Netting more ways to keep fish farms sustainable

Netting more ways to keep fish farms sustainable

SINGAPORE aims to be partly self-sufficient in three food items as part of an overall strategy to safeguard food security.

It strives for self-sufficiency for 30 per cent of egg, 15 per cent of fish and 10 per cent of vegetable supplies.

Producing food locally has the additional benefit of mitigating climate change through reduced food miles.

Unlike egg and vegetable production - where layers are kept in shelters and vegetables are grown under controlled conditions - fish farms are highly dependent on water and environmental conditions.

The current plankton bloom that has caused massive fish deaths is not likely to be the last.

If it wants to be self-sufficient for 15 per cent of fish supply, Singapore needs a more sustained effort to make fish farms more sustainable, and less subject to environmental damage.

This calls for changes in fish farming techniques, and substantial investments in capital - both financial and technological.

The plankton bloom now hitting Singapore's fish farms has caused at least 600 tonnes of fish losses, more than 10 per cent of annual production.

More than 55 out of 117 floating fish farms have been affected, with losses estimated at between $15,000 and $300,000 per farm.

The total losses could be between $4 million and $5 million. A similar amount of fish loss occurred last year.

In 2009, fish farms in Singapore were affected by their first plankton bloom and a total of 400,000 fish were lost.

While the numbers are small compared to fish consumption in Singapore and are unlikely to affect total supply, fish farmers have been hit hard by the recurring events.

Interestingly, fish grown in tanks were also affected by the plankton bloom due to the use of unfiltered sea water.

Plankton bloom, or harmful algal bloom, is caused by a combination of higher concentrations of nutrients, which can be enhanced by organic runoff and increase in decaying matter such as fish feeds, high temperatures and sunlight, as well as poor water exchange.

Warm temperatures and high solar irradiance during the dry season can encourage growth of phytoplankton through better photosynthesis.

Poor water circulation in the Johor Strait enhances the rapid multiplication of these organisms.

Plankton bloom results in lower oxygen levels in the water and this can cause fish deaths.

To provide support during massive fish deaths due to plankton bloom, the Agri-Food and Veterinary Authority (AVA) introduced assistance packages to the fish farmers who were affected.

To prevent the deaths, AVA also implemented round-the-clock real-time monitoring and early warning systems to provide information on increase in plankton levels to farmers via SMS.

Yet, even with these policies in place, the recent damage to fish stocks suggests that risk mitigation measures must go beyond financial support for recovery and monitoring of water conditions.

While AVA had alerted farmers to elevated plankton levels, some could not take action as they lacked the tools or financial resources to do so.

The real question, then, is whether the present approach is sufficient to ensure local fish production, and at what cost?

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