In addition to chemical contamination, physical habitat alteration due to shoreline development and infrastructure projects, freshwater diversions, and increased boat traffic is also of concern. Dolphins in areas affected by the 2010 Deepwater Horizon oil spill were found to have compromised immune systems and decreased reproductive success (PDF, 685 pages). For example, in areas with high levels of polychlorinated biphenyls (PCBs) dolphin immune systems can be negatively affected. Habitat Destruction and DegradationĬommon bottlenose dolphins living near shore are also susceptible to habitat destruction and degradation by contaminants and oil spills. In addition, fishermen sometimes become frustrated when dolphins take their catch and can retaliate with violence towards dolphins. This problem is increasing, especially in the southeast United States and is largely the result of dolphins taking the bait and the catch directly from fishing gear, eating discarded fish, or being fed fish (illegally) by humans, causing them to associate anglers with food. In addition to interactions with commercial fisheries, dolphins may become entangled in or ingest rod-and-reel gear used by recreational anglers or for-hire fishing vessels, such as charter boats and headboats, which can lead to serious injury or mortality. Dolphins can become entangled or captured in commercial fishing gear such as gillnets, seines, trawls, trap pots, and longlines. One of the main threats to bottlenose dolphins is getting caught in fishing gear. Some of the most pressing threats are discussed below. Where They Liveīottlenose dolphins are exposed to a variety of human-caused and natural threats and stressors. Instead of using their teeth to chew, dolphins grip fish with their teeth, then swallow the fish whole-head first-so the spines of the fish don't catch in their throats. They also use passive listening and/or high frequency echolocation to locate prey. They may also trap schools of fish against sand bars and seawalls for an easy meal. For example, they work together to herd fish into groups and then take turns charging through the school of fish to feed. They use different techniques to pursue and capture prey, searching for food individually or cooperatively. When in baby position, the mom surfaces first, and the calf surfaces slightly after and just behind and to the side of its mother.īottlenose dolphins can thrive in many environments and feed on a variety of prey, such as fish, squid, and crustaceans (e.g., crabs and shrimp). In this position, the calf has easy access to nursing and may gain benefits by reducing drag from swimming in it’s mom’s slip stream. Calves maintain what is called “baby position” while swimming. Social behavior includes breeding, playing, aggression, and gentle body contact, such as rubbing. Resting is often characterized by tight group formations, slow movement, and intervals of methodical breathing. Their travel is characterized by persistent movement in a consistent direction.
We facilitate collaborative approaches to better understand and reduce harmful effects of human activities on bottlenose dolphins and their habitat based on sound science, conservation, public input, and public outreach.īottlenose dolphins may travel alone or in groups, and the groups often break apart and reform. Our scientists use a variety of innovative techniques to study, protect, and rescue bottlenose dolphins in distress (e.g., disentanglement response and strandings). NOAA Fisheries helps conserve bottlenose dolphins through collaborative management, integrated science, partnerships, and outreach. They are vulnerable to many stressors and threats including disease, biotoxins, pollution, habitat alteration including freshwater incursions, vessel strikes, human feeding of and activities causing harassment, interactions with commercial and recreational fishing, energy exploration and oil spills, and other types of human disturbance, such as underwater noise. They are a highly intelligent species and use sound both for communication and to hunt for food.īottlenose dolphins in the United States are not endangered or threatened under the Endangered Species Act (ESA), but they are protected under the Marine Mammal Protection Act (MMPA). But this puts bottlenose dolphins at increased risk of human-related injuries and death.
In addition, they are easy to view in the wild because they live close to shore and are distributed throughout coastal and estuarine waters. They are one of the most well-studied marine mammals in the wild. Common bottlenose dolphins (referred to hereafter simply as bottlenose dolphins) are found throughout the world in both offshore and coastal waters, including harbors, bays, gulfs, and estuaries of temperate and tropical waters (estuaries are the areas where rivers meet the sea).
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