CETACEANS OF THE GULF OF CALIFORNIA
By Prof. Roy Houston
Many a conversation that I have with others inevitably leads to “Did you see the whales today?” or “I was in my kayak the other day and 15 dolphins surfaced just 10 feet away!” Since we are fortunate to observe these magnificent creatures, it is appropriate to discuss the basics of marine cetaceans. Whales, dolphins, porpoises are marine mammals and belong to the Order: Cetacea. There are two main groups: the mysticetes or the baleen whales which include blue whales, fin whales, and the
grey whale. Baleen is composed of keratinized fibers (similar to our finger
nails but more flexible) that extend from the upper jaw and function to filter
plankton, small crustaceans and fish from the water. The other group is the toothed
whales or odontocetes include sperm whales, killer whales, dolphins, and
porpoises. These creatures are characterized by having homodont teeth which are
used for grasping food. Other mammals including humans have heterodont teeth
like canines, molars, etc. that perform different functions like grinding,
piercing, and cutting food. California
Like all mammals these creatures breathe air. Therefore they have to surface to ventilate and take in fresh air. When they exhale air through the blowhole they produce the “spout” which is helpful is observing and identifying the individual species. Humans inhale and exhale several times a minute where as cetaceans can ventilate many times faster in same amount of time. This is because their lungs are more elastic and can expand and contract rapidly which allows the individual to store huge amounts of oxygen in their blood and tissues. In addition, they exhibit a “diving reflex” where the heart slows way down, one to two beats/min. in some cases; this is accompanied with a reduction in the peripheral blood circulation. As a result some dolphins can dive down to over 600 ft. while the sperm whale can dive to several thousand feet!
Cetaceans utilize a remarkable means of communication known as echolocation. This is a process of transmitting sound waves usually through a series of nasal air passages and directed outward through a lipid filled chamber that function as a lens. The individual receives sound usually through the jawbone which carries it to the inner ear. Most sound waves produced are ultra high frequency, up to 200,000 hertz, and are therefore beyond the reach of the human ear. The amazing thing is that these creatures have the ability to detect and distinguish different textures, sizes and thicknesses of objects by echolocation. Based on sonogram data there is evidence of a language composed of high frequency sound patterns that are transmitted among individuals of the same species.
Many species of cetaceans have been sited in the northern
Gulf of California, however,
only a handful are seen on a more or less regular basis. Even so it may be only
for a fleeting moment, just enough to keep one hooked! The following species of
cetaceans are the ones most commonly sited in the San Felipe- Puertecitos
Fin whale, Balaenoptera physalus
The second largest of the great whales, the largest being the blue whale, the fin whale reaches a length of 80 feet and weighs up to 80 tons! This is amazing because these large animals live primarily on small plankton, crustaceans and fish they filter out of the water with their baleen plates. It takes the energy produced by 6 trillion plankton to support just one fin whale for one day! Unfortunately this plankton diet led to the demise of several individuals during the recent harmful algal bloom which occurred in late January and February of this year. Fin whales are probably the fastest of the great whales and have been referred to as the “greyhounds of the seas”. This species has a small, crescent-shape dorsal fin about two-thirds of the way back on the body. In addition, there is also a conspicuous ridge between the dorsal fin and the tail fluke. Moreover, it is the only consistently asymmetrically colored mammal in the world: all fin whales are white on the right side of the lower jaw and black on the left. Just like Beal for you classic Star Trek fans! The reasons for this unusual coloration are unknown but it may have something to do with feeding or to blend in with the waves at the surface. This whale can also be identified by a fountain-shape or column spout. Fin whales feed in the arctic water in the summer and migrate south during the winter months where they can be seen off the coasts of the northern
Gulf of California.
This is the most commonly sited species in the area.
Gray Whale, Eschrichtius robustus
This species differs from the fin whale in that the body has a mottled grayish appearance and “knuckles” or bumps where a dorsal fin would otherwise be located. This species is famous for its 13,000 mile round trip migration from the arctic to the water off the Pacific coast of
This is the longest migration of any mammal. There is also a resident
population that occurs in the Baja California of which
individuals are occasionally sited off the waters of San Felipe and environs. Once
thought to be nearly extinct because of heavy whaling pressure, this species
was placed on the endangered species list. Since then the population as
increased to the point that it has been removed from the endangered species
list- what a success story! Sea
Bottlenose Dolphin, Tursiops truncates
By far the most familiar of all the dolphins, this is the one that comes to mind when one thinks “dolphin”. It is the species that made “flipper” famous and is found at Sea World and aquariums around the world. Because of its adaptability to captivity, bottlenose dolphins and been the subject behavioral research. Much of the information on echolocation has come from the study of this species. They occur worldwide except in polar waters and occur within a few miles of the coast. The head is characterized by the well-defined melon or bump on the forehead with a short snout that is sharply set off from the head by a transverse crease. The body is stockier than the common dolphin and is light gray to white underneath. The best time to spot these wonderful creatures is when the seas are calm in the early morning hours.
Gulf Harbor Porpoise, Phocoena sinus
This article has focused on common species; however, it is important to briefly mention the harbor porpoise or “vaquita”. This species is one of the smallest cetaceans in the world with adults reaching a length of four feet. It is endemic to the northern Gulf of California and is extremely rare with only 60 individuals counted in the most recent census. This makes it the most endangered cetacean in the world and there have been numerous conservation efforts to save this little guy. Most of the mortality occurs by individuals drowning in gill nets from fishing boats.
Marine mammals including cetaceans have been the subject of conservation efforts for many years and it is most important that these efforts remain in place so that future generations may enjoy their beauty and elegance. Moreover, they play important roles in the stability of marine ecosystems.