ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

River Dolphins of the World

Updated on January 10, 2016
Amazon river dolphin
Amazon river dolphin | Source

There are four different species of river dolphins throughout the world:

  • Amazon river dolphin
  • South Asian river dolphin
  • La Plata dolphin
  • Yangtze river dolphin

The Amazon river dolphin, or boto, is the largest river dolphin in the world, with males weighing as much as 400 pounds. There are two additional subspecies: The Araguaian river dolphin and the Bolivian river dolphin, which inhabit different river systems in South America.

The South Asian river dolphin can be found in the nations of Pakistan, India, Nepal and Bangladesh on the Indian sub-continent. There are Ganges River and Indus River subspecies.

The La plata dolphin can live in brackish and saltwater as well as in rivers. It lives along the Atlantic coast in southern Brazil, Uruguay and northern Argentina.

The Yangtze River dolphin, also known as the baiji, is now believed to be extinct.

The Baiji or Yangtze River dolphin
The Baiji or Yangtze River dolphin | Source


River dolphins evolved independently from local saltwater dolphins, so they are more closely related to ocean going dolphins in their region than they are to each other. Because they have adapted to similar environments (rivers), they look similar. Common characteristics of all river dolphins include:

  • Small size: The ocean going bottlenose dolphin can be as long as 13 feet and weigh up to 1,400 pounds. By contrast, the boto is the largest river dolphin, a little over 8 feet long with a weight just over 400 pounds. The La Plata dolphin is under six feet long and weighs around 100 pounds.
  • Long thin beaks: Compared to saltwater dolphins, the beaks of river dolphins are thinner and longer, as a percentage of body length. For the La Plata dolphin, its beak can be 15% of its body length.
  • Poor eyesight: River dolphins typically live in muddy rivers where sight is not very useful for locating prey. Instead, they rely on echolocation.

Two Indus River dolphin calves trapped in canal
Two Indus River dolphin calves trapped in canal | Source

Conservation Status

River dolphin populations are vulnerable due to the fact that they are restricted to a very limited number of river systems. If these rivers become polluted or otherwise become unsuitable habitat, an entire river dolphin species could become extinct. Also, populations can be broken up by waterfalls, very shallow sections of river, or dams.

Amazon river dolphins are in good shape, with a population in the tens of thousands. La Plata dolphins are also numerous, with an estimated population of forty thousand, based on aerial surveys. Other river dolphins are not doing so well.

The south Asian river dolphin, is considered endangered, and conservation efforts are needed. It has small but viable populations. When a survey was performed in 2001, The Indus River subspecies numbered about 1,100 dolphins, split into five different populations by dams. Reserves have been created, and hunting has been banned. Also, animals which become stranded in shallow water or irrigation canals are rescued and transported to deeper water. Estimates of the current Ganges River dolphin population are slightly less than 2,000. In 1982, the population in Indian alone was estimated to be in the four to five thousand range.

The Chinese river dolphin is now believed to either be extinct, or the population has dropped so low and scattered that extinction is unavoidable. In the 1950s there were an estimated 6,000 baijis. As China industrialized, their numbers dwindled, due to increasing pollution and river traffic. The Chinese government declared the baiji endangered in 1979, and in 1983 hunting it was banned. In 1986 the population was down to around three hundred. By 1997 the estimated population dropped to under 50 after a survey could find only 13 animals. In 2006 a six week survey was done by experts from around the world, using the most sophisticated technology available. They found no baiji, and an analysis of the water quality yielded stunning results:

"There is already no plankton to speak of in the Yangtze. We used a specialized plankton net to trawl the river for 10 hours and only caught two shrimp, which were less than one centimeter long. It's hard to imagine that fish could survive here, and with no fish the baiji will starve."

In 2007 video was taken of an animal in the Yangtze River which was believed to be a baiji, but no sightings have been made since.Conservation efforts for this species were too little, too late.

Rescued baby La Plata dolphin being bottle fed
Rescued baby La Plata dolphin being bottle fed | Source


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)