Whales, Dolphins, and Porpoises of the Western North Atlantic
A Guide to Their Identification
STEPHEN LEATHERWOOD, DAVID K. CALDWELL, and HOWARD E. WINN
with special assistance by
William E. Schevill and Melba C. Caldwell
SEATTLE, WA
AUGUST 1976
DEPARTMENT OF COMMERCE
Elliot L. Richardson, Secretary / NATIONAL OCEANIC AND
ATMOSPHERIC ADMINISTRATION
Robert M. White, Administrator / National Marine
Fisheries Service
Robert W. Schoning, Director
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402
Stock No. 003-020-00119-0 / Catalog No. C 55.13: NMFS CIRC-396
PREFACE
In March 1972, the Naval Undersea Center (NUC), San Diego, Calif. in cooperation with the National Marine Fisheries Service (NMFS), Tiburon, Calif. published a photographic field guide—The Whales, Dolphins and Porpoises of the Eastern North Pacific. A Guide to Their Identification in the Water, by S. Leatherwood, W.E. Evans, and D.W. Rice (NUC TP 282). This guide was designed to assist the layman in identifying the cetaceans he encountered in that area and was intended for use in two ongoing whale observer programs, NUC's Whale Watch and NMFS's Platforms of Opportunity. The rationale of these programs was that since oceanographers, commercial and sport fishermen, naval personnel, commercial seamen, pleasure boaters, and coastal aircraft pilots together canvas large areas of the oceans which scientists specializing in whales (cetologists) have time and funds to survey only occasionally, training those persons in species identification and asking them to report their sightings back to central data centers could help scientists more clearly understand distribution, migration, and seasonal variations in abundance of cetacean species. For such a program to work, a usable field guide is a requisite. Because the many publications on the whales, dolphins, and porpoises of this region were either too technical in content or too limited in geographical area or species covered to be of use in field identification, and because conventional scientific or taxonomic groupings of the animals are often not helpful in field identification, the photographic field guide took a different approach. Instead of being placed into their scientific groups, species were grouped together on the basis of similarities in appearance during the brief encounters typical at sea. Photographs of the animals in their natural environment, supplemented by drawings and descriptions or tables distinguishing the most similar species, formed the core of the guide.
Despite deficiencies in the first effort and the inherent difficulties of positively identifying many of the cetacean species at sea, the results obtained from the programs have been encouraging. Many seafarers who had previously looked with disinterest or ignorance on the animals they encountered became good critical observers and found pleasure in the contribution they were making. The potential for the expansion of such observer programs is enormous.
Because of these initial successes and the large number of requests for packets from persons working at sea off the Atlantic coast of North America, this guide was planned. Many of the errors and deficiencies of the Pacific Guide have been corrected, and the discussions of the ranges of many of the species have been expanded with considerations of the major oceanographic factors affecting their distribution and movements. While the present volume, like the Pacific Guide, is intended as an aid to the identification of living animals at sea, new materials have been provided to aid in the identification and reporting of stranded specimens, a major source of data and study material for museums. This new dimension is expected to assist the U.S. National Museum, various regional museums, and other researchers actively collecting cetacean materials for display and study in the implementation of their stranded animal salvage programs. Through a cooperative effort of this kind, the best possible use can be made of all materials that become available.
As a part of continuing research, this guide will be revised whenever possible. Suggestions for its improvement will at all times be welcome.
Funds for the preparation of this guide were provided by a grant to Stephen Leatherwood from the Platforms of Opportunity Program, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Tiburon, Calif., Paul Sund, Coordinator.
CONTENTS
The National Marine Fisheries Service (NMFS) does not approve, recommend or endorse any proprietary product or proprietary material mentioned in this publication. No reference shall be made to NMFS, or to this publication furnished by NMFS, in any advertising or sales promotion which would indicate or imply that NMFS approves, recommends or endorses any proprietary product or proprietary material mentioned herein, or which has as its purpose an intent to cause directly or indirectly the advertised product to be used or purchased because of this NMFS publication.
Whales, Dolphins, and Porpoises of the Western North Atlantic
A Guide to Their Identification
STEPHEN LEATHERWOOD,[1] DAVID K. CALDWELL,[2] and HOWARD E. WINN[3]
with special assistance by
William E. Schevill[4] and Melba C. Caldwell[2]
[1] Biomedical Division, Undersea Sciences Department, Naval Undersea Center, San Diego, CA 92132.
[2] Biocommunication and Marine Mammal Research Facility, C. V. Whitney Marine Research Laboratory of the University of Florida, St. Augustine, FL 32084.
[3] Graduate School of Oceanography, University of Rhode Island, Kingston, RI 02881.
[4] Woods Hole Oceanographic Institution, Woods Hole, MA 02543 and Museum of Comparative Zoology, Harvard University, Cambridge, MA 02138.
ABSTRACT
This field guide is designed to permit observers to identify the cetaceans (whales, dolphins, and porpoises) they see in the western North Atlantic, including the Caribbean Sea, the Gulf of Mexico, and the coastal waters of the United States and Canada. The animals described are grouped not by scientific relationships but by similarities in appearance in the field. Photographs of the animals in their natural environment
A dichotomized key is provided to aid in identification of stranded cetaceans and appendices describe how and to whom to report data on live and dead cetaceans.
INTRODUCTION
All whales, dolphins, and porpoises belong to an order or major scientific group called the Cetacea by scientists. They are all mammals (air-breathing animals which have hair in at least some stage of their development, maintain a constant body temperature, bear their young alive, and nurse them for a while) which have undergone extensive changes in body form (anatomy) and function (physiology) to cope with a life spent entirely in the water. The breathing aperture(s), called a blowhole or blowholes, has (have) migrated to the top of the head to facilitate breathing while swimming; the forward appendages have become flippers; the hind appendages have nearly disappeared, they remain only as small traces of bone deeply imbedded in the muscles. Propulsion is provided by fibrous, horizontally flattened tail flukes.
Scientists recognize two suborders of living cetaceans: the whalebone whales, suborder Mysticeti, and the toothed whales, suborder Odontoceti. The two groups are separated in the following ways:
BALEEN OR WHALEBONE WHALES. These animals are called whalebone whales because when fully formed instead of teeth they have up to 800 or more plates of baleen or whalebone depending from the roof of the mouth. They use these plates to strain their food, which consists of "krill" (primarily small crustaceans) and/or small schooling fish, by taking water into the mouth and forcing it out through the overlapping fringes of the baleen plates. Baleen whales are externally distinguishable from toothed whales by having paired blowholes. There are eight species of baleen whales in the western North Atlantic, ranging in size from the minke whale (just over 30 feet [about 9.1 m])[5] to the blue whale (85 feet [25.9 m]).
[5] Throughout this guide, measurements are given first in feet or inches, followed in parentheses by their equivalents in meters or centimeters. It is recognized that field estimates cannot be as precise as most of the conversions used.
TOOTHED WHALES. Unlike the baleen whales, the toothed whales do have teeth after birth. The teeth vary in number from 2 to over 250, though they may sometimes be concealed beneath the gum. In addition, toothed whales have only a single blowhole. This group includes the animals commonly called dolphin or porpoise as well as some commonly called whales (for example, the sperm whale). There are currently about 30 species of toothed whales known from the western North Atlantic, ranging in maximum adult size from the common or harbor porpoise, which is approximately 5 feet (1.5 m) long, up to the sperm whale which reaches a length of 68 feet (20.7 m). Several other species which are expected to be found in this region, though they have not yet been reported, are also included in this guide.
CLASSIFICATION OF CETACEANS
In addition to the two suborders (Mysticeti and Odontoceti), the cetacean order contains numerous families, genera, and species. Each of these groupings represents a progressively more specialized division of the animals into categories on the basis of similarities in their skulls, postcranial skeletons, and external characteristics. The discipline which concerns itself with naming an animal and assigning it to its appropriate scientific category is known as taxonomy. An example of the classification of a cetacean species is shown in the following:
SCIENTIFIC CLASSIFICATION OF THE ATLANTIC BOTTLENOSED DOLPHIN
Modern taxonomy had its origin with the Swedish naturalist Linnaeus, whose tenth edition of the Systema Naturae in 1758 forms the official starting point. Following Linnaeus, modern scientific names consist of two words, a generic name, which has an initial capital, and a species name, which rarely does, occasionally in botany (some species names deriving from a person's name are capitalized). Both names are usually of Latin origin (sometimes Greek) and are italicized or underlined. These scientific names are of particular importance because, although common names of species often are different in different countries or even in different regions of the same country, the scientific name remains the same. For example, the right whale is universally known as Eubalaena glacialis though its common names include black right whale, nordcaper, sletbag, Biscay whale, and Biscayan right whale.
Although classification of many species is still in a state of flux, the classification of western North Atlantic cetaceans followed in this guide is as follows:
synoptic account
of the species Order Cetacea Suborder Mysticeti—Baleen whales Family Balaenopteridae—Rorquals Balaenoptera acutorostrata Lacepede 1804 Minke whale 63 Balaenoptera physalus (Linnaeus 1758) Fin whale 26 Balaenoptera musculus (Linnaeus 1758) Blue whale 19
This tentative classification follows an unpublished list by W.E. Schevill and E.M. Mitchell currently under review. The scientific names are followed by the name of the individual who named the species and the year of naming, and then by the common name most often used in the western North Atlantic.[6] It may be noted that some of the authors are in parentheses. This indicates that though the species name has remained the same since the date of naming the species has since been assigned to another genus. Because the species are not arranged in taxonomic order in this field guide, the page of the synoptic account of each is provided in the column to the right.
[6] Most common names are based on some characteristic of the species (e.g., spotted dolphin, striped dolphin, rough-toothed dolphin); others are the names of authors of the species (e.g., True's beaked whale) or of habitats or macrohabitats which they inhabit (e.g., North Sea beaked whale and harbor porpoise); the origins of some common names, however, are less obvious (e.g., dense-beaked whale), and of less use in field references.