Barry and I spend as much time on deck as possible. Our main work is monitoring interactions between seabirds and the two warp cables at the stern. To do this, we sit for hours on end on the 'catwalk', a raised metal gantry above the stern of the boat.

Barry's work has shown that it is collisions with these two thick steel cables that is causing problems. Seabirds are attracted to the discards from the trawler, and as they fly in around the stern of the vessel, some collide with the warps, because they simply do not see them in time. The smaller sooties don't seem to collide much, the white-chins more often, but both seem reasonably robust.

But it is the albatrosses that are more prone to drowning or fatal injury. When feeding, they often sit with wings raised or flap around, and with the vessel moving forward or in a heavy swell, the warp cable can instantly dunk an unsuspecting bird, sending it down rapidly into the depths.

Sometimes the birds pop up many yards further astern, but often they do not. We see one shy caught in such a way, the body brought up later on the warp cable onto the deck in a broken and bloody mess. Those that survive often have broken wings, meaning a slow lingering starving death.

Observations made over several years have shown the potential toll that these collisions may be having on albatrosses. Numbers are lower in summer when more birds are at their breeding grounds, much higher in winter, and based on the numbers of trawlers known to fish in southern African waters, an estimated 18,000 seabirds may be being killed each year, the majority of them albatrosses.

Tori (the Japanese word for bird scaring) lines, modified from those now being used on longliners, are beginning to provide an effective solution on trawlers too. They are simple and cheap to make, costing as little as R300 (about £25).

A large orange traffic cone is tied to a length of rope, some 50 metres long, onto which loops of bright yellow garden hose are tied. The lines are attached above and outside the warps, the cone keeps the line taught, so that the lengths of hose touch the water, providing a 'curtain' that the birds can see - and avoid.

Barry's work shows they really work, reducing collisions by between 80 and 95%. I soon see just how effective they are. In the right conditions, we have two v-shaped areas of water with no birds around the two warp cables. Heavy wind, swell or currents sometimes push the tori lines away from the warps, making them less effective.

I ask Barry what measures could be introduced to make trawlers totally safe for albatrosses. 'Stop dumping discards, either completely or at least whilst shooting the nets. You can't deploy the toris until the warps have stopped feeding out, otherwise they can get entangled and just snap off. That's when birds are most vulnerable.'

For four days, we fish within sight of Cape Point some 15 miles distant. At times, we are followed by flotillas of small boats, hoping to hook some of the yellow-finned tuna that are attracted to the discards. Some days we see them, bright white flashes under the water, as they hunt small fish. We even see a few leaping from the water like dolphins.

On the Sunday night, we sail the 90 miles to Danger Point. The change in bird numbers and species is remarkable - gone are the Cape gulls, and instead of a few dozen albatrosses, we have over a thousand.

And this is summer. In winter, there are even more birds, as adults and youngsters desert the breeding islands. On Monday, the bad weather results in a European storm petrel and two white-chins colliding with the vessels. We gingerly pick each up, take photos, and release them over the side.