Finally, species composition may change significantly over the years 

 in response to long-term shifts in ocean conditions. Therefore, the 

 characterization of composition and abundance is only good as long as 

 the conditions in ettect when it was made continue to exist. The 

 clearest example from the northeastern Pacific is that involving Risso's 

 dolphins. These large dolphins, apparently abundant at least as far 

 north as Monterey during a warm water decade overlapping the turn of 

 the twentieth century, were unreported north ot Southern California 

 and were rare in or near the SCB for the first seven decades ot this 

 century. During the early 1970's, however, sightings began to increase, 

 apparently in response to a long term warming trend in ocean waters. 

 That warming trend has continued. By the early 1980's, especially when 

 "El Nifio effects increased water temperature in the northeast Pacific, 

 this ordinarily oceanic species was again being seen with regularity 

 north of Point Conception and became a common sight in the SCB, in 

 general, and in and near the CINMS, in particular. Comparable 

 increases in the SCB in abundance of otherwise northerly species 



might well be expected during exceptionally cold periods. No doubt 

 there are other more subtle responses which cetaceans exhibit to 

 changes in other environmental variables. Such changes may have 

 pronounced effects on which cetaceans use the SCB and in what 

 relative numbers. Despite significant increases in recent decades in the 

 amount of cetacean research we are far from understanding those 

 effects. 



Acknowledijing all the above factors, we undertook to inventory 

 cetaceans which at present occur or probably occur within the CINMS 

 and attempted to characterize, at least subjectively, their relative 

 abundance, seasonality and habitat use. The SCB straddles major 

 migratory pathways and the coast and shelf edge apparently are 

 important reference features to some migrating cetaceans. Therefore, 

 this inventory includes species which are migratory as well as those 

 which are resident, those which are present seasonally in predictable 

 numbers, and those which have been reported but are not to be 

 expected at present. 



METHODS 



This report was prepared from a variety' of information sources. We 

 examined all publications we could locate which contained orii;inal 

 data on cetaceans of the region, concentrating on more recent studies 

 and reviews. A partial list, containing the most important sources 

 consulted, is presented in the selected bibliography. Although we also 

 consulted "gray" literature (government reports, mimeographed re- 

 ports, etc., not subjected to peer review) and used original data from 

 such publications, where appropriate, we were cautious about accept- 

 ing and reporting on analyses presented m some of them. Conclusions 

 in such reports often change under the hard scrutiny of peer review 

 which precedes publication m refereed purnals. For most species the 

 most important sources were unpublished: files of various colleagues 

 who have worked off Southern California in recent years, the Scripps 

 Institution of Oceanography (principally the files of the late Carl L. 

 Hubbs\ the San Diego Museum ot Natural History (principally the 

 files of the late Raymond M. Gilmore), the Naval Ocean Systems 

 Center (NOSC ), Hubbs Marine Research Center ( HMRC ), the 

 National Parks Service, and the Island Packers Company. The 

 National Marine Fisheries Service (NMFS) provided recent data as 

 follows: stranding records and miscellaneous sii;htini;s and pho- 

 tographs (Long Beach ), stranding records, miscellaneous photographs 

 and numerous sightings from recent surveys by aircraft (1980-1985) 

 and ship (1979-1985 ) designed specifically to search for marine mam- 

 mals (La JoUa ). 



Data from all the above sources and from miscellaneous sightings 

 prior to 1979 in files of NMFS, SWFC and NMML, formed the basis 

 of some previous species reviews: northern right whale dolphin, 

 Lissodelphis honalis (Leatherwood and Walker, 1979), Risso's dolphin. 

 Grampus griseus ( Leatherwood et. al, 1980), Pacific white-sided dolphin, 

 Lagcnorhynchus ohliqmitm 'Leatherwood et. al, 1984) and killer whale, 

 Orcmus orca ! Dahlheim et. al. 1982 1. Surveys by the Universm- ot 

 California, Santa Cruz, off Southern California, 1975-1977 (Dohl et. 

 al, 1978) and Central and Northern California 1980-198; (Dohl et. al, 

 1983) were important additional sources. 



Sightings from all sources were plotted (a lengthy and tedious 

 process 1 and examined along with anecdotal data for evidence of 

 patterns of occurence in and near the CINMS. No attempt was made 

 to treat data quantitatively. Most records were incidental sightings 

 without associated information on levels of effort. Even those data 

 from more systematic protJrams ( i.e. NOSC aerial and ship surveys 

 1968-1977, Bureau of Land Management i BLM i aerial and ship 

 surveys 1975-1977 and 1980-1983 and NMFS aerial and ship surveys) 

 were generally incomplete in seasons or areas covered. Therefore, plots 

 are cautiously interpreted as they are at best incomplete and at worst 

 uninformative or even misleading. Further, for most species it was 

 necessary to examine data from over 1 5 years together as sample sizes 

 for any given year or for small blocks of years were usually inadequate. 

 Therefore, trends occuring in that period were likely masked. 



Overall the review and evaluation confirmed two basic expectations. 

 First, there is little direct information on cetaceans withm the bound- 

 aries of the CINMS itself Therefore, one must rely on all available 

 pertinent data from the cool temperate eastern North Pacific, with 

 special emphasis on that from the SCB and adjacent pelagic zones. 

 Second, there are recent trends apparent in use of the SCB and 

 CINMS by species formerly not found there in any significant 

 numbers - because of changing environmental conditions or recovery 

 from previously depleted levels, or both. This second factor strongly 

 supports our recommendation that a coordinated program of research 

 be implemented within the CINMS to continue to monitor status of 

 Its cetacean inhabitants. 



Towards that end the following report includes four sections: 

 systematic accounts, treating each resident, migratory, or reported 

 species from the SCB; recommendations tor further research [not 

 included in this version, see publication notes]; aids tor implementing 

 a proposed sightings network, including a mmiguide to identification 

 of the common cetaceans in and near the CINMS (appendix I); and 

 aids for implementing a proposed strandings network, including a 

 dichotomized key to the identification of cetaceans ; Appendix II). 



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