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3Z Rethinking the Stock Concept interest should be carefully weighed and considered in selecting an expert or panel of experts to make the classification: Ideally, populations should be surveyed and phylogeographically classified before situations de- manding m~gement decisions arise. Acknowledgments We thank Robin Waples for providing reviews of the first real draft with which we "went public." Most of his suggestions were gratefully used. We also thank John C. Avise and an unknown reviewer for critical comments that materially improved the final draft, Appendix In the earlier part of this paper, we endeavored to show how stocks may be classified, with the aid of some guidelines, into one of four major categories, Informa- tion that describes characteristics of populations may then be added as qualifiers, to include (a) distribution, (b) population response (demographic or behavioral), ( c) phenotypic information (morphologic), and (d) ge- notypic infotmation (Fig. 3). Arguments for classifica- tion must be made in the knowledge that information is constantly being updated and that intraspecific popula- tions themselves are dynamic and therefore subject to change over time and in response to new information, Our attempts at classifications are thus open to testing both now and in the future. Minke Whale Balaenoptera acutorostrata L Taxonomy A. Subspecies-bonaerensis B. Morphs 1. Davidsoni-type 2. Bonaerensis-type 3. Dwarf II. Provisional management units- A. Southern Hemisphere-six management areas de- fined by longitude from the equator to ice edge 1. Area I, 120OW-60OW 2. Area II, 6OOW-oo 3. Area III, 00 _700E 4. Area IV, 700E-1300E 5. Area V, 1300E-170OW 6. Area VI, 170OW-120OW B. Northern Hemisphere-two main populations, one smaller 1. North Atlantic a. Canadian east coast b. Central I I ~ . Populalfons and stocks as defined by the /Wc---Intematlonal Con- wntton for the R;egulatton of Whaling. 1946. Schedule October 1989. Conscrvadon Biology Volume 6, No, I, Match 1992 Dizon et a1. c. West Greenland d. Northeastern 2. North Pacific a. Okhotsk Sea-Western P~s;ific b. Sea of Japan-Yellow SealEast China Sea c. East Okhotsk Sea-Western Pacific 3. Northern Indian Ocean III, Evidence A. Distribution 1. Range Distribution is global, but there is no evidence from tagging, abundance, etc., that Northern and Southern Hemisphere populations mingle at any time, even though the equator may be breached in some regions, for example, off Brazil. The pattern of latitudinal sea- sonal migration associated with feeding (in polar wa- ters) and breeding (in warm low latitudes) effectively isolates the populations of the two hemispheres, which are out of phase by 6 months. However, there is a pos- sibility, yet to be proved, (or interchange in some mar- ginal equatorial regions where temporarily segregated portions of the population such as mature females or males may reside almost year-round. Latitudinal segre- gation of different portions of the population by sex, age, and reproductive status are well documented (Wada 1989). Tag return data suggest mixing longitudinally at the boundaries (as defined above) between southern stocks (Wada 1984). There is evidence for interchange be- tween Areas IV and V, for example. The region of occu- pation of the dwarf form in the southern oceans is lon- gitudinally wide (Southwest and Southeast Atlantic, Southwest Pacific), but it is perhaps excluded from high latitudes (Best 1985; Arnold et al. 1987). In the Northern Hemisphere, stocks have been de- fined mainly in response to national and regional exploi- tation patterns and to a large extent were originally not biologically based. Tag experiments do not link West Greenland animals with the eastern Atlantic ones, and they appear to be separate. The species is highly migra- tory, and movements of several thousands of kilometers, even within a few days, are well documented in latitu- dinal direction (Horwood 1990). Unless there are actual or partial geographic, oceanographic, or other barriers to east-west excursions, the whales from the various regions must be considered to probably intermingle. The relationships of the minke whales in the southern and northern Indian Ocean are not known, although populations exist on each side of the equator. The south- ern animals clearly occur in and around Areas III and IV. In the northern region, animals are observed year-round in the Red Sea, Gulf of Aden, Persian Gulf, and the seas sur- rounding Sri Lanka and Indonesia (Horwood 1990). 2. Contaminants Tanabe et at (1986) reported concentrations of PCBs (0.0031-0.029 ppm wet weight) and DDEs (0.013-0.14