05/07/13: Cage culture brings hope to Haitians; Delaware Aquaculture Act passed; copper prevents fish from avoiding danger

Haiti is the poorest country in the western hemisphere with more than half of its population malnourished. However, a NGO is trying to change this by investing in cages for tilapia. The Caribbean Harvest Foundation has provided cages able to hold up to 20,000 tilapia to seven villages in the main eastern highway linking Haiti and the Dominican Republic region.

Dr Valentin Abe, who is behind the scheme, wants to use modern aquaculture technology to create a domestic fishing industry for Haiti. For Haiti to have fish consumption that’s close to the world’s average, you need to produce about 120 million pounds of fish a year. However, at present, the entire country produces less than 30 million pounds of fish.
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Delaware looks set to joins its fellow east coast states in commercial aquaculture after the Senate unanimously passed the Delaware Aquaculture Act of June 26, 2013.

The bill allows the Delaware Department of Natural Resources and Environmental Control to establish regulations for the leasing of acres in the Inland Bays.If signed into law, the bill would allow commercial shellfish farmers to lease one- to five-acre tracts of shellfish grounds in Delaware’s Inland Bays.
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Fish fail to detect danger in copper-polluted water. A new study, to be presented at the meeting of the Society for Experimental Biology on the 5th of July, shows that fish cannot smell a danger odor signal emitted by other fish in waters contaminated with copper.

Research conducted by Dr Bill Dew at the University of Lethbridge in Canada looked for the first time at the effect of the metal contaminants nickel and copper on specific fish olfactory sensory neurons, and how these affect the fish's ability to detect and swim away from an odour released by other fish of the same species (conspecifics) when a predator attack takes place.

Dr Bill Dew said, "Our research shows that copper affects the function of a specific type of olfactory neurons in fish, preventing them from detecting important olfactory signals used to detect fish injured by predation."

Using a technique that measures the response of the olfactory system to odours, the researchers showed that copper and nickel affect the ability of different cells to detect odours. Furthermore, using a series of anti-predator trials, which measured avoidance of fish to a conspecific skin extract, the researchers found that fathead minnows exposed to copper do not avoid the skin extract, while unexposed and nickel-exposed fish do. 

Dr Bill Dew said, "This means that fish in an environment contaminated with copper would not be able to detect compounds released during a predation event and potentially not avoid predators, while fish in a nickel contaminated environment would be able to detect these compounds and undertake predator-avoidance behaviours."
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Tilapia (Photo credit: Wikipedia)