Friday, June 19, 2009

Hatchery breeding for reintroduction into Lake Malawi

Evidence is increasing on the downside of captive breeding aimed for reintroduction into the wild. A study published in Biology Letters suggest that wild born offspring from hatchery raised Steelhead Trout parents has only 37% reproductive fitness as compared to 87% if only one of the parents was wild breed. These differences are still detected even if the fish have spent one generation in the wild.

Lake Malawi holds one of the stunning cichlid biodiversity in the world, however this biodiversity is believed to be only 1 to 2 million years old. In other words is still going through sysnthesis, thus most of the cichlids still interbreed naturally during a secondary contact. The results from the above mentioned study should tell us that one of our cards to mitigate for overfishing of the most sort Tilapia should not be hatchery raised ones, but reinforcement of the fishing season and fishing gear size.

If hatchery breed fingerlings are to be used in Chambo restoration plan, then genetic differences between them and wild types should be well studied. As far as I know the aquaculture stock at the moment may not be the best candidates for this exercise. Molecular studies have already revealed that the aqua stock has a mixed up gene pool, that is neither pure Chambo (O. karongae), nor Makakana (O. mossambicus) to mention a few.

All the evidence points us to one thing, Chambo restoration plan should be based on proper scientifc evidence not emotions or personnal gains if we are aiming to produce and really preserve the original (OK) gene pool, which is tasty and tender as claimed by the Lake shore crew.

On a lighter note, while my emphasis has been on the famous chambo, the same principle should also apply on the red listed Ntchila, Sanjika, Ningwi ect in river shire and its catchment.

Have a nice weekend.


HastingsZidana said...


Oregon State University. "Hatchery Fish May Hurt Efforts To Sustain Wild Salmon Runs." ScienceDaily 13 June 2009. 20 June 2009 FROM SCIENCE DAILY

mike said...

wow... find it interesting... hope it'll be beneficial for me and my friends...

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