Hook Pod Update
Introduction The Hook Pod , designed and developed through collaboration between BirdLife International and Fishtek Ltd, is an emerging mitigation measure designed to mitigate the incidental capture of seabirds during pelagic longline fishing operations. The Hook Pod is designed to easily attach to pelagic longline gear and prevents incidental seabird capture by protecting the barb of the hook during setting operations. Once the fishing gear sinks to a predetermined depth, the pod opens, releasing the hook to begin fishing. The pod is then simply retrieved during hauling operations closed and stored in standard setting bins until the next set.
Background At the third meeting of the SBWG, we reported on 2009 trials onboard FV Strike Force in the Australian East Coast Tuna and Billfish Fishery (ETBF) to investigate how hook pods fit in the deck practices and setting, hauling and storage practices. These trails indicated that the pod would integrate well into standard fishing practices, and helped us identify several areas for improvement (SBWG 3Doc 17). From the start of the development of the pod in 2007, we have worked closely with fishermen to incorporate improvements, including a spring loaded gate to enable the rapid and safe loading of the hook, and a twist collar to enable a quick retro-fit to the longline.
In November 2010, we conducted further trials in the ETBF (onboard the FV Vanessa S) with a prototype pressure release mechanism (closed diaphragm) incorporated for the first time. Previous trials in 2008 (Tasmania) and in 2009 had used closed cell foam to achieve the appropriate release depth, but this was always a temporary solution as the foam required replacing after a few sets and did not open with the precision required.
In the 2009 and 2010 trials, two different methods of storing the hook pods in the setting bins were trialed (1) pods were left hanging from the swivels in the bin (Figure 1), and (2) pods were fleeted into the bin along with the branchline (Figure 2). Both methods worked well with no issues with entanglements in our out of the box. In 2010, we added lead weight to the inside of the pod to increase its weight. Using CEFAS G5 Time Depth Recorders (TDRs) we investigated the sink rate of the pod with >60g of weight 'on the hook' compared to a standard weighted swivel placed at 3.5m form the hook. The pod achieved a sink rate 0.475m/second (for dead bait) for the first 2 m. Further sink rate data are available in Appendix I and sink rates under controlled (pool) conditions are available in SBWG-4 Doc 5.
The trials in November 2010 provided more useful data including the second set of trials when the pod was used successfully with a range of bait types and hooking positions (large and small fish, live bait and squid). However, we did encounter some difficulties, including, some release mechanism failures and latches loosening, which enabled hooks to fall out of the pod.