National Geographic
Menu

Shark Tagging & Tracking: Separating Fact from Fiction

For several years now, I have been using electronic tagging to study the movements and behaviors of sharks. You can find out more about this research HERE and watch a video HERE.

1397354_10152193972993265_1324283571_o

 

I previously wrote about the state of electronic tagging and tracking marine animals. However, recently there have been a lot of myths, false criticisms and misinformation being spread about shark tagging and tracking research. Here I list and address some of these common myths or misinformation and use examples based on my personal experience and research.

 

 Does tagging cause shark’s pain?

 No. Recent research shows that the sensory receptors (known as nociceptors) responsible for feeling pain in humans and other mammals are not present in the sharks studied to date.  Moreover, many tags are attached to shark fins, which have no nerve supply. The type of response to injury that sharks exhibit is unconscious reaction or reflexes, not pain-induced response. For more information on sharks and pain, please click Here & Here

 

Do publishing shark movements tell fishers where they are and make them more vulnerable to exploitation?

No. The reality is that fishing is everywhere. Except where they are already protected and properly managed, there is no place where sharks are safe from fishing (see image below). The fishing industry is way ahead of scientists in terms of knowing where the sharks are. Sometimes, the fishing industry even hires oceanographic data analysts to identify potential fishing “hot spots” in real time, reporting these locations to fishers at sea. It is scientists that are playing catch up and the tracking data generated is used to help managers make informed conservation decisions (Excerpts from HERE). In addition to publishing our data in scientific reports, our lab website also provides an online interactive google earth map, allowing the public to track our sharks. To us, the tracking data not only helps conservation management, but the educational benefits of the online tracking helps generate public awareness and support for shark conservation.  Our online tracking system does not provide GPS coordinates and also utilizes a time-delay to prevent the possibility of someone trying to find and catch the tracked sharks. That said, at times it is necessary to keep some information “privy” (i.e., shared only with regulators) such as the location of a specific unknown aggregation site, but such instances are uncommon. 

 

Global Analysis of Fisheries by Watson et al. (2012). The study revealed that fishing fleets now fish the worlds' oceans. Fishing effort have increased by an average of 10-fold (25-fold for Asia) since the 1950s

Global Analysis of Fisheries by Watson et al. (2012, Fish & Fisheries). The study revealed that fishing fleets now fish the worlds’ oceans, now including the arctic and antarctic oceans. Fishing effort have increased by an average of 10-fold (25-fold for Asia) since the 1950s.

 

Does attaching tags to shark fins cause permanent damage that can influence shark survival?

 No. While tags mounted to fins may cause fin irritation, drag or even result in fin damage, there is no evidence to date suggesting that it will impact the survival of sharks. In fact, most sharks swim around with severely deformed or damaged fins as a result of fighting and in many cases mating, where males bite females on the fins to enable mating (see image below). Some of the damage can be extreme, but sharks are also well-known for their remarkable “healing power”, and shark fins, like fingernails, can regenerate to a large extent. Many tags that are attached to shark fins are non-permanent; some are programmed to detach, some are created to corrode off or fall out, and in some circumstances the shark fins can heal around the tag, forcing the tag to ‘migrate’ out the fin. Ideally, tags should be engineered to have the least impact on the animal’s health, programmed to release or designed with materials that cause the tag attachment points to corrode and/or detach at some point. While each research team uses different methods (and therefore each researcher is the best person to comment on his or her own tagging work), our fin-mounted tags are attached with medical-grade, bio-compatible, titanium that ensures it will corrode (usually in less than a year). Like many other research groups, we also coat our tags with anti-fouling paint to prevent organisms from growing on the tags. I believe that the potential negative effects on the sharks from tags are minimal considering the research and education benefits it provides, which will help protect these threatened species. For more information, please read our paper on satellite tags, which further discuss the potential negative impacts of tags on sharks

Oceanic Whitetip with pilot fish_Neil Hammerschlag

A healthy female oceanic whitetip shark cruises by with a missing dorsal fin. The fin was probably bitten off by a male shark during a natural mating event (Image: Neil Hammerschlag)

 

Can shark tracking data help with shark conservation?

Yes. In many cases, policy makers have been unable to conserve threatened sharks due to the lack of appropriate data on shark movements and behaviors, data which tagging and tracking work can provide. Moreover, Vessel Monitoring Systems (VMS) that track the movements of fishing boats through satellites in combination with real-time tracking of sharks can be used by management agencies to set protection boundaries around shark aggregations or insure that fishing vessels are not moving into core areas the sharks are using. Some of the other conservation benefits of tagging and tracking data include:

  • Revealing key areas to prioritize for protection, such as mating, feeding or nursery grounds.
  • Determining sites where sharks are most likely to interact with fishing activities
  • Evaluating whether marine protected areas are sufficiently sized or placed to adequately protect sharks
  • Predicting the impact of climate change on shark movement and distributions
Schematic of a Vessel Monitoring System (VMS). The system can be modified to keep track of fishers and sharks simultaneously to coordinate and enforce conservation of threatened species

Schematic of a Vessel Monitoring System (VMS). The system can be modified to keep track of fishers and sharks simultaneously to coordinate and enforce conservation of threatened species. Image from http://www.marineinsight.com

 

Do electronic tags interfere with shark electro-magnetic senses?

No. There is no scientific evidence that satellite tags interfere with shark senses. Martin (2003) wrotedespite the phenomenal electrosensitivity some elasmobranchs have demonstrated under laboratory conditions, the functional distance of a White Shark’s — or other elasmobranch’s — ampullae of Lorenzini in the wild may be limited to very short distances (say, on the order of a foot [30 centimetres] or less).  So, unless the power pack of an electronic tag is strapped to the underside of a shark’s snout, it seems unlikely that the tiny energy output of an Archival satellite tag would significantly affect a shark’s ampullae of Lorenzini or behavior.” For further discussion, click HERE.

 

Is shark tagging a science?

No. Shark tagging is a research technique and tags are a research tool. It is no different than a hammer for a carpenter. The scientific process includes designing a project to test hypotheses or address study objectives. In fact, it is quite easy for anyone to purchase tags and attach them to a fish; however, that does not mean that the tagger is a scientist more than a person hammering in a nail is a carpenter.

 

Is shark tagging & tracking essential to study sharks?

 No. Electronic tagging is a relatively new scientific tool. Depends on the question being addressed; some questions do not require tagging, while others do. For example, over the past 10 years I have studied and published on the hunting behaviors of white sharks in South Africa based purely on observations from a boat. However, our lab has satellite tagged over 100 tiger, bull and hammerhead sharks to address a variety of research questions that have required tagging. In the end, tags are just one tool in the toolbox available for the study of wild sharks.

 

Is there an authority that reviews and provides permission for scientists to tag sharks?

Yes. Tagging is only implemented after a long process of proposals and approval. First, the study needs to be funded, which requires writing a proposal that is first reviewed and assessed by a funding agency. Next, the study often needs to be approved by the Animal Welfare and Care Committee of the researcher’s institution. Finally, the study requires permitting from the government in which the study is being conducted. Along each step of the process the researcher needs to justify the study need, significance and methodology taking into account animal welfare needs.

 

Are scientists and engineers working to improve tagging technology and practice?

Absolutely. Scientists and engineers are constantly working together to improve tag performance, power, data acquisition, sensor capabilities, data acquisition attachment techniques as well as reduce tag size, drag and improve animal welfare.

Comments

  1. Roy Mulder
    BC Canada
    March 25, 1:27 pm

    Tagging can be invasive if located incorrectly. A post mortem of this giant Pacific skate revealed the tag location in the wing as the likely cause of death. The area of the floy tag was infected and likely a contributor to the death of this beautiful creature.

  2. Martin Graf
    san diego
    March 24, 5:42 pm

    Great article by Neil. He hit the nail on the head, when he mentioned that anyone with an internet connection can make comments and assumptions.

    I’m no marine biologist, far from it. I actually failed biology miserably. The things I do know, I know from observing sharks, specially Great Whites, for 13 years and during those years I’ve learned that a lot of “everyone knows that….” is actually wrong.

  3. Steven F
    San Diego
    March 13, 9:24 am

    This article is another example of why we must think for ourselves and not go by what someone with a credential behind his name states as fact. These “facts” as Hammerschlag calls them, are massively assumptive, rely upon a select group of publishings, and dismiss other findings completely. That doesn’t mean Neil is a bad person, but it is upsetting when you see people such as Barbara Biggerstaff (above) being miseducated by reading stuff like this. ANYONE can get a degree then publish something. That doesn’t make it fact. Nat Geo makes money off shows which exploit animals, even protected species, so we can’t trust an article posted on their site based upon what used to be a trusted name; National Geographic.

    • Neil Hammerschlag
      March 13, 2:32 pm

      Steven

      Thanks for your comment. What I have done is noted the assumptions and concerns that many uninformed or misinformed people have and then stated what is known and unknown. Not any one can get a degree…this is wrong and rude. Advanced degrees are earned. Given that now days anyone with an internet connection and keyboard can make claims and statements, it is important that people have access to credible information. The training that an individual has allows someone to judge the level of their knowledge on a subject. Moreover, rather than simply dismiss the facts, it would be more beneficial if you can provide your factual information showing that contrary to what I have provided. You have not provided anything constructive to the conversation and encourage you to do so.

  4. Kathy C
    March 12, 6:09 pm

    The comment that scientists notice a jolt by a shark when tagged doesn’t surprise me. Any animal capable of feeling ANYTHING would experience something, anything, when something is attached to them. As to whether it affects the shark’s survival, that is something to think about. Perhaps there is another way to tag these animals without compromising their survival capabilities. Keep us posted!

  5. Arthur Thompson
    Australia
    February 5, 1:34 am

    Perhaps you should send the link for this article to Western Australian Government Premier, Colan Barnett, who instead of solving W.A.’s Shark issue using this great technology he is choosing to put out drum lines and catch sharks and any over 3 metres in length are shot repeatedly until dead and dragged out to sea to be disposed of :(

  6. steve brown
    cali
    February 4, 8:33 pm

    nothing wrong with tagging sharks it seems to me they dont feel pain,what needs to be done is all countys need to stop killing them before its to late

  7. Chris Hartzell
    California
    February 1, 2:17 am

    Neil is one of few researchers whose integrity is unquestionable and I have the highest respect for his work. However, being involved in the shark research debate for quite a few years now I feel compelled to add comments to his article which I feel should be addressed.

    Does tagging cause shark’s pain?
    No. But there are more and more first hand experiences with researchers who are witnessing ‘shudders, jolts, and reactions’ by sharks during different kinds of research (including tagging of fins) in which even the researchers are questioning if there may be a level of “feeling” that is not fully understood yet and is beyond just a reaction or reflex. What is unfortunate is I am hearing these researchers acknowledge it informally, but refuse to acknowledge it otherwise.

    Does attaching tags to shark fins cause permanent damage that can influence shark survival?
    Maybe. Recent slow motion footage has some researchers wondering if the dorsal fin is more critical in predation success than previously thought. Although they can survive with malformed fins, it may affect them in other ways that could contribute to the mating hierarchy in layman’s terms (or survival of the fittest depending on how you look at it).

    Can shark tracking data help with shark conservation?
    Yes and No. Tracking data has been on hand for some species for decades, yet no actions have been taken. The data that is on hand is obviously not significant enough as sharks are not receiving protections in areas while other species are receiving equal to greater protections without similar or comparable data. The answer is not black and white and lies more in politics and government than with researchers. Even the greatest amount of data cannot overturn lax government enforcement of existing laws, or overturn long established government ideals (i.e. shark culls).

    Is there an authority that reviews and provides permission for scientists to tag sharks?
    Yes and No. In some places it is exactly as Neil describes. However, with “research” being the new cash cow of the 2010’s, more and more areas are seeing half-assed research as a means of money making. In fact, I am in the process of writing up a recent experience of one organization that has marine biology students who need field time pay them thousands of dollars to come out and do half-assed tagging and not only failing in placing tags, but harming the sharks in the process. I witnessed sharks stabbed in the bellies and with multiple tags of the same kind in the same shark and then a total lack of means to collect needed data from the tags. I myself have seen where it is offered that anyone from the public with absolutely no experience can randomly tag a shark unsupervised for a price. There is definitely a growing list of “researchers” who should not be allowed to operate or whose practices are in need of modification due to questionable motives of either the lead agency or the individuals involved (i.e. Ocearch). As Neil pointed out, the risk vs. gain is the most important factor in research and more and more there is a lack of proper assessment of it, even among some of the top researchers. The authority and that Neil talks about may apply to him, but is not a worldwide standard.

    This is a great write-up on the issue of shark research, but some of it applies regionally or under certain circumstances and should not be seen as broadly and globally applicable and some of the ‘facts’ could possibly change as more knowledge is gained.

  8. Michael Stocker
    Northern California
    January 31, 12:40 pm

    A great article clarifying some of the aspects of satellite tagging. The author does not mention acoustic tags, which are also common and I find somewhat problematic.

    See: http://ocean-noise.com/blog/2013/08/shark-week-tagging-a-tale-of-sharks-fish-and-seals/

    • Neil Hammerschlag
      January 31, 10:43 pm

      Michael – thanks for bringing up your concerns. However, according to Dr. Steve Cooke of Carleton University – the issues raised about acoustic tags in the article you posted is “irrelevant because acoustic tags don’t send out signals at regular intervals and there is too much time between signals to aid them in honing in on them. Vemco tags send out signals say on average every 120 second with a range of 30 to 240 to minimize code collisions”

  9. Barbara Biggerstaff
    Corolla, NC
    January 31, 9:00 am

    thank you …. that helps me understand and better explain to others.