Marine Life

From Costa Rica Travel Guide: Vacation and Travel tips

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Tucuxi (Gray or River Dolphin)

First of all, this species of dolphin wasn’t even confirmed officially until 1997, but locals had observed groups of tucuxis in salt and fresh water off the coast of the Gandoca Manzanillo area since the early 1990’s.

The tucuxi is the only dolphin, of the six species found in Costa Rica, that forages almost exclusively in freshwater. However, the bottle-nosed dolphin will enter the river mouths to feed. To put this in perspective, the bottle-nosed dolphin has never been observed more than 550 yards inland from the mouth of the river, where the tucuxis have been seen several kilometers upstream. Even when in saltwater the tucuxi won’t venture too far from the coast. The tucuxi and the bottlenose are similar in color, but the tucuxi are much smaller in size. The tucuxi have a triangular and only slightly curved dorsal fin; whereas the dorsal fin on the bottlenose is more apparent and curved. The tucuxi is also distinguished from the bottlenose because it has a thinner, longer snout. When these two species swim together, which they often do, the tucuxi appear as the younger calves of the bottle-nose dolphin.

Tucuxis typically feed in the daytime, particularly in the early morning and early evening. Tucuxis feed on members of the following families of fish: herring, croaker and seatrout, coney, and anchovy, but also enjoy shrimp and crabs. They normally won’t take a fish that are more than about 15 inches in length. Tucuxis, young and old alike, have extremely worn-down teeth, and it is thought to be a result of chewing on hard or silt-ridden prey.

Tucuxis usually travel in groups of just two or four, but are also comfortable traveling in pods of up to 30 or more. Pod members will work together in order to fish, as they can often be observed forming circles around schools of fish and then converging in on them at the same time or herding fish up against banks or even fishing nets.

Tucuxis will surface at least once a minute to breath. The tucuxi are less gregarious than other dolphins and will quickly swim away if they feel the sense of danger. Although very capable of leaping out of the water and performing spectacular acrobatics, tucuxi tend to swim much slower, and leap out of the water much less than other dolphins.

The gestation period for the tucuxi is approximately 11 to 12 months, resulting in a single young. The calf will be a little over two feet in length. Like other dolphin species, the young calf can stay with its mother for several years.

In Manzanillo, Costa Rica, the tucuxis have become quite the tourist attraction, but they are also susceptible to irresponsible fishing practices, and closer inland, much of their freshwater habitat has become polluted or corrupted by human disturbance.