We’re about 200km off the coast of South Africa, sailing in the high seas of the Indian Ocean. During the night we caught up to a Spanish longliner, one of the many foreign vessels fishing in the region, others coming from places like Taiwan, Japan, and the United Kingdom.

Since yesterday morning we’ve been in an area of higher fishing activity; warmer waters in the Mozambican channel have pushed Albacore tuna further south and fishing vessels have followed. This ship seems tiny to be all the way out here, much smaller than the Japanese boats we’ve come across. Crew members in faded blue overalls are busy on deck, chances are they’ve had their fishing line out all night and are ready to start hauling it in.

Today the Indian Ocean provides about a quarter of the world’s tuna catch, much of it caught by longline and purse seine fishing. Most of the tuna is then shipped out of the region and sold in European, Asian, and other markets.

According to available data, the tuna catch from the Indian Ocean peaked in 2006. Although yellowfin tuna populations shrunk by a staggering 45% in the last ten years, they are now recovering somewhat as piracy in the East African region has reduced the size of fishing fleets working there. But sadly that fishing capacity is now focusing on other tuna species in different regions of the Indian Ocean, and Albacore tuna is feeling the pressure.

Illegal and unreported fishing is a major problem in the region. According to one report, approximately 18% of all fish caught in the Indian Ocean is illegal, unreported, or comes from completely unregulated fisheries. For countries like Mozambique, illegal fishing is a real problem, and monitoring their waters effectively is not an easy task due to resource constraints. During the last two weeks Greenpeace has worked with the Mozambican government, helping officials to patrol the country’s waters and prevent illegal fishing.

02 October 2012

Shark fin dry on deck of the Japanee longliner Matsuei Maru no 11, South West Indian Ocean. Greenpeace is observing fishing activities in the Indian Ocean where poor management has left many stocks over exploited. 09/27/2012 © Paul Hilton / Greenpeace

Although the vessels we came across were targeting mainly tuna and tuna-like species, we found that sharks were being frequently caught and killed for their fins, a practice fueled by an increasing demand for shark fin soup. Shark fins are currently amongst the most expensive fish products in the world, selling for $740 a kilogram. Globally a third of shark species are now endangered, with shark numbers having dropped by 80%.

Against this backdrop of unsustainable industrial-scale fishing, we find coastal communities whose livelihoods depend on the ocean. In the Maldives, for example, the average person gets half their protein from fish – not to mention the millions of people all along the Indian Ocean coastline who are employed through fishing. For these communities, empty seas aren’t just a matter of collapsing ecosystems – they’re about food-security and human rights.

We’re currently sailing in a part of the Indian Ocean not frequently monitored by third-parties – in fact, as far as we know, this is the first time an NGO has come to this particular area to document fishing activities. We’re here to get a better understanding of what happens in the high seas: who’s fishing what, where are they landing the fish and exporting it to, and are they following international regulations? We also want to learn from coastal communities, hearing their ideas on what can be done to improve the sustainability and fairness of this fishery.

From the deck of the Rainbow Warrior, I can see the Spanish vessel’s line being pulled in now. Every second or third fish is actually just a bloody head, it’s body having been eaten by something else. And sure enough a minute later, the shadow of a blue shark whips alongside the boat, and is gone.

It’s a reassuring thought that there’s still life in these oceans – that although fishing operations have increased to unsustainable levels, the majesty of the ocean lives on. There’s still something to be saved out here.