JARPA program, while
not required under the RMP, have the potential to improve management of minke
whales in the Southern Hemisphere in the following ways: (1) reductions in the current
set of plausible scenarios considered in ISTs; and (2) identification of new scenarios towhich future ISTs will have to be developed (e.g. the temporal component of stock
structure). The results of analyses of JARPA could be used in this way perhaps toincrease the allowed catch of minke whales in the Southern Hemisphere, without
increasing depletion risk above the level indicated by the existing ISTs of the RMP for
these minke whales” (IWC, 2007).
REFERENCES
International Whaling Commission. 2007. Report of the Intersessional Workshop to
Review Data and Results from Special Permit Research on minke whales in theAntarctic, Tokyo 4-8 December 2006. Paper SC/59/REP1 presented to the IWC
Scientific Committee. May 2007 (unpublished). 49 pp.
Punt, A. and Donovan, G. 2007. Developing management procedures that are robust touncertainty: lessons from the International Whaling Commission. Ices Journal ofmarine Science 64: 603-612.

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