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At-sea and on-shore trials were conducted to test the safety and effectiveness of an alternative line weight called the Safe Lead.  This new line weight is designed to reduce danger to the crew in the event of a bite-off by sliding down or off the line.  At-sea trials were conducted in South Africa and indicated that dangerous fly-backs, a result of a bite-off, were reduced when the Safe Lead was used. During these trials, only 4.2% of Safe Lead fly-backs reached the fishing vessel, compared to 73.3% with traditional leaded swivels.  On-shore trials indicated that the degree of slippage of the Safe Lead off the line was dependent on the distance from the Safe Lead to the hook and the tension on the line. When the Safe Lead was placed within 2m of the hook, it slid off the line under all four tension treatments.  Safe Leads appear to be both a cost effective and operationally simple alternative to traditional leaded swivels.

Two new branch weighting techniques were tested aboard Australian pelagic longline vessels to determine their effect on catch rates of both target and non-target species and their potential use for seabird mitigation.  The two new branch lines included one with a 120 g lead weight < or equal to 2 m from the hook or a branch line with a 40 g lead weight placed at the hook.  There were no significant differences in catch rates for either the main target (yellowfin tuna, albacore tuna, bigeye tuna, swordfish and mahi mahi) or non-target species (sharks) between the industry standard branch line and either of the new ones.  However, the new branch line with the 40 g weight sank more quickly than the industry standard, improved crew safety and reduced the amount of time spent constructing gear. Therefore this option may have the potential to reduce seabird interactions without affecting catch rates of target species.

Experiments were conducted aboard pelagic longline vessels in the western North Pacific to determine the effectivness of paired tori lines in reducing seabird bycatch.  Paired tori lines (PT) were compared against single tori lines (ST) during these tests.  The most abundant species of bird attacking longlines was the Laysan albatross (90.2%).  There was a significant difference in the mean number of albatross and shearwater birds between ST and PT deployments, with the mean number of birds being lower with PT deployments.  PT deployments reduced attacks by albatross's by 47.8% and few attacks occurred within 75 m of the stern.  However when ST were deployed, albatross attacked from 25 to 200 m of the stern.  The number of secondary attacks was significantly lower when PT were used compared to ST, with PT deployments reducing secondary attacks by 43.4%.  In addition, no statistically significant difference in the distribution of secondary attacks between port and stern were found when ST were used but statistical differences were found during PT deployments.

This paper is a global review of seabird bycatch in gillnets. The authors identified 148 seabird species as susceptible to bycatch in gillnets, of which 81 have been recorded incidentally caught. A review of reported bycatch estimates suggests that at least 400,000 birds die in gillnets each year. The highest levels of bycatch are reported in the Northwest Pacific, Iceland, and the Baltic Sea.  

Several seabird bycatch mitigation techniques were tested aboard distant water tuna fisheries in the South African EEZ.  Two types of bird scaring designs, light lines with short streams vs. hybrid lines with a mix of streamer lengths were compared with unweighted branch lines. In addition, unweighted to weighted branch lines were tested and night vs. day setting with a combination of bird scaring lines were tested for their effects on seabird avoidance and targeted fish catch rates.  A total of twenty seven seabird species were observed, but white-chinned petrels were the most common seabird observed and had the highest seabird mortality rate in the study. Albatross (black-browed, yellow-nosed and shy-type) also suffered high mortality rates while stealing bait from the petrels.  Other common surface foraging species included cape petrels. Hybrid lines did appear to reduce sea bird attacks for both species, but the results are not conclusive because the birds could still attack the line at points not protected by the bird scaring lines.  Sets made at night caught far fewer seabirds (0.439 birds/1000 hooks vs. 2 birds/1000 hooks) and catch rates were 18 times higher on the unweighted compared to weighted branch lines (1.07 birds/1000 hooks and 0.06 birds/1000 hooks respectively). The weighted and unweighted branch lines did not affect targeted fish catch rates.

Several seabird bycatch mitigation techniques were tested aboard distant water tuna fisheries in the South African EEZ.  Two types of bird scaring designs, light lines with short streams vs. hybrid lines with a mix of streamer lengths were compared with unweighted branch lines. In addition, unweighted to weighted branch lines were tested and night vs. day setting with a combination of bird scaring lines were tested for their effects on seabird avoidance and targeted fish catch rates.  A total of twenty seven seabird species were observed, but white-chinned petrels were the most common seabird observed and had the highest seabird mortality rate in the study. Albatross (black-browed, yellow-nosed and shy-type) also suffered high mortality rates while stealing bait from the petrels.  Other common surface foraging species included cape petrels. Hybrid lines did appear to reduce sea bird attacks for both species, but the results are not conclusive because the birds could still attack the line at points not protected by the bird scaring lines.  Sets made at night caught far fewer seabirds (0.439 birds/1000 hooks vs. 2 birds/1000 hooks) and catch rates were 18 times higher on the unweighted compared to weighted branch lines (1.07 birds/1000 hooks and 0.06 birds/1000 hooks respectively). The weighted and unweighted branch lines did not affect targeted fish catch rates.

Several seabird bycatch mitigation techniques were tested aboard distant water tuna fisheries in the South African EEZ.  Two types of bird scaring designs, light lines with short streams vs. hybrid lines with a mix of streamer lengths were compared with unweighted branch lines. In addition, unweighted to weighted branch lines were tested and night vs. day setting with a combination of bird scaring lines were tested for their effects on seabird avoidance and targeted fish catch rates.  A total of twenty seven seabird species were observed, but white-chinned petrels were the most common seabird observed and had the highest seabird mortality rate in the study. Albatross (black-browed, yellow-nosed and shy-type) also suffered high mortality rates while stealing bait from the petrels.  Other common surface foraging species included cape petrels. Hybrid lines did appear to reduce sea bird attacks for both species, but the results are not conclusive because the birds could still attack the line at points not protected by the bird scaring lines.  Sets made at night caught far fewer seabirds (0.439 birds/1000 hooks vs. 2 birds/1000 hooks) and catch rates were 18 times higher on the unweighted compared to weighted branch lines (1.07 birds/1000 hooks and 0.06 birds/1000 hooks respectively). The weighted and unweighted branch lines did not affect targeted fish catch rates.

Seabird bycatch in the tuna and billfish longline fishery in South African waters has had one of the highest seabird bycatch rates in the world. Research was carried out aboard two Japanese longline vessels in the South African EEZ in 2010. Half of the branch lines on each vessel were weighted using the double-weight configuration, which consists of a weighted section that was inserted into the monofilament section of a branch line 2m above the hook. Each vessel also deployed two "hybrid" bird-scaring lines during every set. the lines had a mix of long and short streamers. The rate of bird attacks on baited hooks was four times higher on unweighted lines. Mortality of seabirds on weighted branchlines combined with bird-scaring lines was six times less than on unweighted lines. The rate of seabird bycatch was more than 13 times higher during the day than at night. The authors conclude that the combination of two bird-scaring lines, weighted branch lines, and night setting qualify as best practices for seabird bycatch mitigation for fleets targeting tuna and related species in the South African EEZ. 

The Hawaii longline swordfish fishery reduced seabird captures through mitigating bycatch during setting. Now, 75% of bycatch occurs during hauling. Observer data was fit to a generalized additive regression model and found that density of albatrosses during hauling, leader length, and year had the largest model effects. Heavier swivels, greater than 65g, had significantly fewer catch rates for seabirds. However, heavier weights with longer leaders had reduced effects. Shorter leaders with weighted swivels closer to the hooks, significantly reduced the likelihood that baited hooks could become available to albatrosses at the surface. There was no significant difference in catch rate between hauls made with vs. without blue-dyed bait. Future haul mitigation should focus of reducing bird access to hooks as crew coil branchlines. 

The Hawaii longline swordfish fishery reduced seabird captures through mitigating bycatch during setting. Now, 75% of bycatch occurs during hauling. Observer data was fit to a generalized additive regression model and found that density of albatrosses during hauling, leader length, and year had the largest model effects. Heavier swivels, greater than 65g, had significantly fewer catch rates for seabirds. However, heavier weights with longer leaders had reduced effects. Shorter leaders with weighted swivels closer to the hooks, significantly reduced the likelihood that baited hooks could become available to albatrosses at the surface. There was no significant difference in catch rate between hauls made with vs. without blue-dyed bait. Future haul mitigation should focus of reducing bird access to hooks as crew coil branchlines.