Four days at the International White Shark Symposium

Posted on February 16, 2010
Written by: Hannah Medd

Image Gallery

The great white shark, Carcharodon carcharias, is a formidable study subject. This is not only because of the inherent dangers of dealing with an animal that can reach a length of 19.5 feet with several sets of large triangular serrated teeth, but also because of its rare occurrence in an unforgiving environment. 

Some people question the sanity of those who eagerly face rough seas to observe, photograph, handle, track, and monitor an animal that has the potential to kill a human but there is a hardy stock of marine researchers that believe there is more to these animals than the archaic image from the movie Jaws and have dedicated much of their lives to elucidate the mysteries of this elusive shark to better understand its role in the ocean ecosystems. 

These characters of somewhat dubious career choice descended upon the Hawaiian island of O’ahu, gathering at the New Otani Hotel on Waikiki Beach for four days of networking and presentations from February 7-10, 2010.    It has been several years since a dedicated white shark symposium has been held and it seemed about time to revamp the old reference volume with the technological advances and renewed interest in this species of shark.

Years ago, my mother begged me to reconsider my choice of traveling to South Africa to work with white sharks, claiming the same excitement could be had at the local college studying butterflies.  I calmly disagreed and hopped a flight to Cape Town and spent three years putting my own master’s thesis on the back burner for any chance to be on the water with white sharks. 

I consider white sharks charismatic megafauna, the poster child for shark and marine conservation because they do get a lot of attention for their sheer size, strength and efficient hunting capabilities.  I’ve been fascinated with them since I was a kid on the shores of Florida and have read the books and papers. But, this symposium was a chance to finally get some accurate information from the people in the field to help dispel the myths and misconceptions about these animals. 

The welcome reception was held in the Sans Souci Room overlooking the beach and surf dotted with locals carving into regular sets of waves as the sun dipped lower, a true Hawaiian scene.  Drinks and sushi in hand, name badge visible, I set off to meet some of the people whose work I’ve admired for years. 

Rumor had it that most people who pursue white shark research are glory seekers with alarmingly enormous egos.  Intimidation gave way to relaxation as the conversations flowed, revealing common interests and manageable egos.  I only used my two drink vouchers so I’d be ready for the marathon day of talks starting and 9 am the next day!

The talks were divided by area, as presented here.

Mexico: 

  • Michael Domeier and Nicole Nasby-Lucas described the Shared Offshore Foraging Area (SOFA), a seemingly nondescript region in the Pacific Ocean where sharks tagged off of California and Guadalupe Island, Mexico spent up to 5 months a year.  The SOFA was found to be relatively devoid of life except for squid.
  • Chi Lam presented a description of movements around Guadalupe Island with white sharks demonstrating a residency from September to December.
  • Mauricio Hoyos-Padilla identified ten potential prey items in the area for juvenile and adult white sharks, observed size-based hierarchy at meal time, and the maximum recorded difference between the temperature of a white shark stomach and the surrounding water, a staggering 16°C!  
  • O. Santana-Morales presented the issue of bycatch of white sharks in Mexico’s artisanal and commercial fisheries, signifying the coast of Baja California might be a nursery area as indicated by the small size of the sharks and seasonality of the catches, despite white shark protection by Mexican law.

California:

  • Salvador Jorgensen’s presentation on The Tagging of Pacific Pelagics (TOPP) program that has revealed the specific migratory pattern of Pacific white sharks from coastal hotspots to oceanic sites and back, indicating a distinct population that may be easier to census and monitor but also leaves them at higher risk of overexploitation. 
  • Kevin Weng reported on the five white sharks released from the Monterey Bay Aquarium, all data reported back by satellite tags indicate the previously captive sharks behaving similar to wild sharks of the same age. 
  • Chris Perle used oceanic data to describe the pelagic habitat preferred by California sharks from March to June, hypothesizing that their decision to migrate back to the coast is based on food availability or mating. 
  • Scot Anderson presented the longest running dorsal fin identification database of white sharks, one record returning over 22 years! 
  • Chris Lowe looked at incidental white shark catches in the Southern California Bight over 71 years and found that entangling net fisheries caught the most white sharks and despite a gill net ban the catch rates have increased suggesting the population is increasing.

Northwest Atlantic coast:

There was a shocking dearth of information presented on the white sharks off the Atlantic coast of the U.S., partially due to the lack of known aggregation sites so apparent in the other regions. 

  • Toby Curtis reviewed the distribution, albeit sparse, of white sharks from Newfoundland to the Caribbean Sea in temperatures ranging from 11-28° C.  The records indicate that the sharks migrate from Massachusetts and New Jersey in the summer months, to the Florida coast in the summer months, a pattern shared by red drum, grouper, porpoise and Northern Right whales, all possible prey. 
  • Toby also presented Greg Skomal’s study on that predicted the increase of white sharks in the area of an increasing population of grey seals (Halichoerus grypus) on Monomoy Island near Cape Cod as well as the tag data from those sharks, demonstrating a depth preference of less than 50 meters and temperature preference of 15-21°C.

South Africa:

  • South Africa’s turn at the podium started with a summary of research by Sheldon Dudley.  The white sharks of South Africa increase in abundance from the east to west coast and there seems to be a paucity of mature females with a record 567 cm caught in Gansbaai. 
  • Alison Kock gave one of the most excited presentations revealing novel white shark behavior captured by a Crittercam, a video system attached to white sharks in False Bay that collected hours of footage and loads of data on 27 white sharks.  Through 63 hours of video there were very few moments of shark to shark interaction, specific swimming activity near the seal colony where they feed, investigations of jellyfish, boats, kelp, fish, seals, and a long segment showing a shark inspecting a soda can on the sandy bottom, passing it several times, swallowing it and finally regurgitating it.  Other footage exposed a white shark chasing and eating several white steenbras fish in the shallows. 
  • Ryan Johnson reported on the movement patterns of white sharks in Mossel Bay in relation to the local seal colony.

New Caledonia:

Eric Clua reported on the records of white sharks in the tropical waters of New Caledonia, linking their presence to humpback whales.

New Zealand:

New Zealand white shark research was presented by Clinton Duffy, describing the migration of tagged sharks to the tropical islands to the north, and Malcolm Francis who described the diving patterns of the same tagged sharks.  Near the seal colonies, the sharks stayed relatively shallow, but after embarking on the long oceanic migration north, the diving profile showed periodic depths of up to 1,200 meters and a temperature of 4.2°C!

Australia:

Australian research is some of the longest running and comprehensive programs. 

  • Barry Bruce summarized the ecology of white sharks in Australian waters.  White sharks are common along all coasts in Australia. The east coast and west coast populations do not seem to mix but they do hang around in certain areas depending on the season and taking long distance swims between areas.  Despite a long history of research, it was acknowledged that there was a need for population estimates which would be integral for future conservation management. 
  • Rebecca Robbins reported that larger white sharks were abundant from June to September at the Neptune Islands, South Australia and sea surface temperature was related to the sexual and size segregation. 
  • Russell Bradford focused on the white sharks of Port Stephens, a known nursery area of about 1,000 sq km, and identified a host of behaviors as the sharks travelled back and forth to the other nursery area, the Bass Strait.   
  • Jonathan Werry presented data of juvenile white shark catches from the Shark Control Programs of eastern Australia compared to the satellite tracking data and found that the areas with the highest catches are areas preferred by the tagged sharks.

Biology

  • Jose Castro validated the maximum length record for a white shark as 19-19.5 feet and Michael Gottfried clarified the skeletal aspects of the white shark that have been inaccurate for years.

An interesting departure from tag and tracking data was a focus on stable isotope analysis which is used to estimate an animal’s trophic level.  As the white sharks diet changes with size, the abundance of stable isotopes of carbon and nitrogen also changes, helping to place them in the food web. 

  • Luis Malpica-Cruz presented results of blood and tissue samples extracted from sharks taken as bycatch near Baja California and sharks at Guadalupe Island, indicating evidence that juveniles may partake in benthic feeding and graduate to coastal waters for pelagic feeding.
  • Sora Kim’s study looked at the ratio of isotopes in the growth rings of white shark vertebrae caught off California and demonstrated that this population consists of generalists and not just specialists that specifically feed on pinnipeds, as previously thought.

A newer aspect of white shark biology that was highlighted at the symposium was the vulnerability to accumulate hazardous compounds because of their position at the top of the food chain.

  • Mary Ellen Blasius looked at the levels of organochlorines in the liver and white and red muscle tissues of California’s YOY (young of the year) and juvenile white sharks which revealed the highest levels of such compounds known in elasmobranchs, some of which is offloaded by the mother shark and some may be accumulated through diet.
  • Chris Mull presented information on the levels of heavy metals and trace elements in muscle and liver tissue of juvenile white’s of the Southern California Bight, thought to be a nursery ground.  High levels of these compounds have been found to disrupt systems of osmoregulation, reproduction and neurological functioning.  The mercury levels in the liver was three times higher than the reported “no eat” levels of fish.
  • Heather McCann looked at the vertebrae of white sharks caught in beach protection nets in KwaZulu-Natal, South Africa, identifying calcium concentrations to signal seasonal changes and barium as an indication of movement between nutrient and non-nutrient areas as well as other elements that could show migration and depth profiles.
  • J. A. Sulikowski reported on a technique to examine the reproductive state of white sharks without having to sacrifice the animal by examining the hormone (testosterone and estradiol) levels in a blood samples.

Husbandry

The Monterey bay Aquarium and its team have been the example of successful husbandry of several white sharks for any significant amount of time. 

  • John O’Sullivan described the cautionary methods used in acquiring the young white sharks, transporting them to the facility and maintaining their health while they are on display.  The described goals of the Aquarium are to tag and sample the specimens, determine the viability of keeping a white shark on display and the development of an outreach and educational aspect.
  • Juan Ezcurra described the success of the sharks held in the 3.8 million liter exhibit, four of which fed on king salmon and Pacific mackerel and sablefish, growing at a mean rate of 60.2+/- 13.7 cm per year.  The transport tank was designed to measure oxygen consumption rates at different water temperatures, helpful in determining the growth capacity of young sharks, and was found to be among the highest ever recorded for any shark species.

Monitoring, Management, and Conservation:

  • Irina Kogan highlighting the regulations for cage diving operations, filming, researchers and general water users with reference to the white shark population in the Gulf of the Farallones National Marine Sanctuary.  The Sanctuary has instituted an outreach program, naturalist training, permitting system, school education and monitoring.  Olivares Banuelos reviewed the regulations and laws in place for the protection of white sharks at Guadalupe Island Biosphere Reserve, decreed in 2005.
  • Taylor Chapple used dorsal fin photographs to identify 131 individuals off the central California coast and used that to estimate the abundance of white sharks to be 251 individuals.  O. Sosa-Nishizaki estimated the white shark population off the coast of Guadalupe Island to be between 117-158 individuals.
  • Randy Hamilton described his White Shark Logic Model used to “inspire conservation of the oceans” and the success of the white sharks on display at the Monterey Bay Aquarium, seen by over 2.5 million people, as an ambassador for conservation.
  • Alison Kock explained the details of the unique program in Cape Town, South Africa, called Shark Spotters that employs previously disadvantaged people to sit above 5-10 popular beaches and look for sharks.  The program has a flag system that indicates conditions and whether sharks have been sighted and the spotters collect valuable data each day.
  • Chris Ball emphasized the importance of using familiar community members when initiating a conservation program for maximum participation.
  • Chrysoula Gubili illustrated the significance of molecular genetics in describing white shark populations and movements and first ever evidence of multiple paternity in the species, all imperative to the future management of these sharks.

Several impressive posters were presented during the poster session including Alison Towner’s record of the healing rate of a severe wound on the top of a white shark’s head caused by a propeller in Gansbaai, South Africa, and the subsequent return of the female shark one year later.

The symposium finished with round table discussion on research ethics, shark tourism, and shark attack response.  I’d love to say I lasted until the bitter end but the truth is, I had one day to get to the legendary North Shore, to Pipeline, and the swells were coming in huge so I bailed.  My I ditched my nerdliness for the afternoon, grabbed my camera and took killer pictures of professional surfers dropping in on 20-30 foot walls of water.  As much as I love my sharks, it was an opportunity not to be missed.

The banquet was rather civilized until someone plugged in the ipod and certain researchers started stealing wine off the tables.  It was good to see the academics letting loose all in the name of white shark information

The organizing committee was Michael Domeier of the Marine Conservation Science Institute, Alison Kock of the Save Our Seas Foundation, John O’Sullivan of the Monterey Bay Aquarium and Kevin Weng of the Pelagic Fisheries Research Program.  The symposium was sponsored by the Guy Harvey Ocean Foundation, the Monterey Bay Aquarium, the Marine Conservation Science Institute, the Save Our Seas Foundation, and the Pelagic Fisheries Research Program