A Greenpeace activist holds a sign as he confronts the deep sea mining vessel Hidden Gem, commissioned by Canadian miner The Metals Company, as it returned to port from eight weeks of test mining in the Clarion-Clipperton Zone between Mexico and Hawaii, off the coast of Manzanillo, Mexico November 16, 2022. REUTERS/Gustavo Graf/File/23081826
This article has been drawn largely from two reports. One was published in the journal Nature in June 2023, and the other, a Secretariat for the Pacific Community (SPC) report from 2018. These references are available on request.
Climate change is driving and increasing
overlap between eastern Pacific tuna fisheries and the emerging industry of
deep-sea mining. Climate models suggest that tuna distributions will shift in
the coming decades. Within the Clarion-Clipperton Zone of the Pacific Ocean, a
region containing 1.1 million km2 of deep-sea mining
exploration contracts, the total biomass for bigeye, skipjack, and yellowfin
tuna species are forecasted to increase relative to today under two tested
climate-change scenarios. Percentage increases are 10–11 per cent for bigeye,
30–31 per cent for skipjack, and 23 per cent for yellowfin. The interactions
between mining, fish populations, and climate change are complex and unknown.
Just as there is a very real risk that deep sea
mining in the CCZ could impact tuna fisheries as they move east with climate
change, here in the Cook Islands we also run a risk that any deep sea mining in
our Marae Moana may also impact our tuna fishery.
The 2018 paper by SPC predicted an increase in
tuna catch in the Cook Islands of around 18 per cent, as the warming seas push
the tuna further to the east. This has potential significant economic benefits
for the country. However, interaction of tuna stocks with the impacts of deep
sea mining in our EEZ may create conditions much less favourable for an
increase in tuna stocks, with the potential for conflict and resultant
environmental and economic repercussions.
If any, or all, of the three deep-sea mineral
companies issued with exploration licences in the Cook Islands, are permitted
to move to a commercial mining phase, conflict between fisheries and deep-sea
mining will likely occur. Impacts can occur from a number of pathways.
During the mining process, there will be two
plumes, one where sediment is stirred up by the mining of the nodules at the
seafloor, and a second where unwanted water and material separated from the
nodules is discharged into the ocean from the surface mining vessel. The
discharge plumes will raise the particle concentration in the water column.
This could interfere with and harm filter feeding apparatuses and gills of tuna
and their prey (which include marine organisms that move into much deeper
waters), reduce visual communication, and increase stress hormone levels. This
could extend the impacts of deep-sea mining horizontally for tens to hundreds
of kilometres and vertically for hundreds to thousands of metres.
Second, the return-water discharge plume is
expected to contain elevated concentrations of metals. As minerals are
collected, they will likely fragment with some dissolving into seawater and
some sticking to sediment or organic particles. Such particles could be
ingested and incorporated into deep-sea food webs entering our seafood supply
with toxins accumulating in tuna, as they are predators near the top of the
food web. Even if there were only localised effects or low risks from toxic
accumulation or contaminant presence, this could still have a high impact on
tuna fisheries through a negative consumer/market reaction.
Third, mining noise could also be extensive and
cause physiological impacts in tuna and their prey, leading them to alter their
feeding and/or reproductive migrations, and potentially reducing catch rates.
At this stage, the only research being done on
the potential impacts of deep seabed mining is being done by the companies
intending to mine. Dr Amon, quoted in another article in Scientific American released
this month, says “there’s a fundamental difference between science to
understand and science to exploit”—something she has learned from working in
both situations. She says science to exploit often becomes “a tick box
exercise”— doing only what’s needed to satisfy a checklist. The problem with
that, Amon says, is “not all contractors are doing high-quality science. Not
all contractors are doing a lot of science. And not all contractors are making
their science accessible.” Dr Malcolm Clark, a New Zealand biologist who has
served as an adviser on the ISA’s Legal and Technical Commission for the past
seven years, and also advises the Cook Islands Seabed Minerals Authority, agrees.
Given the many outstanding critical scientific
gaps related to the impacts of deep-sea mining, fisheries, and climate change,
as well as their interactions, that must be closed through scientific research
for effective management to be possible, it would make sense for the Cook
Islands not to permit mining unless and until the likely impacts are properly
understood, and manageable within agreed thresholds including consideration of
potential effects on tuna stocks. This will require a significant amount of time,
with 10 years or more of comprehensive and independent scientific research.