Table 4 Results of study validity assessment using the critical appraisal tool (see Table 3)
Category | Reason | Projects (#) |
|---|---|---|
Low | Replication: less than 50 fish released or not indicated | 28 |
Measured outcome: semi-quantitative | 1 | |
Outcome metric: risk of entrainment/impingement, not mortality/injury per se | 2 | |
Intervention and Comparator Bias: habitat type confounding | 19 | |
Intervention and Comparator Bias: confounding sampling factors | 39 | |
Intervention and Comparator Bias: confounding environmental factors | 15 | |
Intra-treatment Performance Bias: variation within treatment/control samples (intervention type) | 12 | |
Intra-treatment Performance Bias: variation within treatment/controls samples (sampling) | 8 | |
Medium | Sample size: between 50 and 100 fish | 24 |
Measured outcome: quantitative approximations (estimates) | 16 | |
High | Control-impact or randomized controlled trial design | 128 |
Sample size: greater than 100 fish | 76 | |
Measured outcome: quantitative | 111 | |
Outcome metric: related to fish mortality, injury, or productivity relative to control | 126 | |
Intervention and Comparator Bias: habitat type homogenous | 109 | |
Intervention and Comparator Bias: homogeneity in sampling distance/time | 89 | |
Intervention and Comparator Bias: homogeneity, environmental factors | 113 | |
Intra-treatment Performance Bias: No heterogeneity within treatment and control samples (intervention type) | 116 | |
Intra-treatment Performance Bias: no sampling heterogeneity within treatment/control samples | 120 |