Better monitoring of Great White sharks needed in Northwest Pacific, grad student says

Heather ChristiansenGrad student Heather Christiansen holds up part of a jaw bone from a great white shark.

It would appear, at least for now, that the great white shark population in the northwest Pacific Ocean has remained fairly stable over the last 60 years. Heather Christiansen would like to keep it that way.

A PhD student in the University’s Great Lakes Institute for Environmental Research, Christiansen recently conducted a ‘meta-analysis’ of great white shark population data in the Pacific, spanning a 4,300 km distance from as far north as Russia all the way to tropical waters off Vietnam, and covering the time period from 1951 to 2012.

Based on 240 observations of white sharks taken from media accounts and reports of by-catch by commercial fishermen, personal communications and documentation of shark-human interactions, Christiansen concluded that other than a slight decrease in abundance over the last decade, great white numbers have remained stable in that part of the world.

She did admit, however, that the data paints an incomplete picture and strongly suggested a more formal shark monitoring system, similar to those used in other parts of the world, needs to be established in that region.

“I hope this is used as a starting point,” she said of her results, published in a paper in the academic journal PLOS ONE. “The scientific community, fisheries and governments need to come together to better understand what needs to be done to protect these animals. Top predators are a critical part of any ecosystem. We know these sharks are slow-growing and vulnerable to fishing pressure, but we know relatively little about their specific life-history characteristics in this part of the world.”

Among her other findings were:

  • The observation of 11 pregnant females, which accounts for 42 percent of the total number of pregnant sharks documented globally
  • The recording of a 602 cm long shark, the largest accurately measured shark on record
  • The observation that smaller sharks were broadly spread out through the region, suggesting that there may be multiple nursery grounds for shark pups

Co-author Nigel Hussey, research associate at GLIER and the Ocean Tracking Network, said the data Christiansen gathered and compiled provides an important baseline for stimulating research and management on one of the most enigmatic predators in that region.

“Future satellite tagging work would provide critical new insight in to the movement patterns of these animals that would assist management efforts,” he added.

Christiansen said many of her co-authors on the paper are well-established shark researchers in the Pacific region and she hopes her research will equip them with the information to spur the creation of new shark monitoring and conservation programs there.

One of those co-authors is Sonja Fordham, president of Shark Advocates International. She said white sharks are among the most popular and protected shark species globally, but noted that conservation efforts are lagging in western North Pacific.

“White sharks are listed under the Convention on Migratory Species, which provides a unique platform for regional cooperation in science and conservation,” she said. “Unfortunately, the Philippines is the only country in this region engaging in CMS shark activities, so most of the area is missing a significant opportunity to safeguard this and other vulnerable species.”  

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