Global fishing vessel activity, May 2017 - November 2017. Graphic: Global Fishing Watch

By Shreya Dasgupta
24 February 2018
(Mongabay) – Industrial fishing takes place across more than 55 percent of the world’s oceans, according to a new study published in Science.Fishing is vital for food security and livelihoods across the globe, yet the extent of industrial fishing has remained largely unknown. Now, a team of researchers has tried to solve this problem by using the Automatic Identification System (AIS), an automatic ship-tracking system that uses satellite and land-based receivers to monitor a ship’s location, originally designed to help prevent ship collisions.To see where and when fishing takes place, the researchers tracked 77,000 industrial ships, including more than 75 percent of large-sized commercial vessels, using 22 billion AIS positions from 2012 to 2016.“It was an immense effort to organize and process the AIS data, and then build complex machine learning algorithms,” said lead author David Kroodsma, the director of research and development at Global Fishing Watch, a collaborative non-profit supported by Oceana, SkyTruth and Google. “Global Fishing Watch and our partners have been working on this for several years.”The resulting global maps revealed that industrial fishing vessels operated across more than 55 percent of the ocean, or over 200 million square kilometers (77 million square miles), in 2016 alone. That’s higher than the proportion of land (34 percent) used in agriculture or grazing, the researchers write.The dataset also showed that in 2016, commercial ships spent 40 million hours fishing and covered more than 460 million kilometers (286 million miles), equivalent to traveling to the moon and back nearly 600 times. While most countries fished predominantly within their own exclusive economic zones, five nations — China, Spain, Taiwan, Japan, and South Korea — accounted for more than 85 percent of observed fishing in the high seas (part of the oceans not within any country’s jurisdiction).The researchers could also identify the kind of fishing gear the ships used. They found that longline fishing, which uses lines with evenly placed baited hooks, was the most widespread, seen in 45 percent of the ocean. By contrast, the team detected purse seine vessels, which use large dragnets, in 17 percent of the ocean, and trawlers in about 9 percent. [more]

New maps reveal industrial fishing in over half of world’s oceansNumber of fishing hours by country in 2016. Graphic: Global Fishing Watch

By Rob Jordan
22 February 2018
(Stanford News) – Seafood provides sustenance for billions of people and livelihoods for tens of millions, yet the full global reach of high seas fishing has remained largely a mystery until now. A team of researchers, including Stanford scientists, has directly quantified industrial fishing’s footprint using satellites and onboard ship-locating technology.Their data reveal, among other surprises, that five countries account for more than 85 percent of high seas fishing, and holidays affect fishing patterns much more than fish migrations or ocean conditions.“This highlights the impact of industrial fishing with an unprecedented level of detail and transparency,” said study co-author Barbara Block, the Charles and Elizabeth Prothro Professor in Marine Sciences. “It could help shape more sustainable practices that ensure a future for tunas, billfish, and sharks.”The study, published on 22 February 2018 in Science, opens a gateway to better management of global fleets and their response to changes in climate, policy, economics and other drivers.

An innovative approach

Advances in satellite technology and big data techniques have previously led to more accurate agricultural forecasts and more effective forest carbon storage approaches, but they had done little to clarify the global footprint of fishing.“To realize the potential of these new technologies, we assembled a team of data scientists, software engineers, ecologists and economists,” said study lead author David Kroodsma, director of research and development at Global Fishing Watch. “It was the only way to process such a vast amount of data and turn it into knowledge about where and when fishing is taking place.”Ships routinely broadcast their identity, position, speed and turning angle every few seconds as a way of preventing collisions. As it turns out, satellite-based receivers also pick up on these signals, sent through a system called Automatic Identification System (AIS). To take advantage of this existing data, the researchers designed artificial intelligence algorithms to process billions of AIS position signals from more than 70,000 fishing vessels over a four-year period (2012 – 2016).The algorithms detected ship positions indicative of fishing vessel type and activity. They identified vessel characteristics such as length (from 18 to 438 feet), engine power and gross tonnage – all with more than 90 percent accuracy when compared to official fleet registries.Although the researchers tracked only a small proportion of the world’s estimated 2.9 million motorized fishing vessels, they collected data on up to 75 percent of vessels in the world longer than 72 feet and more than 75 percent of vessels longer than 108 feet. Ships in these two categories are responsible for the majority of global high seas fishing.

A clearer picture

The resulting dataset was eye-opening.While most nations appeared to fish predominantly within their own exclusive economic zones, China, Spain, Taiwan, Japan, and South Korea accounted for more than 85 percent of observed fishing effort on the high seas beyond their territorial waters.Unlike agriculture, which revolves around seasonal cycles of plant and animal growth, the temporal footprint of fishing appeared surprisingly consistent through time. Christmas and weekends had the greatest effect on fishing patterns in most of the world, while Chinese New Year and state-imposed summertime fishing bans had the biggest impact on the movements of Chinese fleets.  While some fleets displayed seasonal movements, the work week, holidays and political closures were much more influential than natural cycles in determining the temporal footprint of fishing at a global scale.

The researchers calculated that more than 55 percent of the ocean was fished in 2016 alone. While this estimate is lower than previous studies have suggested, it is more precise and still more than four times the area of all the world’s agricultural land.

Ocean opportunities

While the study shows fishing hotspots in the Northeast Atlantic, Northwest Pacific, and some regions off South America and West Africa, it also shows low levels of fishing in the Southern Ocean and parts of the Northeast Pacific that may be among the most pristine open ocean areas on the planet and where Block and colleagues spent over a decade tagging and studying large pelagic fish and sharks. Some of these regions – such as an important migratory gathering spot halfway between Hawaii and California, dubbed the White Shark Café – have been proposed as potential world heritage sites.To further understanding of global fisheries, the researchers have made daily high-resolution graphical overviews of global of fishing effort publicly available through globalfishingwatch.org. These data not only provide a powerful tool for improved ocean governance, but can help assess existing management regimes and accelerate development of new approaches that respond in real-time to changing ocean conditions, management issues or conservation concerns.“This is a game-changing platform that can generate validated local and global maps of industrial fishing at unprecedented scale and resolution,” said study co-author Francesco Ferretti, a research associate at Stanford’s Hopkins Marine Station.

Contact

Stanford researchers use satellites to map global fishing footprint

ABSTRACT: Although fishing is one of the most widespread activities by which humans harvest natural resources, its global footprint is poorly understood and has never been directly quantified. We processed 22 billion automatic identification system messages and tracked >70,000 industrial fishing vessels from 2012 to 2016, creating a global dynamic footprint of fishing effort with spatial and temporal resolution two to three orders of magnitude higher than for previous data sets. Our data show that industrial fishing occurs in >55% of ocean area and has a spatial extent more than four times that of agriculture. We find that global patterns of fishing have surprisingly low sensitivity to short-term economic and environmental variation and a strong response to cultural and political events such as holidays and closures.

More than half the fish in the sea: As the human population has grown in recent decades, our dependence on ocean-supplied protein has rapidly increased. Kroodsma et al. took advantage of the automatic identification system installed on all industrial fishing vessels to map and quantify fishing efforts across the world (see the Perspective by Poloczanska). More than half of the world’s oceans are subject to industrial-scale harvest, spanning an area four times that covered by terrestrial agriculture. Furthermore, fishing efforts seem not to depend on economic or environmental drivers, but rather social and political schedules. Thus, more active measures will likely be needed to ensure sustainable use of ocean resources.Science, this issue p. 904; see also p. 864

Tracking the global footprint of fisheries