Table 1.
Genetic individual assignment of tagged cod in groups with different migratory behaviours
| Group | Numbers | Proportions | |||
|---|---|---|---|---|---|
| Kattegat | North Sea | Sum | Kattegat | North Sea | |
| a | |||||
| Reference samples: | |||||
| Kattegat | 359 | 76 | 435 | 0.83 | 0.17 |
| North Sea/W Skagerrak | 43 | 158 | 201 | 0.21 | 0.79 |
| Behavioural groups: | |||||
| Skagerrak → North Sea | 10 | 17 | 27 | 0.37 | 0.63 |
| Kattegat → North Sea | 2 | 3 | 5 | 0.40 | 0.60 |
| Skagerrak → Kattegat | 3 | 0 | 3 | 1.00 | 0.00 |
| Nonmigratory Skagerrak | 11 | 18 | 29 | 0.38 | 0.62 |
| Nonmigratory Kattegat | 24 | 12 | 36 | 0.67 | 0.33 |
| b | |||||
| Assignment to | Migration towards | ||||
| Kattegat | North Sea | ||||
| Kattegat | 3 | 12 | |||
| North Sea/W Skagerrak | 0 | 20 | |||
Each of the in total 100 tagged cod were assigned to either the Kattegat reference or to the North Sea/W Skagerrak spawning reference. For definitions of groups see Table 2, Fig. 3 and text. Self-assignment of reference samples to either Kattegat or North Sea/W Skagerrak was performed by leaving the assigned individual out of the sample
Summarizing assignment for the 35 migrating individuals from part a. An exact test of independence showed that fish were more likely to migrate towards the population they were genetically assigned to (P = 0.032), indicating philopatric behaviour in the migrating fish