Study Reveals GMO Salmon Mating Dangers

One of the key con­cerns about a trans­gene escape is the “Trojan gene effect”, caused when a GM fish out­com­petes or repro­duces equally against wild rivals, how­ever if the result­ing off­spring are genet­i­cally infe­rior this could lead a species towards even­tual extinc­tion. Until now there is no empir­i­cal research to demon­strate the abil­ity of trans­genic Atlantic salmon to breed nat­u­rally and infil­trate the wild gene pool.

In the wild, repro­duc­ing males present two main forms of rivals which any escap­ing trans­genic male would have to com­pete with; large males which have migrated and returned from the sea and smaller male parr which have matured in fresh­wa­ter. The large males are aggres­sive and develop attrib­utes to fight off their rivals, while the smaller male parr use cryp­tic colour­ing and ‘sneak fer­til­i­sa­tion’ to compete.

To mea­sure the abil­ity of trans­genic males to com­plete with wild males dur­ing the repro­duc­tive sea­son the team mon­i­tored breed­ing behav­ior in a nat­u­ral­ized lab­o­ra­tory set­ting and used genetic analy­sis to deter­mine the suc­cess of com­pet­ing indi­vid­u­als at pro­duc­ing offspring.

Large, migra­tory wild males out­per­formed their captivity-reared trans­genic coun­ter­parts in terms of a vari­ety of spawn­ing behav­iors. Moreover, despite being less aggres­sive, non-transgenic male parr were also able to out­per­form their GM rivals in terms of spawn­ing behav­ior, and as a result, achieved higher over­all fer­til­iza­tion success.

“While the trans­genic males dis­played reduced breed­ing per­for­mance rel­a­tive to their non-transgenic rivals they still demon­strated the abil­ity to suc­cess­fully par­tic­i­pate in nat­ural spawn­ing events and thus have the poten­tial to con­tribute mod­i­fied genes to wild pop­u­la­tions,” said Moreau. While the study pro­vides an esti­mate of breed­ing per­for­mance under only a sin­gle set of phys­i­cal and demo­graphic envi­ron­men­tal con­di­tions, it does mimic a likely inva­sion sce­nario where the genetic back­ground of the trans­genic pop­u­la­tion dif­fers from that of the wild population.

“Our study pro­vides the first empir­i­cal obser­va­tions on the nat­ural repro­duc­tive capac­i­ties of growth hor­mone trans­genic Atlantic salmon,” con­cluded Moreau. “While the result­ing eco­log­i­cal and genetic effects of a trans­gene escape remain uncer­tain, these data high­light the impor­tance of pre­vent­ing reproductively-viable GM salmon from enter­ing nat­ural systems.”

Source: EurekaAlert.com