Mean (± S.E.) Cath per unit effort (number of fish/Megalitre) across different mesh and velocity treatments.

<p>Mean (± S.E.) Cath per unit effort (number of fish/Megalitre) across different mesh and velocity treatments.</p

Predicted relationship of probability of screen contact with length and rheotaxis of fish (see methods for description of rheotactic behaviour).

<p>Solid lines are at 0.1 m.sec⁻¹ and broken lines are at 0.5 m.sec^−1.</p

Number of fish entrained within the experimental pump system.

<p>Catches are pooled within each velocity and mesh combination. The electrofishing/seine column demonstrates the composition and relative abundance of fish captured at all the experimental site using electrofishing and seine netting.</p

Length frequency plot for fish sampled a) by electrofishing and seine netting at pumping sites, and b) those collected after being entrained by the pump (all treatments pooled).

<p>Length frequency plot for fish sampled a) by electrofishing and seine netting at pumping sites, and b) those collected after being entrained by the pump (all treatments pooled).</p

Length frequency plot showing the size range of fish observed by sonar to make a) contact or b) avoid contact with the experimental screen.

<p>Length frequency plot showing the size range of fish observed by sonar to make a) contact or b) avoid contact with the experimental screen.</p

Tabular representation of the two Latin square experimental designs showing the order of allocation of mesh treatments within replicate runs for each of two approach velocities.

<p>Tabular representation of the two Latin square experimental designs showing the order of allocation of mesh treatments within replicate runs for each of two approach velocities.</p

Odds Ratios of rheotactic categories compared to random orientation.

*<p>The odds ratio is the increase in the probability of contact when compared to random orientation. For example, fish showing positive rheotaxis at the 0.1 m/s velocity are 14×less likely to make contact (1÷0.07 = 14).</p>†<p>Significant (sig) or non-significant (ns) at the p = 0.05 level.</p

Location of the four study sites on the Namoi River showing the Murray-Darling Basin (grey thatched).

<p>Location of the four study sites on the Namoi River showing the Murray-Darling Basin (grey thatched).</p

Odds ratios for probability of screen contact for different mesh sizes when compared to the no mesh treatment at 0.1 m.sec^−1.

*<p>The odds ratio is the increase or decrease in the probability of contact when compared to the ‘no mesh’ treatment. For example, at 10 mm mesh size the probability of screen contact is 1÷0.62 = 1.61. Therefore contact is 61% less likely using the 10 mm mesh than the ‘no mesh’ treatment, however this was non-significantly (ns) different than a 1∶1 ratio at the p = 0.05 level.</p

Diagram of the experimental fish screen showing position of mesh screen panels (M) and position of sonar for the a) 0.1 m.sec⁻¹ approach velocity, b) 0.5 m.sec⁻¹ approach velocity.

<p>Degrees are relative to 0° facing directly into downstream flow (indicated by the arrow). Mesh panels (M) of different aperture size could be interchanged or replaced with solid panels to manipulate approach velocity. To achieve the maximum velocity of 0.5 m.sec⁻¹ all sides except two needed to be fitted with solid panels.</p