Seabed mining could sink the fishing industry

By Jesse van der Grient, University of Hawaii Falkland Islands, July 3 (360info) If deep-sea mining goes unchecked, it can have an impact on fish stocks, and therefore on communities in the Pacific Ocean.

Drilling for deep-sea minerals could begin soon as the regulatory agency takes steps to finalize the rules and could begin considering mining applications this month.

But there’s still a lot we don’t know about the potential impacts of deep-sea mining and it’s a matter of concern, especially for ocean-dependent communities.

The Pacific Ocean is home to the world’s largest tuna industry and tuna fisheries are known to operate in areas explored for mining.

An irreversible impact on these fish stocks could be disastrous for the Pacific archipelago communities that depend on the ocean for their food and livelihoods.

Seafood caught near mining sites may be contaminated with metals.

Climate change and increased activity near spawning grounds can affect available stocks, resulting in loss of income, employment and food supplies.

Since tuna is a highly migratory species, the impacts in one area could potentially be transferred to other areas otherwise unaffected by mining but dependent on the fishing industry.

Several tests and simulations show how mining can adversely affect seafloor organisms and that their rate of recovery can be slow, for both microbes and animals.

But it’s not just limited to the seabed. The effects extend to the water column above.

The materials extracted from the seafloor will be brought to the surface via risers, causing light and noise pollution in dark environments where animals have adapted to see extremely low levels of bioluminescent light.

The effects of changing noise levels are also poorly understood.

Effects of discharge plumes (sediment loading) can be minimized by releasing them onto the sea floor, but this is costly.

The introduction depth of these plumes is currently not considered in the draft mining regulations.

However, plumes are expected to be released at some depth in the ocean below the sunlight zone (upper 200 meters of the ocean that still sees the sunlight), where photosynthesis takes place. This could potentially prevent direct effects of discharge plumes on commercial fish such as tuna and billfish.

But an expansion in the twilight zone (between 200 and 1,000 meters below the ocean surface) can still have indirect consequences for fisheries. Many twilight zone animals, including fish, crustaceans and squid, migrate to the surface at night to feed, while hiding from predators in the deeper dark waters during the day.

These vertical migratory birds are important prey for tuna and billfish.

Models predict that these discharge plumes could span 10 to 100 km, depending on factors such as the size of the sediment particles and the depth of the discharge (deeper discharges will result in smaller plumes).

The discharge plumes will likely have elevated metal concentrations because ores break during collection, allowing metals to leak out and possibly stick to sediment particles.

Increased sediment concentrations in the water column will cause damage by reducing the feed rate. Predators will have difficulty finding their prey and the concentration of food particles of suspension feeders will be diluted by the sediment particles.

It can also damage sensitive surfaces such as gills and cause stress in marine animals.

All of these effects can affect the growth, reproduction and survival of various organisms, with implications for the wider biological community.

Many countries with adjacent fishing industries discuss deep-sea mining rules and regulations with the International Seabed Authority, the governing body for deep-sea mining.

They are able to consider these trade-offs as they are most likely to be affected by increased seafloor activity.

Fisheries could be treated as stakeholders in deep-sea mining.

Regional Fisheries Management Organizations — international organizations regulating regional fishing activities on the high seas — could become observers at the Authority or involve their Member States, which are also delegates.

The Authority wants an ecosystem approach to management and discussing the possible interactions between these different industries fits well into this endeavour. The deep sea is one of the least explored areas of our globe with countless species yet to be discovered. It provides many services to humanity, including climate regulation and fisheries, which we all need to understand better before destroying them. ( GRS GRS

(This story has not been edited by Devdiscourse staff and is automatically generated from a syndicated feed.)

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