Nicks 'n' Notches Online
A monthly newsletter from the SDRP
Red Tide/Dolphin Update, Aug. 26, 2018
An Update on Sarasota Dolphins
& Red Tide
By Sarasota Dolphin Research Program Staff
The Sarasota Dolphin Research Program conducts year-round, monthly photographic identification surveys of the Sarasota dolphin community range, covering Terra Ceia Bay to Venice Inlet, including coastal Gulf of Mexico waters. The aerial photo to the right shows the red tide bloom off City Island, Sarasota — near where our offices are located, though we are on the opposite side of City Island. [ Image courtesy of Kerri Scolardi, Manatee Research Program, Mote Marine Laboratory.]

During our surveys, we collect data on the animals that are present, their locations, their condition, their activities and the other dolphins they are with. We also collect environmental data, including water depth & temperature and even gather water samples for red tide monitoring of cell counts.

Our monthly surveys — made possible thanks to support from the Charles and Margery Barancik Foundation — show that there are about 170 dolphins that live year-round in the multi-generational Sarasota Bay dolphin community. We know these dolphins well and are documenting the changes that are now taking place due to the red tide that is devastating the fish populations.

Typically, dolphin groups are small and fluid, though basic social associations are built around nursery groups of females with their most recent calves; juveniles and adult males, either alone or as strongly bonded pairs.

We recently completed three days of on-the-water surveys and our findings were very unusual — which we can only attribute to the current red tide bloom.

The dolphins have shifted their distributions, with many of the residents concentrating in large aggregations in a few places and many parts of their long-term community home range unoccupied. During our surveys earlier this week:

  • We did not find any dolphins along the near-shore Gulf of Mexico coastline between Venice and the northern edge of Anna Maria Island.
  • There were also an unusually low number of dolphins at the southern end of our range.
  • These areas are all known to have been highly impacted from red tide with widespread fish kills.
The map to the right shows our entire survey range.

This summer, in July and earlier this month, we saw between 10-27 and 13-16 dolphins, respectively, along our southern route — which includes the coastline from Siesta Key down to the Venice Pier and the inshore waters from Siesta Key to Venice Inlet.

This past week, we saw only four dolphins throughout that entire area.
There were also an unusually large number of dolphins clustered at the northern end of our survey range, in areas with lower levels of red tide.
For example, we saw 14-27 dolphins in July in one area during a period of low red tide. This accounted for 16-25% of the individuals seen across our survey range during each survey. In that same area, when the red tide hit Sarasota in early August, we saw 14-43 dolphins (20-36% of the total number of individuals seen).

By contrast, this past week, we saw 41 dolphins in that same area, which now accounted for 46% of dolphins seen across our survey range. Only 11 dolphins of the 90 distinct individuals sighted this past week were seen south of the Cortez Bridge. The rest — 83 individuals, or 92% — were all to the north.

What about the youngest of our dolphin residents?
So far, we have nine known births in the community this year. We know that two calves died before the red tide came inshore. A third mom was seen once without her new calf but we have not seen her again to confirm that the calf has been lost. We saw two of the remaining six dolphin calves this week.

The picture above shows resident mom, F223, and her 2018 calf, 2232. This is one of the nine new calves born this year and the mom and calf were re-sighted this week at the north end of our survey area.

Four of the calves born in 2018 are unaccounted for, but it could be that we just didn’t happen to see those animals and they’re OK.
There are still a large number of known residents that we didn't see this past week, but given that we made only one pass through our survey range, we can't say they were not here. Although the majority of animals found this past week were in the northern end of our survey range, of the dolphins we did come across, there were no obvious cases of individuals that appeared to be outside of their normal home range.

According to SDRP Research Associate Christina Toms, crews saw other differences on the water as well. “Usually we see a lot of diving birds and fish — mullet jumping, things like that,” she reported. “This week, we saw very few fish and birds. It was a big difference.”

Water samples also showed that the areas with the fewest dolphins had the lowest oxygen concentration, which was at levels too low to allow fish to survive.
This image shows red tide off Venice Inlet. Photo courtesy of Kerri Scolardi, Manatee Research Program, Mote Marine Laboratory.
This image shows red tide in Sarasota Bay off Longboat Key. Photo courtesy of Kerri Scolardi, Manatee Research Program, Mote Marine Laboratory.
In addition to our dolphin-focused work, we’ve also been helping to support Mote Marine Laboratory’s Stranding Investigations Program — shown in the image to the right collecting a deceased dolphin [ photo copyright Mote Marine Laboratory]. The Program responds to reports of sick, injured and deceased dolphins, whales and sea turtles in Sarasota and Manatee counties and helps to support FWC response to sick, injured and deceased manatees.

The amazing Stranding Investigations team has been working around the clock and, so far this year, has gathered 226 sea turtles — including 126 since July 20 alone. They have helped FWC with the collection and transport of numerous deceased manatees and have collected 19 dead dolphins.
We know that at least one of the dolphins they collected was a long-term member of the Sarasota Bay dolphin community named Speck, a 12-year-old male. ( Please see our last Facebook post for details.)

So far, no others have been identified as members of our resident community, but the losses are nonetheless disheartening.

Some of you have asked about results from necropsies of the animals that have died during this red tide. The most up-to-date report from Mote and the Stranding Investigations Program can be found in a recent post to Mote Marine Laboratory and Aquarium's Facebook Page.

We know from our long-term research that the dolphins that do survive this environmental catastrophe will be faced with much-reduced prey fish availability for quite some time into the future.

During our last major red tide, during 2005-2006, our research found that some of the dolphins’ prey fish species were reduced by more than 90 percent and that Sarasota’s dolphins showed increased interest in anglers and their bait and catch. Ultimately, two percent of the resident dolphin community then died in 2006 from ingesting recreational fishing gear and calves were as much as 20 percent below their typical weight.

What can you do to help dolphins?

  • Boaters should be on the lookout for turtles, manatees and dolphins. The red tide may slow their reactions to approaching vessels.
  • Anglers should also be aware of a potential increase in dolphins attracted by your bait and catch while you’re out fishing. If dolphins do show interest, please reel in your line and wait for them to pass and/or change your location if you can do so without affecting the dolphins. If you’re releasing your catch, do so quietly, away from dolphins.
  • See more tips on Dolphin Friendly Fishing & Viewing Tips.

And lastly, please consider whether you really need that fish you caught or if it would be better to put it back to help rebuild the fish populations when this red tide finally ends.

We will continue to document the impacts of this red tide event on our dolphin community and report back to you new information as we gather it.

—The SDRP
This is one of several leaping and socializing juveniles we saw recently in Palma Sola Bay.
This is a nursery group of local resident dolphins sighted in the northern area of our range recently. From left to right is F155 — a resident mom we call Murphy Brown; F259, a 5-year-old also known as Zoey; and F131, called Claire, along with her 2-year-old calf, 1318.
Helpful Red Tide Links for Humans
For the latest information on the red tide bloom and its impacts to our human population, here are some resources you can use:

The Florida Department of Health advises that people with underlying chronic respiratory problems like asthma or COPD should avoid red tide areas, especially when winds are blowing toxins on or near shore, and that you take all medications as prescribed, including having rescue inhalers.
Research, Conservation
and Education Since 1970
The Sarasota Dolphin Research Program (SDRP) is a collaboration dedicated to dolphin research, conservation and education.  
 
It began in 1970 at Mote Marine Laboratory when Blair Irvine and high school student Randy Wells started a pilot tagging study to find out whether dolphins on Florida's central west coast remained in the area or traveled more widely. In 1974, with a contract from the U.S. Marine Mammal Commission, they were joined by Michael Scott and expanded the study with radio-telemetry.
 
Their subsequent discovery of long-term dolphin residency set the stage for today's efforts by demonstrating opportunities to study individually identifiable dolphins throughout their lives in a natural laboratory setting.  

Our work is conducted under the name "Sarasota Dolphin Research Program." This name ties together several organizations dedicated to ensuring the continuity of our long-term research, conservation and education efforts in Sarasota Bay and elsewhere.

The SDRP has been operated by the Chicago Zoological Society (CZS) since 1989. 

"Dolphin Biology Research Institute," is a Sarasota-based 501(c)3 nonprofit corporation established in 1982. It provides logistical support with research vessels, towing vehicles, computers, cameras, field equipment, etc. Since 1992, the program has been based at Mote Marine Laboratory on City Island in Sarasota Bay, with office, lab, storage and dock space and easy access to boat launching ramps within the home range of the Sarasota Bay resident dolphins.