Sunday, November 7, 2010

Sterile Fish Grow Faster and Reduce the Genetic Effects of Escapees

Fish escape from fish farms: this is a known and accepted fact.  Farmers do their best to reduce the risk of escapees, but often they still occur, and the effects that the escaped fish have on the environment is still being examined.  However, it is known that escapees can sometimes breed with wild fish, which can have severe genetic consequences for the wild population.

However, there is a method that can be used to create sterile fish, fish that are physiologically incapable of reproduction: this method is called ‘triploidy’.  Without delving into too much scientific jargon, triploidy involves interfering with the process of fertilization, resulting in an embryo that has more chromosomes than occur naturally.  These fish grow normally, but when they mature and are ready to mate, their gonads do not develop and they are incapable of producing viable sex cells.

This is NOT genetic modification: no genes have been changed or inserted.  Instead, artificial methods have been used to manipulate the number of chromosomes present, resulting in infertility.

But the benefits of triploidy do not stop at sterility: normal mature fish invest massive amounts of energy into gonad production.  In triploid fish, where the gonads do not develop, this energy can be utilized for growth instead of reproduction, meaning that triploid fish grow faster and have better feed conversion ratios than non-triploids: this has large implications for the economic viability of a given fish farm.  Plus, if these fish escape, they are guaranteed to not interbreed and hybridize with wild populations!

From a practical and an economic perspective, producing triploids is not challenging, so more commercial attention should be focused on this practice.  In my opinion, the benefits clearly outweigh the costs, and in an ever-growing effort to become more sustainable, this is a no-brainer for the aquaculture industry.

1 comment:

  1. Brian, the triploids of Rainbow trout become giants (23 kg is the record in NY) and their meat has better taste