Expedition White Shark

Below is a list of frequently asked questions in regards to catching and tagging great white sharks…

Dr. Domeier and other white shark researchers have used satellite tags in the past that do not require the shark to be captured and lifted from the water, why is Dr. Domeier using new tags that do require handling the shark?
The older generation of satellite tags could only track a shark for one year at the very most.  Once we learned that adult white sharks have a migration pattern that exceeds one year, he turned to the newer SPOT tags.  The SPOT tags he developed with the tag manufacturer will track individual adult white sharks for 4-6 years. This technology is ideal for looking at large scale long term movement patterns and will help reveal the entire migratory patterns of these sharks. This is especially important for tracking the mating and birthing areas for the females which have a 2-3 year migration cycle.

Is the data important?
The more we know about these sharks that more we can protect them, and there is still much that we don’t know. This is especially important since they cross international boundaries and we are dealing with mating areas, pupping areas and nursery grounds. These are particularly sensitive areas that need to be protected.

Does it hurt the sharks to drill into their dorsal fin?
Sharks do not have the same sensitivity to pain as humans.  The sharks do not even react when the tags are being attached to their fins.

The sharks you are tagging are huge; can their own weight harm the sharks while they are on deck?
We know that whales can sometimes incur internal injury when they get stranded on the beach, so this issue was a concern.  Fortunately sharks are much smaller than whales, and we started out by testing our methods on relatively small sharks.  Our early success allowed us to slowly start working on larger and larger sharks and likewise found that they go through the tagging process without serious injury.  We could run into problems if we captured a female with a late-term pregnancy, but we target females at sites and times when they are not pregnant.

What are your biggest concerns when catching the shark?
The most important thing is to keep a good supply of fresh seawater flowing over the gills and return the shark to the water as soon as possible.  As we gain experience the total time we must keep the shark out of the water has been cut in half.

After being released do the sharks flee the area right away?
Fortunately we have a lot of previous experience with these sharks so we know the general behavior patterns.  We have not found the capture and tagging to alter the migratory habits of these fish.  Instead, the SPOT tagging has allowed us to answer research questions that we could have never addressed using older technologies.

What is tonic immobility and how does it work?
Tonic immobility is a trance-like state experienced by sharks when they are placed and held upside down.  It is not know why this phenomenon occurs, shark researchers often use tonic immobility to their advantage, so they can safely handle live sharks.  Once placed upright, the sharks snap out of tonic immobility and resume normal behavior.

How long will the tags transmit data for?
Our SPOT tags are designed to transmit from 4-6 years.

How do you know that the sharks survive?
We know the sharks survive because the SPOT tags can only transmit to orbiting satellites when the shark is swimming at the surface.  If the sharks did not survive the tagging method then we would not get any signal.  We’ve gotten signals from all of our tagged sharks.

While you were tagging one of the sharks I noticed blood coming out of the shark’s mouth when you put the water tube in its mouth. Can you tell me what this is from?
It is unavoidable that the hook will make a puncture wound in the mouth.  The seawater from the irrigation hose mixes with the blood from the hook wound and the resulting red water looks like a LOT of blood, but it is mostly water and actually a trivial amount of blood for such a huge animal.  These sharks are quite aggressive towards each other and they routinely inflict far more damage to each other than our hook.

What is the brown, sometimes shaggy or stringy looking stuff that can be seen on the fins and bodies of the sharks?
Those are a type of external parasite, most likely a parasitic copepod.  They are very common, not only on sharks, but on other species of fish as well.  Just imagine your dog without a flea treatment! If you would like additional info on parasitic copepods click here.

For more information on our comprehensive white shark research program click here