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Dolphins

What does this mean?

Bottlenose dolphins are common along the coast of Florida. During the spring and summer, mothers and calves can be found in the shallow waters of the bays and estuaries where they enjoy pinfish, pigfish and striped mullet. Additionally, the newborns are safer in the shallow coastal waters away from such predators as adult Bull Sharks. In the fall and winter, dolphins are more frequently found in the passes and along shorelines.


How are the data collected? (Methods)

Long-term studies by the Sarasota Dolphin Research Program, initiated by Mote Marine Laboratory in 1970, and continuing today in conjunction with the Chicago Zoological Society, are monitoring a resident community of four generations of dolphins in Sarasota Bay. Approximately 150 identifiable dolphins use the bay regularly. Some of the individuals are more than 50 years old, and have spent most if not all of their lives in the bay. Other communities reside in the waters to the north, south, and offshore of Sarasota Bay. The dolphins of Sarasota Bay face a variety of threats from human activities, including disturbance and collisions from boat traffic, recreational fishing gear, crab traps, human feeding of dolphins, humans swimming with dolphins, habitat alteration through loss of mangrove fringing forests and seagrass loss, and pollution. Dolphins have a reputation for being friendly, but they are really wild animals who should be treated with caution and respect. They are protected by the federal Marine Mammal Protection Act.

The waters of Sarasota Bay are the dolphins' home, and we are visitors to their home. For more information on the dolphins of Sarasota Bay, visit: www.sarasotadolphin.org. This website provides information on the activities of the world's longest-running study of dolphins, as well as directing you to sources of additional information on the animals themselves.

The dolphins using Sarasota Bay have been monitored since the 1970s. Mark-recapture estimates in 1976 and 1983 (shown on the graph) indicated that about 100 dolphins were present on a regular basis. Since 1984, intensive efforts to monitor recognizable individual dolphins have produced the census numbers shown in this graph.


Calculations

Trends in number of dolphins frequenting Sarasota Bay are provided annually by the Sarasota Dolphin Research Program.


Caveats and Limitations

The data from 1984 through 2003 show numbers of identifiable individuals recognized during any given year—it should be noted that this is not the same as a population estimate because it does not include the non-identifiable individuals using the bay. Increases from 1984 through about 1990 likely reflect improvements in scientists' abilities to identify dolphins, more than increases in numbers of dolphins present. Increases since the mid-1990's correlate with presumed fish stock increases since the net ban, but cause-effect relationships have not been conclusively established.


Additional Information


An Edition of wateratlas.org
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