These are the oldest resident females in Sarasota Bay. They are now 62, 59, and 56 years of age.

Female dolphins in Sarasota Bay tend to live longer than males, and they may give birth when they are as old as 48 years of age.

The oldest female dolphin in the Sarasota community is a female nicknamed Nicklo, who is now 62 years old.

Males may live into their 40s. Our most long-lived male, nicknamed Jimmy Durante, was 50 years old when last seen in 2009.

These whistles appear to communicate the identity, location, and also the emotional state of the dolphin making the whistle.

Vocal learning appears to help dolphins develop a novel whistle, and this happens early in life.

Signature whistles usually make up about half of the whistles of a wild dolphin, but they may increase to 100% of the whistles when a dolphin is isolated from other dolphins.

When isolated, a dolphin emits more signature whistles than any other whistle-type, which often helps researchers  identify the signature of that dolphin

When dolphins are in a group, researchers have long had difficulty sorting out the whistles.  Which are signature whistles and which are non-signature whistle-types?

New research, however, has developed a novel identification method, called SIGnature IDentification (SIGID). It can identify signature whistles among recordings of groups of dolphins.

It turns out that signature whistles tend to be repeated in groups, each within 1-10 seconds of each other, while non-signature whistles tend to occur in longer or shorter intervals between whistles.

Long-time SDRP collaborator Vincent Janik, from the University of St. Andrews, Scotland, and his colleagues used 47 hours of recordings of wild SDRP dolphins to develop and test the SIGID method. They then verified it with a sample of dolphins from the Duisburg Zoo in Germany.

Their article was published on-line in Marine Mammal Science, and is available from the publisher.  SDRP Director Randy Wells is a co-author on the paper.  The abstract is below.

The SIGID method has already been applied successfully on a project by Nicola Quick and Vincent Janik to identify signature whistles in Scottish bottlenose dolphins. Their efforts helped to document how dolphins exchange signature whistles when they meet each other at sea. This article was published on-line in the Proccedings of the Royal Society B, is  available from the publishers.

Janik, VM , King, SL, Sayigh, LS & Wells, RS 2012, ‘ Identifying Signature Whistles from Recordings of Groups of Unrestrained Bottlenose Dolphins (Tursiops truncatus) ‘, Marine Mammal Science   Article first published online: 19 MAR 2012. DOI: 10.1111/j.1748-7692.2011.00549.x

ABSTRACT

Bottlenose dolphins (Tursiops truncatus) have individually distinctive signature whistles. Each individual dolphin develops its own unique frequency modulation pattern and uses it to broadcast its identity. However, underwater sound localization is challenging, and researchers have had difficulties identifying signature whistles. The traditional method to identify them involved isolating individuals. In this context, the signature whistle is the most commonly produced whistle type of an animal. However, most studies on wild dolphins cannot isolate animals. We present a novel method, SIGnature IDentification (SIGID), that can identify signature whistles in recordings of groups of dolphins recorded via a single hydrophone. We found that signature whistles tend to be delivered in bouts with whistles of the same type occurring within 1–10 s of each other. Nonsignature whistles occur with longer or shorter inter-whistle intervals, and this distinction can be used to identify signature whistles in a recording. We tested this method on recordings from wild and captive bottlenose dolphins and show thresholds needed to identify signature whistles reliably. SIGID will facilitate the study of signature whistle use in the wild, signature whistle diversity between different populations, and potentially allow signature whistles to be used in mark-recapture studies.

Quick NJ & Janik VM.  2012. ‘Bottlenose Dolphins Exchange Signature Whistles when Meeting at Sea’, Proceedings of the Royal Society B. Article first published online: 29 FEB 2012. DOI: 10.1098/rspb.2011.2537

Preliminary results show that many of the 32 dolphins sampled in a NOAA health assessment in summer, 2011, are underweight, anemic, have low blood sugar and/or some symptoms of liver and lung disease. Nearly half also have abnormally low levels of the hormones that help with stress response, metabolism and immune function.

Barataria Bay suffered heavy and prolonged exposure to oil from the Deepwater Horizon oil spill in spring and summer 2010.

Even before the oil spill, this region was included in an area for which a marine mammal Unusual Mortality Event was declared, beginning in February 2010 and continuing today.

Some of the study dolphins are in such poor health that researchers fear for their survival. One of these dolphins, last observed in late 2011, was found dead in January 2012.

Randall Wells during a dolphin health assessment in Sarasota Bay. Results from this ongoing study of dolphins not exposed to the oil spill, are being used for comparison with results from the dolphin health assessment in Barataria Bay, LA.

This news is especially troubling because 27 dolphins from Sarasota Bay, FL, are not showing similar symptoms. They were sampled during 2010 and 2011 health assessments. The  same methods were used in Sarasota and in Barataria Bay, LA.

NOAA is sharing the preliminary results from the comparative study of dolphins in Barataria and Sarasota Bays so that stranding responders and veterinarians can better care for live-stranded dolphins and look for similar health conditions.

An informal Questions and Answers pdf provided by NOAA is available as a download.

In other news:

Investigation of Dolphin Strandings in the Northern Gulf Continues

Since February 2010, more than 675 dolphins have stranded in the northern Gulf of Mexico (Franklin County, Florida, to the Louisiana/Texas border). This is a much higher mortality rate than the usual average of 74 dolphins per year, and it is what prompted NOAA to declare an Unusual Mortality Event, and investigate the cause of death for as many of the dolphins as possible.

Follow these links to:

read the NOAA information release on March 23, 2012 which is only briefly summarized here; you can get on the email list here too.

see a Photo Gallery supplied by NOAA with pictures of dolphins, health assessments, and a data graph from the northern Gulf of Mexico;

read more Questions and Answers provided by NOAA about Barataria Bay and Northern Gulf of Mexico dolphins.

They are called low frequency narrow band (LFN) sounds, and they seem to be associated with socializing, sexual, or aggressive behavior, or possibly foraging activities.

LFN sounds have  conservation implications because acoustic communication is particularly important in inshore areas where vision is often limited.

Dolphins are well known to emit whistles, echolocation, and burst-pulses.  Click here to hear samples.

• Whistles are tonal signals, audible to humans, which have a social function.
• Echolocation consists of short, high intensity pulses produced in rapid succession in “click trains,” and it is used for navigation and to capture prey.
• A burst-pulse is acoustically similar to echolocation pulses, but with higher pulse rates.

How LFN sounds fit into the dolphin sound repertoire is unclear because LFN sounds infrequently are heard, and they are not often reported in the scientific literature.

A recently published article, however, focuses on LFN sounds, comparing them across dolphin populations in Sarasota Bay, Tampa Bay, and the Mississippi sound in the northern Gulf of Mexico.

This is important research because so little is know about the context LFN communication. The frequencies of these sounds are below what is normally thought of as the range of good hearing in bottlenose dolphins.

Noise from boat motors potentially could interfere with, or mask LFN sounds, thus limiting dolphin communication in areas with high motorboat use.  SDRP studies have shown that dolphins whistle more frequently when boats approach, but the context is unclear.

The research article was published in the Journal of the Acoustical Society of America.  SDRP Director Randall Wells as one of the co-authors, and former SDRP intern and graduate student Ester Quintana-Rizzo also is a co-author.

Simard, P., Lace, N., Gowans, S., Quintana-Rizzo, E., Kuczaj, II., S. A., Wells, R. S., & Mann, D. A. (2011), Low frequency narrow-band calls in bottlenose dolphins (Tursiops truncatus): Signal properties, function, and conservation implications J. Acoust. Soc. Am. 130, 3068  DOI:10.1121/1.3641442

Abstract

Dolphins routinely use sound for social purposes, foraging and navigating. These sounds are most commonly classified as whistles (tonal, frequency modulated, typical frequencies 5–10 kHz) or clicks (impulsed and mostly ultrasonic). However, some low frequency sounds have been documented in several species of dolphins. Low frequency sounds produced by bottlenose dolphins (Tursiops truncatus) were recorded in three locations along the Gulf of Mexico. Sounds were characterized as being tonal with low peak frequencies (mean 1⁄4 990 Hz), short duration (mean 1⁄4 0.069 s), highly harmonic, and being produced in trains. Sound duration, peak frequency and number of sounds in trains were not significantly different between Mississippi and the two West Florida sites, however, the time interval between sounds within trains in West Florida was significantly shorter than in Mississippi (t 1⁄4 p 3.001, p 1⁄4 0.011). The sounds were significantly correlated with groups engaging in social activity (F1⁄48.323, p1⁄40.005). The peak frequencies of these sounds were below what is normally thought of as the range of good hearing in bottlenose dolphins, and are likely subject to masking by boat noise.

SDRP staff member Aaron Barleycorn participated, along with volunteers from a multi-agency team from throughout Florida.

SDRP responsibility on the project involved tagging Seymour with a satellite-linked tag to facilitate monitoring his progress after treatment, and to perform the post-release tracking.

This collaboration was organized by NOAA Fisheries Service in Miami, FL. An informal report is included below:

March 12, 2012

A young dolphin nicknamed Seymour, who became entangled in fishing line in the Ten Thousand Islands area in Southwest Florida, was successfully rescued and released on Friday, 9 March, 2012.

The fishing line was surrounding and cutting deeply into Seymour’s tail, and it could have impacted his long-term survival.

The team included 26 people from NOAA Fisheries Service, Harbor Branch Oceanographic Institute, Sea World Orlando, Chicago Zoological Society (SDRP), Mote Marine Laboratory, the Florida Fish and Wildlife Conservation Commission, and the University of Florida.

Upon capture, Seymour was taken to a boat ramp for further diagnoses by veterinarians. He was released when the veterinarians determined that he was healthy enough to not require further treatment in a rehabilitation facility.

Prior to release, Seymour was tagged with a satellite-linked transmitter, and his movements will be monitored for several months. Tag location data will help the Ten Thousand Islands Dolphin Project to locate Seymour to monitor his recovery. It will also provide new information about bottlenose dolphin movements in the Southwestern Florida area.

Previously, Seymour had been documented in the Marco Island area since 2006. At the end of 2011, members of the Ten Thousand Islands Dolphin Project reported seeing Seymour with fishing line wrapped around his tail.

Since then, an expert panel made up of researchers and biologists (including the SDRP Director Randall Wells) have been working together to determine whether or not to intervene based on the severity of the injury (i.e., life threatening or not). After much consideration, the team determined that intervention would benefit Seymour and possibly save his life.

Led by NOAA and Harbor Branch Oceanographic Institution, planning involved pulling together an experienced rescue team of biologists, veterinarians and a professional dolphin catcher, arranging for six boats, determining the range of the animal to facilitate search operations for capture, and working around weather conditions. For Seymour’s rescue, the rescuers came from as far as Gainesville, FL, some 300 miles away.

Dolphin attempts to whack a fish. It’s not clear if the fish is jumping to escape or if another fish was the target.

As first documented in the SDRP in the 1980s (and more recently in Time Magazine), a dolphin will “whack” a fish with its tail flukes, sometimes sending the fish 20 ft or more in the air.

Then the dolphin will swim leisurely over to eat the stunned fish.

This behavior typically occurs in shallow water.

The whacked fish lands and will soon be picked up and eaten, most likely by the dolphin who whacked it.

Learn about different prey-catching behaviors, like fish whacking, kerplunking, and pin wheeling .

While they eat many different fish species, among the favorites in Sarasota Bay are soniferous or noise-making fish, which include pigfish and toadfish.

That’s right, dolphins,  which are famous for their sonar, use passive listening to help when hunting prey.

Building on ground-breaking work by the late Dr. Nélio Barros, and Dr. Damon Gannon, our foraging ecology research indicates that while soniferous fish make up only 6% of the fish species in Sarasota Bay, these species make up 52% of the dolphins’ diet.

And dolphins are selective feeders, not opportunistic predators.

That means that relatively less abundant species like pig fish and toad fish tend to be selected over the more abundant mullet.

Further, the energy content of prey species varies seasonally, which may cause dolphins to vary their diet at different times of the year.

Some important dolphin prey species, such as pinfish have shown a decline in average body size since our research began in 2004.

Thus, less available energy is obtainable from each prey capture event. This might have negative implications for the growth of weaning dolphin calves, which are often observed to feed on pin fish.

For more information on foraging ecology and our other research, download our yearly Nicks_n Notches newsletter. Click here to learn more about  soniferous fish.

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Do you support conservation organizations? If so, please consider supporting the SDRP.  Become a member or donate to the SDRP.

Multiple research efforts are on-going to study the potential impact(s) on dolphins of the Deepwater Horizon oil spill, which occurred during April – July 2010, .

Bottlenose dolphins are the most common cetacean in inshore waters in the southeastern United States, but little is known about how an oil spill impacts these dolphins.

Dolphins may be impacted by direct contact, ingestion, or by inhaling oil or associated chemicals in the air.

The food chain may also be impacted, which affects dolphins as a top predator.

Efforts are underway to learn more about the spill effects throughout the northern Gulf of Mexico, and the long term research of the SDRP, more than 80 miles from the closest approach of oil from the spill, is important as a benchmark for comparison with areas closer.

Nicks_n_Notches (pdf), the yearly SDRP newsletter reports on a number of research projects related to the Deepwater Horizon oil spill. Articles include:

 Deepwater Horizon Oil Spill: 2010-2011 Efforts to respond to threats to dolphins along the central west coast of Florida

Deepwater Horizon Oil Spill: 2010-2011 Natural Resource Damage Assessment (NRDA) of the St. Joseph Bay bottlenose dolphin community

Deepwater Horizon Oil Spill: 2010-2011 Biopsy sampling of estuarine dolphins in the western Florida Panhandle potentially exposed to contaminants from the spill

2011: Assessing the potential sublethal and chronic health effects of dolphins from an area oiled by the Deepwater Horizon Oil Spill

Deepwater Horizon Oil Spill: 2011 Bottlenose dolphin tracking in Barataria Bay, Louisiana

West Florida Shelf bottlenose dolphins: Population structure, health, and oil spill impacts

Research efforts to learn more about spill effects have been funded by the Morris Animal Foundation’s Betty White Wildlife Rapid Response Fund, NOAA, Disney Worldwide Conservation Fund, Florida Institute of Oceanography, and BP.

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Do you value conservation?

If so, please donate to the SDRP.    Your contribution will help make our work possible.

In 2011, operating at the request of Federal authorities, staff from the SDRP led or participated in 3 rescue attempts involving entangled dolphins.

Most often, a dolphin requiring a rescue is entangled, and its swimming movements are restricted.

Often, lines cut deeply into the animals creating visible wounds that may become infected.

Synthetic fishing lines, especially some of the newer stronger designs  are surprisingly sharp and dangerous when they come into contact with a dolphin’s soft skin.

An article summarizing dolphin rescue attempts from 2006-2011 is included in the recently published Nicks_n_Notches   newsletter (pdf).

While the need for a rescue attempt is often caused by fishing lines or rope, which is cutting through the skin, but in the case of Scrappy, it was a Speedo swim suit that caused life-threatening wounds.

The goal of a rescue is to free the dolphin from the threat, and each case is different.

Occasionally, as in the case of FB28, the line can be cut with a long handled tool from a boat, without requiring capture.

If capture is needed, however, the ideal solution is to briefly capture the dolphin, free it from the threatening condition(s), and release it after examination by a marine mammal veterinarian. If necessary, the rescue team must be prepared to transport the dolphin to Mote Marine Laboratory’s Dolphin Hospital for rehabilitation, and hopefully eventual release.

As you might imagine, putting a dolphin rescue together is quite a task. Multiple boats, a dolphin catcher (using a 500 meter long net), and 25 or more staff and experienced volunteers must be gathered on short notice.

Sometimes the rescue crews will spend fruitless days on the water searching for the threatened dolphin, while very occasionally everything comes together and a successful rescue can be accomplished in a matter of hours.

Some dolphins, such as FB28, Scrappy, and Nellie are sighted for years after the rescue, but as detailed in the link above, the outcome is not always so positive.

Partial funding for past rescue operations has been provided by support from NOAA, but these funds are no longer available. Funding for future rescues will have to be obtained through individual donations.

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Want to help? If so, please support the SDRP. Become a member or donate to the SDRP.

You can read about them by downloading a pdf of our annual newsletter Nicks n Notches.

It contains articles written by SDRP staff, students, visiting scientists, and current and former interns.

We’ll be highlighting some of the research in upcoming posts to this website.