Nearly a third of fish caught in the world's oceans goes unreported, according to new research from UBC's The Sea Around Us project.

Each year, the UN releases official capture reports outlining how much marine life each country has fished through the calendar year. In 2015, 81.2 million tonnes were reported to have been harvested from the ocean.

But researchers say the official numbers don't paint a complete picture.

"Fifty per cent more fish were actually taken out, were caught by fisheries around the world, than the officially reported data that countries provide actually would suggest," said Dirk Zeller, a senior scientist and executive director for the Sea Around Us project at UBC.

The research initiative assesses the impact of fisheries on marine ecosystems.

Research conducted by the group concluded that as much as 120 million tonnes was fished from the oceans in 2015. Zeller said the numbers show that the planet's fish stocks are under threat.

Restructuring data

Zeller is part of a team of nearly 400 scientists and researchers who worked to compile the new data, which is featured in a new online interactive graphic.

He said the team was able to uncover the unreported fishing activity by restructuring the official data provided by the UN with external data, such as university studies, nutritional surveys, and local knowledge.

The number of fishing fleets across the planet have soared, but the total number of fish being caught has declined since the mid-1990s, according to UBC senior scientist Dirk Zeller. (Living Oceans Foundation/Vimeo)

Piecing together the data took 10 years, but he said it has given them a greater sense of the immense pressure commercial fishing has put on fish populations.

"Catches around the world peaked around the mid-1990s — [and] that's been declining steadily by about 1 to 1.2 million tonnes per year ever since," he said, adding that the number of boats and fishermen on the water have increased in the same time period.

"So if you combine that, more and more fisherman, catching less and less and less — that is a sign of overfishing."

Total global catch has declined steadily since the mid-1990s, ranging from a decrease of one million to 1.2 million tons of fish annually. (Living Oceans Foundation/Vimeo)

Missing Catch

Zeller said many fish stocks are on the brink of collapse — and bringing them back to healthy levels isn't easy.

"If you take a fish population and you deplete it substantially to a very small percentage of its original version ... then you create a situation where these fish might not be able to recover — even if you stop harvesting it, purely because its place in the ecosystem might have changed."

Zeller and members from The Sea Around Us team recently captured the global overfishing crisis in a new documentary, titled An Ocean Mystery:The Missing Catch, which will screen at UBC's Institute for the Oceans and Fisheries on April 28.

The devastation of fish stocks is on full display.

"If you go to Vietnam or China, you will find that the trawlers there — they catch stuff that anyone in the Western world, or even China itself, [wouldn't eat]."

"It's basically slime, sledge, tiny little fish, or juveniles."

With files from CBC's BC Almanac