Onboard protocol. The sink rate of baited hooks was recorded by attaching CEFAS G5 Time Depth Recorders (TDRs) to the third of five branch lines at a position 30 cm above the hook (Figure 2). On each set TDRs were deployed on randomly selected sections of the main line (the start, middle or end). TDRs were configured to register depth (pressure) every second to generate the sink rate for each treatment. Figure 2: Basic configuration of Brazilian pelagic longline gear, showing the position where TDRs were attached in relation to hooks between buoys. The number of seabirds present was estimated immediately prior to the set and each subsequent hour within a 250 m hemisphere centred at the vessel xxxxx. During the set seabird attacks on baited hooks were recorded as a function of distance aft (0-50 m, 50-75 m, 75-100 m, and > 100m) in ten minute periods while light persisted. Seabird attacks were defined as any attempt by a bird to take bait, including surface attacks and dives to access sinking baited hooks. Tori line aerial extent was recorded for each ten minute period using white streamers as distance markers placed every 10 m along the length of the tori line. Tori line entanglements were recorded when these occurred. Target and non-target species were recorded during the haul to species level.
Onboard protocol. The sink rate of baited hooks was recorded by attaching CEFAS G5 TDRs at three positions (1st, 2nd and 3rd of five secondary lines) at a position 30 cm above the hook (Figure 2). On each set TDRs were deployed on randomly selected sections of the main line (the start, middle or end). TDRs were configured to register depth (pressure) every second to generate sink rate profiles. During tori line treatments, aerial extent was estimated for each observation period using the distance between streamers. Detailed information was recorded each time the tori line became entangled. Observations on seabird attack rate during the set were recorded using PAP protocols3. Where seabird mortality occurred, the section, buoy and hook position were recorded to enable the mortality event to be related to the setting operation.
Onboard protocol. The sink rate of baited hooks was recorded by attaching CEFAS G5 Time Depth Recorders (TDRs) to the middle (third) branch line at a position 30 cm above the hook. TDRs were deployed on randomly selected sections of the main line (the start, middle or end). TDRs were configured to register depth (pressure) every second to generate the sink rate for each treatment. Setting observations Experimental branch lines were stored and set from two bins; one containing Treatment 1 (60g SLs) and the other Treatment 2 (150g SLs). Sample units were colour-coded red and green to aid recording on retrieval (Figure 8a). The line was set from a central position at the xxxxx of the vessel. Treatment hook bins were situated on the starboard (Treatment 1) and port (Treatment 2) sides. For each Treatment two crew members were included in the setting operation. The first removed the hook and branch line from the bin, attached a light stick and passed the assembly to the second crew member who baited and deployed the hook. The weighted swivel was tossed into the propeller wash, which trailed until the monofilament branch line had completely unravelled; the snap was then attached to the mainline and the hook deployed into the water between the main line and the edge of the wash. This process was repeated for Treatment 2. A fifth crewman set floats from the port quarter of the aft deck. Hauling observations Hauling commenced within an hour of first light. All experimental branch lines were observed and the following details were recorded: Operational data recorded included: Treatment, time, sample unit number, sub unit number and hook number (within sub unit). For a sub-sample of 160 branch lines, the distance of SLs from their original position was measured to determine slippage toward the hook. Catch data recorded included: Species, size and condition (i.e. partially predated). For target species (i.e. tunas and swordfish) a size class was recorded. Sharks were assigned to one of three size classes: small (<1 m), Medium (1-2 m) and large (>2 m). All bite-off events were classified into one of five categories 0-4 (0- bite off occurs under water and weight stays under water; 1- weight lands on water; 2- weight hits the bottom half of the boat; 3- weight hits the upper half of the boat; 4- weight flies above the boat). During the haul all SLs were checked and positioned at a standard distance of 3.5 m (adjacent to the un-weighted swivel) from the hook.
Onboard protocol. Seabird abundance was estimated for all experiments by conducting approximately 10- minute observations within a semi-circle extending 200 m aft of the xxxxx of the vessel. The three treatments were deployed sequentially during each experimental trawl. The order in which the three treatments were deployed on each trawl was randomly allocated. Experimental treatments began once the net was on the seabed, each treatment lasting 15 minutes. Data collected during trawls that finished before all three treatments could be deployed were excluded from data analysis. Observations on seabird interactions with trawl warp cables were carried out in 45 minute periods (3x 15 minutes). A single warp cable was chosen for observations based on the side of the vessel where most offal was discharged. Interaction protocols were adapted from Xxxxxxxx and Xxxxxxxxx (2001). This included recording light and heavy contacts between birds on the wing and on the water, and the warp cable. Offal discard was recorded for each new observation period.
