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Summary: The use of circle hooks (4.3 sun and 5.2 sun) instead of standard Japanese tuna hooks (3.8 sun) on pelagic longlines, had little impact on catch rates, mortality or size composition of blue sharks.

Summary:

The catches from five experimental trawls (TED + fisheye BRD, upward facing TED, downward facing TED, bigeye BRD and square-mesh panel BRD) were compared to those of the standard twin Florida Flyer prawn trawl. Nets with a combination of a TED and BRD reduced sea turtle catches by 100%, large sponges by 85.3%, sharks by 36.3% and rays by 17.7% and reduced the proportion of soft and damaged prawns by 41.6% and catches of tiger prawns by 6.5%. Upward and downward facing TED's reduced sea turtle bycatch by 99% and 100% respectively and large sponges by 81.6% and 95.9% respectively. Catches of tiger prawns were reduced by 6.3% with the use of TED's. The BRD's had little impact on the catch of either the target or bycatch species.

Summary:

The catches from five experimental trawls (TED + fisheye BRD, upward facing TED, downward facing TED, bigeye BRD and square-mesh panel BRD) were compared to those of the standard twin Florida Flyer prawn trawl. Nets with a combination of a TED and BRD reduced sea turtle catches by 100%, large sponges by 85.3%, sharks by 36.3% and rays by 17.7% and reduced the proportion of soft and damaged prawns by 41.6% and catches of tiger prawns by 6.5%. Upward and downward facing TED's reduced sea turtle bycatch by 99% and 100% respectively and large sponges by 81.6% and 95.9% respectively. Catches of tiger prawns were reduced by 6.3% with the use of TED's. The BRD's had little impact on the catch of either the target or bycatch species.

Summary: The use of light torilines (made with nylon monofilament branch lines and streamers made from other light material) on pelagic longlines reduced the incidental capture of seabirds by 64%. The capture of target species, including swordfish and blue sharks, was increased by 32% and 15.1% respectively when light torilines were used.

Summary: The extended mesh funnel (EMF) and Florida fisheye (FFE) bycatch reduction devices (BRD) were evaluated in otter trawls with three different sized openings (circumference = 14 m, 17 m, and 20 m). The mean ratio of finfish bycatch to shrimp in nets equipped with BRD's was substantially lower but not significantly different than the ratios in the control nets. The biomass and number of finfish was lower and significantly different in nets equipped with the BRD's compared to the control nets except in the winter, and the catch per unit effort of finfish was always lower in the nets equipped with the BRD's. The number and biomass of shrimp was not reduced in the 17 m or 20 m nets equipped with the BRD's and differences in the catch per unit effort of shrimp between nets with the BRD's and the control net varied by season and net size.

Summary: The Florida fisheye (FFE) bycatch reduction device was tested in a skimmer trawl fishery in Florida. Trawls equipped with the FFE had significantly lower finfish bycatch than the control nets but there was no difference in the quantity of shrimp caught between the two nets. The amount of reduction in finfish bycatch in the FFE equipped nets did vary by season and among fish species.

Summary:

Codends modified with rectangular mesh panels (one oriented length-wise in the cod end and one oriented width-wise, each measuring 7 x 11 bars) reduced the weight of discarded bycatch by 46% and 38% respectively but did not significantly reduce the catch of targeted prawns. A haulback delay of 10-15 seconds allowed juvenile red spot to escape through the square mesh panels, while trawls with no delay showed no significant reduction in the bycatch of this species.

Summary:

White Dukane pingers with a fundamental frequency of 10kHz and harmonies of up to 160 kHz, elicited the strongest response from Hector's dolphins, compared to the black Pice and red Dukane pingers. More than half (62.5%) of the dolphins exhibited avoidance when exposed to the white pinger. However, no significant differences between pingers were found in the rate of echolocation clicks per dolphin or dolphin group, or among the peak frequencies of subset clicks.

Summary:

Codends modified with rectangular mesh panels (one oriented length-wise in the cod end and one oriented width-wise, each measuring 7 x 11 bars) reduced the weight of discarded bycatch by 46% and 38% respectively but did not significantly reduce the catch of targeted prawns. A haulback delay of 10-15 seconds allowed juvenile red spot to escape through the square mesh panels, while trawls with no delay showed no significant reduction in the bycatch of this species.

Summary:

Tests were conducted to determine if twin trawl nets containing a Turtle Excluder Device (TED) and a Popeye Fishbox caught less bycatch then nets fitted only with a TED. Nets that had the Popeye Fishbox located 70 meshes from the codend draw strings had a 48% reduction in the weight of small bycatch, an 87% reduction in number of sea snakes and a 35% reduction in the number of sharks and rays caught. When the Popeye Fishbox was placed 100 meshes from the codend draw strings, the weight of small bycatch was reduced by 28% and the number of sharks and rays was reduced by 27%. No analysis of sea snake bycatch at this distance was carried out. There was no significant difference in the catch of targeted prawns between nets with and without the Popeye Fishbox.