The Sea of Cortez contains a rich and
diverse marine life, including a number of marine mammals called
Cetaceans. Among the more prominent species of these mammals residing in
the Gulf of California's Sonoran Desert are the Finback Whale, the
California Sea Lion and the Common Dolphin.
A resident population of 250 Finback Whales
(Balaenoptera physalus) feed in the rich waters of the Gulf and are
often seen in the Canal de Ballenas (Channel of the Whales), the deep
chasm between the Baja mainland and Isla Angel de la Guardia. Finbacks,
the second largest animal on the planet, are the most common whale within
the island channels, although Killer Whales, Humpback Whales and Sperm
Whales are also seen.
The Finback (also called Finner and Fin
Whale) is exceeded in size only by its cousin, the Blue Whale; both are
baleen, or toothless, whales. Finbacks can reach a length of 80 feet and
weigh as much as 80 tons. The Finback is streamlined with a pointed snout,
is milky-white underneath and gray-black on top. Its name comes from the
extremely small, hooked fin on its back, which is only a foot long in
This huge predator feeds on krill, one of
the tinniest of all shrimp-like crustaceans, as well as algae, codfish,
herring, sardines, squid, anchovies and octupi. The Finback can remain
underwater for 20 to 30 minutes before rising for air, but it is erratic
in its cycle and is therefore difficult to track.
The Finback is extremely gregarious, showing
no fear of boats and usually travels in pods of 15 to 20, although groups
as large as 100 have been seen. The Finback is monogamous and is extremely
affectionate and loyal to its partner. They breed May through August and
give birth the following year to a 20- to 25-foot-long offspring, which is
nursed for 6 months.
The California Sea
The California Sea Lion (Zalophus
californianus) is composed of 3 geographically isolated populations
numbering between 70,000 and 150,000. The great majority of these live
between the Farallon Islands near San Francisco and the Gulf of California
south to the tip of Baja.
On fairly warm days, seal lions stay
continually wet in tide pools and by rolling in wet sand to keep cool.
After extensive swimming and diving, they may be seen in the water waving
one flipper, another means of dissipating heat.
The adult male may reach a length of 8 feet
and weigh as much as 600 pounds. The adult female will reach only 6 feet
and weigh a third as much.
In order to breed, sea lions establish
rookeries, special breeding grounds where sea lions congregate. The
breeding males, 5 years and older, arrive at the rookeries first in early
spring and battle other males until relatively few are left. The dominant
males shift territory with time of day, level of tides, temperature and
location of females. The harem size of a bull varies between 10 and 20
Females begin to breed at about 3 years of
age. Shortly after arriving at the rookery, she gives birth to a single
pup, then a few days later, she will go into heat and is bred. After a
gestation period of 342 to 365 days, the pup is born and will nurse for up
to 4 months. By mid August, when the breeding seasons ends, sea lions
scatter along the coast, males and females going in opposite directions,
until the following spring.
The Common Dolphin (Delphinis
delphis) has black flippers and back with yellowish flanks and a white
belly. It swims at about 25 mph in medium-size schools, enjoying the warm
and temperate waters of the Atlantic and Pacific Oceans. It has 30 to 40
small teeth and each side of its lower and upper jaw and reaches a length
of about 8 feet.