E. robustus: The Biology and Human History of Gray Whales

By James Sumich

The transformation of our view of gray whales over the past century from devilfish to gentle giants has been nothing short of remarkable. Whether you are a casual whale watcher or an avid observer of these animals, there is something in this book for you. Extensively illustrated with over 140 color photographs, maps and line drawings, this book makes information on the biology and human history of gray whales accessible to those unfamiliar with the published scientific literature on the species.
Topics range from basic anatomy and migratory behavior of gray whales to the latest research on the genetics of western gray whales, early whaling activities, gray whales in captivity and the growth of modern whale-watching activities.

• Language: English
• Publisher: James Sumich
• Release date: Mar 10, 2014
• ISBN: 9781310691690

James Sumich

Jim Sumich is the author of a best-selling textbook on marine biology (now in its 10th edition) and co-author of the widely adopted Marine Mammals: Evolutionary Biology. He has taught at the college and university level for more than four decades and has conducted research on gray whales from British Columbia to Baja California. He currently resides in Oregon where he teaches a course on marine mammals at OSU’s Hatfield Marine Science Center.

Book preview

E. robustus

The biology and human history of gray whales

by James Sumich

Copyright 2014 James Sumich

Smashwords Edition

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Cover photograph: Copyright Alistair Marsh, used by permission

To the reader

Good. You have the book. Whether you are a casual whale watcher or an avid observer of these animals, there is something in this book for you. This book is a reflection of my effort to help you get to know this very special whale and how it relates to the ecosystem it inhabits. For me, writing this book is the best way I know to communicate the sometimes complex body of information about gray whales to avid and curious readers in a manner that is current, accurate and accessible.

Some of the topics I have included stem from my personal and research interests in gray whales, but most are the results of the hard work and excellent science of many colleagues in the field who did most of the work described here. I owe all of them a huge debt of gratitude, so thank you to all the authors of the many primary research papers from which the syntheses of these chapters are constructed. I also appreciate the generous contributions of many of the photographs that grace these pages. Several people invested uncounted hours reviewing these chapters to ferret out typos and errors of grammar and fact. Any remaining errors are mine alone, and I ask that you email me if you discover more.

I hope that this book will contribute in some small way to encouraging a responsible sense of stewardship toward the world ocean and its inhabitants that we all must develop if we are to have healthy populations of gray whales to enthrall future generations.

James L. Sumich

Corvallis, Oregon

March, 2014

Dedication

This book is dedicated to the memory of Dr. Ray Gilmore, a man often referred to as the ‘father of the gray whale’. He would likely disagree with this approbation, as he often disagreed with me on a wide range of topics. Ray was very knowledgeable about gray whales, and was very comfortable pointing out to me what I didn’t know. I hope that since first meeting Ray, his insistence that I dig deeper as well as his assistance in that effort will be reflected in this book.

Ray Gilmore at his desk at the San Diego Museum of Natural History.

Contents

To the reader

Dedication

Chapter One: Roots and Relatives

Relationships

From land to the sea

Roots

A whale by many other names

Taxonomic Classification of Gray Whales

Chapter Two: The Human Touch—Pre-history to the 1980s

Atlantic gray whales

Pacific gray whales

Commercial whaling

The International Whaling Commission

Early Lagoon Studies

American Scientific Whaling

More legal protections

The two Gigis

A bonanza of lagoon studies

Chapter Three: Blubber and Bones—A Gray’s Anatomy

Body shape and size

Traveling companions—barnacles and cyamids

Sense organs

Skin and blubber

Muscles

Skeleton

Internal organs

Chapter Four: Annual CyclesBering to Baja and Back

Summer foraging

The migration south

Winter breeding lagoons

The journey north

Chapter Five: The Human Touch Revisited

Delisting of ENP gray whales

A new salt plant at Laguna San Ignacio?

Whale watching

Operation Breakthrough; a ‘Big Miracle’ ?

JJ-a different rescue story

El Niño and an Unusual Mortality Event

Other causes of mortality

Modern aboriginal subsistence harvesting

The eastern/western population paradox

Polar wanderers

A comment about units

About the author

Chapter One

Roots and Relatives

During the latter part of the 20th Century, large whales were transformed from a commercial commodity of oil and meat products to a powerful icon of our concern for the ecological future of our planet and of our role in it. Yet, in our expression of concern for the future of these spectacular animals, we too often ignore much of their specialness with the casual act of lumping about eighty different species of whales together with that single term ‘whale’. Yes, they are all whales, but ‘whales’ is not a homogeneous group. Although many whales are quite large, some dolphins are smaller than humans when fully grown. Not all species of whales are endangered (either legally or biologically). And some whales exhibit many of the hallmarks of ‘intelligence’ while others rank low on comparative scales of intelligence based on relative brain size or cognitive complexity. Killer whales and dolphins have relatively large brains and are intensely socially interactive, blue and gray whales have not and are not.

This book is about a certain whale, Eschrichtius robustus, the gray whale (Fig. 1.1). Here we will consider its evolution and biology, its history of interactions with humans, and its role within a larger system of marine animal interdependencies. Gray whales share with all other whales a common evolutionary ancestry and a suite of adaptations molded by the challenges this mammalian lineage has faced in its transition from a life on land to one in the sea. Even so, gray whales are distinct from other whales, and this book is an attempt to convey that uniqueness. Along the way, I hope to shed a little light on the lives and lifestyles of other whales as well.

Figure 1.1. A very high gray whale spy-hop. Photo courtesy LSI-ECP.

Gray whales are medium-sized whales that reach maximum lengths of 15m. This single species of whale includes one or two populations from the North Atlantic Ocean that have become extinct within historic times, a western North Pacific Ocean population that is currently critically depleted, and a nearly recovered population inhabiting the eastern side of the North Pacific Ocean. So, with two surprising exceptions described in Chapter 5, members of this species are now completely restricted to the margins of the North Pacific Ocean basin. They are probably as familiar to people as any other kind of large whale in existence. This is partly due to their near-shore migratory habits, making these animals common sights for shore- and boat-based whale-watchers along most of the west coast of North America from the Bering Sea to Baja California.

Gray whales are so distinctive from other whales that they are one of the easiest species to identify in the field. They lack dorsal fins, a feature of most other whales that is obvious when they are at the sea surface. Instead, a low rounded dorsal ridge is followed by a series of 8–9 bumps, or knuckles, extending down the top midline of the tailstock almost to the flukes (Fig. 1.2).

Figure 1.2. Knuckles and dorsal ridge of a gray whale. Its head is to the right. Courtesy Y.Yakovlev and Olga Tyurneva.

At birth, gray whale calves are a uniform dark, gunmetal gray, sometimes with a few scattered light spots of pigmentation (Fig. 1.3), but by three months of age they have developed the overall mottled gray and white color so characteristic of adults. By that age, calves have also collected their first crop of barnacles and cyamids (often referred to as ‘whale lice’, see Fig. 3.10 and 3.11) that create distinctive patches of light orange color over the head and upper torso of the body (Fig. 1.4). Other species, especially right and humpback whales, also have barnacle and cyamid patches; however they are neither as abundant nor as broadly distributed over their bodies as they are on gray whales. These barnacle/cyamid patches contribute to the ease with which individual grays are distinguished as visually unique.

Figure 1.3. Dark gray neonate gray whale with its lighter colored mom in the background.

Figure 1.4. Flattened segmented cyamid amphipods (orange patches) nestled between larger barnacles on the rostrum of an adult gray whale.

In this chapter, the evolutionary history of whales is briefly outlined, and the characteristics of gray whales and other cetaceans are described. Chapter 2 examines some of the complex history of our interactions with this exceptional whale. More details of the biology and behaviors of modern gray whales are presented in Chapters 3 and 4. Finally, an overview of current issues and research directions is addressed in Chapter 5.

Relationships

Let’s begin by fitting gray whales into a larger web of life and look at some of the general evolutionary constraints imposed on gray whales by their marine habitat and their biological heritage. One way of representing the pattern of this heritage is graphically in the form of a cladogram, with the lines of the cladogram representing clades, or descendant lineages through time (Figure 1.5). Similar cladograms will be used in this chapter to represent our best current understanding of the evolutionary history and existing relationships of modern groups of whales.

Figure 1.5. A cladogram outlining the pattern of relationships between four clades of tetrapod vertebrates. The mammalian clade, or lineage, is shaded. Black dots represent speciation events, or evolutionary splits in the lineage. With sufficient fossil or genetic information, the timing of the splits can be estimated.

Whales are mammals, and they share the world ocean with a few species of birds and reptiles, two other kinds of air-breathing tetrapods with a terrestrial predecessor lurking somewhere in their distant evolutionary past. All tetrapods share several basic anatomical features; however, only a few are necessary to emphasize here. Tetrapods have a bony skeleton of vertebrae in the midline of the body to stiffen and support an elongated body form. Extending laterally from that mid-line, or axial, skeleton are two pairs of limbs used for locomotion; a front pair of pectoral limbs and a rear pair of pelvic limbs (hence the name tetrapods = four feet). However, the term ’tetrapod’ is a bit of a misnomer for whales, as modern whales lack the pelvis and rear limbs characteristic of other tetrapods, although several species of extinct ancestral whales were clearly four-limbed (more on this later in the chapter). Convincing evidence of the tetrapod ancestry of whales also can be seen during embryonic development. Rear limb buds develop (Fig. 1.6) and then disappear prior to birth, leaving only a vestigial remnant of pelvic appendages.

Figure 1.6. A 70-day gray whale embryo with rear limb buds indicated by arrow. Photo courtesy D. Rice.

Tetrapods exhibit a suite of specialized attributes for life on land: getting water and food, moving and supporting their bodies, extracting oxygen (O2) from air, and reproducing out of water. Yet it is these same adaptations to a successful terrestrial existence that had to be reshaped by evolutionary processes for marine tetrapods to thrive in the ocean, depending on the sea for food and spending a good portion of time (or, in the case of whales, all their lives) in the sea. These adaptations will be introduced here and expanded more in later chapters.

From land to the sea

All mammals use lungs to breathe air to obtain the oxygen (O2) necessary for their metabolic activities. A large fraction of air (21%) is O2, yet for marine mammals, air is available only at the sea surface. Without gills to extract O2 from water as fish do, marine mammals must return to (or remain at) the sea surface to obtain O2 and store it for use during subsequent dives. Mammals also have body fluids that are less salty than seawater, so they constantly tend to lose body water to the outside environment by osmosis. Mammals living in the sea are living in what amounts to a physiological desert, because drinking seawater costs them additional water to excrete the salts they consume with that water. Many marine mammals satisfy their water needs by metabolically burning fats with O2 to produce water as well as carbon dioxide and usable energy. For every gram of fat burned, a bit over one gram of metabolic water is produced, so storing large amounts of fat is equivalent to storing even slightly larger amounts of ‘potential water’ as long as O2 is available. For many whales, this metabolic water is the only source available to satisfy their water needs.

The sensory systems of mammals have evolved to receive and process information about their surroundings. Compared to other mammals, whales express some major shifts in the sensory systems on which they rely because light does not penetrate water well whereas sound does. So cetaceans rely less on vision than many other mammals do, and shift to increased reliance on hearing. The sea is a noisy place, and those noises travel well underwater, so whales can obtain lots of information about their surroundings just by passively listening to the soundscape around them. In addition, probably all whales communicate at least some information to other members of their species with intentionally produced sounds. And all toothed whales also actively evaluate their surroundings with echolocation, or biosonar, essentially sending information to themselves by producing streams of sound clicks that reflect off targets to convey information about the targets back to the whale producing them.

Like birds, mammals are homeotherms; they maintain high and tightly regulated body temperatures, near 37––38°C. When at sea, marine mammals live in direct contact with seawater that is usually much colder than their core body temperatures. In fact, most live in high-latitude, food-rich waters where water temperatures always hover near the freezing point. But even in more temperate latitudes, the high heat capacity of water (about 25 times higher than air of the same temperature) is a major heat sink and can impose heavy demands on the heat budgets of these homeotherms. To counter these heat losses, whales utilize several adaptive features, including insulating blubber layers under the skin, and large body sizes and streamlined body forms to reduce the extent of exposed surfaces relative to their body sizes.

Only mammals are characterized by true viviparity, the nourishment and extended development of a fetus within its mother’s uterus. Viviparity has resulted in the evolution of long pregnancies and often extended periods of parental nurturing following birth. Other features characteristic of mammals are body hair, milk-secreting mammary glands, separate external openings for the reproductive and digestive systems, specialized teeth, a unique system of three small bones in the middle ear to conduct sound vibrations, and a lower jaw joint (the infamous ‘TMJ’ or temporal-mandibular joint) that differs from all other tetrapods. The last three dental and bony features listed are useful diagnostic tools for establishing the identity of mammalian fossils.

Modern whales (in the taxonomic clade Cetacea) are of two distinct types. The filter-feeding baleen whales (the Mysticeti, including gray whales) lack the teeth just mentioned as being characteristic of mammals and, in their place, two racks of comb-like baleen plates project downward from the outer edges of their upper jaws. All other living whales (including porpoises and dolphins) are toothed whales (the Odontoceti). Most odontocetes are equipped with numerous teeth to catch fish, squid, and other slippery morsels of food.

The evolution of whales from terrestrial ancestors has wrought major changes on the typical mammalian body plan, and many of the obvious features that make a whale look like a whale are losses of features characteristic of other mammals. By the time of their birth, cetaceans usually lack any external evidence of rear appendages, body hair, sweat glands or external ears. Whales are streamlined in body form, and propel themselves with broad, horizontal tail flukes. The front appendages are adapted as flippers for maneuvering. Their heads are highly modified with their nostrils as blowholes (one in odontocetes, two in mysticetes) set well back from the tip