Fluorescent Transgenic Zebra Danio More Vulnerable to Predators than Wild‐Type Fish

There is a knowledge gap in the ecological risk assessment of transgenic fish as to whether novel traits change their vulnerability to predation and thus their ability to establish themselves in nature. The U.S. commercialization of ornamental transgenic zebra danios Danio rerio and the approaching commercialization of other transgenic fish heighten the need for ecologically realistic models with which to address this question. Transgenic zebra danios with fluorescent body colors represent a good model system because marketed lines are likely to be released by hobby aquarists and it is relatively easy to study their interspecific interactions under nearly natural conditions. In experiments including habitat complexity, transgenic red‐fluorescent‐protein zebra danios were approximately twice as vulnerable as the wild type to predation by largemouth bass Micropterus salmoides and eastern mosquitofish Gambusia holbrooki , two native predators that potentially resist invasion by introduced fish. Increased predation vulnerability should decrease the risk of transgenics’ becoming established if other fitness‐related traits are equivalent in nature. The zebra danio model is ideal for further testing the generality of this result under more complex ecological conditions.