Namibia: What Do ‘Rock-Eating’ Bacteria Have to Do With Our Fishing Industry?

EATING fish has become something of a moral dilemma. Reports warn that 70 per cent of global seafood stocks are overexploited or have collapsed altogether.

According to the World Bank, this situation blamed largely on overfishing and corruption now costs the global community US$50 billion annually in lost food.

Historically, Namibia’s marine environment supported an extensive biomass of high-value fish and some of the richest whale and seabird populations on earth. However, during the pre-independence era, intense overfishing of key ecological species, like sardines, managed to alter the original food-web so dramatically that economically low-value or ‘rubbish’ species (like jellyfish, gobies and horse mackerel) now predominate.

Since Independence, Government has done much to rebuild our fish stocks: they’ve clamped down on illegal fishing and promulgated laws and regulations aimed at sustainability. However, no matter what we are made to believe, fisheries research and management (which helps determine things like annual Total Allowable Catches) has largely failed, and our marine resources are still, twenty years after independence, in a miserable state.

There is good news, however: Namibia has begun to make some effort to abandon its ‘single species’ approach to fisheries management and replace it with an ‘Ecosystem Approach’ or EAF. EAF requires multi-species stock assessment and research. It provides valuable insight into the realities of ecosystem dynamics, inter-species competition and predator-prey interactions. Unlike the old methods of fisheries management, EAF attempts to assess the ecological sustainability of different fishing scenarios.

Any research that enhances understanding of how the world’s dynamic, difficult-to-predict, marine environment functions, is also useful for EAF; in particular, research that improves knowledge of the interdependence of, and interactions between, the geology, chemistry and biology (biogeochemical cycling) of the sea. This is important if we are to understand the long-term (sometimes irreversible) impacts linked to overfishing, marine pollution and deep-sea mining.

Current information regarding the finer details of marine science is limited. Of the estimated 1 million species that are believed to live in the sea only 240 000 have been described to date. Furthermore, the seawater we take for granted (think of the ‘harmless’ desalination process) contains considerably more than just water and salt: it teems with vital substances – not least of all the 10 to 100 million microscopic organisms present in just one tablespoon. These invisible communities of viruses, bacteria and miniscule plants kick-start all marine food-chains; they orchestrate the flow of energy and cycling of essential nutrients (like carbon, nitrates and phosphates) throughout the ocean. Without them there would be no other life in the sea and certainly no fish to harvest.

Most mysterious are the colonies of microbes that thrive under extreme conditions at the surface of, and deep within, the sediments of the seabed. Referred to as ‘rock-eaters’ these remarkable communities represent a new world of barely understood biological activity that scientists now believe play a variety of essential roles in the biogeochemical cycling of the world’s oceans.

There is, of course, no one single solution to saving the world’s blighted seas. In addition to overfishing, limited knowledge and poor management, rivers carry sewerage, factory effluent and agrochemicals to the ocean; atmospheric emissions from car exhausts and industry affect the water cycle and the biochemistry of marine life: enormous issues that demand political will and good governance to solve. But we, as consumers, can also do our bit.

One place to start is with the fish we refuse to eat. The Southern African Sustainable Seafood Initiative (http://www.wwfsassi.co.za ) has a list of ‘Green’ seafood, smart choices that will hopefully help keep fish on plates for generations to come.

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Fish & Seafood with Bill & Sheila