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Analysis of 2004-2007 vessel-specific seabird bycatch data in Alaska demersal longline fisheries

Submitted by Kate McClellan on

Average annual seabird bycatch has declined by 73% in the last 5 years (2002-2006) compared to bycatch from the late 1990s. Despite the recent reductions resulting from mandatory mitigation requirements, seabirds continue to be caught at higher rates than would be expected given results of controlled studies that demonstrated bycatch reductions of nearly 100% with paired streamer lines. The results of this study demonstrate that a few individual vessels continue to be responsible for the majority of seabird bycatch.

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Performance in 2004 and 2005 of an alternative leader design on the bycatch of sea turtles and the catch of finfish in Chesapeake Bay pound nets, offshore Kiptopeake, VA

Submitted by Kate McClellan on

Leaders in offshore, deep water pound nets in the Virginia portion of Chesapeake Bay incidentally take protected sea turtles. To reduce this take, federal resource managers restricted the use of traditional leaders during periods of peak sea turtle strandings. In response to these restrictions, a modified leader was developed. Testing of the new design in 2004 and 2005 indicated that the modified leader significantly reduced sea turtle interactions.
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Field Study 335

Study Type
Field study in the wild
Location
Chesapeake Bay, Virginia
Target catch
Finfish, including: Atlantic tread herring (Opisthonema oglinum), harvestfish (Peprilus alepidotus), butterfish (Peprilus triacanthus), Atlantic croaker (Micropogonias undulatus) and weakfish (Cynoscion regalis)
Effect on bycatch species
Significant reduction of sea turtles bycatch
Effect on target catch
No difference for four species, increased catch of a fifth
Bycatch species
Reduction technique
Fishing Gear

Field Study 335

Study Type
Field study in the wild
Location
Chesapeake Bay, Virginia
Target catch
Finfish, including: Atlantic tread herring (Opisthonema oglinum), harvestfish (Peprilus alepidotus), butterfish (Peprilus triacanthus), Atlantic croaker (Micropogonias undulatus) and weakfish (Cynoscion regalis)
Effect on bycatch species
Significant reduction of sea turtles bycatch
Effect on target catch
No difference for four species, increased catch of a fifth
Bycatch species
Reduction technique
Fishing Gear

Field Study 335

Study Type
Field study in the wild
Location
Chesapeake Bay, Virginia
Target catch
Finfish, including: Atlantic tread herring (Opisthonema oglinum), harvestfish (Peprilus alepidotus), butterfish (Peprilus triacanthus), Atlantic croaker (Micropogonias undulatus) and weakfish (Cynoscion regalis)
Effect on bycatch species
Significant reduction of sea turtles bycatch
Effect on target catch
No difference for four species, increased catch of a fifth
Bycatch species
Reduction technique
Fishing Gear

Developing visual deterrents to reduce sea turtle bycatch in gill net fisheries

Submitted by Kate McClellan on

Visual cues are important in sea turtle foraging behavior and likely influence their interaction with fishing gear. This studey examined the potential effectiveness of three visual cues: 1) shark shapes, 2) illumination of nets by LED lights, and 3) nets illuminated with chemical lightsticks - for reducing green sea turtle bycatch in gillnets. The presence of shark shapes significantly reduced mean sea turtle catch rates by 54%, but also reduced target catch by 45%. Nets illuminated with LED lights significantly reduced sea turlte bycatch by 40% and had negligable impact on target catch.

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Effects of circle versus J-style hooks on target and non-target species in a pelagic longline fishery

Submitted by morgaac on

Circle hooks and J-style hooks were tested on pelagic longline vessels (US Atlantic) to determine if the use of circle hooks reduced bycatch mortality while maintaining target species catch rates.  00 offset circle hooks were determined to increase the survival of bycatch species at haulback while having little impact on target species catches.  Specifically, J-style hooks had a significantly higher total overall catch rate.  Catch rates of yellowfin tuna in the fall were higher (significantly) for circle hooks and pelagic stingrays (spring caught) were the only sp

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Field Study 340

Study Type
Field study in the wild
Location
US Atlantic
Target catch
Tuna and swordfish
Effect on bycatch species
Pelagic stingrays had higher catch rates on J-style hooks and survival rates of dolphinfish and escolar were higher when circle hooks were used (fall and spring respectively)
Effect on target catch
Catch rates of yellowfin tuna caught in the fall were higher on circle hooks. Yellowfin tuna were caught four times as often in the mouth when circle hooks were used in the fall.
Bycatch species
Reduction technique
Fishing Gear

Field Study 340

Study Type
Field study in the wild
Location
US Atlantic
Target catch
Tuna and swordfish
Effect on bycatch species
Pelagic stingrays had higher catch rates on J-style hooks and survival rates of dolphinfish and escolar were higher when circle hooks were used (fall and spring respectively)
Effect on target catch
Catch rates of yellowfin tuna caught in the fall were higher on circle hooks. Yellowfin tuna were caught four times as often in the mouth when circle hooks were used in the fall.
Bycatch species
Reduction technique
Fishing Gear

Field Study 340

Study Type
Field study in the wild
Location
US Atlantic
Target catch
Tuna and swordfish
Effect on bycatch species
Pelagic stingrays had higher catch rates on J-style hooks and survival rates of dolphinfish and escolar were higher when circle hooks were used (fall and spring respectively)
Effect on target catch
Catch rates of yellowfin tuna caught in the fall were higher on circle hooks. Yellowfin tuna were caught four times as often in the mouth when circle hooks were used in the fall.
Bycatch species
Reduction technique
Fishing Gear

Effectiveness of rigid grate for excluding Pacific halibut, Hippoglossus stenolepis, from groundfish trawl catches

Submitted by morgaac on

Groundfish trawl nets were fitted with a rigid grate in an effort to exclude Pacific halibut while retaining the target species.  The grate was placed in front of the trawl codend, which allowed the target species to pass through while Pacific halibut escape.  Escape rates of Pacific halibut were 94% when the grate was used while 72%, 67% and 79% of Dover sole, rex sole and flathead sole were retained respectively.  These values were significantly different except for flathead sole.  The only size class of halibut that passed through the gate in large proportions were le

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Field Study 345

Study Type
Field study in the wild
Location
New South Whales, Australia
Target catch
School prawn
Effect on bycatch species
Retained fewer fish
Effect on target catch
In experiment 2, where a trawler was placed in front of the mouth of the net, the selection range of school prawns was incrementally smaller from the 1-m square-mesh codend to the 3-m square mesh codend compared to the diamond mesh codend and school praw
Bycatch species
Reduction technique
Fishing Gear