Table 3.
Output of GLMs testing for differences in the temporal development of fish variables in Björnöfjärden and the reference site. Analyses were performed over years 2011–2020 for perch, cyprinids and herring in the gill net survey (CPUE and WPUE) and for perch, cyprinids and pike in the juvenile fish survey (CPUE). Temperature at the time of fishing, “Temp0”, was included as a covariate for the gill net data. A significant interaction “Site*Year” indicates a different directional development and a potential effect of the restoration (model output for individual factors not shown). Values show F. df = degrees of freedom. Significance of variables: *** for p < 0.001, ** for p < 0.01, * for p > 0.05. ns = not significant
| Taxon | Depth | df | WPUE | CPUE | ||
|---|---|---|---|---|---|---|
| Temp0 | Site*Year | Temp0 | Site*Year | |||
| Gill net data | ||||||
| Perch | All (0–20) | 1569 | 342*** | 18.8*** | 288*** | 9.9** |
| 0–6 m | 1288 | (ns) | 11.6*** | (ns) | (ns) | |
| 6–10 m | 1190 | 45.8*** | 5.4* | 24.9*** | 6.9** | |
| Cyprinids | All (0–20) | 1569 | 281*** | (ns) | 235*** | 10.6** |
| 0–6 m | 1288 | (ns) | (ns) | (ns) | (ns) | |
| 6–10 m | 1190 | 114*** | (ns) | 62.1*** | (ns) | |
| Herring | All (0–20) | 1569 | 6.9** | 8.3** | 16.2*** | 13.6*** |
| 0–6 m | 1288 | (ns) | 5.3* | (ns) | 5.9* | |
| 6–10 m | 1190 | 6.4* | 5.3* | 10.4** | 13.6*** | |
| Juvenile survey | ||||||
| Perch | 0–5 m | 1650 | – | – | – | (ns) |
| Cyprinids | 0–5 m | 1650 | – | – | – | (ns) |
| Pike | 0–5 m | 1650 | – | – | – | (ns) |