Table 1. Slipping behaviour ethogram.
Ethogram of collective fish behaviour during escape from purse seines.
| Behavioural unit | Type | Description | Hypothesised welfare impact |
|---|---|---|---|
| No escape | State | Discharge channel (or its immediate area) in field of view of cameras, but with no fish escaping the net | Uncertain–positive impacts resulting from maintenance of schooling; negative impacts resulting from continued risk of impact of capture stressors |
| Single fish | Event | Discharge channel (or its immediate area) in field of view of camera, with a single fish escaping the net | Moderate–loss of schooling advantages in an obligatory schooling species |
| Small group | Event | Discharge channel (or its immediate area) in field of view of camera, with a small group1 of fish (<30) escaping the net with a coordinated schooling structure | Minor–school structure remains intact, low probability of contact related injuries |
| Orderly | State | Discharge channel (or its immediate area) in field of view of camera, with a large group of fish (>100) escaping3 the net with a coordinated schooling structure | Minor–school structure remains intact, low probability of contact related injuries |
| Disorderly | State | Discharge channel (or its immediate area) in field of view of camera, with a large group of fish (>100) escaping3 the net without a coordinated schooling structure, often with collisions between fish and into gear | High–schooling structure lost in an obligatory schooling species, high probability of contact related injuries |
| Disagreement | State | Discharge channel (or its immediate area) in field of view, but with disorderly behaviour and orderly behaviour evident on different cameras | Minor / High–as for orderly or disorderly above. |
| Return | Event | Discharge channel (or its immediate area) in field of view of camera and an escape taking place, with ≥ 1 fish of the group re-entering the net | Uncertain–positive impacts resulting from joining large school inside the net; negative impacts resulting from increased risk of impact from capture stressors |
| Not in view | State | Either: 1) both camera views obscured, or 2) discharge channel (or its immediate area) not in field of view of either camera | NA |
1A group was defined as >1 fish in close proximity (less than approximately 5 body lengths distance between individuals)
2A coordinated structure was defined as a polarized group of fish, capable of collective schooling movements
3The start and end of an escape for groups of >100 fish was defined as when the first and last fish passed the discharge channel threshold.