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Tursiops truncatus gephyreus is only found in the inshore waters of the Southwestern Atlantic Ocean. They are organized in small socially, structured groups, which lead to low genetic variability and high anthropogenic threats. Currently, the information about their reproductive biology and management is still insufficient. Thus, this study aims to present novel information recorded for 20 years regarding reproductive parameters in a small population of captive T. t. gephyreus. Three of the animals involved were found stranded in La Plata River estuary and, the other two were born at the oceanarium. Thirteen semen evaluations showed high-quality semen with a low percentage of sperm abnormalities. Twelve pregnancies and parturitions were observed. There was a clear calving seasonality during austral spring and summer. The duration of phase-2 of labor was approximately 80 min, being the caudal presentation the most frequent. The average inter-birth interval (IBI) was about 33 months. This is the first report that closely monitored parturition, IBI, and seminal evaluation in this species. Information gathered during this program will allow the development of adequate conservation plans for free-ranging populations.

Signature whistles are stereotyped and individually distinctive acoustic signals used as individual recognition calls, for maintaining group cohesion and during stressful situations. Here, it’s proved the occurrence of stereotyped whistles and how it changes, by an isolated adult female of short-beaked common dolphin (Delphinus delphis) kept in rehabilitation. Twenty-three hours of continuous recordings were collected until the dolphin death for hepatitis. A total of 64 whistles were analyzed along the hours and only an ascending-descending frequency contour was detected. The number of whistles decreased during the rehab period. Whistles showed a mean peak frequency contour (PFC) of 9.45 ±1.09 kHz, a mean maximum frequency value of 12.0.4 ±1.65 kHz, a mean minimum frequency of 7.04 ±1.16 kHz, a mean duration of 0.75±0.27 seconds and a number of harmonics ranging from 1 to 3. The low variability of whistles parameters along the hours and the only whistle contour found in an isolated and stressed dolphin support the hypothesis of stereotyped whistles. It is the first evidence of the use of this signal by Delphinus delphis in Southwestern Atlantic Ocean (SWAO) and is first step to understand the sound production related to the rehabilitation process.Signature whistles are stereotyped and individually distinctive acoustic signals used as individual recognition calls, for maintaining group cohesion and during stressful situations. Here, it’s proved the occurrence of stereotyped whistles and how it changes, by an isolated adult female of short-beaked common dolphin (Delphinus delphis) kept in rehabilitation. Twenty-three hours of continuous recordings were collected until the dolphin death for hepatitis. A total of 64 whistles were analyzed along the hours and only an ascending-descending frequency contour was detected. The number of whistles decreased during the rehab period. Whistles showed a mean peak frequency contour (PFC) of 9.45 ±1.09 kHz, a mean maximum frequency value of 12.0.4 ±1.65 kHz, a mean minimum frequency of 7.04 ±1.16 kHz, a mean duration of 0.75±0.27 seconds and a number of harmonics ranging from 1 to 3. The low variability of whistles parameters along the hours and the only whistle contour found in an isolated and stressed dolphin su...