# Dolphin — Facts, Threats & Conservation

*Family Delphinidae — oceanic dolphins including Tursiops truncatus (common bottlenose) and Delphinus delphis (common dolphin)*

> Oceanic dolphins (family Delphinidae) include the common bottlenose and common dolphin — social toothed whales of seas worldwide, distinct from river dolphins; IUCN status ranges from Least Concern to Critically Endangered by species.

**IUCN status:** Varies by species (Least Concern to Endangered)  ·  **WARN range:** All oceans, some rivers (separate WARN river-dolphin guides)

## Quick facts
| Fact | Value |
| --- | --- |
| Focus | Oceanic dolphins (not river dolphins) |
| Common species | Bottlenose and common dolphin |
| Echolocation | Yes — click-based sonar |
| Social structure | Fission-fusion groups |
| Main threat | Fisheries bycatch |
| Related guide | Orca (largest dolphin) |

## Scientific classification
- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Mammalia
- **Order:** Artiodactyla
- **Family:** Delphinidae (oceanic dolphins)
- **Example species:** Tursiops truncatus, Delphinus delphis

## Conservation status
- **Status:** Varies by species. Common bottlenose Least Concern; common dolphin Least Concern globally but declining regionally; Maui's dolphin Critically Endangered.
- **Population:** Bottlenose: hundreds of thousands globally; Maui's dolphin fewer than 50 adults
- **Trend:** Decreasing for several regional stocks; stable for widespread species
- **Assessed:** Varies by species
- **CITES:** Appendix II for most listed species
- River dolphins are assessed separately — see WARN river-dolphin guides.

## Key facts: Dolphin
- This guide covers oceanic dolphins — not river dolphins (see separate WARN river-dolphin pages).
- Bottlenose dolphins are not one global species; coastal and offshore forms differ genetically.
- Dolphins sleep with half the brain awake, maintaining breathing and vigilance.
- Bycatch in gillnets and tuna purse seines kills hundreds of thousands annually worldwide.
- Captive display remains controversial; wild dolphins need kilometres of ocean daily.
- Orcas are the largest dolphins — see the WARN orca guide for that species.

## Oceanic dolphins — not river dolphins
Delphinidae includes bottlenose, common, striped, spinner and Risso's dolphins among others. River dolphins — Amazon pink, Ganges, Indus and others — belong to separate families with distinct anatomy and are covered in dedicated WARN wildlife guides.

The common bottlenose dolphin Tursiops truncatus inhabits coastal and offshore waters globally, often associating with estuaries but not living exclusively in rivers. The short-beaked common dolphin Delphinus delphis forms large pelagic schools feeding on small fish.

Confusing oceanic dolphins with river dolphins misdirects conservation — river species face sharper extinction risk from dams and entanglement in freshwater fisheries.

## Echolocation, society and intelligence
Dolphins produce click trains reflected off objects, building acoustic pictures of prey and terrain. Whistles may function as signature calls identifying individuals across years.

Social groups change size dynamically — fission-fusion — with alliances among male bottlenoses lasting decades. Cooperative foraging includes mud-ring feeding and driving fish toward shore.

Cognitive studies show mirror self-recognition, tool use in some populations and cultural transmission of foraging techniques. Intelligence does not justify captivity; it increases welfare requirements wild conditions best meet.

## Fisheries, captivity and conservation
Global bycatch in gillnets, trawls and tuna fisheries remains the leading threat to many oceanic dolphins. IUCN assessments note declining common dolphin numbers in the Mediterranean and eastern tropical Pacific.

Maui's dolphin — a New Zealand subspecies — is Critically Endangered with fewer than 50 adults, threatened by gillnets in shallow habitat. Vaquita is a porpoise, not a dolphin, but illustrates gillnet extinction risk in similar fisheries.

Live capture for aquaria continues in some regions despite growing bans on breeding and import. Marine protected areas, pingers on nets and dolphin-safe tuna certification reduce mortality where enforced.

## Dolphins and people
Dolphin-watching tourism thrives from Scotland to New Zealand when boats follow approach guidelines — avoiding crowding, not feeding and reducing speed near calves.

Indonesia and Malaysia — WARN partners — host diverse oceanic dolphins in archipelagic waters where fisheries overlap requires careful management.

Readers should distinguish ethical wild observation from swim-with-dolphin programmes that stress animals and risk disease transmission. Oceanic dolphins belong in the sea, not resort lagoons.

## Related WARN guides
Oceanic dolphins differ from river dolphins — read WARN's pink river dolphin and Indus river dolphin pages for freshwater specialists. Orca, sperm whale and whale hub guides cover other cetaceans.

Seal and sea turtle pages address shared bycatch and habitat pressures.

Never support captive swim-with-dolphin programmes that drive wild capture.

## What WARN does
WARN educates readers in Indonesia, Malaysia, Brazil and Colombia about marine mammals and fisheries overlap. This oceanic dolphin hub complements separate river-dolphin guides — free education explaining species differences and habitat needs across partner countries.

If this guide helps you understand wildlife and the pressures it faces, a gift to WARN supports habitat protection and free public education in our partner countries.

## Frequently asked questions: Dolphin
### Is a dolphin a whale?
Yes. Dolphins are toothed whales (odontocetes) in family Delphinidae. Orcas are the largest dolphins.

### What is the difference between oceanic and river dolphins?
Oceanic dolphins live in marine and coastal salt water. River dolphins inhabit freshwater systems and belong to different families with distinct anatomy. WARN covers river dolphins separately.

### Are bottlenose dolphins endangered?
The common bottlenose is Least Concern globally, but some regional populations are depleted. Maui's dolphin is Critically Endangered.

### How do dolphins sleep?
They rest one brain hemisphere at a time, keeping one eye open and maintaining breathing — unihemispheric slow-wave sleep.

### What do dolphins eat?
Fish and squid primarily. Bottlenoses hunt individually and cooperatively; common dolphins feed on small schooling fish in groups.

### Should dolphins be kept in captivity?
Welfare experts increasingly oppose captivity for non-releasable rescue cases only. Wild dolphins range over large areas in complex societies impossible to replicate in tanks.

## Sources
- [IUCN Red List — common bottlenose dolphin](https://www.iucnredlist.org/species/2250/50374096)
- [IUCN Red List — short-beaked common dolphin](https://www.iucnredlist.org/species/6337/50352337)
- [Smithsonian Ocean — dolphin](https://ocean.si.edu/ocean-life/marine-mammals/dolphins)
- [Wikipedia — Dolphin](https://en.wikipedia.org/wiki/Dolphin)

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Full guide: https://worldanimalrescuenetwork.org/wildlife-guides/dolphin