Whales, Dolphins, and Porpoises of the Western North Atlantic Part 39

Logical extensions of these developments include the addition of numerous other sensors to permit simultaneous monitoring of multiple aspects of the animal's environment and the transmission of these data first to aircraft and subsequently to satellites for relay to sh.o.r.e-based laboratories.

In addition to permitting scientists to define movement patterns and daily diving patterns of cetaceans, the use of such devices offers an exciting means of determining the environmental parameters that trigger changes in their behavior.

Radio transmitter tags, in a variety of configurations, may be constructed and attached for short-term studies or for long-term monitoring of migrating animals. In either case, depending on their size and methods of attachment, radio transmitter tags may be visible on a free-swimming animal even at a considerable distance.

[Ill.u.s.tration: Appendix Figure A7.--A saddleback dolphin wearing a radio tag transmitter surfaces to breathe off southern California. (_Photo courtesy of W. E. Evans._)]

[Ill.u.s.tration: Appendix Figure A8.--A radio transmitter package attached to the dorsal ridge of a California gray whale. This yearling animal, captive for most of the first year of its life, was released into the ocean off San Diego, Calif., in March 1972 and subsequently tracked from s.h.i.+pboard and aircraft for over 30 days. The sensor transmitter package, shown in detail in the inset, was designed to measure the maximum depth of the animal's dive and the water temperature at that depth. (_Photo by S. Leatherwood._)]

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.

[Ill.u.s.tration: Appendix Figure A9.--A piebald saddleback dolphin on the bow of a research vessel off San Clemente Island, Calif. (_Photo by B.

C. Parks._)]

[Ill.u.s.tration: Appendix Figure A10.--A nearly all-white pilot whale seen off Catalina Island, Calif., in April 1971. The observation of this same animal at least once each quarter of the year is evidence that it is resident in that area. (_Photo by S. Leatherwood._)]

[Ill.u.s.tration: Appendix Figure A11.--A herd of pilot whales off Catalina Island, Calif., including an animal with a partially chopped-off dorsal fin, which has made him recognizable in repeated encounters with pilot whales around the various channel islands. (_Photo by G. E. Lingle._)]

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 ident.i.ty, 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 partic.i.p.ation 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, s.h.i.+p'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 s.h.i.+p'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.

[Ill.u.s.tration: Appendix Figure B1.--A sample cruise track with cetacean sightings. See text for detailed data recording.]

GENERAL INFORMATION

RV Melville (34-foot converted fis.h.i.+ng boat) U.S. Department of Commerce NMFS

Hydrographic Cruise Miami, Florida to Flamingo, Florida

28-31 January 1973

2 observers (G.E. Lingle and G.M. Mohr)

EYE LEVEL OF OBSERVERS: 16 feet above water

AVERAGE s.h.i.+P SPEED: 8.0 knots during continuous watch

CONTINUOUS WATCH INFORMATION (REFER TO FIG. B1):

START END START END LEG DATE TIME TIME POSITION POSITION WEATHER--VISIBILITY

1-2 2/28 1200 1730 U. Miami Dock 25-42N Beaufort II Visibility Va. Key 80-02W 3 miles

3-4 2/29 0800 1500 24-26N 25-00N Beaufort I Visibility 80-04E 81-04W 3.5 miles

5-6 2/30 0700 1680 25-12N 25-12N 3.5 miles 80-46W 81-10W

7-8 2/31 0700 0900 25-00 Flamingo 3.5 miles 80-45W

CETACEAN OBSERVATIONS (REFER TO FIG. B1):

A-2/28 1048 16 bottlenosed dolphins, _Tursiops truncatus_. 6 miles outside our course, headed west--rode bow briefly. Large concentrations of sea birds in area. One porpoise freeze branded N-1 on dorsal fin.

B-2/29 1100 2 right whales directly ahead of vessel headed NE--40-foot female? with calf. 2 bottlenosed dolphins accompanying the whales were riding pressure wave off whale's head.

C-2/29 1400 25-30 spotted porpoises, _Stenella plagiodon_, 1.25 miles outside our course, heading 240 mag. Did not ride bow wave.

D-2/30 1300 8 bottlenosed dolphins, _Tursiops truncatus_, 200-300 yards insh.o.r.e of our course, milling in area of concentrations of mullet and other small schooling fishes, dolphins (porpoises) and birds feeding on fish.