Figure 1.

An illustration of the naturalised stream mesocosm (1.25 × 7.8 × 0.25 m per channel), which was divided into two channels and used to compare the reproductive performance of growth hormone transgenic and nontransgenic Atlantic salmon (Salmo salar) males, both as anadromous fish and as precocial parr. Behavioual data were collected using a combination of video observation and passive integrated transponder tag detection, with the respective underwater cameras and antenna moved in response to the location of female nesting activity. Thick arrows indicate the direction of water flow.