Bycatch

Question 1

Hall et al (2000)

Answer 1

dolphin-tuna conflict

Question 2

Stehn et al (2001)

Answer 2

Collected global data on longlines and bird mortality and estimated that around 140,000 birds are killed each year in longlines.

Question 3

Bjorge et al (2013)

Answer 3

using ladning statistics between 2006-2010 for vessels using gillnets of Norway it was estimated that over 2 years the annual bycatch rate of harbour porpoise was around 6,900 individuals. Dropped by nets was cast below 50m.

Question 4

Ryan & Watkins (2001)

Answer 4

Demonstrated that by using tunnel setting on the longlines used in Patagonian tooth fish fishery the lines are set 1-2m below surface. 52% of 1,700 were used with funnels and bycatch of Procelariformes was reduced by around 3 times.

Question 5

Senko et al (2014)

Answer 5

Compared bycatch reduction measured for leathered backs, alabatorss and vaquita and decided that gear modification was the best methods. Time area closures and by outs were expensive and resulted in long drawn out conflicts with fishermen.

Question 6

Lokkebord & Robertson (2001)

Answer 6

1999, around 58,000 hooks were set in longline fishery off Norway. When bird scaring lines whih are streamers pulled along above the hooks to prevent birds diving were used, no birds were caught with the exception of one fulmar.

Question 7

Barlow & Cameron (2003)

Answer 7

Pingers were deployed around gillnet fisheries in a controlled experienent between 1996-1997

Question 8

Kraus et al (1999)

Answer 8

Large scale experiment in the Golf of Maine, and idepndent obersever was placed on each vessel. Pingers reduced porpoised baycatch by as much as 97% and didn not effect the target species catch.

Question 9

Larsen et al (2007)

Answer 9

Danish North Sea, gill-net fishery October-Sptmeber 2000. High-density iron oxide nets were deployed alongside control nets. iron oxide has the ability ot reflect sound at high levels so porpoise are able to detect the net from far away. 8 porpoise were caught in the control nets, only 1 target speces was reduced

Question 10

Read (2006)

Answer 10

Efficiency of circle hooks assessed in North Atlantic, The Azores, GOM and Ecuador. Emplyed more than 1m hooks between 2000-2004. 4/5 expeirments showed a significant reduction in capture rates of sea turtles.
Has the potentially to reduce mortality. 1 one trial circle hooks reduced catch of target species to a level that was unusable.

Question 11

Cox et al (2007)

Answer 11

They need to be designed well, TEDs in America were still having lots of turtles washed up on beaches, found that 40% of these were too large for the escape flaps. Well implemented ones in Austrlia reduced bycatch by 99%.