In June of 2014, almost 400 of the world’s top shark researchers gathered in Durban, South Africa for the 2nd Sharks International conference. The four keynote presentations have just been put online.
Beyond Jaws: Rediscovering the “lost sharks” of South Africa
Dave Ebert, Moss Landing Marine Laboratory
Biography:Dave Ebert earned his Masters Degree at Moss Landing Marine Labs and his Ph.D. at Rhodes University, Grahamstown, South Africa. He is currently the Program Director for the Pacific Shark Research Center, a research faculty member at Moss Landing Marine Laboratories, and an honorary research associate for the South African Institute for Aquatic Biodiversity and the California Academy of Sciences Department of Ichthyology. He has been researching chondrichthyans around the world for nearly three decades, focusing his research on the biology, ecology and systematics of this enigmatic fish group. He has authored 13 books, including a popular field guide to the sharks of the world and most recently he revised the Food and Agriculture Organization’s Catalogue of Sharks of the World. He has published over 300 scientific papers and book chapters, and contributed approximately 100 IUCN Shark Specialist Group Red List species assessments. Dave is regional co-Chair of the IUCN Northeast Pacific Regional Shark Specialist Group, Vice Chair for taxonomy, and a member of the American Elasmobranch Society and Oceania Chondrichthyan Society. He has supervised more than 30 graduate students, and enjoys mentoring and helping develop aspiring marine biologists.
Prof Colin Simpfendorfer is the Director of the Centre for Sustainable Tropical Fisheries and Aquaculture at James Cook University. He has more than 25 years of experience in researching sharks, and has published extensively in the scientific literature on shark biology, ecology, fisheries and conservation. He is a graduate of James Cook University where he undertook both his undergraduate and postgraduate training. After completing his PhD he worked on shark fisheries at the Western Australian Fisheries Department before moving to Florida to work at the Center for Shark Research at Mote Marine Laboratory. He returned to JCU in 2007 to lead the Fishing and Fisheries Research Unit, where he has helped build a research group focused on improving our understanding of sharks and how best to conserve and manage their populations.
Call it a shark cull, shark control or bather protection, for decades governments have been trying to reduce the risk of humans being killed by sharks – by killing sharks. New South Wales, Queensland, KwaZulu-Natal (South Africa), Hawaii, Dunedin (New Zealand), Hong Kong, Somalia (during the US military intervention) and now Western Australia have, or had, shark control programs to reduce the risk of human-shark interactions.
Western Australia’s new program has sparked huge controversy, with many calling for the government to stop and pursue alternatives.There have been a range of claims that there is no science to support shark control. Many of these have been based on the effects of removing large predatory sharks on ocean ecosystems or that there is no evidence that shark culls reduce the risk of attack.Both of these are valid scientific considerations and need to be taken into account. However, neither addresses whether there is some scientific basis to shark control programs.
So here I would like consider whether there is a scientific basis to shark control programs. To do this I’ll look first at the theory, and then if there is evidence to support it based on analysis of data from the programs in KwaZulu-Natal and Queensland.
It took a team of over 300 scientists nearly two decades, but the first systematic analysis of the conservation status of chondrichthyans (sharks, rays and chimaeras) has been completed. The results, published today (open access) in a paper titled “Extinction risk and conservation of the world’s sharks and rays,” are chilling.
“Our unprecedented analysis shows that sharks and their relatives – which make up one of the earth’s oldest and most ecologically diverse groups of animals — are facing an alarmingly elevated risk of extinction,” said Dr. Nick Dulvy, IUCN SSG Co-Chair and Professor at Simon Fraser University in British Columbia.
As of the writing of this paper, the IUCN Shark Specialist Group recognized 1,041 species of chondrichthyans. However, a new species is described, on average, every two or three weeks! Out of these 1,041 species of chondrichthyans, approximately one in four are considered “Threatened” by IUCN Red List criteria; 113 species are Vulnerable, 43 are Endangered, and 25 species are Critically Endangered. 487 species are considered Data Deficient, but the IUCN Shark Specialist Group estimates that 68 of them are likely to be Threatened as well! Most alarmingly, only 23% of known chondrichthyan species are considered Least Concern, the lowest percentage out of any group of vertebrates on land or sea!
A hierarchy of IUCN Red List categories. Note that “Threatened” includes Vulnerable, Endangered, and Critically Endangered
One of the two main factors influencing Threatened status is the size of the animal. Larger bodied species are sensitive to overfishing because they typically have a life history with slow growth, late age at maturity, and relatively few offspring. Additionally, living in coastal habitats (in other words, close to humans) makes a species more likely to be Threatened.
The American Elasmobranch Society is a non-profit professional society focusing on the scientific study and conservation of sharks, skates, and rays. AES members meet each year in a different North American city, and this meeting is the world’s largest annual gathering of shark scientists. AES recently met in Vancouver, British Columbia for the 2012 meeting, and for the first time the event was live-tweeted by meeting attendees, including myself. I’ve organized the best conference tweets by session using Storify. If anyone has any questions or comments about the research presented below, please feel free to share it in the comments section of this blog post.
Here are selected tweets from the Deepwater Chondrichthyans Symposium.
Photo credit: study author Pascal Geraghty, New South Wales Department of Primary Industry
Last week, a team of 10 Australian scientists announced that they had found the world’s first “shark hybrids”, offspring of individuals from two different shark species which had interbred. During a routine survey of Australian marine life, 57 sharks were found that physically resembled one species of shark, but had genetic markers inconsistent with that species. Subsequent genetic investigation revealed that these 57 animals were hybrids between common blacktip sharks (Carcharhinus limbatus) and Australian blacktip sharks (C. tilstoni).
Some of these hybrids were “F1″, meaning that one parents was a common blacktip and one was an Australian blacktip. Others were “B+”(backcrossed), which means that one parent was a common blacktip/Australian blacktip hybrid, and the other was a “purebreed” of one of those two species. According to the study’s lead author, Dr. Jess Morgan of the University of Queensland, “our genetic marker tells us that these hybrids are ‘at least’ F1, and that these animals are reproductively viable and can produce an F2…the hybrids may be generations past F2 but the existing genetic markers can’t distinguish how many generations past the second cross have occurred.”
“There are known knowns; there are things we know we know. We also know there are known unknowns, that is to say we know there are some things we do not know. But there are also unknown unknowns – the ones we don’t know we don’t know.” – Former U.S. Secretary of Defense Donald Rumsfeld.
As nature documentary viewers often hear, there is a lot about sharks and rays that scientists don’t know… but what are the most important things that we need to know? A new paper written by Colin Simpfendorfer, Will White, and former Shark Science Monday interview subjects Michelle Heupel and Nick Dulvy attempts to identify these “known unknowns” of shark and ray conservation. “The importance of research and public opinion to conservation management of sharks and rays: a synthesis”, which arose out of the 2010 Sharks International conference, is the most complete record ever created of the research questions that we need to answer in order to better conserve and manage these animals. For young shark researchers eager to work on projects with practical conservation importance, this paper is a great place to start looking for ideas. Additionally, future published work that claims to be important for conservation and management would do well to cite it, and anyone interested in this subject should read it.