Dolphins off Dana Point

Overview

Dolphins off Dana Point

General information

Bottlenose Dolphins
Bottlenose

Quick Facts
Order Cetacea
Suborder Odontoceti
Family Tursiops
Species Tursiops truncatus
Status Common
Weight Up to 1500 pounds
Diet A wide variety of sea creatures including fish, squid, octopus, rays, eels, and crustaceans
Size Up to 12-13 feet long
Home World-wide tropical and temperate waters, favoring coastal areas

How Smart Are Dolphins?

This is a very difficult question since we have not developed a reliable method for assessing non-human intelligence. Of all cetaceans, however, the behavior and intelligence of bottlenose dolphins is the most studied, albeit mostly in captivity. One method for estimating intelligence is the ratio of brain size to body size, called the “encephalization quotient.” The bottlenose dolphin’s encephalization quotient is second only to humans and well above the great apes. Other tests held in captivity such as mirror recognition, problem solving, and mimicry all indicate a high level of intelligence. In the wild, bottlenose dolphins live in extremely complex social groups. This complexity also supports the theory of high dolphin intelligence because the young dolphins must learn a great deal about the rules, conventions, cooperative processes and personalities of other pod members in order to be successful.

Offshore vs. nearshore bottlenose

There are two recognized varieties of bottlenose dolphins off the coast of Dana Point: offshore and nearshore. The offshore variety are larger and more robust that the inshore variety and exhibit some behavioral differences. If you have been standing on the beach or cliff in Southern California and seen dark gray dolphins surfing in the waves, you’ve seen the nearshore bottlenose. If you were several miles offshore and ran into a pod of very large and playful gray dolphins, then you have seen the offshore bottlenose. On the R/V Sea Explorer, we frequently encounter both varieties. Bottlenose dolphins are a favorite because of the amazing acrobatics that they perform in the wake of the boat. Very powerful animals, they can leap up to 10 feet out of the water and have been known to purposefully splash passengers!

General information

Common Dolphin
Common

Quick Facts
Order Cetacea
Suborder Odontoceti
Family Delphinidae
Species Delphinus delphis and Delphinus capensis
Status Common
Weight Up to 170 pounds
Diet Mainly feed on small schooling fish and squid
Size Average about 6 feet
Home All tropical, subtropical and temperate waters of the world.

A Marine Acrobat that Likes to Catch Major Air!

The name “common dolphin” actually refers to two species of dolphins: the short-beaked common dolphin (Delphinus delphis) and the long-beaked common dolphin (Delphinus capensis.) They can be very difficult to tell apart, but the main differences are the size of the beak and the size of the black line that goes from chin to pectoral fin. Typically, off the coast of Dana Point, we find more short-beaked common dolphins. At times, these dolphins are found in tremendously large pod sizes of 5000 or more. On the Sea Explorer, there have been days when you could not see the end of the pod on all sides of the boat. Common dolphins are always a favorite for kids (and adults too!) because of their outrageous behavior. Common dolphins frequently leap 6 or more feet out of the water, splashing down on their sides. They are also seen tail-walking, breaching, tail-slapping, mating, and feeding. 

How Big is a Common Dolphin Calf?

Common dolphin calves are a frequent sight on the Sea Explorer. Calves are born at about 2 ½ feet long and are born year round. Since dolphins are mammals, the calves will nurse from their mothers for over 6 months. When they are born, they swim close to their mother?s dorsal fin, drafting on her. In this way, they are able to keep up with her swimming speed. In the event of a threat, they will drop below and swim under her belly.

Modern Threats

Common dolphins are frequently found in association with tuna fish. Because of this, one danger to common dolphins is fishing nets. In the United States, dolphin-safe tuna laws have prevented the death of our local dolphins, however, the same laws do not always exist outside of the US. Only pantropical spotted dolphin and spinner dolphins incur more fishing net related mortality. 

General information

Pacific White-Sided Dolphins
Pacific White-Sided

Quick Facts
Order Cetacea
Suborder Odontoceti
Family Lagenorhynchus
Species Lagenorhynchus obliquidens
Status Common
Weight Up to 300 pounds
Diet Small schooling fish and squid
Size Up to 8 feet
Home North Pacific only

The Dolphin with the Best “Paint Job” According to Captain Mike

Pacific white-sided dolphins could be considered the most beautiful of dolphins seen in Dana Point. With an almost air-brushed appearance, it is difficult to mistake them. They are black on top, white on the bottom, with whitish swirls and streaks along their flanks. They have a short black beak, a dark ring around their eyes, and a black and gray dorsal fin that is sharply curved (or falcate.) Pacific white-sided dolphins strongly resemble Dusky Dolphins which are only found in the southern hemisphere and therefore do not pose an identification problem. Near Dana Point, they are most often found in small pods of 10-50, but in other regions are found in much larger numbers.

When and Where Can I See Pacific White-sided Dolphins?

These dolphins are found off the coast of Southern California more frequently in the winter months, as there appears to be some north-south migration according to seasons. They are also more frequently found in deep waters, but may come inshore searching for food, especially where there are deep water canyons. There are several geographically distinct populations, some of which may be residents while others may be more migratory.

General information

Risso’s Dolphin
Risso's

Quick Facts
Order Cetacea
Suborder Odontoceti
Family Grampus
Species Grampus griseus
Status Common
Weight Up to 1100 pounds
Diet Primarily squid, but some fish too
Size Up to 13 feet
Home Worldwide in tropical and temperate waters

Why is a Risso’s Dolphin so Scarred?

When a Risso’s dolphin is young, it is slate-gray to black with no scarring. As they age, they lighten in color and acquire white scars all over their body. These scars are assumed to be from the teeth of other Risso’s dolphins (called rake marks) and from the squid that they eat which have sharp hooks on their tentacles. Eventually, the Risso’s dolphin can be almost completely white. This striking coloration along with the absence of a beak make the Risso’s Dolphin easy to identify. Risso’s specialize in eating squid, but may consume some fish as well. They eat primarily at night as their prey species migrate toward the surface to feed.

A Relative Newcomer

Risso’s have not always been found off the coast of Dana Point. In a 1995 paper, Susan Shane documented a shift in observed species from Long-finned Pilot Whales to Risso’s Dolphins which took place around the 1982-83 El Nino event. Aggressive behavior of the Risso’s toward the Pilot Whales was observed and may have resulted in a competitive displacement since they both specialize in the same food type. Since then, Pilot whales have not been present, but Risso’s are frequently sighted.