Science versus cool; it’s not all diving with sharks

Written by Dr. Michelle Heupel

We’ve all seen the documentaries about marine biology and sharks. I grew up watching Jacques Cousteau (some of you will have to go look him up, but trust me he was a hero to many kids). Being a marine biologist looked amazing. Jacques and his crew went on these fantastic ocean explorations and saw all sorts of amazing fish. What’s not to love?

Nature documentaries have come a long way from watching Jacques in the 1970s. The video is better and technology has allowed us to get closer to more and more animals, but some of the impressions are probably still the same. I know this because a lot of students contact me and want to tell me right away how much diving experience they have. Too bad they probably won’t get to do much diving if they come work with me…. What did I think marine biology was about growing up watching these programs? Going to amazing places and spending a lot of time diving to study the fish. Boy was I wrong! Now I watch these programs and I think, how are those guys so clean?? When I’m in the field I am very regularly covered in mud, saltwater and fish guts. This is the difference between filming what I do and an average day in the field.


My friend and colleague Beau Yeiser after a day of work in the Everglades.

So what is reality? For many of us we spend much more of our time fishing and servicing equipment than diving. A day of fishing involves a lot of jobs that aren’t very glamorous. Cutting up bait and setting baited lines means you smell like dead fish pretty early in the day. Even wearing gloves can’t save you. I can’t count the number of sandwiches I’ve eaten while my hands stink from bait even though I’ve tried to wash them over the side of the boat. The objective of the day dictates how bad you smell when you get home. Tag and release is pretty good and fairly low on the stink meter, dissecting sharks to collect samples though is not. Dead shark is a pretty interesting smell and one that has to be washed off – how does that smell get into your clothes?

When we’re not fishing for sharks my team and I are downloading data from acoustic receivers that track shark movements. This often involves handling very muddy receivers and scraping off a lot of barnacles. Another pretty unglamorous job. This all sounds pretty bad doesn’t it? I come home stinking of dead fish, covered in mud, fish guts and whatever else I happen to get on myself during the day. They don’t show this version of things on TV unless you’re watching Dirty Jobs. What can I say except that the dirty, stinky gross jobs and long days on the boat are the best part of my job. This is really getting in and doing science. Cleaning the junk off receivers so we can get the data and see where our animals went is really cool even if it makes a mess. Learning new things no one else knows yet is exciting.


The glamour of fishing – what you can’t see is one of my students holding onto my feet (so I don’t fall overboard) and the bruises on my ribs.

So what about all that diving I thought I’d be doing?  I’ve spent a lot of time studying coastal sharks in the tropics. The water is so brown and muddy you can’t even see your hand in front of your face underwater, let alone any fish. These days I do a lot more work on coral reefs. We can definitely see in the water, but unfortunately when we go diving we have a very specific job to do. When we download the receivers here the dives are short and targeted, not a lot of time to look around and be in awe of the reef. We do see sharks on some of these dives though and it’s always a treat to see them.


Sometimes a shark swims by like this blacktip reef shark. It’s not very close, but at least we saw it.

So, science versus cool? Well I’m a nerd so I think science is cool. A day getting dirty and smelly on the boat is still better than a lot of other jobs I could have and I really do love it. This is a great career, just don’t count on staying clean or getting to dive all the time and you should be fine.


Cat Island- Science in a Sharks’ Safe Haven

Written by Lucy Howey

Gill Club members Lucy Howey, Brenda Anderson and Debbie Abercrombie just wrapped-up another successful oceanic whitetip field season in Cat Island, The Bahamas. The oceanic whitetip was once one of the most numerous large vertebrates on the planet, but unfortunately, overfishing and demand for their fins have severely declined their numbers. Beautiful Cat Island is one of the last known places in the world that oceanic whitetips can be found with such reliability. Our team is incredibly fortunate to have the opportunity to work in Cat Island and to be so welcomed by its kind people. The sharks are lucky too; The Bahamas has been a shark sanctuary since 2011, meaning there is no trade or landing of sharks within its EEZ. Longlining is also illegal and the effects of this legislation are evident – sharks are abundant – making it a shark scientist’s dream study site. We’ve dedicated such a large amount of energy and time to this project and it is amazing to watch its evolution over the last four years. In 2011 a group of us decided to do this project with one small center console boat, no bait freezer (not pleasant), small rations of peanut butter and jelly for lunch and absolutely no funding, and now in 2014 we’ve captured almost 100 oceanic whitetips and satellite tagged 83. In addition to the tracking project, this year we were also working on a reproductive study, an accelerometry study, a genetics study, and a stable isotope project, concurrently. Definitely an exhausting trip, but it was scientific collaboration at its finest. Every shark, caught on circle hook and baited polyball, is carefully tied to the side of the smaller work-up boat, measured and sexed. DNA and stable isotope samples are collected from a fin and muscle, respectively. A number ID tag is attached to the dorsal fin in the event that a SCUBA diver sees the shark again, and the satellite tag is placed with a small plastic dart into the dorsal musculature. Lastly, blood is taken from the caudal vein for a reproductive hormone study and, if the shark is a female, an ultrasound is completed to determine pregnancy status. This year collaborators from the University of North Florida were able to positively identify pregnancy in 13 mature females. When coupled with tracking data, the ability to identify the movements of pregnant females is an extremely exciting prospect. Since we use pop-up archival transmitters (PSATs) we will have to wait until the tag detaches from the animal (in this study between 8-10 months) and transmits its data through the satellite system before we have any insight into the sharks’ behavior. In addition to migration data, the X-Tags that we use also collect ambient pressure (depth) and temperature data every two minutes during their deployment. When studying migratory species it’s important to examine not only where they move but how they move. The depth data are where the “real” conservation implications lie. At what depths are these endangered sharks spending their time, and how does that information correlate to fisheries data? How can the biological and environmental data that we’ve collected be used for oceanic whitetip preservation and management? Now that the gear is stored and the samples are labeled and catalogued, these are the types of questions we will spend the next year working hard to answer, truly a small price to repay the amazing creatures that allow us share to their world for two weeks every May.

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Photos by: Stan SHEA/BLOOM

This project is generously supported by The Moore Charitable Foundation, Stony Brook University, Microwave Telemetry, Inc., The Cape Eleuthera Institute, The University of North Florida, The Save Our Seas Foundation and The National Institute of Polar Research.

Rays need love too

Written by Dr. Michelle Heupel

I learned something new last year. I love learning new things, but I sort of wish I didn’t have to learn this. The International Union for Conservation of Nature (IUCN) has something they call the Red List. This is a list of all the species of plant and animal (or as close as we can get to all of them) and their conservation status. Scientists volunteer their time to assess species and the results are listed with IUCN. An analysis of the IUCN data for sharks, skates and rays last year revealed that 5 of the 7 most threatened families were rays, not sharks. And on top of that there are more threatened ray (107) than shark (74) species. Wow, who knew?

This result was published in a paper by Nick Dulvy and a slew of us who contributed to the listings ( I think all of us were stunned to see that the rays were so much more threatened than the sharks. So what does this mean in the real world? It means we have been catching and removing a lot of rays without realising the damage we are doing to their populations.

imageA figure from Dulvy et al. 2014 indicating the families of greatest and least conservation concern.

How did this happen? Great question. Skates and rays are not as well studied as sharks. Maybe they aren’t as cool? Maybe they aren’t as obvious? The reasons why vary, but the reality is not many people have or do study them. One reason these species aren’t well studied is that they have never really been the target of fisheries. They are typically taken as bycatch, meaning they just come up in the nets or lines when fishers are trying to catch something else. Historically bycatch species were usually not well studied because they weren’t high value or important species. Many of the rays that are killed each year may not even be harvested for food. They may simply be caught in nets, die during the fishing process and get tossed overboard. This means we haven’t really understood how many were being affected by fishing. Another, and possibly very important factor, is money. It is easier to get research money to study a target or high value species, it is much more difficult to get money to study bycatch, although that is changing as we grow more and more aware of the importance of bycatch species.


A giant shovelnose ray, one of the species with high value fins.

We haven’t done a good job of keeping track of what is happening with rays for a variety of reasons. In the meantime some rays have become pretty important to fisheries. For example, sawfish and guitarfish have some of the most valuable fins in the shark fin market. This means there is a lot of money to be made which provides incentive to fish these species, especially guitarfish. Sawfish, unfortunately are one of the groups that is worst off. These are amazing animals. A slightly flattened shark with a hedge trimmer for a nose! They use their nose, or saw, to whack fish and stun them or grub around in the mud for food. They are truly bizarre and beautiful. This really cool saw, however, means they get tangled up in nets very easily. Fishermen in the Gulf of Mexico used to kill them to get the out of their nets. And then there are the people who want the saw for a trophy. It’s surprising how many sawfish saws I have seen hanging on walls in bars, marinas, etc. When we viewed our current house the previous owner had a sawfish saw hung on one of the walls! All 5 species of sawfish are listed by the IUCN Red List as Endangered or Critically Endangered and their populations have declined around the globe. Australia is one of the remaining strongholds for many of these species, and in the US the smalltooth sawfish was the first elasmobranch included under the Endangered Species Act after their populations had declined by 95%. Recovery from such a large decline will be very long.


Dr Colin Simpfendorfer releasing a smalltooth sawfish in the Florida Everglades.

So, we need to start doing a better job conserving ray species. They need to become a priority research area. We know very little about even the basic biology of many species and under the current circumstances that isn’t good enough. We can, and should, do better. So while campaigning for better conservation and management of sharks spare a thought for the rays. They need our help too.

White sharks in the Northwest Pacific Ocean

Written by Heather Christiansen

White sharks are one of the most protected shark species globally. However, unlike other well-known aggregations in the Northeastern Pacific Ocean, South Africa, and Australia, relatively little is known about white sharks in the Northwest Pacific Ocean. Unfortunately, this region also has little white shark specific protection measures in place.

mapMap of study region

 White shark’s behavior can vary depending on where they live. In order to determine the best way to protect white sharks in the Northwest Pacific Ocean it is important to gather details on what habitat they are using, if habitat use varies seasonally, how large and fast individuals grow, migration patterns and information on reproduction (mating, birthing areas, number of young per mother etc).

In order to collect as much information as possible on white sharks in the Northwest Pacific Ocean we worked with regional scientists and gathered all records and observations of white sharks in the area since 1951. Records were obtained from a variety of sources including scientific literature, newspapers, news websites and museums. There were a total of 240 records of white shark occurrences from Russia in the north down to Vietnam in the south. Individual sharks weighed between 35 to 5578 lbs (about the weight of an average pickup truck!). The size of the white sharks were wide ranging from young of the year at just over 4′ total length (measured from it’s snout to the end of its tail) up to the largest white shark on record at 19′ 9″ total length!

White Shark size comparison

Size of the largest and smallest white sharks in this study compared to the size of an average 10 year old girl.

We found that white sharks live in this region year round, but were absent from northern waters (near Russia and Republic of Korea) during autumn and early winter and southern waters (near China, Taiwan, Vietnam, and the Philippines) in July and August. White sharks have been recorded in a wide range of water temperatures, but this data indicates a preferred temperature range.

Based on the number of observations over the study period we estimated the trend in the relative abundance of white sharks in this region. We determined that the population was relatively stable until recently (approximately the last 10 years) where the relative abundance has started to decline slightly. We need to be careful interpreting these results though because they are based on reports from observers and not focused monitoring. These results indicate that there is a regional population of white sharks and further monitoring is required to estimate the number of animals living in the region.

One of the most interesting results of this study was the number of pregnant females recorded. There have only been 26 pregnant white shark females reported worldwide, 11 of which were found in this study. We were able to estimate females in this region are pregnant for 20 months and had up to 10 pups per litter.  Pregnant females were also recorded in more southern waters around Taiwan and Okinawa early in their pregnancies and around mainland Japan towards the end of their pregnancies. We don’t know very much about the reproductive strategies of white sharks worldwide so this study gave us a unique look at what pregnant females are doing. Additionally, we recorded young of the year white sharks in four countries indicating they may be using multiple countries as nursery areas.

Created with GIMPCreated with GIMP

Left: ovary from early term pregnant white shark, Right: egg cases from same shark  approx. 4″ long

This study provides important information that helps fill in gaps in our knowledge for white sharks in the Northwest Pacific Ocean. This study will be used to guide future research and determine what conservation measures are necessary to protect white sharks in the Northwest Pacific Ocean. Formal monitoring programs both nationally and internationally will help improve biological knowledge and assess future population trends.

If you would like more information on the observation records of white sharks in the Northwest Pacific Ocean you can look at the full publication here:

Christiansen HM, Lin V, Tanaka S, Velikanov A, Mollet HF, et al. (2014) The Last Frontier: Catch Records of White Sharks (Carcharodon carcharias) in the Northwest Pacific Ocean. PLoS ONE 9(4): e94407. doi:10.1371/journal.pone.0094407

available at:

Gizmos and Shark Science

Written by Dr. Michelle Heupel

I love gizmos. There are so many cool machines in the world now that make life more interesting and entertaining, and in science they let us do things we couldn’t even have dreamed of in the past. In this post I want to tell you about some of the cool tools that we can use to help learn about what sharks are doing.

Shark movement:

This is my area of research and we have some of the best gizmos around. If we want to track the long-range movements of sharks the go-to gizmo is the satellite tag. This comes in two types. One that gives positions every time the shark comes to the surface and one that records data to send back to you later. Heather Marshall is using both of these tags if you’ve seen her posts. The first tag is one that you attach to the dorsal fin and has a small antenna on it. The unit has a sensor on it that tells it when it is out of the water and then it sends a signal to the satellites to say “here I am!”. Researchers use these tags on all kinds of animals, not just sharks, including turtles and marine mammals. The second satellite tag is what we call a pop-off tag. It looks like a microphone and gets attached to the back of the shark. This tag records the light level so it can tell when it is day or night, has a depth sensor to tell how deep the shark was swimming and a temperature sensor. It records data for a programmed time and then like the name suggests it pops itself off the shark, floats to the surface and sends back its data. These tags are usually programmed to record for up to a year. We can use the data from both of these tags to see how far a shark has moved and learn about their diving patterns.

Blog Photo

John Tyminksi from Mote Marine Lab releasing a blacktip shark with a pop-off satellite tag off the coast of Florida.

If you want to track a shark that lives in a relatively small space then you can use passive acoustic tracking. This is mostly what I do. We put listening stations (or receivers) in our study sites. Then we go out and catch some sharks and put a transmitter in them. The transmitters send out an ID code for the shark and can also report temperature and depth. The receivers sit and listen for a shark to swim by and record the information from its transmitter. This way I can track where my sharks are for really long periods because acoustic transmitters can last for years, some of them last as long as 10 years.

The earliest tracking of sharks was done by active acoustic tracking where you attach a transmitter and then follow the shark in the boat with a hydrophone (an underwater microphone) for as long as possible. We still do this if we want to know detailed movements of sharks. It is hard work though and most people can only last a few days before the track is terminated. This means we only get short bits of information about movements of the individuals tracked. However, this method gives really detailed information about what the sharks are doing and in that respect is better than some of the other approaches depending on your research question.


Understanding how much energy it takes for a shark to swim or how often they really eat are difficult questions to answer. People have been thinking about these things for a long time. To test the energy needs of sharks we have to put them in a tank, make them swim against a current and then measure how much oxygen they use from the water. There are some new approaches coming though that might help answer some of these questions. Chris Lowe, (California State University Long Beach – look him up!) did an interesting study where he fitted a transmitter to the tail of a shark to see how many times the tail moved. Kind of like a pedometer you can buy to count how many steps you take, except for sharks. New transmitters are coming out that can tell us about the acceleration of sharks. This tells us when they make burst speed swimming movements or other behaviours. These tags have been used to look at nurse shark mating behaviour (Nick Whitney, Mote Marine Laboratory) and to look at energy needs of great white sharks (Jayson Semmens, University of Tasmania). Other researchers are trying to build transmitters that will tell us when sharks eat. All of these tools and toys tell us a little bit more about what sharks are doing out in the wild.

Technology keeps evolving and I have no doubt we will keep seeing cool new gadgets and gizmos not only in our daily lives, but also in the daily lives of sharks. We have so much more to learn and I can’t wait to see what the next set of gizmos can tell us.

Top 10 things you didn’t know about white sharks

Written by Michelle Wcisel
1) They are picky eaters

South Africa is an area of high whale abundance, and when a whale dies, the white sharks come rushing in!  Recent research highlighted that “sharks generally exhibited an initial preference for feeding on the whale caudal peduncle and fluke, before moving to feed along the rest of the body” (Fallow et al. 2013).  Sharks will feed for hours on a dead whale carcass to the point where they “would simply bounce off the carcass and slowly sink underwater.”  Talk about gluttony!!

2) They are 
warm-blooded (kind of)
White sharks are “lamnid sharks” which have a unique system called a ‘counter current heat exchange,’keeping their body warmer than the outside conditions by +/- 10-15 C°. So if a white shark is in 9 C° water, its body temperature will be +/- 19-24 C° and so on.  The generator of all this heat comes from the long muscles running down the length of their bodies, which charge a core of ‘white muscle’ ready for quick bursts of energy even in cold environments, which is why they are the apex predator of our temperate seas. Researchers call this, “heterothermy”.

3) They can 
heal themselves
Many white sharks have been shown to heal themselves for minor wounds, but there has never been such a severe case as ‘Prop’ – a Gansbaai shark that was nearly split in half by a boat propeller.  In 9 months, this shark’s wounds were entirely healed (see the video: ).

4) They like it 

White sharks have never been filmed mating, but we have a good indication that there are no roses and poetry involved!  We have seen several female white sharks with bite wounds along the gill areas (above!)

5) They don’t have passports

Gansbaai white sharks have been documented in Mozambique, near Marion Island, Madagascar, even western Australia!

6) Where they 
give birth

You don’t know this about white sharks because NO ONE knows this about white sharks.  White sharks around 1.0-1.7m are considered young of the year and are seldom documented along the South Africa coastline.  Internationally, YOY white sharks are regularly found within the southern California bite in summer time.

7) They save lives

Problem: Hospital acquired infections kill 99,000 people/year.  Solution: Shark skin?  Fine, this isn’t white shark specific, but it turns out that shark skin’s unique design makes it almost impossible for living organisms to attach and grow on its surface (which is why you never see a shark covered in algae – for example!). Biomimicry engineers have developed shark skin surfaces to implement in hospitals, cutting bacteria growth by over 80%!

8) They have blue eyes

No “black dead eyes of a killer” here!  They actually have beautiful baby blues.

9) They 
like calamari

White shark stomach contents off of KZN found cephalopod beaks in 24 white sharks.  Of the 24, small 2.5m sharks had “mesopelagic and oceanic prey with few coastal taxa.

10) They can get massive!

Check out this well over 5.0m female next to a 4.5m cage….ay caramba!

Sharks and Storms

Written by Dr. Michelle Heupel

Stories about animals reacting to storms are not uncommon. We’ve all seen news reports of dogs running away before earthquakes suggesting they knew it was coming. This is really interesting, but dogs are mammals and considered to be fairly smart – can fish, which are not considered to be terribly bright, also sense these kinds of events?

This question is one I have had the luck (or misfortune) to test several times now. I have been tracking the long-term movements of sharks in coastal systems for many years now and one of the consequences of working in the tropics is we get tropical storms that come ashore. The first time we got a glimpse into how sharks respond to tropical storms was in 2001 when Tropical Storm Gabrielle made landfall in central Florida. I was tracking a population of juvenile blacktip sharks in a small bay and was in my third year of tracking their movements. Blacktip sharks in this bay are resident for 6-8 months during the summer before migrating south for the winter. They typically do not leave the area until migration time, and they definitely don’t leave in large groups.

As Tropical Storm Gabrielle approached the coast we didn’t have enough time to remove our array of acoustic receivers (listening stations) from the water so we left them in and hoped for the best. When we downloaded the data a couple of weeks later (luckily all of the equipment was still there) what we found was that all of the sharks we had been tracking left. Not only did they all leave, but it turns out they all left 7 hours before Gabrielle hit the coast! This was an amazing finding and one never recorded before. Digging further into the data we found that the sharks most likely responded to the decrease in barometric (air) pressure that comes along with these big storms. This means these small sharks could sense this storm coming and swam out into the deeper water of Tampa Bay to get out of harm’s way. What was even more amazing is that after the storm had passed and things in the bay returned to normal all of our tracked sharks came home and went back to swimming around the area like normal.


                                                            A juvenile blacktip shark tracked in Florida.

So it looks like sharks can sense big changes in their environment, like tropical storms, similar to the response of dogs to earthquakes mentioned above. But was this a fluke? Is it unique to this one species? The answers to those questions were answered thanks to a much bigger storm occurring half way around the world. In 2010 I was tracking a variety of sharks in north Queensland, Australia. While we were tracking sharks in this region we experienced Tropical Cyclone Yasi. This was an enormous Category 5 storm (the highest category packing 130 mph winds) that spanned most of the Queensland coast and came ashore not far from our study site. What we found this time was that 4 of the 5 shark species we were tracking left the bay. At the peak of the storm all of the acoustic receivers we use to track the sharks stopped recording data. This made it look like everyone had left the area, but really the wave action was so strong the units could no longer hear the shark transmitters over the rushing waves. Once the receivers could hear again it was clear that one group of sharks had not left. All of the blacktip reef sharks we were tracking had stayed in the bay during the storm. This species is typically found in reef habitats and was living on an inshore reef area inside our study site.


Category 5 Tropical Cyclone Yasi’s path to the Queensland coast. The yellow box shows our study site.

Why would blacktip reef sharks stay during this huge storm while all the others left? This is a difficult question to answer because all of the sharks we were tracking were of a similar size, so there was no obvious reason for them to react differently. The one difference between the sharks we were tracking was that all the sharks that left were coastal. They can live in bays anywhere along the coast, so if they leave and need to find a new bay they can do that. Blacktip reef sharks, however, need reef habitats to live in. So maybe the blacktip reef sharks stayed because they didn’t want to risk not being able to find another reef. In the end most of the coastal sharks came back to the bay, like we saw in Florida and went back to their home areas. The question still remains though, why exactly didn’t the blacktip reef sharks leave?


A blacktip reef shark, the shark that didn’t leave when the storm came.

Studying the response of sharks to storms has been something of a happy accident and I feel fortunate to have had the chance to find out how sharks react to these events. It’s great to know they have good instincts and can get out of the way when a big storm is coming, and nice to know that when the sun comes back out that they can find their way home. We have a long way to go before we fully understand all of these behaviours, but this is a very interesting start to that process.

If you’d like to learn more about studies on sharks and storms you can take a look at these two publications:

Heupel MR, Simpfendorfer CA and Hueter RE (2003) Running before the storm: blacktip sharks respond to falling barometric pressure associated with Tropical Storm Gabrielle.  Journal of Fish Biology 63: 1357-1363

Udyawer V, Simpfendorfer CA, Chin A, Knip DM, Heupel MR (2013) Variable response of coastal sharks to severe tropical storms: environmental cues and changes in space use. Marine Ecology Progress Series 480: 171-183

If you can’t find them online you can request free copies of these papers from James Cook University here: