Research on Batching Intervals to Reduce Seabird Interactions in Scampi Fisheries

Batching intervals are currently utilised as a discharge management measure across commercial fisheries, yet limited data is collected on this practise e.g. no data on time between discharge outfalls.

Following recommendations from MIT2017-02, this project aims to investigate varied batching intervals with the objective of determining if an �optimum� batching discharge interval exists in reducing seabird activity around working fishing vessels and seabird interactions with fishing gear or the vessel.

Batching may be beneficial in disrupting the flow of attractant for seabirds to fishing vessels; therefore, reducing abundance and potential capture during haul and the subsequent set of fishing gear.

The key aspects of batching discharge involve: a holding period of fish waste, offal or returned baits (for a minimum of 30 minutes) and swift discharge (five minutes or less) as opposed to continuous discharge (Pierre et al. 2012; Kuepfur and Pompert 2017). The scampi fishery is a bottom trawl fishery conducted by a small number of vessels <32 metres in length.

Vessels typically conduct 2-3 long, slow speed tows per day. The fishery is characterised by a relatively high proportion of non-target bycatch (due to the small mesh size of trawl nets) which is currently discharged at sea.

On-board fish waste management equipment differs across vessels, though may consist of holding/storage tanks for bycatch that can be periodically discharged via a chute, other vessels store fish bycatch in bins prior to discharge. This project will involve an analysis of past observer data on batching practices in the scampi fishery to provide an overview for developing the methodology for this study.

The methodology will be oriented around the analysis of differing batching regimes and the impact it may have on seabird activity and observed seabird interactions/captures. The timing (in relation to set/haul), location (haulside, offside), type (offal, whole fish, baits) and efficacy of batching will be investigated across the scampi trawl fleet.

Recommendations will be sought, for example, on what additional information might observers be required to collect on batching and seabird activity.