Natural Markings
In addition to these man-made and applied tags, variations in natural markings and unusual appearances may be used to identify individuals and herds on repeated encounters. Although many species of cetaceans are characterized by changes in color pattern with age, individuals occasionally differ radically in their coloration from their fellows (App. Figs. [A9], [A10]). In addition, individuals are sometimes seen with unusually shaped dorsal fins or scarring patterns (App. Fig. [A11]). These unusually marked animals should stand out in repeated encounters and can be a help in identifying a herd from one encounter to another.
Obviously, this list of tags and anomalous markings is not exhaustive. New marks may be developed at any time. The discussion is intended to make the reader aware of the value of information on natural or man-made marks in studies of cetacean natural history. Your cooperation will perhaps help us to unravel some of the mystery surrounding the distribution and movements of porpoises, dolphins, and whales.
APPENDIX B
RECORDING AND REPORTING OBSERVATIONS OF CETACEANS AT SEA
To increase reliability of identifications, observers should train themselves to ask the following kinds of questions each time cetaceans are encountered:
- 1. How large was the animal?
- 2. Did it have a dorsal fin? If so, what was its size, shape, and position on the animal's back?
- 3. Was the animal's blow visible? If so, how tall did it appear? What was its shape? How frequently did the animal blow?
- 4. What was the animal's color and color pattern?
- 5. Did it have any highly distinctive markings?
- 6. If it was a large or medium-sized animal, did it show its tail flukes when it began its dive?
- 7. If it was a medium-sized or small animal, did it approach, avoid, or ignore the vessel? Did it ride the bow wave?
- 8. What was its behavior? Did it jump from the water? If so, did it make a smooth graceful arching jump, or did it spin, somersault, or reenter with a splash?
One characteristic is rarely sufficient by itself, and the greater amount of relevant evidence the observer can obtain, the greater the likelihood he can make a reliable identification. But it is important to remember that even the most experienced cetologists are often unable to make an identification. Therefore, even if you cannot positively identify an animal or even make a good guess as to its identity, do not hesitate to fill out the rest of the sighting record form and submit it to an appropriate office. Listing the characters you observe and filling in as much of the form as possible may enable a cetologist to make an identification based on those characters and his knowledge of the distribution, movements, and behavior of cetaceans. In this regard, a sketch made as soon as possible after the encounter and photographs taken from as many angles as possible will aid in the identification.
Two sample sighting reports are provided to demonstrate a method of recording observations. The first report, "Sighting Information," is completed as an example and is footnoted for explanation. The second report, "Cetacean Data Record." located at the end of the guide, is blank and may be photocopied in bulk for use in the field. Copies of this or similar forms are available from any of the authors or from National Marine Fisheries Service, Tiburon, Calif. Even if no form is available, however, observations should be recorded in rough form, in as much detail as possible.
Reliable intermittent reports of cetaceans are of interest to cetologists. Their locations indicate seasonality of distribution, and their frequencies help indicate relative abundances of the various species. Because scientists are attempting to determine areas in which cetaceans are often, occasionally, seldom, or never found, and are ultimately describing why animals are found in one area and not another, persons who want to go a step further in their participation in observer programs may want to keep and report records of their entire cruise tracks and zones in which vigilance was maintained but no cetaceans were observed. Data obtained in this manner may be used as the foundation of estimates of cetacean populations, estimates which are extremely difficult to obtain by any other method.
To be of maximum use in such calculations, however, records of this kind must include the following minimum information: time and location of beginning and ending of each continuous watch, weather conditions as they affect visibility, sea state, ship's speed, height of the observer(s) above the water, number of persons on watch, and details of each sighting, particularly the estimated distance of the animal(s) from the ship's track.
For a sample of a fictional continuous watch report might look like the following. If sighting forms are available, these observations may be recorded directly onto them. Additional information can be recorded on the opposite side of the forms.
