I recent took my granddaughter on a dolphin tour out of Pensacola Beach. It was amazing. It was a cool October morning, not a cloud in the sky, the winds were calm, the water crystal clear due to the lack of rain over the past few weeks, and the dolphins were out.
They are amazing animals and always seem to grab your attention no matter how many times you see them. I was a student at Dauphin Island Sea Lab from 1980-81 and taught there from 1985-1990. No matter how many times we heard “dolphins” when out on one of the research vessels, everyone had to run over to look. People do enjoy seeing dolphins. There is just something about them.
A group of small dolphin leap from the ocean.
Photo: NOAA
During the tour at one location, we saw a group of them (a pod) feeding on fish in the shallow water. They would roll and chase, you could see the sand being kicked up from the bottom as they did. At another location we saw them in breeding mode. Slower moving, caressing, fluke slapping as they turned all around in the water near us. The tour guide told us all sorts of dolphin facts, and some great jokes to go along with them. It was a good program, and my granddaughter was loving it.
She looked over at me at one point and said, “dolphins use to walk on land”. I responded that actually their ancestors did. Dolphins, as we know them, were very much aquatic animals. This led to thoughts on other dolphin questions I have heard over the years.
What is the difference between a dolphin and a whale?
Size… and in some cases teeth.
All whales and dolphins are in the mammalian order Cetacea. Mammalian orders are divided based on the type of teeth they have. Cetaceans are homodonts, meaning they have only one type of tooth. For the toothed whales, these are canines, they lack the molars and incisors that many other mammals have. But some have no teeth rather a specialized fibrous material called baleen, similar to the bristles of a broom, with which they can filter plankton from the water.
There are over 90 species of cetaceans in the world’s oceans, 21 of those are known from the Gulf of Mexico. In a recent published survey by the National Marine Fisheries Service, most of the cetaceans in the Gulf of Mexico are of the toothed whale variety and most occur beyond the continental shelf (which is between 60 and 140 miles south of Pensacola). The only baleen whale in their report was the Byrde’s Whale (Balanopatera edeni). They estimate about 33 of these whales based on their transect surveys and all of these were found beyond the continental shelf between Pensacola and Apalachicola Florida. The largest of the toothed whales reported was the sperm whale, which can reach over 60 feet. They estimate 763 sperm whale in the Gulf, and they were found across the basin beyond the continental shelf.
But it is the bottlenose dolphin (Tursiops truncatus) that we see on the dolphin tours. This is a relatively small toothed whale, reaching lengths of 13 feet, though most in the Gulf region are less than 10 feet. They are the most abundant and most frequently encountered cetacean near shore and within the estuaries and seem to prefer these shallower waters to the open Gulf beyond the shelf. The National Marine Fisheries Service divides them into stocks based on their geographic distribution. They report 37 different stocks of bottlenose dolphins in the northern Gulf. These are divided into western, eastern, and northern stocks, and then subdivided into estuarine stocks. There are separate stocks for the Perdido Bay and Pensacola Bay groups. This report indicated the stock size for the Pensacola and Perdido Bay dolphins was unknown, though our tour guide indicated there were about 250 in the Pensacola Bay stock. The National Marine Fisheries Service did report about 179 dolphins in the Choctawhatchee Bay stock. The reports estimated over 51,000 individuals for the northern Gulf.
Though not listed as endangered or threatened by the Endangered Species Act, there is some concern on the smaller estuarine stocks and so they have been labeled as “strategic”. There has been fishery related mortality with these dolphins in our waters, primarily with longlining and otter trawl operations, but losses are less than four animals/year and do not seem to be impacting their populations.
What is the difference between a dolphin and a porpoise?
Though many associate the long beak as a dolphin, there are dolphins with short snouts. Killer whales are actually large dolphins. The answer goes back to the teeth, as it always does when classifying mammals. Dolphins have conical shaped teeth where porpoise have more spade shaped ones.
How smart are dolphins?
As everyone knows these are highly intelligent animals. They use an audible form of communication that includes squeaks, clicks, and whistles, to keep the pod together. Researchers have discovered that these audible sounds have a sort of “accent” to them that tells dolphins which pod the dolphin communicating is from. This appears to be very important being that dolphins from one social pod may not accept others from different one. I remember in 1993 when a group of five pantropical spotted dolphins stranded on Pensacola Beach. There were four adults and one 3-month year old in the group. After failed attempts to return the dolphins back to the Gulf, it was decided to transport them to a quarantine area near the EPA lab on Pensacola Beach. There was a virus spreading through some European populations and they did not want to risk taking them to the Gulfarium. In route three of the four adults passed away. The remaining adult was named Mango and the juvenile was named Kiwi. After a period of time in quarantine Mango passed away leaving on the young Kiwi. There was a move to return Kiwi to the wild but some of the dolphin experts on scene told me the likely hood of a different pod accepting Kiwi was a risk, and finding her original pod was very unlikely. After determining the dolphin did not have the virus of concern, they decided to move her to the Gulfarium in Ft. Walton Beach, where she lived the rest of her life.
How does dolphin echolocation work?
Echolocation is different than communication, in that it is inaudible. As with communication, the sounds are produced by expelling air through the blowhole. In the case of communication, there is a muscle that partially closes the opening of the blowhole producing the sounds we hear. In echolocation this is completely closed, and the sound waves are moved through a fat filled melon near the head. The shape and density of the melon can be changed by the animal to produce different frequencies of sound but all inaudible to our ears. These sounds are emitted through the melon into the environment, where they contact something and “echo” back to the dolphin. These echoes are received in a fat filled cavity of the lower jaw and transferred to the brain – where the animal is then made aware of the object out in front of them. Some studies suggest that it may be more than knowing there is an object, they may be able to distinguish different kinds of fish. Though it is most effective within 600 feet, studies show their range may be up to 2000 feet. Studies have also shown that some species of toothed whales can alter the frequency of these echolocated sounds to stun their prey making them easier to catch.
Dolphins are amazing animals.
They live between 30 and 50 years in the wild. During this time, they form tight social groups, feed on a variety of prey, and produce new members every 2-3 years. There is so much more to the biology, ecology, and social life of these animals and we recommend you read more. Once you understand them better, we also recommend you take a dolphin tour to view these amazing creatures.
In recent weeks there have been reports of large masses of jellyfish along the Gulf Coast. I have actually heard people state “I would rather be in the water with 100 sharks than 100 jellyfish”. Maybe that is true from some. Honestly, it seems dealing with sharks could be easier. Jellyfish are just there in a swarm. The more you try to move them away, the more they come towards you – it is like trying to avoid the smoke from a campfire.
But jellyfish exist and people sometimes have to deal with them. The thing they hate about them, of course, are their painful stings. As Jimmy Buffett puts it – “They are simple protoplasm – clear as cellophane – they ride the winds of fortune – life without a brain”. This is prreeettttyyyyy close.
Jellyfish are common on both sides of the island. This one has washed ashore on Santa Rosa Sound.
The “cellophane” jelly material is called mesoglea and it is a protein-based material that is 90% water. Lay a jellyfish on a deck and see what is left at the end of the day – not much. The bell undulates rhythmically controlled not by a brain but by a series of nerves – what some scientists call a “nerve net”. At the base of the bell is a single opening – the mouth. There are no teeth and whatever they swallow enters a simple gut where digestive enzymes do their work. But it is the only opening – so, waste material must exit through the same opening. Yes… they go to the bathroom through their mouth. Nice eh…
Then there are the tentacles – those lovely tentacles. These are armed with small cells called nematocysts that harbor a small dart tipped with a drop of venom. Each nematocyst as a small trigger which, when bumped, will fire the dart injecting the venom. When you bump a tentacle, you are literally bumping hundreds of these nematocysts and receive hundreds of drops of venom. Some species hurt, some do not. Those that hurt are no fun.
So, why SO many at one time in one place?
Most jellyfish feed on small food. Those food sources tend to multiple when the water is warm (and it is warm right now) and there are lots of nutrients in the water. When we have heavy rain (and we have had heavy rains this year) the runoff introduces large amounts of nutrients to the system. Warm nutrient rich water mean increase in jellyfish food, which in turn means increase in jellyfish. With winds and tides working together (and we saw this with the recent front that passed through), the jellyfish are shoved into smaller locations. In recent weeks that has been close to shore and the thick masses of jellyfish we have witnessed.
They do fly the purple flags when jellyfish are spotted. It us unusual for them to be a problem on both the Sound and Gulf sides. So, usually if they are bad on the Gulf side, you can move your beach day to the Sound and be fine. And remember – this too shall end. It won’t last forever.
This is an amazing animal – the horseshoe crab (Limulus polyphemus). A relic of an age before the dinosaurs, they have been plowing the sediments of our marine and estuarine waters for over 400 million years.
They are thick armored tanks, shaped like horseshoes with a long spikey tail giving them appearance of a stingray. They are usually a deep green color, though some have a brownish hue, and have two lighter colored eyes on each side of the head, though there is a third you cannot see. They crawl across the bottom of the Gulf and bays seeking smaller invertebrates to eat. Their armor protects them from most predators, but they do have a few, like the loggerhead sea turtle. Though harmless to people, they don’t appear that way with numerous spines running along their abdomen and the long spine extending from the rear on a ball and socket joint that allows them to swing it, albeit slowly, in circles. They are pretty cool actually.
This female is carrying a male on a beach in Big Lagoon within the National Seashore.
Photo: Bob Pitts
They are actually not crabs. They are in the Phylum Arthropoda, like crabs, but not in the Subphylum Crustacea, as crabs are. Rather they are in the Subphylum Chelicerata and more closely related to the arachnids like spiders and scorpions. There are four species of these creatures remaining on the planet, three of those live in Asia, one along the Atlantic and Gulf coast of the United States.
Horseshoe crabs vary in size throughout their range but are typically between one to two feet in length and up to one foot across the head. This would be the size of a large female; males are much smaller.
They are benthic creatures exploring the bottom of both the bays and the open oceans searching for food.
Life for a horseshoe crab begins on the shore. Mom buries her eggs in the sand at the tideline during the spring high tide of either the spring or fall season. They young emerge between two and four weeks and begin life as plankton (though they resemble the adults at this stage). They eventually settle out as juveniles in the seagrasses near where they were born and begin their life as benthic creatures. The large adults eventually work their way out into the open ocean to feed before returning to start the cycle over.
A large horseshoe crab found in Little Sabine.
Photo: Amanda Mattair
When the females return, smaller males pursue her to shore in hopes of being the one to fertilize her eggs. Many times, a male will use a modified claw that resembles a hook to grab on to the back of the female and ride in with her. But several other males, called satellites, will continue across the bottom in pursuit. Once on the beach she will begin to deposit her eggs in the sand at high tide and the males rush in to fertilize. Studies show that more often than not it is one of the satellites who is successful. And so, it goes over their 20 year life span, and this has been going on for hundreds of millions of years.
Their range extends from the Gulf of Maine to the Gulf of Mexico. Populations within this range have declined in recent years and there have been efforts throughout to manage this problem. Here in Florida the Florida Fish and Wildlife Conservation Commission (FWC) has developed a citizen science project they call The Florida Horseshoe Crab Watch where volunteers visit nesting beaches to collect information from the animals and tag them. Here in Pensacola Bay, though we have seen horseshoe crabs, we have not identified any nesting beaches and that is the focus of our Pensacola Bay Horseshoe Crab Hunt… to find those nesting beaches.
In 2017 we began marking horseshoe crab sightings in the Pensacola Bay area on a map. The purpose of this was to determine if there were “hotspots” (locations that had repeated sightings) that we could use to search for nesting locations. Beginning in 2020 we trained citizen science volunteers to survey one of nine such hotspot locations. Each of these were laid out with beach walking transects that ranged from 0.30 to 0.95 miles in length (mean = 0.69 miles).
In 2022 we trained 14 volunteers in March to survey these transects. They were instructed to visit one of the nine locations ± 30 minutes of spring high tide during the spring months (April-June). All of the spring tides were provided to them, but they had to use an outside resource to determine what time high tide as their location. Each volunteer was provided an FWC data sheet to complete after each survey and submit these to the local Sea Grant Extension Agent.
This horseshoe crab pair was found on shore near Wakulla Florida.
Photo: Charles Pulley
12 of the 14 volunteers (86%) did conduct at least one survey. These surveys covered six of the nine transect locations (67%) and others surveyed nine new locations.
A total of 77 surveys were conducted during the spring of 2022 for a total of 23.7 miles and logging 77 hours. No horseshoe crabs were sighted, and no nesting beaches were found.
That said, the general public continued to call in sighting reports outside of the official surveys. Six residents sent the Sea Grant Extension Agent records of sightings at six locations around the bay area. Three of these were locations were transect locations we are currently surveying, further confirming these are good places to search. Those three were Big Sabine, Little Sabine, and Sharp Point on Pensacola Beach. The other three locations included Portofino and the point at Ft. Pickens on Pensacola Beach as well as Navarre Beach.
Locations that were surveyed and no sightings were reported included Park West and Morgan Park on Pensacola Beach, Naval Live Oaks in Gulf Breeze, Sanders Beach and Bayou Grande in Pensacola, and Galvez Landing, Perdido Key State Park, Big Lagoon State Park and Tarkiln Bayou out near Perdido Key.
We will continue to search these sites each year in hopes of finding nesting horseshoe crabs. We encourage everyone to continue to report sightings to the Sea Grant Extension Agent in Escambia County (850-475-5230; roc1@ufl.edu ) and consider becoming a volunteer in the spring.
Horseshoe crab molts found on the beach near Big Sabine.
Photo: Holly Forrester.
“Bluefish!” … “It’s just a school of bluefish!” So yelled the lifeguard in Jaws II when Chief Brody had mistaken a school of bluefish for the rogue great white shark that was plaguing the town. He would not have been the first to mistake these large schools for a larger fish, particularly a predatory shark, but as some know, bluefish are quite predatory themselves.
Bluefish Image: University of South Florida
Growing up along the Florida panhandle we heard little about this species. We had heard stories of large bluefish schooling along the Atlantic coast killing prey with their razor-sharp teeth and, at times, biting humans. But not much was mentioned about them swimming along our shores. But they do, and I have caught some.
Bluefish are one of several in a group Hoese and Moore refer to as “mackerel-like fish” in Fishes of the Gulf of Mexico. They differ in that they lack the finlets found along the dorsal and ventral sides of the mackerel body and mackerels lack scales having a smoother skin. Bluefish are the only members of the family Pomatomidae. They can reach three feet in length and up to 30 pounds. They travel in large schools viciously feeding on just about anything they can catch and seem to really like menhaden. They move inshore for feeding and protection from larger ocean predators but do move offshore for breeding.
Bluefish landed from the Gulf of Mexico are much smaller than their Atlantic cousins, rarely weighing in more than three pounds. They do have a deep blue-green color to them and thin caudal peduncle and forked tail giving them the resemblance of a mackerel or jack. Some say they are bit too oily to eat while others enjoy them quite a bit. There is a commercial fishery for them in Florida and, as you would expect, it is a larger fishery along the east coast. Most of the panhandle counties have had commercial landings, albeit small ones.
Biogeographically, the blue fish are found all along the Atlantic seaboard and into the Gulf of Mexico. It is listed as worldwide but seems to be absent from the Caribbean and other tropical seas. This could be due to a distaste of warmer waters, or the lack of their prey targets.
They are an interesting and less known fish in our region. Swimming in a school of them should be done with caution, there are reports of nips and bites from these voracious predators.
This began with a call from one of my volunteers who was checking salinity at Shoreline Park. She reported the salinity, but also reported to smell of dead fish – though she could not see them. I visited Shoreline Park the following day on another project and could smell it as well. There was a large amount of dead seagrass washed ashore from a recent storm and I thought this may be the cause of the smell because I did not see the dead fish either.
When I got home, I checked the FWC fish kill database. It reported a redfish kill in Pensacola Bay. It is unusual to see a kill of only one species. Many times, these are releases from fishing activity, particularly bait, and thought this must be the case – FWC did not mention the cause. I let the volunteer know and asked to keep an eye out.
I reported this to the Escambia County Division of Marine Resources to (a) let them know, and (b) to find out if they had any idea of cause. They replied that the location was incorrect. The kill was actually near Galvez Landing on Innerarity Point. He (Robert Turpin) had visited the site and did find any dead fish. I have a lot of volunteers over that way so asked each to take a look. They did not see any dead fish. I asked them to keep an eye out and collect a dead fish if they saw one for testing. Often when a large fish kill occurs, and it is only one species, the suspect cause is disease. Tissue samples could confirm this.
And then came another call.
This time it was from one of our Master Naturalist who lives on the eastern shore of Mobile Bay. He wanted to know what was up with all of the dead redfish along the shore of the bay. He sent photos and his beach was littered with them. I reached out to Mississippi/Alabama Sea Grant to see if they knew what was going on. They had heard about the situation and knew the Alabama Department of Natural Resources was collecting samples. The Gulf Islands National Seashore then reported large numbers of dead redfish along the National Shores property in Mississippi, something was up.
Dead redfish on the eastern shore of Mobile Bay. Photo: Jimbo Meador
I eventually got word from Dr. Marcus Drymon at the Dauphin Island Sea Lab. They had a team working on this. Their team reported that stratification of the Gulf had created a hypoxic (low dissolved oxygen) layer on the bottom and the male “bull redfish” had gathered for breeding and died.
So, we are back to our title – what is stratification and how did this cause the fish kill?
Stratification is the layering of the water. Less dense water will sit atop the more dense. Water temperature or salinity can cause this density difference and layering. Colder and/or saltier water is denser and will form the bottom layer. If you have high winds, it will mix the water and the stratification disappears. Tides and currents can affect this as well.
What they believe happened recently was excessive amounts of rainfall created a large layer of freshwater to move from Mobile Bay into the open Gulf. The combination of tides and wind allowed a stratified layer to form. The oxygen that marine life uses is dissolved into the water at the surface and referred to as dissolved oxygen (DO). If the system is stratified, then the oxygen dissolved at the surface will not reach the bottom and hypoxia (low DO) can happen. They this is what happen. It just so happens that the large male redfish (bull reds) had congregated just offshore for breeding. They are more sensitive to low DO than the smaller females and any juveniles. So, the males died. To answer the question as to why other fish did not die (what you typically see in a DO related fish kill) – the numbers were not mentioned by there was one reference to 4.0 ppm. This is the high threshold of hypoxia. Many fish can tolerate at this concentration, but the male redfish could not.
So, that is what we think happened. The perfect storm of the demise of a group of male redfish just off of Mobile, and the carcasses drifted to other locations.
Do you live in Bay, Gulf, and Franklin County? We need your help! Scallop Sitters is one of our cooperative volunteer programs with Florida Fish and Wildlife (FWC).
Historically, populations of bay scallops were in large numbers and able to support fisheries across many North Florida bays, including St Andrew Bay, St Joe Bay, and Alligator Harbor (Franklin County). Consecutive years of poor environmental conditions, habitat loss, and general “bad luck” resulted in poor annual production and caused the scallop fishery to close. Bay scallops are a short-lived species growing from babies to spawning adults and dying in about a year. Scallop populations can recover quickly when growing conditions are good and can decline dramatically when growing conditions are bad.
An opportunity to jump start restoration of North Florida’s bay scallops came in 2011. Using funding from the Deepwater Horizon Oil Spill, a multi-county scallop restoration program was proposed and eventually set up in 2016. Scientists with FWC use hatchery reared scallops obtained from parents or broodstock from local bays to grow them in mass to increase the number of spawning adults near critical seagrass habitat.
FWC also created another program where volunteers can help with restoration called “Scallop Sitters” in 2018 and invited UF/IFAS Extension to help manage the volunteer part of the program in 2019 which led to targeted efforts in Gulf and Bay Counties.
Giving scallops a helping hand, “Scallop Sitters” work with UF/IFAS Extension, Florida Sea Grant, and FWC restoration scientists by cleaning scallops and checking salinity once a month from June through January. Photo by Tyler Jones, UF/IFAS Extension and Florida Sea Grant.
After the 2020 hiatus due to COVID-19, the program boasted nearly 100 volunteers for the 2021 campaign. UF/IFAS Extension is once again partnering with FWC in Bay and Gulf and Franklin Counties. Despite challenges with rainfall, stormwater runoff, and low salinity, our Scallop Sitter volunteers have supplied valuable information to researchers and restoration efforts, especially in these beginning years of our program. Scallop Sitters collect useful information about salinities throughout the target bays. But the bulk of the impact comes with keeping a close watch on their scallops. The scallops maintained by their sitters have a better chance of a successful spawn when the time is right.
A “Scallop Sitter” cage ready for placement near seagrasses. The cages are restoration tools used to produce baby scallops during the annual growing cycle. Photo by L. Scott Jackson.
So, what does a Scallop Sitter do? Volunteers manage predator exclusion cages of scallops, which are either placed in the bay or by a dock. The cages supply a safe environment for the scallops to live and reproduce, and in turn repopulate the bays. Volunteers make monthly visits from June until January to their assigned cages where they clean scallops removing attached barnacles and other potential problem organisms. Scallop Sitters watch the mortality rate and collect salinity data which helps figure out restoration goals and success in targeted areas.
Bay County: June 16th Kickoff Reception 9:30AM, Pick-up 10:00AM – 1:00 PM (Central)
An Equal Opportunity Institution. UF/IFAS Extension, University of Florida, Institute of Food and Agricultural Sciences, Andra Johnson, Dean for UF/IFAS Extension. Single copies of UF/IFAS Extension publications (excluding 4-H and youth publications) are available free to Florida residents from county UF/IFAS Extension offices.
