Satellites see big fishing’s footprint on the high seas | Hacker News Reader

Satellites see big fishing’s footprint on the high seas

digitaledition.baltimoresun.com

63 pointshispanic11 comments

When I read "but they hover at the edge of marine protected areas" I'm wondering if anyone's done any analysis to see whether the AIS signals for some of those ships mysteriously disappear for periods which coincide with them reaching the edge of marine protected areas...

(Edit: they have done this for a region of interest: http://globalfishingwatch.org/fishing-vessel-behavior/signal... )

This absolutely happens. Fisher boats will turn off AIS routinely. The nonprofit Global Fishing Watch is doing research to analyse AIS signals, and determine if illegal fishing happens in protected areas. See http://globalfishingwatch.org/fishing-vessel-behavior/signal...

If you browse their site, there's also stories about other illegal activities, such as laundering fish (it's being mixed with fish caught in legal areas on sea). Also some boats are staffed with people that are essentially slaves. They typically stay on sea permanently, and are fueled on sea. (http://oceana.org/blog/how-global-fishing-watch-can-combat-s...)

You posted about the same time as me!

(Having worked with people involved in EO and law before, I know it's not just fishing boats where AIS being switched off in certain places may or may not be evidence of other stuff happening)

Actually a couple of people mention the GFW in this page. Good to see that people are aware of the work being done.

Absolutely, it's known to be a common occurrence.

In South Africa, the Council for Scientific and Industrial Research (CSIR) has a solution called SeaFAR [0] that combines satellite-based AIS reception with low-resolution synthetic aperture radar satellite imagery to track ships with AIS turned off. The solution uses some machine learning approaches to not only classify (and if possible, recognise) ships from low-resolution SAR imagery, but to associate those with their tracks from before AIS was turned off.

I've seen the solution in use, it's surprisingly effective. I have no doubt there are similar approaches elsewhere, this is just one I'm familiar with.

[0] http://www.defenceweb.co.za/index.php?option=com_content&vie...

Compare with chlorophyll levels in the ocean:

https://svs.gsfc.nasa.gov/30786

Essentially there are small diatom things at the bottom of this food chain (and at the top of the ocean) that do the heavy lifting of converting sunlight into energy. Plankton (diatoms and the many, many, many variants) then get eaten by fish and then those fish get eaten by bigger fish and then the Japanese/Chinese/Spanish fishing fleet scoops them all up.

Temperature is important to the phytoplankton so there are places like the seas around Iceland that are extraordinarily rich for marine life. Also important is what flows out of rivers and gets blown off the land, grasses on land are therefore surprisingly important for fisheries - nitrogen has to come somewhere.

In conclusion I am surprised at how different the two maps are of where the fishing happens and where marine life as measured by chlorophyll happens.

The backstory behind the data gathering to make the map is a good read. They have put a lot of effort to cleanse and understand the raw data. There are plenty of nice articles on the what and why: http://globalfishingwatch.org/explainers/data/what-does-an-a...

Is this dataset available anywhere, it could be very interesting to play with.

Data's here for registered noncommercial project use http://globalfishingwatch.org/research/research-accelerator-...

More generally, there's plenty of AIS data providers who'll sell you raw data and have visualizations on their website, though there's a lot of cleanup work to narrow it down to things like fishing activity. AIShub offers free feeds, but only if you've got AIS data of your own to share (or maybe if you have a particularly good reason and ask them very nicely)

What are the empty circles and squares?

Some of them (like the ones in the south Pacific and the one south of India) are exclusive economic zones around islands. EEZ boundaries typically extend 200 nautical miles from shore (or until they run into another EEZ). See this map [1].

Presumably the nations that control these zones aren’t fishing them extensively, but other nations are fishing the international waters surrounding them, which is why you can see certain EEZs as negative space on the map in TFA.

[1]: https://en.wikipedia.org/wiki/Exclusive_economic_zone#/media...

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