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This Handbook aims to:detail the design, operation and use of hoppers (back deck water tanks/sorting devices) in trawl fisheries across Australia;enable the sharing of industry knowledge on hoppers amongst fishers from all Australian trawl fisheries;provide readily accessible information to fishers on the use and application of hoppers;>facilitate the broader adoption among trawl fisheries of best practice use of hoppers. In fisheries where hoppers are not yet widely used but may be useful, help stimulate the development and uptake of new and suitable hopper designs; and provide a tool to inform and educate the general community, fisheries and environmental managers about the initiatives developed and adopted by Australian trawl fisheries to reduce the impacts of trawling on the aquatic environment, and to work towards achieving sustainable operating practices and improved economic efficiency.This handbook is primarily a technical handbook for fishers. It is also however, a useful resource for others interested in the environmental management of Australian trawl fisheries.

Three modified hoop-net designs were tested in the Gasconade and Osage Rivers of Missouri to determine their ability to reduce turtle bycatch without reducing the capture of targeted catfish.  The three designs included an excluder net with tightly spread mesh and a sewn in ring, a chimney-set design and a loose-weave design.  The chimney-net design was the only one that significantly reduced turtle bycatch (84%), while not decreasing the number of average size of flathead catfish.

Wisconsin-type fyke nets were modified in an effort to reduce the incidental bycatch of turtles, without significantly reducing the catch of targeted fish species.  The tests were conducted in three rivers (Missouri, Mississippi and Gasconade) in Missouri.  The net was modified by adding four lines in the vertical gap of the net and this modification was successful at significantly reducing turtle bycatch with no significant decrease in the quantity of fish caught.

An experimental leader design was tested on pound nets in the Chesapeake Bay in 2004 and 2005 to determine their effectiveness in reducing the incidental catches of sea turtles.  The experimental design consisted of replacing the top two thirds of the traditional mesh panel leader with vertical ropes spaced 61 cm apart. During the study, 21 sea turtles interacted with the control net, while only 1 interaction with the experimental net occurred, which was a significant difference.  In addition, there was no significant differences in the harvest weight or size selectivity of finfish between the two net types, although these results were not considered very robust. 

An experimental leader design was tested on pound nets in the Chesapeake Bay in 2004 and 2005 to determine their effectiveness in reducing the incidental catches of sea turtles.  The experimental design consisted of replacing the top two thirds of the traditional mesh panel leader with vertical ropes spaced 61 cm apart. During the study, 21 sea turtles interacted with the control net, while only 1 interaction with the experimental net occurred, which was a significant difference.  In addition, there was no significant differences in the harvest weight or size selectivity of finfish between the two net types, although these results were not considered very robust. 

Experiments were conducted aboard Korean pelagic longline vessels to determine if there were differences in the catch rates of target (tuna and billfish) and bycatch (sharks and other bony fish) species between 3 types of hooks; 4.0 traditional tuna hook (J-4), size 15 circle hook (C15) and size 18 circle hook (C18).  Within the target group significant differences between catch rates were only found between the J-4 and C18 hooks.  In the bycatch species group, significant differences were found between J4 and C15 and between J4 and C18.  Overall, the large circle hook (C18) had the lowest catch rates for tunas and other fish, while small circle hooks (C15) had the lowest catch rates for billfish and sharks.  Any differences in the length of fish caught by the individual hooks were minimal.

An experimental release panel was installed in purse seine nets to determine their ability to release both silky sharks and non-target finfish.  The release panels (5.5 m wide, extending down from the corkline for 11 m) were installed in a portion of the net that forms a "pocket" toward the end of net retrieval.  Dive surveys previously reported that silky sharks tend to segregate and collect in this section of the net.  The release panel was tested during seven purse seine sets, but only two silky sharks (out of 105) exited through this panel. In net observations indicated that sharks and other non-target finfish did not appear to recognize the opening as an escape route out of the net. Despite this initial failure of the release panel, the authors feel refinement of the panel and additional testing is still warranted.

An experimental release panel was installed in purse seine nets to determine their ability to release both silky sharks and non-target finfish.  The release panels (5.5 m wide, extending down from the corkline for 11 m) were installed in a portion of the net that forms a "pocket" toward the end of net retrieval.  Dive surveys previously reported that silky sharks tend to segregate and collect in this section of the net.  The release panel was tested during seven purse seine sets, but only two silky sharks (out of 105) exited through this panel. In net observations indicated that sharks and other non-target finfish did not appear to recognize the opening as an escape route out of the net. Despite this initial failure of the release panel, the authors feel refinement of the panel and additional testing is still warranted.

Wisconsin-type fyke nets were modified in an effort to reduce the incidental bycatch of turtles, without significantly reducing the catch of targeted fish species.  The tests were conducted in three rivers (Missouri, Mississippi and Gasconade) in Missouri.  The net was modified by adding four lines in the vertical gap of the net and this modification was successful at significantly reducing turtle bycatch with no significant decrease in the quantity of fish caught.

Three modified hoop-net designs were tested in the Gasconade and Osage Rivers of Missouri to determine their ability to reduce turtle bycatch without reducing the capture of targeted catfish.  The three designs included an excluder net with tightly spread mesh and a sewn in ring, a chimney-set design and a loose-weave design.  The chimney-net design was the only one that significantly reduced turtle bycatch (84%), while not decreasing the number of average size of flathead catfish.