Category: New Research

Grading ocean health: 60/100

The Ocean Health Index is the first global quantitative assessment of ocean health (Map credit: Halpern, et al, Nature)

The health of the world’s oceans received a score of 60 out of 100 from a team of international scientists, including researchers with the Sea Around Us Project. Kristin Kleisner, Dirk Zeller, Rashid Sumailaand Daniel Pauly were part of the team that undertook the first global quantitative assessment of ocean health and created the Ocean Health Index by evaluating ecological, social, economic and political conditions for every coastal nation in the world.

The Sea Around Us Project in particular was responsible for measuring the amount of seafood that is sustainably generated by fisheries and marine aquaculture for human consumption, which contributed to calculating the score for ocean health.

The article, published in Nature, is available here and the press release is here.

Law That Regulates Shark Fishery Is Too Liberal

Shark fins are worth more than other parts of the shark and are often removed from the body, which gets thrown back into the sea. To curtail this wasteful practice, many countries allow the fins to be landed detached from shark bodies, as long as their weight does not exceed five per cent of the total shark catch. New University of British Columbia research shows that this kind of legislation is too liberal.

A study published this week in the journal Fish Biology analyzes the fin to body weight ratios for 50 different shark species.  The authors find the average fin to body mass is three per cent  – considerably lower than the five per cent ratio currently legislated by the EU and other countries.

“The five percent ratio provides an opportunity to harvest extra fins from more sharks without retaining 100 per cent of the corresponding shark carcasses,” says Sea Around Us Project researcher Leah Biery, lead author of the study. “It does not prevent waste or overfishing, as the law intended.”

Currently, the EU and eight other countries use at least a five per cent shark fin to body weight ratio for landed catch. Only 59 countries in the world have any legislation related to sharks.

“Sharks are sensitive to overfishing and it’s embarrassing how little we have done to protect them,” says Daniel Pauly, principal investigator of UBC’s Sea Around UsProject and co-author of the study. “We would like to see more science in the management and protection of sharks in the coming years.”

Researchers estimate about 26 to 73 million sharks are killed each year to feed the growing demand for shark fin.  Sharks are sensitive to overfishing because they often grow slowly, mature later, and have very few offspring.

Canada MP Fin Donnelly introduced a bill last December that would ban the import of shark fin into Canada, but it has not been voted on. The Canadian municipalities of Brantford, Mississauga, Oakville, Pickering, London and Toronto have all banned the sale and possession of shark fin.

Fish Farms from Space: The Ground Truth from Google Earth

The Great Wall of China is not the only thing you can see from space. Fish farming cages are clearly visible through Google Earth’s satellite images and University of British Columbia researchers have used them to estimate the amount of fish being cultivated in the Mediterranean.

The study, published yesterday in the online journal PLoS ONE, is the first to estimate seafood production using satellite imagery.

“Our colleagues have repeatedly shown that accurate reporting of wild-caught fish has been a problem, and we wondered whether there might be similar issues for fish farming,” says lead author Pablo Trujillo, an Oceans Science Advisor for Greenpeace International, who conducted the study while a research assistant at the UBC Fisheries Centre.

“We chose the Mediterranean because it had excellent satellite coverage and because it was of personal interest,” says Chiara Piroddi, co-author and an ecosystem modeler at the UBC Fisheries Centre. “We hand counted 20,976 finfish cages and 248 tuna cages, which you can differentiate due to their extremely large size – each tuna cage measured at more than 40 metres across.”

Almost half the cages were located off the coast of Greece and nearly one-third off of Turkey – and both countries appear to underreport their farmed fish production. The researchers note that not all areas had full satellite coverage – for instance, images were missing for large portions of the coasts of France and Israel, for reasons the authors do not fully understand.

Combining cage counts with available information on cage volume, fish density, harvest rates, and seasonal capacity, the research team estimated ocean finfish production for 16 Mediterranean countries at 225,736 tonnes (excluding tuna). The estimate corresponded with government reports for the region, suggesting that, while there are discrepancies at the level of individual countries, overall, the Mediterranean countries are giving accurate counts.

“The results are reassuring, and the methods are inspiring,” says co-author Jennifer Jacquet, a post-doctoral researcher with UBC’s Sea Around Us Project. “This shows the promise of Google Earth for collecting and verifying data, which means a few trained scientists can use a freely available program to fact-check governments and other large institutions.”

Trujillo adds that Google Earth, with its high-resolution images and consistent time series, can be a powerful tool for scientists and non-governmental organizations to monitor activities related to ocean zoning and capture fisheries.

See some coverage of the work at The Scientist.

New Study Published in MEPS about Marine Predator Declines

Iconic marine predators such as sharks, tunas, swordfish, and marlins are becoming increasingly rare under current fishing trends, according to a new study published in the journal Marine Ecological progress Series. In half of the North Atlantic and North Pacific waters under national jurisdiction, fishing has led to a 90-per-cent decrease in top predators since the 1950s, and the impacts are now headed south of the Equator. The study was lead authored by former Sea Around Us Project M.Sc student Laura Tremblay-Boyer. The study is available here and the press release is here.