Bait condition and bait size play a part in bait sink rate. The faster bait sinks, the less available it is to predatory seabirds during line setting. Bait condition also plays a part in the ease of hooking ('baiting') and whether the bait will stay on the hook (quality).
Bait Life Status
Use of live bait should be avoided. Live bait sinks more slowly than dead bait; individual live baits can remain near the water surface for extended periods. Thus using live bait increases the likelihood that seabirds will be caught.
Bait Thaw Status
Thawed baits are believed to sink faster than frozen baits. However, Robertson & van den Hoff (2010) concluded that the bait thaw status has no practical bearing on seabird mortality in pelagic fisheries. Baits cannot be separated from others in frozen blocks of bait, and hooks cannot be inserted into baits unless they are partially thawed (it is not practical for fishers to use fully frozen baits). Partially thawed baits sink at similar rates to fully thawed baits.
Bait Size (and species)
Small species of fish bait should be used in preference to squid bait. This is because larger squid bait sinks considerably more slowly than small fish bait. Common fish baits are pilchards, sardines and various species of mackerel (Japanese, blue, yellow-tail). The difference in sink rates between large and small fish baits of the same species is minor. Bait species affects the probability of catching different bycatch species (see the description for 'Fish not squid bait'.
Bait hooking position is important. To ensure fast sink rates, baits should be hooked in either the head (fish) or tail (fish and squid), not in the middle of the back (fish) or top of the mantle (squid).
- ACAP. 2011. AC5 Annex 7: Summary advice statement for reducing impact of pelagic longline gear on seabirds. Seabird Bycatch Working Group. Fourth Meeting of the Seabird Bycatch Working Group, Guayaquil, Ecuador.
ACAP. 2021. ACAP Review of mitigation measures and Best Practice Advice for Reducing the Impact of Pelagic Longline Fisheries on Seabirds. In: ACAP - Twelth Meeting of the Advisory Committee. Online
- Robertson, G. and van den Hoff, J., 2010. Static water trials of the sink rates of baited hooks to improve understanding of sink rates estimated at sea. Agreement on the Conservation of Albatrosses and Petrels, Third Meeting of the Seabird Bycatch Working Group, Mar del Plata, Argentina, 8 - 9 April 2010, SBWG3 Doc 31.