By Dhiladhila Magazine · Issue 15

The richest fishing water in the region and the richest diamond field share one seabed. A larger vessel raises the stakes on sharing it.

The Atlantic off Namibia is two resources stacked on one seabed: a diamond field and one of the most productive fisheries on the continent. The Benguela Gem enlarges the mining side of that overlap, which makes the question of how the two coexist more pressing, not less. The science on the trade-off is set out in the literature on the Benguela Current ecosystem.

The Benguela upwelling drives that productivity, feeding fisheries that employ thousands. Any expansion of seabed mining has to be read against the health of the water column above it, not just the value of the stones below.

Two harvests, one seabed

The Benguela Current Large Marine Ecosystem is nutrient-rich and heavily fished, and the diamond fields sit inside it. That is the core sustainability tension: the same waters that hold the stones support a food system built on hake, horse mackerel and rock lobster. A larger recovery vessel intensifies the human footprint on that shared ground.

The reassurance in the research is one of scale. Studies of the deepwater fields find the mined area is small against the whole ecosystem, with something like three square kilometres worked a year, so the disturbance, while real, is localised rather than basin-wide.

The stones and the fish share one seabed, and the case for mining rests on the footprint staying small.

What the dredging does to the floor

Seabed recovery excavates and disturbs the floor, then releases a sediment plume that settles over a wider area than the tool touches. The habitat in the worked zone is altered, and how fast it recovers depends on depth, with the research suggesting recovery times spread across roughly two to fifteen years.

That range is the crux. In shallower, more energetic water the floor reworks itself relatively quickly; in deeper, calmer settings the marks linger. A vessel that mines deeper ground is mining the slower-healing part of the system.

The seabed does recover, but the deeper the mining, the longer the ocean takes to mend it.

The fisheries question

The encouraging finding is that the mining fields and the prime fisheries do not fully coincide. Research notes that relatively few fish species occur in the mined area, that it holds no major spawning grounds, and that the important southern rock-lobster grounds do not currently overlap the diamond operations. Separation, where it holds, is the ocean’s own zoning.

That separation cannot be assumed permanent. As mining moves to new ground and fish distributions shift with a changing ocean, the two uses could meet where they now miss, which is the case for monitoring rather than complacency.

Mining and the best fishing grounds miss each other today, but nothing guarantees they always will.

The stewardship read

For a fisheries manager or a marine scientist, the Benguela Gem is a call to keep the environmental accounting current. A vessel adding 45 per cent to recovery is a larger seabed intervention, and the licence to expand should rest on evidence that the footprint stays contained and the recovery holds.

The sustainable target is coexistence, not maximisation of either use. A diamond field that quietly degrades the fishery it shares water with would be a poor trade, whatever the carat count.

The test is whether two harvests can share one sea, and that is measured over years, not seasons.

For anyone in fisheries policy, marine science or ocean governance, the Benguela Gem is a reminder that Namibia’s seabed does two jobs at once and that expanding one use tightens the case for watching the other. The decision it puts to regulators is whether a bigger mining footprint comes with monitoring good enough to prove the fishery stays intact, because the ocean pays for both resources out of the same account.

Sources: De Beers Group; Marine diamond mining in the Benguela Current ecosystem (ScienceDirect); Marine diamond mining: improving environmental practices (Travel News Namibia)