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Displaying 341 - 350 of 561
Location Gear Catch Technique Bycatch species Type Results
Location

Gulf of St. Lawrence, Canada

Gear
Traps
Catch Crab and whelk Technique
Differently colored ropes
Bycatch species Balaenoptera acutostrata (Minke whale) Type Field study in the wild Results
Summary:

Field experiments were conducted to determine behavioral responses of minke whales to experimental ropes and buoys made up of different colors, simulating those used in crab and whelk fishing gear. Trials were conducted with yellow, orange, green, blue, white and black ropes. Visual and acoustic monitoring was used to assess behavioral responses of whales to the different experimental gears. In addition, remote sensing equipment was used to monitor oceanographic conditions, underwater sounds and to video the whales as they swam near the experimental ropes. The results indicated a positive correlation between whale approach velocity and depature velocity and bearing changes. Minke whales decreased their swimming velocity and altered their bearing when passing by these ropes and increased their velocity once they had passed by the ropes. This was most evident when the ropes were black and white. Low frequency vocalizations and altered swimming trajectories were also noted in some whales as they passed near the ropes. 

Effect on Bycatch: Minke whales decreased swimming velocity and altered bearing when approaching a rope, particularly when ropes were black and white; some minke's altered underwater swimming trajectories when passing ropes and produced low-frequency vocalizations.
Reference:
Kot, B.W., Sears, R., Anis, A., Nowacek, D.P., Gedamke, J., Marshall, C.D., 2012 , Behavioral responses of minke whales (Balaenoptera acutorostrata) to experimental fishing gear in a coastal environment
Location

Newfoundland and Labrador, Canada

Gear
Traps
Catch Snow crab Technique Bycatch species Type Field study in the wild Results
Summary:

Five biodegrabable twine types were investigated for potential use in the snow crab (Chinoecetes opilio) fishery that operates off Newfoundland and Labrador, Canada. The five twine types included 1) 2-ply Sisal, 2) 3-ply Cotton 60-threated, 3) 3-ply Cotton 72-thread, 4) 3-ply Cotton 96-thread and 5) 3-ply Hemp 40 strand. Each twine was deployed at sea for 124 days and their degradation rates over time were studied. The results indicate variability in twine degradation rates. The 3-ply cotton 96-thread twine was the best performing twine.  Over the study period, this twine rapidly declined in breaking strength. The total reduction was 63% of the initial strength.  In addition, there was a statistical relationship between breaking strength and soak time for three twin types 1) 2-ply Sisal, 2) 3-ply Cotton 60-thread and 3) 3-ply Hemp 40 strand. The 2-ply cotton 96-thread is now required for use by all fisheries in the province of Newfoundland and Labrador targeting snow crabs.

Reference:
Winger, P.D., Legge, G., Batten, C., Bishop, G., 2015 , Evaluating potential biodegradable twines for use in the snow crab fishery off Newfoundland and Labrador
Location

Peru

Gear
Gillnets
Catch Various Technique Bycatch species Large Cetaceans (maximum length > 7.5 meters), Megaptera novaeangliae (Humpback whale) Type Summary study Results
Summary:

Entanglements of large cetaceans in fishing gear that occurred off the coast of Peru between 1992 and 2012 were catalogued. Direct observations, local news and online graphical evidence was used to identify any entanglements. A total of 15 confirmed entanglements were identified. The species involved in these entanglements included humpback whales (Megaptera novaeangliae), sperm whales (Physeter macrocephalus) and Antarctic minke whale (Balaneoptera bonaerensis). The most common entanglements occurred in gillnets, followed by longlines. This study did not investigate the use of bycatch mitigation techniques.

Effect on Bycatch: None tested
Reference:
Garcia-Godos, I., Waerebeek, K.V., Alfaro-Shigueto, J., Mangel, J.C., 2013 , Entanglements of large cetaceans in Peru: few records by high risk
Location

Peru

Gear
Hooks-and-Lines
Catch Various Technique Bycatch species Large Cetaceans (maximum length > 7.5 meters), Megaptera novaeangliae (Humpback whale) Type Summary study Results
Summary:

Entanglements of large cetaceans in fishing gear that occurred off the coast of Peru between 1992 and 2012 were catalogued. Direct observations, local news and online graphical evidence was used to identify any entanglements. A total of 15 confirmed entanglements were identified. The species involved in these entanglements included humpback whales (Megaptera novaeangliae), sperm whales (Physeter macrocephalus) and Antarctic minke whale (Balaneoptera bonaerensis). The most common entanglements occurred in gillnets, followed by longlines. This study did not investigate the use of bycatch mitigation techniques.

Effect on Bycatch: None tested
Reference:
Garcia-Godos, I., Waerebeek, K.V., Alfaro-Shigueto, J., Mangel, J.C., 2013 , Entanglements of large cetaceans in Peru: few records by high risk
Location

North Sea

Gear
Trawls
Catch Flatfish Technique
Electromagnetic deterrents
Bycatch species Bony Fishes, Invertebrates Type Summary study Results
Summary:

This is a comprehensive, critical overview of studies on the use of electrotrawling in the North Sea. Electrotrawling, involves replacing the tickler chains or bobbins with electrical stimulation. The result is reduced contact with bottom habitats, reduced fuel costs and reduced discards. An overview on the current status and implementation of this technique in flatfish, shrimp and razor clam fisheries is provided. In terms of the flatfish fisheries, while electrotrawling is a promising alternative, potential negative impacts (i.e. safe range of pulse parameters, differences in sensitivities of species, effects on early life stages, long-term effects, impact on electrosensitive fish and potential electrolysis effects) were not quantified. Regardless, it appears that electrified trawls are superior to conventional trawls in terms of ecological impacts, management and carbon footprint.

Effect on Bycatch: 30-50% reduction in fish and 48-73% reduction in benthic discards
Reference:
Soetaert, M., Decostere, A., Polet, H., Verschueren, B. Chiers, K., 2013 , Electrotrawling: a promising alternative fishing technique warranting further exploration
Location

North Sea

Gear
Trawls
Catch Shrimp Technique
Electromagnetic deterrents
Bycatch species Bony Fishes, Invertebrates Type Summary study Results
Summary:

This is a comprehensive, critical overview of studies on the use of electrotrawling in the North Sea. Electrotrawling, involves replacing the tickler chains or bobbins with electrical stimulation. The result is reduced contact with bottom habitats, reduced fuel costs and reduced discards. An overview on the current status and implementation of this technique in flatfish, shrimp and razor clam fisheries is provided. In terms of the flatfish fisheries, while electrotrawling is a promising alternative, potential negative impacts (i.e. safe range of pulse parameters, differences in sensitivities of species, effects on early life stages, long-term effects, impact on electrosensitive fish and potential electrolysis effects) were not quantified. Regardless, it appears that electrified trawls are superior to conventional trawls in terms of ecological impacts, management and carbon footprint.

Effect on Bycatch: Overall reduction in bycatch of 35%
Reference:
Soetaert, M., Decostere, A., Polet, H., Verschueren, B. Chiers, K., 2013 , Electrotrawling: a promising alternative fishing technique warranting further exploration
Location

Tropical northeast Atlantic

Gear
Hooks-and-Lines
Catch Swordfish Technique
Alternative bait
Bycatch species Type Field study in the wild Results
Summary:

Field studies were conducted in the tropical northeast Atlantic to determine the effect of different hook types (J and circle) on target, bycatch and discard species caught in pelagic longline fisheries. Tests were conducted comparing J-hooks with squid bait and two circle hooks (non offset and 10 degree offset) with mackerel bait. Swordfish catches were negatively impacted when circle hooks were used. However, bait type had a bigger impact than hook style. Yellowfin tuna and escolar catches were lower when mackerel instead of squid bait was used. Longfin mako shark catch rates were lower when circle hooks were used. Hook style and bait type did not influence at-haulback mortality rates of the majority of discarded species. Based on these results the authors suggest that using circle hooks in this region to reduce sea turtle bycatch would not negatively impact the economic viability of the fishery.

Effect on Bycatch: None reported
Location

Tropical northeast Atlantic

Gear
Hooks-and-Lines
Catch Swordfish Technique
Circle hooks
Bycatch species Sea Turtles Type Field study in the wild Results
Summary:

Experimental studies were conducted over a three year period (August 2008-December 2011) to determine the effects of changing traditional J-hooks baited with squid bait to circle hooks (offset and non offset) with mackerel bait on sea turtle interactions. Studies were carried out aboard pelagic longline vessels targeting swordfish in the tropical northeast Atlantic Ocean. Overall, sea turtle interactions were reduced when circle, compared to J-hooks were used. However species specific differences did occur. Leatherback interactions were only reduced when circle hooks with an offset were used. Leatherback interactions can be reduced by 55% in this fishery by switching from J-style to circle hooks. Hardshell turtle interactions were reduced when both circle hook styles and mackerel bait were used. Interactions with hard shelled turtles can be reduced by 50-55% in this fishery by switching from J-style to circle hooks.  A 55% reduction in hardshell turtle bycatch is expected to occurr in this fishery by switching from squid to mackerel bait.

Effect on Bycatch: Hardshell turtle interactions were reduced when both circle hook styles and mackerel bait were used.
Reference:
Coelho, R., Santos, M.N., Fernandez-Carvalho, J., Amorim, S., 2015 , Effects of hook and bait in a tropical northeast Atlantic pelagic longline fishery: Part I - Incidental sea turtle bycatch
Location

Tropical northeast Atlantic

Gear
Hooks-and-Lines
Catch Swordfish Technique
Circle hooks
Bycatch species Demochelys coriacea (Leatherback sea turtle) Type Field study in the wild Results
Summary:

Experimental studies were conducted over a three year period (August 2008-December 2011) to determine the effects of changing traditional J-hooks baited with squid bait to circle hooks (offset and non offset) with mackerel bait on sea turtle interactions. Studies were carried out aboard pelagic longline vessels targeting swordfish in the tropical northeast Atlantic Ocean. Overall, sea turtle interactions were reduced when circle, compared to J-hooks were used. However species specific differences did occur. Leatherback interactions were only reduced when circle hooks with an offset were used. Leatherback interactions can be reduced by 55% in this fishery by switching from J-style to circle hooks. Hardshell turtle interactions were reduced when both circle hook styles and mackerel bait were used. Interactions with hard shelled turtles can be reduced by 50-55% in this fishery by switching from J-style to circle hooks.  A 55% reduction in hardshell turtle bycatch is expected to occurr in this fishery by switching from squid to mackerel bait.

Effect on Bycatch: Leatherback interactions can be reduced by 55% in this fishery by switching from J-style to circle hooks.
Reference:
Coelho, R., Santos, M.N., Fernandez-Carvalho, J., Amorim, S., 2015 , Effects of hook and bait in a tropical northeast Atlantic pelagic longline fishery: Part I - Incidental sea turtle bycatch
Location

Lake Opinicon, Ontario, Canada

Gear
Surrounding nets
Catch Panfish Technique
Excluder devices
Bycatch species Terrapins Type Field study in the wild Results
Summary:

A population viability analysis and evaluations of bycatch mitigation techniques were used to investigate the impact of bycatch mortality on the populations of four freshwater turtles (common snapper, Chelydra serpentina, eastern musk, Sternotherus odoratus, northern map, Graptemys geographica, and painted, Chrysemys picta) incidentally captured in small-scale commercial fisheries operating in Lake Opinicon, Ontario, Canada.  Two approaches to bycatch reduction were investigated. The first was the use of a bycatch reduction device (BRD) and the second was the use of effort reductions (BRSs). The BRD was an exclusion device, which was vertically oriented within the funnel of the nets, which acted as a phycial barrier preventing turtles from entering. The BRSs consisted of reducing the season length.  The population viability analysis results indicated that even low levels of additional bycatch mortality of females (annual) would either result in a reduction of the population sizes or extirpation of the local population within 500 years.  The results also indicated that the use of BRD's and/or BRSs could help reduce the risk of extirpation.  The BRD's reduced the bycatch of snapping turtles by 95-100% and 0-97% for the other three species.  BRSs can also be used to reduce turtle interactions for some species. Specifically, significantly more painted turtles were caught before May 20th, than between May 20th and June 20th. Significantly less snapping turtles were caught before May 20th. No significant differences were found for the other two species. The combined use of the BRD and BRSs would prove beneficial in this fishery.

Effect on Bycatch: The excluder device reduced bycatch of turtles by 95-100%
Reference:
Midwood, J.D., Ciarns, N.A., Stoot, L.J., Cooke, S.J., Blouin-Demers, G., 2014 , Bycatch mortality can cause extirpation in four freshwater turtle species

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Traps

Traps are baited or nonbaited stationary devices set on the bottom or, less frequently, in midwater. Fish enter the trap freely but fond it diggicult to exit them. Large traps are more common in coastal waters while smaller traps may be deployed to greater depths. Fyke nets and stow nets are fixed to the bottom and rely on currents to bring fish into contact with them. Additionally, fyke nets use "wings" to guide the fish into mesh bags, where they are captured. Both types are most commonly set near shore.


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Differently colored ropes

Various colored rope or other vertical line material used as 1) buoy lines for crab, whelk or lobster pots, 2) end lines of connected pots or 3) end or anchor lines for gillnet systems (Kot et al. 2012).


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Traps

Traps are baited or nonbaited stationary devices set on the bottom or, less frequently, in midwater. Fish enter the trap freely but fond it diggicult to exit them. Large traps are more common in coastal waters while smaller traps may be deployed to greater depths. Fyke nets and stow nets are fixed to the bottom and rely on currents to bring fish into contact with them. Additionally, fyke nets use "wings" to guide the fish into mesh bags, where they are captured. Both types are most commonly set near shore.


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Gillnets

Gillnets are single, double, or triple layers of net suspended vertically in the water column. The top of the net is connected to floats (headrope), while the bottom is weighted (footrope). Adjustment of the floats and weights allows gillnets to be positioned at varying depth, depending on the target species. Gillnets are generally deployed in large numbers and trap fish either by entangling the gills or by entangling all or part of the fish body. Variation in net mesh size allows fishermen to control the size of their catch.


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Hooks-and-Lines

Fish are attracted to hooks-and-lines by natural or artificial bair placed on a hook, which captures the fish when it bites the bait. One or multiple lines may be used to catch pelagic, demersal, or benthic species. Different line and hook types are used depending on the target species.

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Trawls

Trawls are cone-shaped nets with two, four, or more panels, ending in a bag. They are towed at midwater or near the bottom, and held open horizontally by heavy doors (otter trawls), by beams, or by the tension created by lines connecting the net to two separate vessels (pair trawls). The net opening is sustained vertically by floats and weights. Fish size and species is controlled by mesh size; pelagic, demersal, and benthic fish can be targeted.

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Electromagnetic deterrents

Electromagnetic fields created in the vicinity of a fishing activity to deter interaction of non-target species with fishing gear, bait, or target species. For example, rare earth metals, such as cerium or lanthanide, are attached or imbedded into hooks (longline, hook and line etc.) in an effort to deter the incidental bycatch of sharks and rays (Tallack et al. 2009).


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Trawls

Trawls are cone-shaped nets with two, four, or more panels, ending in a bag. They are towed at midwater or near the bottom, and held open horizontally by heavy doors (otter trawls), by beams, or by the tension created by lines connecting the net to two separate vessels (pair trawls). The net opening is sustained vertically by floats and weights. Fish size and species is controlled by mesh size; pelagic, demersal, and benthic fish can be targeted.

Read More

Electromagnetic deterrents

Electromagnetic fields created in the vicinity of a fishing activity to deter interaction of non-target species with fishing gear, bait, or target species. For example, rare earth metals, such as cerium or lanthanide, are attached or imbedded into hooks (longline, hook and line etc.) in an effort to deter the incidental bycatch of sharks and rays (Tallack et al. 2009).


Read More

Hooks-and-Lines

Fish are attracted to hooks-and-lines by natural or artificial bair placed on a hook, which captures the fish when it bites the bait. One or multiple lines may be used to catch pelagic, demersal, or benthic species. Different line and hook types are used depending on the target species.

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Alternative bait

Changing the type of bait, such as switching from squid to mackerel, to deter non-target animals (such as sea turtles) that prefer one type of bait versus another (Watson et al. 2005).


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Hooks-and-Lines

Fish are attracted to hooks-and-lines by natural or artificial bair placed on a hook, which captures the fish when it bites the bait. One or multiple lines may be used to catch pelagic, demersal, or benthic species. Different line and hook types are used depending on the target species.

Read More

Circle hooks

A circular hook design in which the point of the hook is perpendicular to the hook shank. Circle hooks are used widely in many recreational and commercial fisheries and recently have been shown to reduce both the hooking rate and the mortality of turtles that are hooked on pelagic longline gear.


Read More

Hooks-and-Lines

Fish are attracted to hooks-and-lines by natural or artificial bair placed on a hook, which captures the fish when it bites the bait. One or multiple lines may be used to catch pelagic, demersal, or benthic species. Different line and hook types are used depending on the target species.

Read More

Circle hooks

A circular hook design in which the point of the hook is perpendicular to the hook shank. Circle hooks are used widely in many recreational and commercial fisheries and recently have been shown to reduce both the hooking rate and the mortality of turtles that are hooked on pelagic longline gear.


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Surrounding nets

Surrounding nets enclose fish in net from both sides and bottom, effectively preventing escape.

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Excluder devices

These can consist of a grid of metal bars or mesh placed usually within the neck of a trawl that has an opening for escape at either the top or bottom. Examples include “skylights” which consist of a mesh opening located at the top of the codend. ”Skylights” can be combined with guiding funnels that create visual and tactile stimuli to direct finfish towards the “skylight” escape sections.


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