Finding the Dolphin Way:
A Study of the Little-Known Franciscana

It might seem strange to climb to the top of a lighthouse to study dolphins—especially ones known to be among the smallest in the cetacean (whale and dolphin) family. However, Dr. Randy Wells of the Chicago Zoological Society and Argentine scientist Pablo Bordino of AquaMarina and Wildlife Trust, along with their research team, did so when high winds kept them off the coastal waters of Argentina in 2005.

Wells has more than 35 years of experience with capture/release, tagging, and tracking of cetaceans. Bordino has pioneered research on Franciscana abundance, mortality, and fisheries mitigation. Their collaboration on this project marks a crucial step towards the conservation of Franciscana dolphins.

From atop the San Antonio lighthouse, they monitored radio transmissions of Franciscana dolphins they had tagged in March 2005 with small transmitters. An endangered species, the Franciscanas dolphins are native only to coastal waters of Uruguay, Argentina, and Brazil. Little is known about their range and travel patterns.

Wells and Bordino had tagged three female Franciscanas with radios in 2005, constituting the first time the species had ever been tagged. The scientists returned to the site this year to increase the sample size of tagged dolphins and the precision of tracking data. With the support of the Chicago Board of Trade and Disney Wildlife Conservation Fund, another group of dolphins was tagged with satellite-linked transmitters, and released in March 2006.

The new radios send a signal to orbiting National Oceanic and Atmospheric Administration (NOAA) satellites. The location information is then relayed by email to the scientists via a processing center. Long hours of tracking from the lighthouse and listening for occasional “beeps” in a sea of static are no longer necessary to keep tabs on the locations of the dolphins.

Because of the Franciscanas’ small size (approximately 80-110 pounds), short dorsal (back) fin, barely detectable blow for air at the surface, and tendency to stay underwater without jumping like other dolphins, it is extremely difficult to spot them. Their size and behavior, combined with the mystery of their travel patterns, leaves little information for scientists to estimate the total number of the species remaining in the wild. Likewise, this prohibits scientists from defining population units so that the dolphins can be protected appropriately.

Unfortunately, it is most common to see the Franciscanas after they have been caught in fishing nets. This is the biggest threat to their survival, followed closely by habitat decline and over-fishing. During the two weeks in March 2005 that the scientists conducted their tagging operation, they recovered 10 dolphin carcasses resulting from fishing operations.

Tracking for Survival
By collecting data on the movements of the tagged individuals, Wells and Bordino can begin to determine the species’ overall range and movement and how fishing operations affect the species. This information will help the scientists determine population numbers and threats to the species. Ultimately, they will be able to coordinate effective conservation management for the species.

To date, Wells and Bordino have found that the original tracked group of females stayed within about 12 miles of the tagging site, over a six week period. The new tracking information will reveal if this pattern is consistent from year to year, or provide an indication of how much variability may exist.

The transmitters used on the March 2006 group have a battery life of about two months and are linked to a satellite to provide more precise location data. The tags offer information eight hours per day, and are turned off for 16 hours to save power. A company called Service Argos receives and processes the location data, and distributes it online on a daily basis.

Three of the dolphins tagged in March 2006 are shown on the tracking map below. They include:

•Chica (short for Chicago Zoological Society)—adult female (Tag #65624)
•Bruce—juvenile male (Tag #65625)
•Tango—juvenile male (Tag #65628)

San Antonio Lighthouse, Argentina

A Franciscana being tagged by researchers.

Where's Chica today?
Stay tuned as we update this Web page to provide you with current tracking maps. See for yourself where the dolphins are traveling, and watch along with scientists to find out what new information the Franciscanas will reveal to aid in the survival of the species.

August 29--Final Update
No signals have come in from Bruce yet today. I suspect that he has stopped transmitting. His (poor quality grade) locations for yesterday are shown in the attached map. The previous day, a fisherman reported to Pablo Bordino that a tagged dolphin was seen in this general area. Unless we begin to receive signals again, this will be the last daily update. I will provide summary maps as soon the final data are sent to me from CLS (used to be Argos). Even without a detailed review of the position data, it is clear based on the the seven franciscana dolphins
tagged to date that at least some of the dolphins in the vicinity of Punta Raza have a very limited, multi-season range.

My thanks to Pablo Bordino and the Aquamarina team, Disney Wildlife Conservation Fund, the Chicago Zoological Society, and Wildlife Trust for making this important research possible -- the animals should benefit significantly from these findings.

September 4, 2006 Update
Chica (PTT 65624) re-appeared on 2-3 September, producing several signals, 2 of which were of high quality and gave very reasonable positions within Bahia Samborombon. She had not been heard from since 2 June, in the same area. I am inclined to believe that these are real signals from the animal. Battery strength is still high, and the cumulative number of transmissions is what would have been expected based on cessation of signals in June (based on data from the other tags). Chica's transmission counter was not functioning properly during April-June, suggesting problems with the electronics of the tag. Given that the battery strength is still very good, another possiblility is that the tag became repositioned on the fin in June such that it did not clear the water and initiate the transmit sequence; some further change in its position led to the recent transmissions. Without direct observations of the animal and the tag on the fin, it is impossible to provide an definite explanation for this occurrence.

November 24, 2006 Update
Chica continues to transmit from Bahia Samborombon, but none of the signals from yesterday were of sufficient quality to warrant plotting points on a map. Whether this is due to rough seas or decline in battery strength remains to be determined.

November 25, 2006 Update
No signals from Chica yesterday.

November 26, 2006--FINAL UPDATE
Chica's last transmission was on November 23rd, and based on battery status we do not expect any additional transmissions. After more than 43,000 signals, battery voltage was well below the optimal level. Over a period of nearly nine months, her transmitter provided about 50% more transmissions than expected. Her patterns over the time period that her transmitter functioned demonstrated remarkably localized movements, further confirming the patterns demonstrated by the other six tagged Franciscana dolphins, and extending them through most of a year, hinting at year-round site fidelity to the southern portion of Bahia Samborombon.