Emerging Subspecies of Bottlenose Dolphin Identified in Eastern Pacific Waters

A new subspecies of common bottlenose dolphin has been identified in the tropical regions of the eastern Pacific Ocean by researchers from the University of Miami. This new subspecies is characterized by its small size and is only found in the tropical regions of the eastern Pacific Ocean. The researchers, including marine scientist Ana Costa from the Rosenstiel School of Marine, Atmospheric, and Earth Science, analyzed several specimens to determine the differences between this subspecies and other common bottlenose dolphins.

In a study published in the Journal of Mammalian Evolution, scientists have identified and named a new subspecies of common bottlenose dolphin found in the eastern tropical Pacific Ocean. The subspecies has been named the Eastern Tropical Pacific (ETP) bottlenose dolphin, or Tursiops truncatus nuuanu in scientific terms. Common bottlenose dolphins are found in many parts of the world, including temperate, subtropical, and tropical oceans, with a global population estimated to be around 600,000 individuals. These dolphins are known for their intelligence and can grow to be between 6.5 and 13 feet in length, weighing more than 1,000 pounds. Their name refers to their short, thick snout, or rostrum.

While the common bottlenose dolphin is generally considered to be a single species (Tursiops truncatus), there are some locations where scientists have observed distinct populations that have different ecological and habitat preferences. These preferences can lead to differences in genetics or physical characteristics that can potentially separate populations found in the same region into what scientists call ecotypes (a distinct population of a species adapted to local conditions). This process, known as speciation, occurs when populations evolve to become distinct species. In the case of the new subspecies identified in the eastern tropical Pacific Ocean, the researchers believe that the dolphins' distinct habitat preferences may have contributed to the development of their unique characteristics.

Bottlenose Dolphin Subspecies

In previous research, Costa and colleagues from the National Oceanic and Atmospheric Administration (NOAA) have demonstrated that there are two ecotypes of bottlenose dolphins living along the U.S. Atlantic coast that are distinct enough in terms of genetics and physical characteristics to be considered separate species. Based on their findings, the scientists proposed that one ecotype of the U.S. Atlantic bottlenose dolphin, which prefers shallow waters, is recognized as a new species called Tursiops erebennus (Tamanend's bottlenose dolphin).

The other ecotype, which is typically found in deeper, offshore waters, would continue to be referred to as the globally distributed Tursiops truncatus (common bottlenose dolphin). These findings suggest that distinct populations of common bottlenose dolphins may evolve into separate species over time due to differences in habitat preferences and other ecological factors.

According to Costa, two ecotypes of common bottlenose dolphins have been identified along the U.S. Pacific coast, specifically along the coast of California. Previous studies in the eastern Pacific Ocean, including in California, have revealed differences between common bottlenose dolphin populations. However, these studies were conducted in specific local areas. In the early 1900s, it was also suggested that a distinct form of bottlenose dolphin existed in the eastern tropical Pacific region, based on a small number of specimens and field records. However, this suggestion was not fully supported by scientific evidence until the recent study.

Resemblance to Common Bottlenose

In their analysis, the researchers observed significant differences in physical characteristics between the bottlenose dolphins from the Pacific Ocean, identifying two distinct clusters. The bottlenose dolphins found in offshore waters of the eastern tropical Pacific formed a single cluster and were significantly smaller, based on skull and body length, compared to the common bottlenose dolphins in the other cluster. The researchers concluded that the offshore bottlenose dolphins of the eastern tropical Pacific are evolving into a distinct subspecies from the globally distributed common bottlenose dolphins.

This new subspecies is only found in the eastern tropical Pacific and likely has a preference for deeper, offshore waters between southern Baja California and the Galápagos Islands. The researchers believe that the differences between the ETP bottlenose dolphins and other common bottlenose dolphins may be influenced by the distinct environmental conditions in the eastern tropical Pacific and potential variations in feeding behaviors.

For Costa, the specimens in this new subspecies are among the smallest common bottlenose dolphins found. While it is common for the public to assume that all dolphin species are already known, the use of improved technologies and integration of different methodologies, as well as the increase in samples from various locations, has revealed greater biodiversity in recent years. The findings of this latest study may have implications for the protection of these animals. By gaining a better understanding of the biodiversity in the ocean, we can learn more about the relationship between dolphins and their environment, as well as the threats they face. This can help us to define conservation and management strategies for these animals.

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