Shark Savers on the Importance of ‘Zero Data’

Shifting Baselines

What is a “shifting baseline” and why is it important?

The term “shifting baseline” refers to the situation where we observe the natural world as it is now, often forgetting the former state of populations or habitats, and measure change against a ‘baseline’ condition that has often already changed or declined. It was first defined by fisheries biologist Daniel Pauly of the University of British Columbia in 1995.

This is particularly important with regard to sharks because some local populations have declined by 90% or more over the past few decades. Yet as new divers we may perceive that the current frequency that we see sharks is the ‘norm’ for the habitats we frequent.

Zero Data

“Zero-data” is documenting the absence of something – in this case, sharks. And this data is vital for the SharksCount program to have maximum applications to conservation. If you go on a dive and see no sharks, please record that dive on your datasheet and report it to us. All your diving information is valuable.

This is important to remember because when divers record the species they encounter on a dive, this only documents the presence of the species of interest. However it is equally important to record the absence of certain species, like sharks. Today, sharks are largely absent in areas where they were once abundant. Providing data that illustrates where sharks are present and absent helps scientists establish baselines of shark populations.

Scientists use presence/absence data to understand the roles that human disturbance plays in the distribution/abundance of coastal shark populations. Overall, larger shark species are often depleted or absent in areas with high levels of fishing and human disturbance.

The information you submit to the SharksCount Program can help scientists and managers prevent further loss of sharks by designating priority conservation areas, measuring the success of management strategies for protecting sharks, informing communities about the overall presence/seasonality of sharks in their area and dive sites, and understanding population changes through time.