This spring my field team will begin 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. The lagoon is 155 miles long. In and around the IRL biologists have identified more than 1,350 kinds of plants and 2,956 kinds of animals, including the bottlenose dolphin and the Florida manatee.
The IRL is used by people for boating and fishing, so it is important to know about the biology of dolphins and how human activities may affect them. Because bottlenose dolphins (and all
in the United States) are protected by law, we will be doing our work under a
research permit issued to us by the U.S. National Marine Fisheries Service.
The "Indian River Lagoon Dolphin Project" is going to build on an earlier field study that I'll tell you about next week in Chapter 2. This new study has many objectives (or goals), 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 lagoon? 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?
- What times of day do the dolphins feed?
- Do the dolphins spend their entire lives in the lagoon?
- What times of year are dolphin calves born?
- Do human activities like boating and fishing have an effect on dolphin behavior?
To answer these questions, we will spend a lot of time in a small boat surveying the waters of the IRL. We have a 15-foot jet-drive boat that will allow us to work in the shallow waters of the IRL without damaging the sea grasses. Our boat is equipped with all of the required safety equipment plus the special equipment we need for the study. It also has a canvas top to shade us from the hot sun when we are on the water. Because the IRL is 155 miles long, we will have to concentrate our study in the area near the Kennedy Space Center, which is easy to reach and has lots of dolphins.
Like a boat, people to conduct the study are also a necessary piece of equipment! Each time we go out to survey, there will be three or four people on the field team, 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 master's degree in ichthyology (the study of fish) from the University of Central Florida; Rachel Witcher, also a graduate student at the University of Central Florida; and myself.
At first we will make one trip per week and spend the day on the water. We will need to become familiar with the different areas of the lagoon so that we don't run aground. In the summer when the weather is good we may spend several consecutive days on the water, coming back to the field station each night.
There is important survey equipment to bring along. A camera and a field notebook are two major pieces of equipment we need to collect data. Each time we encounter a herd of dolphins we will collect a standard set of data, which includes the date and time of the encounter, the number of animals in the herd, the number of calves present, behavior of the herd (feeding, mating, traveling, socializing), water depth, water temperature, salt content, and the exact location of the sighting on the map.
We also have a handheld instrument called a GPS receiver that helps us 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 so we can map all our sightings on a grid. All data will be written on a standard data sheet and later entered into a computer database.
Finding Dolphin "Fingerprints"
Once the basic data on each sighting have 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 has a unique shape and, as the dolphin gets older, the fin gathers more and more nicks, cuts, and scratches. We think of these as a dolphin "fingerprint," which helps us identify a single animal. To take pictures, we will use both regular 35mm 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.
At the beginning of the study, we will see new and different individual dolphins on each trip and our photo catalog will grow rapidly. So will the workload! The catalog must be kept up-to-date and all of the sighting data entered in the computer. And, no matter how perfect our field schedule is on paper, there will be weather problems to deal with.
It isn't always warm and sunny here in Florida. The winter brings strong winds from the north. In summer there are afternoon thunderstorms as well as tropical storms and hurricanes! Even though we'll be anxious to go and survey, safety always comes first.
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.