Circle hooks catch rate ppt 1 SAR 8 12g

Slide1: 

Comparison of circle hook and J hook catch rate for target and bycatch species taken in the Korean tuna longline fishery in 2006 Soon-Song Kim, Doo-Hae An, Dae-Yeon Moon and Seon Jae Hwang National Fisheries Research and Development Institute (NFRDI), Republic of Korea

Slide2: 

The survey area 9°13’S~1°36’N and 126°00’ ~138°21’W from September 20 to October 23, 2006 1°48’S~7°00’N and 142°00’ ~149°13’W in 2005

Slide3: 

Korean longliner : 416 GRT Monitoring : 28 set (one set per day) No. of hooks used : 62,464 - each set : 2,240 (560 of each type) Set at around 8:30am, finished by 2:00 pm. After about 3 hours of soaking and then hauled until following early morning by 7:00 am - Hauling started at finished point of setting (26) or starting point (2) Fishing Method

Slide4: 

J-4 : size 4.0 traditional tuna hooks C15, C16, C18 : three sizes of circle hook with 10º degree offset type In 2005: J4 and C15 and C18 (straight type) Fishing Gear

Slide5: 

Setting type and bait Hook array : J-4, C15, C16, C18 Hook array: C15, C16, C18, J-4

Slide6: 

Catches in number of tunas and billfishes

Slide7: 

Catches in number of sharks and other species

Slide8: 

Results for each pair of hook types

Slide9: 

Incidental catch information on turtles

Slide10: 

Catch rate (CPUE) of main species caught

Slide11: 

Catch rate of species group by bait

Slide12: 

Length frequency by hook type Bigeye tuna Yellowfin tuna

Slide13: 

Ranges and mean length of other species

Results: 

Results In the target species group no significant differences in catch rate among 4 types hook In 2005 the catch rate of C18 was lower than those of the others hooks J4 and C15 In the bycatch species group significant differences were found among 4 types and between J-4 and C15, C16, C18, respectively. Sea turtles caught by J hooks were dead condition but caught by circle were alive

Results Cont’d: 

Results Cont’d Squid and jack mackerel baits: tuna and other fishes, chub mackerel bait: billfishes and sharks - milkfish bait had low catch rate for all groups except tuna group The length distributions for bigeye and yellowfin tunas are very similar by the hook types There were very slight differences in length size between hook types in the bycatch species The results in 2005 and 2006 have some differences each other. At this point it is hard to decide the efficiency of catch rate by hook type and size.

Future plan: 

Future plan A similar experimental survey will be conducted in the western central Pacific Ocean during May-July 2007 - analyze the results come together to draw the conclusion on the efficiency of the using circle hook