Dolphins of the Gulf of Mexico

Dolphins are a big part of life for the residents and visitors of the Texas Gulf. Whether through interactions on a boat tour, swimming with them, or even just spotting them out on a fishing day-trip, dolphins are a familiar face.

Even though we see these intelligent and majestic creatures with some frequency in the Gulf, there are many misconceptions about them.

First of all, they are not fish. Dolphins are mammals, which means they are warm-blooded, breathe through lungs rather than gills, and the females produce milk to nourish their live-born offspring through specialized organs called mammary glands.  

Secondly, dolphins are not porpoises. The main differences lie in the shape of their heads and bodies. Overall, dolphins have longer beaks, leaner bodies, and a more curved dorsal fin (fin on the top of their back). Outside of physical features, dolphins are also known to be much more vocal than porpoises. 

Thirdly, they are not always happy. While they are known for wearing a cute, seemingly permanent “smile,” this appearance does not actually reflect their emotions. Yes, it’s true that dolphins are extremely intelligent and social, but that doesn’t mean they always want to play with humans or be touched. Dolphins live their own lives and participate in behaviors of courtship, child care, hunting, and aggression in addition to playfulness as we tend to imagine them. This is not to say they are mean, not at all. But people should respect them as sentient, independent beings.

Outside of these misconceptions, there are more common characteristics shared between dolphin species including: 

• The use of echolocation to navigate their surroundings and find predators/prey
• Using clicks, whistles, and squeals to communicate with each other
• Traveling in pods, or groups. 

Now that you know a bit more about dolphins, here is a list of some dolphin species found in the Gulf of Mexico:

Common Bottlenose Dolphin

The Common bottlenose dolphin is found far and wide in the world’s oceans, sticking mainly to temperate and tropical waters like that of the Gulf of Mexico. Within these waters, they can be found in both shallow and deep waters including shipping channels, bays, estuaries, and open water. Because they are often found inshore, the common bottlenose dolphin is at high risk of injury or death by human interactions, such as through boating collisions and fishing mishaps. Additionally, dolphins found in the Texas and Florida bay face threats of being accidentally caught by the commercial shrimp otter trawl fishery. They are currently listed as “least concern” on the IUCN Red List.  

As their name suggests, these dolphins are easy to spot when at or near the beach or harbor and have a short, thick snout (like a bottle). Their color ranges a bit, but they are generally a steel gray color that gets lighter on their underside. They typically measure about 2.5 meters in length and hunt on prey like fish and squid. Interestingly, even though bottlenose dolphins have teeth, they don’t actually chew their prey. Instead, they grip their prey with their teeth to reposition it and swallow head-first so as to prevent the scales and bones from getting stuck. They can hunt independently or in groups where they collaborate to corral fish and take turns rocketing through the swarm. 

Atlantic Spotted Dolphin

Atlantic spotted dolphins are another species you may spot often in the Gulf (pun intended). They get their name from the spotted pattern that appears along their body (not the fins) more distinctively with age. In fact, baby dolphins of this species don’t have spots at all, but start to develop them after about a year. Adults grow between 5 to 7.5 feet long and can weigh between 220 to 315 pounds. They eat small fish, invertebrates, and cephalopods, such as squid and octopi, and their hunting skills are aided by the ability to swim 200 feet below the water’s surface and hold their breath for up to 10 minutes! Atlantic spotted dolphins are known to show many “fun” behaviors like surfing waves created by boats/ships, bow riding, and jumping out of the water. They are also very social and have been associated with other dolphin species while feeding. 

Like other dolphin species, they experience threats such as entanglement, ocean noise, illegal feeding and harassment. Because they are found largely along continental shelves, as well as in deep water, these human-caused dangers are prominent. They are listed as threatened by Texas Parks and Wildlife, but categorized as “of least concern” on the IUCN Red List with not much data to go on.   

Pantropical Spotted Dolphin

The Pantropical spotted dolphin is another beautiful species known to develop spots on its body as it gets older. Typically ranging 6-7 feet in length, pantropical spotted dolphins also have a noticeably darker gray coloration on their back that is separated on their sides from a light-colored underside. 

They are usually found in large groups of about 100 dolphins in coastal waters, where they spend time during the day, and up to 1,000 dolphins offshore, where they aggregate with other dolphin species to hunt at night. Pantropical spotted dolphins have a reputation of being very social and are commonly found in association with other species like the rough-toothed dolphin and spinner dolphin. Keep a lookout for them if you come across a group of dolphins spinning out of the water! 

Like all dolphins, pantropical spotted dolphins are protected under the Marine Mammal Protection Act, but populations in the eastern tropical Pacific are depleted due to entanglement and bycatch by the tuna purse-seine fishery. Their global abundance is high relative to other dolphin species, but not as high as it once was. Because of this fact, further data collection is needed from the tuna industry to determine if it’s still a threat to pantropical spotted dolphin populations. They also fall victim to illegal feeding and human harassment by people seeking wildlife encounters at tourist destinations. They are currently categorized as “least concern” on the IUCN Red List. 

Spinner Dolphin

Spinner dolphins are known for their long and slender beak, slightly curved to triangle-shaped dorsal fins, and – most of all – their acrobatic displays of leaping out of the water and spinning multiple times in the air. Also, Spinner dolphins have been found to feed throughout the night in order to take advantage of the fact that their typical food-source species migrate to shallower, coastal waters at night. They also forage in deep waters where bottlenose and spotted dolphins also feed. 

A notable behavior of Spinner dolphins is that they “rest” for four to five hours a day. To rest, a pod of dolphins will gather in relatively tight formation in calmer waters, engage in longer periods of time underwater, and limit other physically taxing behaviors like fast swimming, leaping, and vocalizing. During this time, they also switch off use of echolocation and rely only on sight to spot predators, which is why they typically rest in clearer waters and close to one another. 

Spinner dolphins’ daily behaviors are easily predictable which promotes the major threat of human interaction and viewing pressure. Because people want to experience close wildlife encounters, many tour boats and kayak trips occur daily to find pods of spinner dolphins. Studies have shown that spinner dolphins display certain behaviors in response to human pursuit including more swimming/leaping displays, aggressive behaviors, and avoidance behaviors. Frequent human interaction can disrupt these dolphin’s daily feeding and resting cycle, causing a hindrance to their ability to perform acts of survival. They also face other threats such as entanglement, marine debris, noise pollution caused by humans, and illegal feeding; but are listed as “least concern” on the IUCN Red List. 

Striped Dolphin

Striped dolphins range from 8-9 feet in length and are distinguishable from other dolphin species by their unique striped markings – hence the name. They have darker colored lines that span from their eyes to flippers and along the sides of their bodies, as well as a whiter v-shape that ends just below the dorsal fin. These beautiful dolphins are mostly found in warm waters, but have been closely associated with upwelling areas in which nutrient-rich, cold water rises from the deep as well as regions where ocean currents meet. 

In the water, striped dolphins display similar leaping displays like other dolphins, but one behavior stands out. They do what’s called “roto-tailing,” which is when they rotate their tail rapidly while jumping out of the water. This behavior can be seen in tight groups of, usually, over 25 individuals. Recent research explores how these striped dolphin pods are organized by sex, age, or breeding status. Another distinguishing feature of striped dolphins is, unlike spotted dolphins or spinner dolphins, they are not typically found associating with other dolphin species.  

Striped dolphins experience threats including chemical contaminants, disease, and entanglement in fishing gear, and their IUCN Red List status is of “least concern.”

These are just a few, but the Gulf of Mexico is home to other species too including the Clymene Dolphin, Fraser’s Dolphin, Rough-toothed Dolphin, and Long-Beaked Dolphin. 

Strandings and common threats

These dolphins are beloved residents of the Texas coastline and greater Gulf of Mexico, so it is important to know what dangers they face and how to protect them. To recap, common threats to dolphins include:

• Entanglements with fishing gear 
• Strandings 
• Pollution (oil spills, plastics, and noise pollution)
• Habitat alteration
• Human feeding, which disrupts natural instincts and behaviors 
• Human harassment 

Dolphin strandings on the Texas coast are currently in peak season: December through April. When an animal is stranded, it means they are beached alive (but unable to return to the water) or are found dead on the coast or in the water. If you find a stranded dolphin, you should immediately call Texas Marine Mammal Stranding Network at 1-800-9MAMMAL (1-800-962-6625) and do NOT try to push the animal back into the water. You can try to keep the animal wet (avoiding the blowhole) and shaded until experts arrive to transport the animal for treatment and, hopefully, release. 

Next time you visit the Gulf Coast, surely keep an eye for these graceful, intelligent creatures and remember to respect both them and their home.