Field Study - Indian River Lagoon Dolphins
Last spring we began a long-term study of bottlenose dolphins in the Indian River Lagoon (IRL) on the east coast of Florida. The lagoon is a long, narrow body of water that stretches from Ponce Inlet in the North to Jupiter Inlet - 155 miles. In and around the IRL biologists have identified over 1,350 kinds of plants and 2,956 kinds of animals including the bottlenose dolphin and the Florida manatee.
Since bottlenose dolphins (and all marine mammals in the United States) are protected by law, we do our work under a research permit issued to us by the U.S. National Marine Fisheries Service. The new study will build on data collected in previous studies. Our study has many objectives (or questions) but all relate to describing the biology of the bottlenose dolphin in the IRL.
Some of the questions that we are asking are:
- What are the movement patterns of individual dolphins?
- Are movement patterns different between males and females?
- How are the dolphins distributed in the IRL? Are they found everywhere or just in certain areas?
- Do movements and distribution patterns change with the season?
- Where do the dolphins feed and what do they eat?
- Do the dolphins spend their entire lives in the IRL?
- What times of day do the dolphins feed?
- What times of year are dolphin calves born?
- Do human activities like boating and fishing have an effect on dolphin behavior?
Because the IRL is used by people for boating and fishing, it is important to know about the biology of dolphins and how human activities may affect the dolphins.
To answer our questions we spend a lot of time in a small boat surveying the waters of the IRL. The study requires a lot of equipment and people and time. Because the IRL is 155 miles long we have to concentrate our study in area that is easily accessible and has lots of dolphins. We have a 15 foot jet drive boat that allows us to work in the shallow waters of the IRL and not damage the sea grasses. Our boat is equipped with all of the required safety equipment plus the special equipment we need for the study. The boat also has a canvas top to shade us from the hot sun when we are on the water. We've begun our field work near the City of Titusville (near the Kennedy Space Center) at the north end of the IRL. We already know that there are lots of dolphins there. Our base of operations is the University of Central Florida's field station located on Mosquito Lagoon (which is part of the IRL) just north of Titusville. The field team will have 3-4 people, including: Dr. Nelio Barros, a research biologist for the Hubbs-Sea World Research Institute; Megan Stolen, a graduate student at the University of Central Florida; Steve Clark, a biologist with a Masters degree in ichthyology (fish) from the University of Central Florida; Rachel Witcher, also a graduate student at the University of Central Florida; and myself.
The two major pieces of equipment that we use to collect data are the camera and the field note book. Each time we encounter a herd of dolphins we collect a standard set of data and try to take pictures of the dorsal fins of as many dolphins as possible. The data that we will routinely collect include: date and time of the encounter; number of animals in the herd; number of calves present; behavior of the herd (feeding, mating, traveling, socializing); water depth; water temperature; salinity; and the exact location of the sighting on the map. We will use a hand-held instrument called a GPS receiver to determine latitude and longitude. GPS stands for Global Positioning System. The receiver picks up signals from several satellites that are orbiting the earth and converts the signals into a latitude and longitude readout. All of these data are written on a standard data sheet and later entered into a computer database. Someday we may have a computer that works well in the boat and we can save a step by not using paper.
Once the basic data on each sighting has been collected we will concentrate on taking photographs of the dorsal fins of all of the dolphins in the herd. Each dolphin's dorsal fin is unique in shape and as the dolphin gets older the fin accumulates nicks, cuts and scratches. We use these as a 'dolphin fingerprint'. We will use both regular 35mm film cameras and a new, electronic digital camera. Each photograph of a unique dorsal fin will be given a code number and placed in a photo identification catalog. As we encounter groups of dolphins in different parts of the IRL we will take photos of their dorsal fins and compare them with those in our catalog. As the catalog grows and we begin to recognize individual dolphins, we will be able to determine which parts of the IRL they use by 'connecting the dots' between individual sightings on the map.
On each trip we will see new and different individual dolphins and our photo catalog will grow rapidly. But, so will the work load! The catalog must be kept up to date and all of the sighting data entered in the computer. Then there's Mother Nature. The weather here in Florida isn't always warm and sunny. The winter brings strong winds from the north and summer the afternoon thunderstorms. And then there's tropical storms and hurricanes! Safety always comes first. A perfect field schedule on paper will always be changed by Mother Nature. At the end of the study we will be able to 'connect all of the dots' for sightings of individual dolphins and see how and where they spend their time in the Indian River Lagoon. During the next several years we will be spending a lot of time on the water taking pictures, recording dolphin behavior at different times of the year, and listening to their sounds with underwater microphones. We may even be able to watch them at night using night vision goggles. And, we hope that we won't be too sunburned in the summer, too cold in the winter or too soaked with water! We will find out where the dolphins spend their time in the summer, fall, winter and spring. We'll find out about their favorite fishing places. We'll find out when they have their babies and watch the babies grow up. In the coming months and years you will be able to keep in touch with the Indian River Dolphin Project within the pages of ANIMALS. Stay tuned...!