Shark species thought to be extinct found in fish market

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After his 1902 trip to Yemen, scholar and naturalist Wilhelm Hein returned with a variety of plants and animals, which he donated to the Vienna Museum. One of these specimens, a shark, sat unnoticed for more than 80 years. In 1985 it was identified as the first (and only known) specimen of Carcharhinus leiodon, the smoothtooth blacktip shark. Because no others had ever been found by scientists, Alec Moore, regional vice chair of the International Union for Conservation of Nature (IUCN) Shark Specialist Group’s Indian Ocean group, says that “some suspected it might be extinct or not a valid species.”

Shark species thought to be extinct found in fish market
Julia Spaet examines the dentition patterns of a large shark for sale at a market in Saudi Arabia. Tooth shape can be a defining characteristic between similar looking species of sharks [Credit: Julia Spaet, Red Sea Research Center, King Abdullah Umiversity of Science and Technology]

In 2008, during a Shark Conservation Society research expedition to Kuwait’s sharq fish market (the name is a coincidence, it means east in Arabic), Moore says that “amongst the many species of whaler shark was one which looked very similar, but different, to a couple of other species.” Later analysis revealed that although this specimen was more than 3,000 kilometers from where Hein caught his, this was a smoothtooth blacktip, the first new individual seen by scientists in over a century.

These sharks are currently considered “Vulnerable” to extinction by on the IUCN Red List of Threatened Species, an assessment that was made before their rediscovery by Dr. Moore and his team. More recent studies in fish markets throughout the region have located 47 additional smoothtooth blacktip sharks, greatly increasing what scientists know about this species with and reported in a 2013 paper in Marine & Freshwater Research. The new study included some of the first data on how large smoothtooth blacktips can grow, how many pups they can bear and their habitat usage as well as other information needed for an effective conservation and management plan in the future.

Shopping for species

Fish market surveys of the kind that resulted in the rediscovery of the smoothtooth blacktip are an increasingly common research tool that offers many advantages over traditional scientific field sampling. Julia Spaet, a researcher at King Abdullah University of Science and Technology in Saudi Arabia, says that “the resources dedicated by a fleet of fishermen will always outmatch any scientific efforts to assess abundances. In other words, the fishing industry is more efficient at finding sharks where there are not much left.”

Shark species thought to be extinct found in fish market
Many large sharks lined up for sale in a United Arab Emirates fish market
[Credit: Rima Jabado, University of the United Arab Emirates]

These surveys are hard work. Researchers have to arrive before dawn, before the boats come in to land their catches. The species of interest have to be identified, counted, measured and sampled before they are sold to customers. When further study is required, researchers need to purchase the fishes themselves. This whole process can be, for lack of a technical term, disgusting. Moore says he “once made the mistake of climbing into a skip [waste bin] to sample a load of rays that had been festering in the sun; the response of my gastrointestinal tract to this was, as an understatement, memorably unfavorable.”

Surveys also offer challenges not faced by scientists who do field surveys, such as gaining fishermen’s trust. Moore says that “although sometimes bemused by what we are doing, they are generally very tolerant of weird foreigners poking around, and we’ve met some incredibly generous, funny and helpful people—we’ve even been given breakfast.”

Researchers have made many discoveries relevant to the conservation of threatened shark and ray species by studying the catches in fish markets in Kuwait, Yemen, Saudi Arabia and the United Arab Emirates. Rima Jabado, a PhD student at United Arab Emirates University, was contacted by a fisherman who found an unusual looking shark, which resulted in the first scientific record of a sand tiger shark in United Arab Emirates waters. Jabado also found species with local legal protections for sale in markets, such as whale sharks and green sawfish, which she says shows “some species should be protected and managed locally and that there is a clear need for better enforcement of some of the current legislation.” Spaet agrees, noting that “in Saudi Arabia shark fishing is prohibited by law, yet we still find large numbers of sharks landed at the markets every day.”

In the meantime Moore has some advice for any shark-o-philes going on vacation: “Always go to the fish market with a camera, especially in tropical countries where there is little data—there is always the chance that you could find something new. Even if you don’t, fish markets in the early morning are amazing—lively places with real character and great food.”

Author: David Shiffman | Source: Scientific American [January 13, 2014]

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