Ocean acidification and fisheries declines

A while back we reported on a study by Cheung and others that looked at how ocean biodiversity might change by 2050 under three different climate change scenarios. Ironically, the study found that under all three scenarios it was developed countries (responsible for the majority of greenhouse gas emissions) that would have improved fisheries production by 2050, and that tropical regions would suffer the greatest losses in fisheries productions.

In that study, the authors raised some caveats with their results, one being that it was a modeling exercise and could contain inaccuracies. Another issue raised was that ocean acidification (the ongoing increase in acidity of the Earth’s oceans caused by the uptake of carbon dioxide from the atmosphere) wasn’t included in the models – and could have magnifying effects of their projections.

A recently published study by Sarah Cooley and colleagues has now looked at how increases acidification of the worlds oceans might affect the mollusk fisheries in African nations.

Mollusks such as clams, scallops and conches are important sources of proteins and export-driven income in many African coastal nations.

Ocean acidification and fisheries declines

However, in the context of ocean acidification, mollusks will need to spend more energy in building their carbonate shells (in essence, the shells dissolve in acidic waters) and less energy on growing and reproducing. This could have a negative impact on their population and stocks.

The study assessed specific countries’ vulnerability to ocean acidification by looking at their reliance on mollusk fisheries, their capacity for aquaculture and their projected population growth.

It found that, 10–50 years from now, many developing countries will face reduced mollusks harvests, with countries like Gambia, Haiti, Madagascar, Mozambique and Senegal to be hit the hardest.

This 10-50 time-frame projection leaves a narrow window of opportunity for policymakers to devise strategies that allow fishermen to continue benefiting from mollusk fisheries.

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