Thursday, September 20, 2012

And the Beat Goes On

Today was our last day in the field for this season. And it was a fantastic day! Again multiple groups were mud plume feeding, providing more data towards our investigation of this interesting behavior. In addition, we ran into most of Key West “gang” one more time, including an old friend who had just given birth (see more detail below).

Florida Keys dolphins move through really shallow water
This morning when we first started encountering groups the tide was low. In the Lower Florida Keys, since the average depth of water is about a meter, many areas become exposed during low tide (see photo below). The first group we encountered moved through a pass so shallow that we had to stop watching the animals and start working to avoid running aground. Dolphins in the keys regularly move in shallow waters and can sometimes be spotted easily because in the shallows the dorsal fins stay above the water between surfacing for air.


Dolphins in the Florida Keys move through shallow water regularly. In the upper left photo is a dolphin moving in the shallows near a sea grass flat that is exposed during a low tide (brown area in background). In the bottom right photo is a group of dolphins in water so shallow that they cannot get entirely under the water in between surfacings.

Meet the newest member of the Key West population
The third group we encountered included what appeared to be 2 adults mud plume feeding and a larger calf born sometime this year. We immediately recognized one of the adults to be Splitfin. It was not until about 10 min into the follow that we got a really nice surprise. Hidden on the other side of Splitfin was a brand new calf no more than a day or two old! We had seen Splitfin previously this season and had no idea she was pregnant and about to give birth. This was a super end to our work this year!


Splitfin and her calf

Wednesday, September 19, 2012

A Day of Feeding and Play

Everyone’s Creating Mud Plumes
Today each group encountered spent time feeding using mud plumes (see previous blog entry on details about this behavior). Our first group included Madbob, who we previously mentioned regarding the lesions on her skin. The good news was that Madbob was one of the adults actively engaged in this feeding behavior. And she also led the group to locations where they then used this behavior. We take this as a positive sign regarding her health.

Madbob lunging through a U shaped mud plume she created over the shallow sea grass beds

What happened to you?
The individual in the photos below has been sighted before, but not long term in the Key West population. We do not know the cause of it's bent fin and back scars. In addition, there are white spots along the area where an obvious injury once
was. Maybe shark attack at a young age? Maybe boat strike? We are hesitant to say birth defect due to the scarring on the back near the fin. The animal does not yet appear to be full grown, and today was hanging out with other juveniles that were in a group we followed. We did note that it did not participate in much of the active behaviors between these juveniles, but continued to stay near them and move with them while they played as their mothers fed (again mud plume feeding).




Tuesday, September 18, 2012

Moms and Calves and More

Moms and calves
Today two of the three groups we encountered had mom/calf pairs. In one was Jpeg and her calf. 

Jpeg and her calf
Previously we discussed what seemed to be an on going trend for Jpeg. Leaving her young calf and moving far away from other group members to feed. Today she was feeding, but the calf remained by her side throughout. Not sure which was responsible for the close proximity between the two of them, Jpeg or the calf.

In our third group was Calusa and her less than one year old calf. 


Calusa and her calf
Calusa has been through a lot in the past, having been struck by a boat once. We noted the presence of fresh propeller scars on her back between her dorsal fin and blowhole during one of our field seasons. She was lucky because the wounds were not deep and they have healed and even re-pigmented. She seems fairly healthy, having raised multiple calves through that time and beyond. Many people are surprised to learn that dolphins can be struck by vessels. Dolphins, while fast swimmers, still do not swim as fast as boats can move. It is not frequent, but other populations near coastal cities also have dolphins with evidence of propeller scars. For this reason, we take great care when moving our boat near dolphin groups. We also make a note of the location and heading of animals when leaving an area, moving slowly in the opposite direction until we are a good distance from the group before we speed away.

Permits required
One thing we have yet to mention, is that in the United States, to directly approach marine mammals, you must work under a permit. Because directly approaching (which we sometimes have to do to collect fin photos) can cause change in behavior, it is considered to potentially be what is called Level B harassment (“potential to disturb”). Prior to the start of our work, we had to first obtain a permit from National Marine Fisheries Service. You will note on our dolphin photographs, we list our permit number. This indicates that the photo was collected legally.

Even though we have a permit that allows us to legally “disturb”, we work very hard to avoid this possibility. This starts with the way we approach and handle our vessel around dolphin groups. For example, when approaching, we work to avoid approaching directly. Instead we point the bow of our boat ahead of the front of the dolphin group and work to move parallel to the group. We also maintain a distance when not working to get dorsal photos. In addition, when collecting behavior data, we monitor the actions of the group members to see if we should back off or even cancel the data collection. Dolphins do attempt to communicate with us at times to let us know they want us to back off. They will either chuf repeatedly (a loud forceful exhalation) or tailslap (slapping the tail on the surface of the water). If dolphins perform these, we back away from them, and if they continue, we terminate the follow.

To learn more about what to do if you encounter marine mammals on the water, please see the following site: http://www.nmfs.noaa.gov/pr/education/southeast/

Monday, September 17, 2012

A Late Day Survey

Today once again storms kept us off the water until late in the day. In fact, we finally thought we were getting a break around 13:00, and left the marina, only to turn back after about 20 min due to a fast moving storm that developed out of no where. We finally got on the water again at 15:00 and were lucky to locate a group of dolphins soon after. 

Dolphins move in crazy places
When following dolphins, each of our pilots eventually gets labeled as a hazard driver for some type of hard to navigate space. This can be really shallow water (Florida Keys dolphins love to travel in waters less than a meter in depth, sometimes in about 1/3 of a meter), in channels with lots of vessel traffic or in mooring fields with many sail boats and mooring buoys. 

Dolphins move through shallow waters in the Florida Keys sometimes less than 1/2m in depth

Today we got the chance to deal with all three as Ingrid our pilot worked to keep us in sight of the dolphins and hazard free. The group of dolphins we found today was located first in a busy channel. They then moved across an area so shallow that we could not cross behind them. To keep up, we had to back track, move around a shallow sea grass bed, and then meet up with the dolphins later on the other side. The dolphins then moved into a mooring area, where not only did we have to locate them between boats but avoid running into the boats as the wind worked hard to push us in other directions. We were successful however and were able to collect the data we needed on this group.

Dolphin moving through mooring area in the Florida Keys

Madbob spotted again
An update on Madbob. We have learned since first spotting Madbob this season that the lesions on her skin are not lobomycosis. Lobomycosis is a fungal infection found only in humans and in bottlenose dolphins. And it can be fatal. We are still working to learn what the lesions are the result of. 


We sighted Madbob again today and she appears to be healthy otherwise, traveling, feeding and socializing with other group members.

Sunday, September 16, 2012

The rain didn't keep us off the water today...at least until after we collected some data

Like yesterday, we woke to a radar full of greens, yellows and reds over our study area, and had to postpone our start time to later in the day. On many days we play the waiting game, continuing to check the radar till we see a clearing. We got a small window today about 10:00 (usualy leave time is 6:30) and were lucky to find a group of dolphins before another large storm developed that moved quickly on us and forced us off for the rest of the day. Below are some summaries about some of the individuals/behavior we noted. 

Younger members of the population
We followed many known animals today including Blip. 


Blip a young female in the Key West population

We have followed Blip, shown in the photo below, since her birth. Her mother was Poweraide, who we have not seen now for 2 years and may have passed away. Blip does not have many nicks but she attained the ones she has early on and they have not changed much over time. Blip is not old enough yet to reproduce. Bottlenose dolphin females generally do not begin reproducing until around age 12. But she interacts with many of the Key West animals socially. To identify an individual as a female, we either note the presence of a calf next to an animal repeatedly over time (days, months) or we have to get that information from genetic analysis of the skin. This is how we were able to determine Blip’s gender. We previously sampled a sub set of dolphins from the area near Key West, where we collected a small plug of tissue (about the size of a pencil eraser or smaller) which included the skin and blubber. With this small tissue sample, we could determine the gender of each individual and much more (e.g. who they were related to, and even what they had been eating).

Tails everywhere
Today we encountered a group that was socializing a great deal. When dolphins socialize from the surface you can see a great deal of splashing and fast movement, including throwing the tail around in the air. In some of the photos shown below you can see that similar to the dorsal fins, flukes of dolphins also sometimes accumulate nicks.


Dolphin flukes
In large whales, these nicks are used to identify individuals similar to the way we use dorsal fins in bottlenose dolphins. We cannot use the flukes in this way because we rarely see the flukes exposed, and when it does occur, it is usually very fast as a part of frenetic social activity. In large whales, for many species, there is no dorsal fin. And in those that have one this fin is very small. Large whales however have characteristic fluke up dives which are usually slow and pronounced, allowing researchers to capture photos of them and then use them to identify who was present.

Saturday, September 15, 2012

Back on the Water!

After three days off the water due to bad weather, we finally got a break today and were able to survey this afternoon. The first dolphin encountered was Jpeg, an older female in the population who we had seen on previous days with a calf who was likely born early this summer (judged by size). This time, the calf was no where to be seen and Jpeg was busy feeding. 

Jpeg diving while searching for fish

We were a bit crestfallen wondering if something had happened to the calf. Jpeg eventually moved towards another group of dolphins (a group that was about 100m away in a tight formation), and low and behold, there was her calf. The calf reunited with Jpeg and they continued to travel next to one another for the rest of the time we got to spend with this group. This behavior had been noted on one other day, where we found a large group of dolphins and the Jpeg's calf surfaced instead near another female who is still too young to start reproducing. Eventually the group came into contact with Jpeg who then, as she did today, reunited with the calf and then continued to travel next to it.

This behavior, separation from such a young calf, is rarely noted, but does occur in some cetaceans. For example, in sperm whales, calves are not big enough to dive to the depths where food for this species is located (giant squid). So when the mother dives for food, the calf is left at the surface. This can be a risky position to be in, as killer whales tend to prey on sperm whale calves. To remedy the situation, other females in the group will stay with the calf (“baby sitting”) until the mother comes back to the surface.

In the Key West population, we rarely see such young calves so far from their mothers. In many groups, calves will move away from the mom and interact with others group members or come over to our boat to check us out, but do not move so far that the researchers could not locate both mom and calf in sighting distance of the boat. In addition, we have never seen Jpeg do this with her previous calves. It could be that this particular calf is more gregarious. It could also be that Jpeg is hungrier and needs to break from the group to feed while others are busy socializing (which is the activity that was occurring in the group where her calf was noted, with the calf at the center of a lot of the activity). 


Jpeg's gregarious calf, playing near other adult dolphins

We will continue to monitor Jpeg's behavior, especially because we also believe her last calf may not have survived. It was born in October of 2010, and should have been almost 2 now. Usually calves in our population stay with moms for over 2 years. It is possible that the October 2010 calf had separated from her, but we were not able to document it, or to relocate it in the population yet this season.

Thursday, September 13, 2012

Wind plus storms equals no surveys


Today in addition to high winds we also have nearly continuous storm development (see radar image for this morning below). Because you can never predict when the weather will prevent you from being able to go on the water, a good rule of thumb is to go out on every single good day. It can be exhausting, but if you take a day off on some of your good weather days, you will regret it when you lose time due to poor weather. And you can always be certain you will eventually get days off at some point because of less than favorable conditions. We worked 12 days straight prior to this break. And while we would love to get back out there, it is nice also to get out of the sun for a bit and catch up on other foundation work. 

Radar Image of Lower Florida Keys on morning of 9-13-12


Wednesday, September 12, 2012

Storms have arrived

Last night our first cold front passed through the bottom of Florida, bringing showers and thunderstorms.
Storm approaches the Keys

In its wake a high pressure system was left over Florida which has increased our winds for the next few days.

The work we do on the water is dependent on the weather. When winds go above 15knots, the chop on the water is to a height where we could miss sighting dolphin fins on the water. Because of this, dolphin researchers do not survey in conditions with winds higher than 15 knots. These conditions are not dangerous, and sometimes we can still do other tasks on the water when winds are at that point. For example sampling for fish.

This season we are not fish sampling, so we stayed on land today. Having a day off the water means time for other work including entering data we collect when on the water.


Ingrid and Jacqueline check data sheets and enter data we have collected on the Key West dolphins

Tuesday, September 11, 2012

Smooth Water

Today was another fantastic day on the water with light winds and no storms. This season we have been really lucky and have now broken our record for the most days out in a row (12). Usually, winds increase or storms come in, keeping us off the water maybe every 5th day or so. Below are some of our observations from today.

Fin Changes
We found many dolphins we have seen before today in an area north of Key West where the bottom is sandy causing the color of the water to appear aqua blue. One of these animals was Dog Bowl, who had some new pieces missing from its fin. It is really important to monitor individuals in study populations frequently, so that researchers can monitor changes over time, and continue to be able to re-identify them. Dog Bowl has a couple of changes, but the biggest is the loss of the top of its fin. You can see this by comparing the photos taken today and previously below. 


Changes in Dog Bowl's fin over time. The first photo was taken previously, the second photo was taken today. One of the most obvious changes was the loss of the tip if the fin.

Caught a fish
In the first couple of groups we encountered, dolphins were chasing down fish. Sometimes we can be lucky enough to actually see dolphins with fish in their mouths. And even luckier if we are able to capture the moment with a photo. The action takes place so fast, we can rarely id the fish species, but with a photograph, we can enlarge and zoom in to examine it. Below you can see a common fish seen in the Lower Keys called a ballyhoo in the dolphins mouth. This fish has a characteristic behavior of skipping along the surface of the water when startled or when trying to escape capture. Dolphins in one of the local communities, feed sometimes on these fish by chasing them. We will see the dolphins moving fast just under the surface and the ballyhoo running along the top of the water, trying to get away.



The Birds are Watching
In many areas, birds will keep an eye out for dolphins feeding near the surface because they may be able to swipe the fish. In the keys, when dolphins fish toss (taking the fish captured and then tossing it in the air) they put themselves at risk of loosing the fish to these watchful birds. We see fish tossing mostly in younger animals. Today after a feeding bout, one dolphin started fish tossing and soon after, frigate birds appeared (see photo below), diving to try and get an easy meal. We did not see if they were successful at “stealing” from the dolphins, but later near our boat one frigate caught a fish without the dolphins "help".


Frigate bird flying over head, looking for a meal (photo one) and diving down to attempt to capture a fish (second photo).

Monday, September 10, 2012

Another Tropical Day

Calf at Play 
This is the third day in a row where we have found Jpeg and her new calf in a group. Jpeg’s calf is less than a year old. We can determine approximate time from birth by comparing the size of the calf with the adults. Calves that are only a few weeks old (called neonates) are about ¼ the size of an adult (average adult bottlenose along Florida = 2.5m). They are usually much darker in coloration with lighter colored lines on their sides. These are what we call fetal folds, from when the calf was bent over on its side when in the womb. In addition, very young calves may have bent dorsal fins and flukes (also from being compacted in the womb) and surface very differently from adults and older calves, raising the entire head out of the water when surfacing.

Jpeg and her young calf
Jpeg's calf is less than a year old. Bottlenose dolphin calves greater than a year are >2/3 the size of an adults. This calf (which the interns have named pixel) is full of energy, and spends most of the time we have seen it, playing. Either on its own or with other group members. Yesterday it was playing with another young female (Captain Runaground). Today it played with a calf that was present. Play involves practice chasing fish, rushing through the water at a fast pace around and around other dolphins in the group and leaping around other dolphins. It sort of resembles a young puppy who is trying to get your attention. Calves are usually the member of the group that will approach our boat and circle us, or attempt to bow ride while we work to get pictures of the adults in the group. When near us, they will roll on their side to get a peek of us. They are very curious about everything.

Splitfin 
Splitfin

Splitfin was also noted over the past two days. Animals with split fins have been noted in many dolphin populations. This can occur either through fighting or by getting caught in fishing line. We think that Splitfin likely got this injury through fighting because the tear is jagged. Fishing line injuries can appear straighter (but not always). I am always worried that Splitfin will get in another fight and loose part of the fin, making it difficult to re identify her. But she has remained the same so far for the number of years we have watched her. She has been a mom in the past but does not have a calf at this time.

Blowhole
The blowhole of the dolphin is the nostril. 



This differs from other mammals, who have the nostril very close to the mouth. Many people are not aware that dolphins actually evolved from terrestrial mammals. And in the fossil record, you can see the change over time, where the nostril slowly migrated backwards to the position it is now. This adaptation is a big help for them. With it in this location they  can surface very quickly without stopping movement to breath.

Dress code

While everyone wants to get a tan, working in the sun in the field daily is hard on the skin. For people who make this type of work a career, special care has to be taken to help reduce the chance of skin cancer. We are lucky that there are lots of specialized clothing available now to help, including headgear that allows you to cover your entire face. 

Saturday, September 8, 2012

Day 10

An old friend is sick
Madbob has been sighted each year in the Key West population since 1999. She is a female and has had multiple calves across this time period. Today we saw her for the first time this season. And while she was moving without issue with other members of her group, we noted the presence of bumps or lesions across her body. 

Madbob, a female bottlenose dolphin with cyst like lesions on her skin.
We do not know how old Madbob is. The only way to determine age of a dolphin is to either be aware of the approximate birth year (by following it over time) or by looking at the layers in a tooth (laid down yearly like a tree). 

We will be sending out photos of her to see if other researchers are aware of what this may be. We are hopeful that this does not indicate severe disease and a negative outcome for her.

Male pairs
Hook and Emily (both males, Emily named prior to gender determination) have also been sighted in the Key West community of dolphins since 1999. In fact, Hook was the second dolphin noted in the area on the first day of surveys in February 1999.

What is interesting about this pair is that they are a relatively new male pair. Male bottlenose dolphins in many populations will form pairs that associate fairly regularly. Pairing may be to help one another get access to females for reproduction. Emily for many years was seen almost always with another male (Corona). But a shift occurred about 3 years ago, and Emily began to associate more often with Hook and another local male. Now Emily and Hook are found together most of the time. 

We have no way of knowing what happened in the previous relationship between Emily and Corona. But documenting the change is interesting and important. This information provided more detail about male relationships, and that they are not necessarily permanent.

Fish Tossing
In our last group sighting of the day, one of the dolphins was “fish tossing”. 

Dolphin "fish tossing"
This involves taking the fish in the mouth, usually turning upside down (the dolphin), bringing the head above the surface and then tossing the fish. Dolphins that do this, then will go and pick the fish back up, and many times will repeatedly toss the fish. We see this type of behavior most often in young animals, usually calves, but it can also occur in adults. Some hypotheses for why this may occur, include 1) possibly a need to break apart the tissue of the fish prior to consumption, 2) play and learning for younger animals and 3) teaching of older animals to younger animals.

Thursday, September 6, 2012

Another Great Dolphin Day!

Jpeg and her calf
Old friends
Our first group encountered today was Jpeg and her less than year old calf. Jpeg is one of the dolphin “leaders” near Key West. When in groups, she usually leads group travel.  She is one of the few individuals that can be found associating with individuals from two of our main communities of dolphins. Communities are individuals that associate with one another more often than others. And they are usually divided geographically. There is not always any identifiable barrier between them. And they do sometimes overlap a bit. In the case of the dolphins near Key West, there are multiple communities. All seem to have some “barriers” between them. These are either extreme shallows that cannot be crossed or large deep channels. 


Because Jpeg “runs” between multiple communities, this means that she may be more knowledgeable about how to move between these areas and how to use these areas. This could be an advantage to those that follow her, if she has more knowledge or experience.

Great Weather

Storm off Key West, Florida
So far we have had fantastic weather this field season, breaking our record for the most days straight on the water this week. Usually in the summer we have at the very least thunderstorm build up each day over the island chain, forcing us off the water by noon, where we wait it out and then run back on the water later in the day. Thunderstorms have developed (and even waterspouts), but not near where we have been collecting data. Winds are expected to drop down to 5 knots tomorrow, which means smooth seas and very easy sighting conditions. Most dolphin researchers do not collect data if the wind is beyond 15knots. This is because the size of the waves gets to a point where you can no longer be certain you have not missed seeing a dorsal fin behind a wave, biasing your sighting data.

Area of disturbance
Each day we survey an area where vessel traffic is heavy and unpredictable in direction of movement. We survey this area prior to the arrival of these vessels (early morning) and then at the height of this traffic in the middle of the day. Today during the height of traffic we sighted a group of dolphins just outside of the area. The dolphins decided to move into the traffic area. Interestingly, they immediately began to porpoise, (fast movement where animals actually break free of the surface of the water when they surface to breath) cutting quickly across the corner of the high traffic area, only slowing once they made it to another shallow area on the northern border of this area. There may be many possible reasons for this behavior. But we cannot help speculate if it may have been in response to the need to avoid this traffic.


Dolphins porpoising

Wednesday, September 5, 2012

Mud Plume Feeding


Our first group of dolphins today included 3 adults and 1 calf. The calf spent time running around our boat checking us out while the adults spread out across a shallow sea grass bed (<1m depth) and  performed a really cool feeding behavior called “mud plume feeding”.

Mud plume feeding involves creation of a U shaped plume of mud in the water column. Dolphins do this with a down stroke of the fluke near the top of the sea grass. Sediment on the sea grass then becomes suspended. Same way that it does if you are new to diving or snorkeling and kick near the bottom.

U shaped mud plume produced by bottlenose dolphin. Bottom of U is towards the right side of the photo. Opening at top of U is towards the left side of the photo.

After they finish making the U, they move back toward the opening of the U and lunge through to capture fish.


Bottlenose dolphin lunging through a mud plume to capture fish.

There are some really interesting characteristics about this behavior. When lunging through the plume, they usually (>90% of the time) lunge on the right side. We do not know why this is the case, but the same thing has been noted for bottlenose dolphins that strand feed (stranding on the right side). Dolphins in the community near Key West also usually travel very close to one another (no more than a body length apart usually), unless they are mud plume feeding. When mud plume feeding they spread up to 400m apart. Animals in the group will continue to move with one another across the shallows, but with a lot of space between them. They also usually follow specific tidal states as the tides move across the sea grass flats. So they continue to travel in between creating the plumes.Key West dolphins will perform this behavior for hours at a time. Sometimes stopping to socialize for a short time. Sometimes coming close to one another for a while traveling to another location further on the flat, then spreading out again for more mud plume feeding.

We are currently investigating whether performing this feeding behavior gives the dolphins that use it any advantage when feeding over sea grass beds, when compared to those that don't use the behavior.

For more information about mud plume feeding, please see the link to our paper about it on our web site: http://tropicaldolphin.org/Lewis_and_Schroeder_2003.pdf


Monday, September 3, 2012

Yes we worked on Labor Day

Sightings in areas with High Traffic
Crazy as it seems, collecting data on days when a lot of people are on the water (Labor Day in the US is a major holiday) can be really important. Because we are trying to document how dolphins are being affected by boat traffic in the Lower Florida Keys, today was a great day to see what was happening. Today we found two groups in areas with heavy boat traffic. However, in both of these cases, the dolphins traveled on the edges of the channels, helping them to avoid the potential for being hit by vessels.

In the area with unpredictable boat traffic (see previous blog post) no dolphins were sighted prior to the arrival of tour boats (7:30am) or later in the day when these vessels were in the area (counts made today of 8 parasails, 5 jet skis, and two ski boats within the area while surveying).

In areas without heavy traffic, two other groups were encountered.

How do we know who is in a group of dolphins?
For some species of dolphins, individuals can be readily identified using nicks along the edges of the dorsal fin. These nicks are obtained generally early on, probably when juveniles, from fighting with others in the population. After a certain point, the addition of new nicks decreases significantly. Because dolphins do not re-grow lost tissue on their fins, these nicks can be used to identify individuals, similar to the way we can identify individual humans using fingerprints.

We immediately recognized Danger Pear in our first group using the pattern on nicks on his dorsal fin. Danger Pear is missing the top piece of his fin and has two smaller nicks on the top half. 


Danger Pear

In our fourth group sighting for the day, we noted another male, Columbia, who has a very distinctive dorsal fin. Columbia has been noted in the Key West population since 2000, and can often be found with another large male, Maple Leaf. Today Columbia was in a group with four other dolphins who were extremely active and social, splashing and leaping, but Columbia did not participate in the activity, staying about 30 meters ahead of the rest of the group, moving slowly.


Columbia
Not all dolphins in a group will participate in social activity. Columbia, who refrained from this today, still seemed to be exerting some control over what the group did, as they continued to move wherever Columbia did as he meandered through the region through the mid morning.

Sunday, September 2, 2012

The Good the Great and the not so Great

The Good:
Saturday on the water was eye opening in many respects. Our first dolphin encounter occurred just NW of Key West in some deeper water (deep in our study area is about 20ft or ~6m) where we found a lone juvenile dolphin feeding. 


The dolphin above is performing what we call a "deep dive". When just surfacing to breath when traveling, dolphins usually only expose the blowhole and the dorsal fin. When surfacing between searches for food (sometimes found deeper under the water), dolphins will angle themselves to move more deeply, showing the tail and sometimes the fluke like in the photo above.
In our study area, juveniles are the animals most likely to be encountered alone. They are found in groups with others, interacting, but also go alone from time to time. These animals are also the only ones that are found in “strange” places that older individuals in the population are never seen, like canals in neighborhoods or inside marinas. We think this period for young bottlenose dolphins, may be important for exploration and learning. It may also be that at a smaller size, they may “forced” to look for food in poorer locations (can’t compete with larger animals who could be dominant). Areas closer to shore like those mentioned above have a lot of human traffic and are more heavily polluted, so are less desirable for these dolphins.

The Great:
Our second encounter was with a group of 4 adults who were frolicking on the south side of Key West. This group was socializing, with some individuals attempting to mate with others. We categorize social behaviors as behavior where individuals in a group appear to be interacting in some way. This can involve chasing, and also actual contact. Social behavior we can easily see usually involves vigorous activity and can be aggressive or playful. For example, animals can chase and push one another. They can also bite, ram and hit each other. They tend to get close to the surface when acting this way, creating large splashes, or rolling on the surface around one another. Sometimes they will exit the water entirely. After rolling on the surface with this group for about 20 minutes, one large male began to leap high in the air repeatedly.



Researchers don’t know the exact reason why dolphins leap. But one hypothesis is that if the animals are males, they could be showing off to females in the group (who can judge their fitness in this way). Another possibility is that it could be for other males. Other males may also judge fitness from the display and use the information to determine who to pick a fight with and who not to. 

The Not so Great:
Part of the research we do near Key West involves examining the impacts of vessel traffic on the local dolphin population. To date we have found that dolphins in the study area near Key West vary in their response to vessel traffic depending on the traffic level. Dolphins are affected by vessel traffic in multiple ways. First, they must expend energy to avoid the vessels (increasing time under water, increasing swim speed) and they also spend less time feeding (when avoiding approaching vessels). In addition, the noise from engines can lower their ability to detect sound producing fish which they rely on as part of their preferred prey in many areas. These factors can add up to a significant reduction in energy intake per day. In the area near Key West, where traffic is high but predictable, moving in a predictable direction (e.g. a transit area where vessels move through and do not stop) dolphins will continue to use the area, but do so in a way that allows them to decrease the chance of being struck and decrease the time spent avoiding collision. They do this by spending more time near the edges of the region, avoiding the center where most of the traffic runs.

While the dolphins we study have found ways to continue to use some high traffic habitat in the Lower Keys, in other areas we have begun to see total abandonment. Near Key West, there is another area that has recently become THE spot for water sport activity. In this region, large catamarans bring in tourists, mooring the catamarans for the day. Tourists can then access on the water activities from these spots, including riding jet skis, parasailing or being pulled behind other boats (on skis or floating water toys). These vessels must remain in the same area to be able to quickly get back and drop off/pick up more tourists (~30 min per trip). With ~8 Parasail boats and up to 20 jet skis in this 2km square area, these vessels (which are running at high speed) must constantly change direction to avoid collision with one another. We have begun to document a decrease in dolphin sightings in this area, even though prey availability is high there. We believe that the unpredictable nature of the activity (all vessels frequently changing direction) could be the reason. In fact, it is risky for us to even move through this area in our boat. 



This season, we are continuing to monitor this situation, collecting data when the boats are absent (early and late day) and also continuing to look for dolphins in the area when the activity is high. We want to determine if dolphins come back when the activity is lower, or if they have completely abandoned the area.

While this has been a large concern for us, we have now found that this type of activity has spread to a larger area, previously used frequently by local dolphins. In addition, the types of activity have also increased with the addition of …..how do I even explain this…..jet packs that allow you to fly over the water using the force of the water (see insane photo below). 



We can only imagine what this does to the bottom community of fish and invertebrates (water here is on average 1 m, range 0-10m). Then the noise to other species like dolphins. I am having a hard time understanding how this is called a National Marine Sanctuary.

Stay tuned to see what we continue to learn about this issue, and our efforts to protect these dolphins.