Collected Evidence: Collected Evidence: Set longlines at night to reduce seabird bycatch Six out of eight studies from fisheries around the world found lower rates of seabird bycatch on longlines set at night, compared with during the day, or with previously collected data. However, effects seemed to depend on the species caught. Two studies found higher rates of bycatch on night-set longlines, due to high numbers of white-chinned petrels Procellaria aequinoctialis or northern fulmars Fulmarus glacialis being caught at night.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F283https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F283Tue, 24 Jul 2012 13:04:04 +0100Collected Evidence: Collected Evidence: Turn deck lights off during night-time setting of longlines to reduce bycatchA single replicated and controlled study in the South Atlantic found significantly lower bycatch rates when deck lights were turned off during line setting at night.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F284https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F284Tue, 24 Jul 2012 14:11:52 +0100Collected Evidence: Collected Evidence: Use streamer lines to reduce seabird bycatch on longlines A total of eight studies and two literature reviews from coastal and pelagic fisheries across the world found strong evidence for reduced seabird bycatch on longlines when streamer lines were used. A replicated, controlled trial from the sub-Antarctic Indian Ocean found no reduction in bycatch rates when using streamer lines, whilst five studies were inconclusive, uncontrolled or had weak evidence for reductions. The effect of streamer lines appears to vary between seabird species: northern fulmars Fulmarus glacialis were consistently caught at lower rates when streamers were used but shearwaters Puffinus spp. and white-chinned petrels Procellaria aequinoctialis were caught at similar rates with and without streamers in one study each. The three studies that investigated the use of multiple streamer lines all found that fewer birds were caught when two streamer lines were used, compared to one, with even fewer caught when three were used.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F285https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F285Tue, 24 Jul 2012 14:37:19 +0100Collected Evidence: Collected Evidence: Use larger hooks to reduce seabird bycatch We captured no intervention-based evidence on the impact of large hooks on seabird bycatch. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action    Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F286https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F286Tue, 24 Jul 2012 16:26:21 +0100Collected Evidence: Collected Evidence: Use a water cannon when setting longlines to reduce seabird bycatch We found no evidence for the effects on seabird bycatch rates of using water cannon when setting longlines. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this actionCollected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F287https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F287Tue, 24 Jul 2012 16:27:42 +0100Collected Evidence: Collected Evidence: Set lines underwater to reduce seabird bycatch Four replicated and controlled studies and a literature review in Norway, South Africa and the North Pacific found reductions in northern fulmar Fulmarus glacialis, albatross and petrel bycatch rates when using an underwater setting funnel. Although one found a disproportionate number of albatross were caught during day line setting. A replicated and controlled study found that underwater setting increased attack rates of shearwaters Puffinus spp. on longlines and did not reduce bycatch.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F288https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F288Tue, 24 Jul 2012 16:38:44 +0100Collected Evidence: Collected Evidence: Set longlines at the side of the boat to reduce seabird bycatch We found no evidence for the effects on seabird bycatch rates of setting longlines from the side of the boat. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F289https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F289Tue, 24 Jul 2012 16:44:03 +0100Collected Evidence: Collected Evidence: Use a line shooter to reduce seabird bycatch A randomised, replicated and controlled trial from a pelagic fishery in the North Pacific found significantly higher seabird bycatch when a line shooter was used to set longlines. A second randomised, replicated and controlled trial (from Norway), found no effect of a line shooter on bycatch rates.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F290https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F290Tue, 24 Jul 2012 16:47:45 +0100Collected Evidence: Collected Evidence: Use bait throwers to reduce seabird bycatchA study from Australia found significantly lower seabird bycatch on longlines set with a bait thrower.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F291https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F291Tue, 24 Jul 2012 16:50:50 +0100Collected Evidence: Collected Evidence: Tow buoys behind longlining boats to reduce seabird bycatch We found no evidence for the effects on seabird bycatch rates of towing buoys behind longlining boats. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F292https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F292Tue, 24 Jul 2012 16:54:34 +0100Collected Evidence: Collected Evidence: Use high-visibility longlines to reduce seabird bycatch We captured no intervention-based evidence on the impact on seabird bycatch of high-visibility longlines. 'No evidence' for an action means we have not yet found any studies that directly and quantitatively tested this action during our systematic journal and report searches. Therefore we have been unable to assess whether or not the action is effective or has any harmful impacts. Please get in touch if you know of such a study for this action.    Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F294https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F294Tue, 24 Jul 2012 16:58:27 +0100Collected Evidence: Collected Evidence: Use a sonic scarer when setting longlines to reduce seabird bycatchA single study from the South Atlantic found that seabird bycatch rates did not appear to be lower on longlines set with a sonic scarer, and that changes in seabird behaviour due to the scarer were only temporary.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F295https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F295Tue, 24 Jul 2012 16:59:51 +0100Collected Evidence: Collected Evidence: Weight baits or lines to reduce longline bycatch of seabirds Three replicated and controlled studies found evidence for reduced bycatch in some species when using weighted lines. One study found low bycatch rates, but was uncontrolled. In Hawaii and New Zealand, rates of bait loss and bycatch of albatrosses Phoebastria spp., white-chinned petrels Procellaria aequinoctialis and sooty shearwaters Puffinus griseus were much lower with weighted baits or integrated weight lines than with control lines. In the North Pacific, two trials found that bycatch rates of some species was reduced when using weights, but that shearwaters Puffinus spp. attacked weighted lines more often. A study off New Zealand found that attaching weights to lines had only localised effects on sink-rate.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F296https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F296Tue, 24 Jul 2012 17:07:29 +0100Collected Evidence: Collected Evidence: Use shark liver oil to reduce seabird bycatch Two replicated and controlled trials found reductions in the number of seabirds following boats, or diving for baits, when shark liver oil was dripped behind the boats. Other oils had no effect. A third replicated and controlled trial in found no differences in the number of seabirds following a bait-laying boat with shark liver oil.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F297https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F297Tue, 24 Jul 2012 17:16:47 +0100Collected Evidence: Collected Evidence: Thaw bait before setting lines to reduce seabird bycatchA single study from Australia found that lines set using thawed baits caught significantly fewer seabirds than controls.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F298https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F298Tue, 24 Jul 2012 17:24:13 +0100Collected Evidence: Collected Evidence: Use acoustic alerts on gillnets to reduce seabird bycatchA repeated, randomised and controlled trial in the USA found that sonic alerts reduced the number of common guillemots Uria aalge but not rhinoceros auklets Cerorhinca monocerata caught in gillnets.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F301https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F301Tue, 24 Jul 2012 18:02:45 +0100Collected Evidence: Collected Evidence: Use high-visibility mesh on gillnets to reduce seabird bycatch A repeated, randomised and controlled trial in the USA found that having gillnets made partially from high-visibility mesh was effective in reducing seabird bycatch. Having a greater percentage (25% vs. 10%) of the net made from high-visibility mesh was more effective, but also reduced catch of the target species.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F303https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F303Tue, 24 Jul 2012 18:10:09 +0100Collected Evidence: Collected Evidence: Use a larger mesh size on trammel nets One study examined the effects of using a larger mesh size on trammel nets on subtidal benthic invertebrates. The study was in the North Atlantic Ocean (Portugal).   COMMUNITY RESPONSE (1 STUDY) Unwanted catch community composition (1 study): One replicated, controlled, study in the North Atlantic Ocean found that using larger mesh sizes in the inner and/or outer panels of trammel nets did not affect the community composition of unwanted catch of non-commercial invertebrates (discard). POPULATION RESPONSE (1 STUDY) Unwanted catch abundance (1 study): One replicated, controlled, study in the North Atlantic Ocean found that using larger mesh sizes in the inner and/or outer panels of trammel nets did not reduce the abundance of unwanted catch of non-commercial invertebrates (discard). Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2141https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2141Tue, 22 Oct 2019 11:07:22 +0100Collected Evidence: Collected Evidence: Set catch limits or quotas for non-targeted commercial catch Two studies examined the effects of setting catch limits or quotas for non-targeted commercial fish species on marine fish populations. One review was in the North Atlantic and Pacific Oceans and one study was in the Pacific Ocean (Canada).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (2 STUDIES) Reduction of unwanted catch (2 studies): One review in the Atlantic and Pacific Oceans found that setting catch limits or quotas for non-commercially targeted fish reduced unwanted catch in two of three cases. One before-and-after study in the Pacific Ocean found that catch limits for non-target commercial species reduced the amount of unwanted halibut, but a previous quota system based on the whole catch (individual transferrable quotas) did not. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2693https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2693Wed, 02 Dec 2020 16:15:52 +0000Collected Evidence: Collected Evidence: Use a different bait type Eleven studies examined the effects of using different bait on marine fish populations. Two studies were global systematic reviews. Three studies were in the North Atlantic Ocean (USA, Iceland).Two studies were in the South Pacific Ocean (New Zealand). One study was in each of the Norwegian/Barents Seas (Norway), the Barents Sea (Norway), the Denmark Strait (Greenland) and the Mediterranean Sea. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (2 STUDIES) Survival (2 studies): One replicated study in the South Pacific Ocean and one global systematic review found that using different bait species did not reduce hooking injuries (associated with higher post-release mortality) of undersized snapper or sharks and rays, and did not increase survival of sharks and rays on gear retrieval. BEHAVIOUR (0 STUDIES) OTHER (10 STUDIES) Reduction of unwanted catch (10 studies): Six of eight replicated studies (three controlled and one randomized) in the Norwegian/Barents Seas, Barents Sea, Denmark Strait, North Atlantic Ocean, Mediterranean Sea and the South Pacific Ocean, found that using a different bait type (including size, species and manufacture method) reduced the unwanted catches of undersized haddock (although in one case in only two of six comparisons), Atlantic cod and other unwanted or non-target fish catch, but unwanted catches of torsk and ling were similar, compared to standard or other bait types. Two other studies found no reduction in unwanted catches of pelagic stingray and overall unwanted fish with different bait types. Two systematic global reviews found that using different bait types did not affect the number of unwanted sharks and rays caught. Improved size-selectivity of fishing gear (1 study): One replicated study in the Denmark Strait found that using a different bait species increased the size-selectivity of commercially targeted Greenland halibut. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2700https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2700Thu, 10 Dec 2020 14:26:24 +0000Collected Evidence: Collected Evidence: Set unwanted catch quotas One study evaluated the effects of setting unwanted catch quotas on reptile populations. This study was in the USA. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Survival (1 study): One study in the USA found that following the re-opening of a swordfish long-line fishery with turtle catch limits in place, loggerhead turtle bycatch reached the annual catch limit in two of three years, and when the limit was reached the fishery was closed for the rest of the year. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3549https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3549Wed, 08 Dec 2021 12:07:09 +0000Collected Evidence: Collected Evidence: Use circle hooks instead of J-hooks Eleven studies evaluated the effects of using circle hooks instead of J-hooks on reptile populations. Five studies were in the Atlantic, three were in the Pacific and one study was in each of the Mediterranean, the Atlantic and North Pacific and the western North Atlantic, Azores, Gulf of Mexico and Ecuador. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (3 STUDIES) Survival (3 studies): Two studies (including one replicated, controlled, paired study) off the coast of Hawaii and in the north-east Atlantic Ocean found that survival of loggerhead and leatherback turtles and leatherback and hard-shell sea turtles caught by circle hooks or J-hooks was similar. One review of studies in five pelagic longline fisheries found that fewer sea turtles died when circle hooks were used compared to J-hooks in four of five fisheries. Condition (3 studies): Two replicated, controlled studies in the Mediterranean Sea and south-western Atlantic Ocean found that fewer immature loggerhead turtles and loggerhead turtles swallowed circle hooks compared to J-hooks. One before-and-after study off the coast of Hawaii found that a lower percentage of loggerhead and leatherback turtles were deeply hooked by circle hooks compared to J-hooks. BEHAVIOUR (0 STUDIES) OTHER (11 STUDIES) Unwanted catch (11 studies): Seven of 10 studies (including six replicated, controlled studies) in the Pacific, Atlantic, Atlantic and North Pacific and Mediterranean and one review of studies in five pelagic longline fisheries found that circle hooks or circle hooks and tuna hooks caught fewer sea turtles than J-hooks, or that non-offset G-style circle hooks caught fewer leatherback and hard-shell sea turtles that offset J-Hooks. One of these studies also found that circle hooks caught slightly larger loggerhead turtles than J-hooks, and one also found that offset Gt-style circle hooks caught a similar number of leatherback and hard-shell sea turtles compared to offset J-hooks. One study found that circle hooks caught a similar number of leatherback, green and olive ridley turtles compared to J-hooks. One study found that fish-baited circle hooks caught fewer loggerhead and leatherback turtles than squid-baited J-hooks. The review found mixed effects of using circle hooks compared to J-hooks on unwanted catch of sea turtles depending on the fishery. The other study found mixed effects of using circle hooks or J-hooks in combination with squid or fish bait on the number of loggerhead and leatherback turtles that were caught. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3559https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3559Wed, 08 Dec 2021 14:21:43 +0000Collected Evidence: Collected Evidence: Use a different bait type: Sea turtles Nine studies evaluated the effects of using a different bait type on sea turtle populations. Three studies were in each of the Atlantic and Pacific, and one was in each of the Atlantic and north Pacific, the Gulf of Garbes (Tunisia) and Italy. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (2 STUDIES) Survival (2 studies): Two studies (including one replicated, controlled study) off the coast of Hawaii and in the Southern Atlantic found that the percentage of loggerhead and leatherback turtles that survived being caught by fish-baited or squid-baited hooks or fish-baited circle hooks and squid-baited J-hooks was similar. Condition (1 study): One before-and-after study off the coast of Hawaii found that fish-baited circle hooks deeply hooked fewer leatherback and hard-shell turtles compared to squid-baited J-hooks. BEHAVIOUR (1 STUDY) Use (1 study): One controlled study in Italy found that loggerhead turtles in a captive setting were less likely to bite at fish bait than squid bait. The study also found that smaller turtles were more likely to bite at mackerel bait and larger turtles at squid bait. OTHER (8 STUDIES) Unwanted catch (8 studies): Four of five studies (including one replicated, paired, controlled study) in the North Pacific, Eastern Pacific, Atlantic and Atlantic and North Pacific found that fish-baited hooks caught fewer sea turtles or were swallowed by fewer olive ridley turtles than squid baited hooks. One study also found that fish bait in combination with larger circle hooks lead to the highest percentage of external hookings. The other study found mixed effects of using fish or squid-baited hooks on the unwanted catch of hard-shell and leatherback turtles. One replicated, controlled study in the north-western Atlantic Ocean found that fish-baited J-hooks caught fewer sea turtles compared to squid-baited hooks. The study also found that unwanted catch was more similar for fish-baited and squid-baited circle hooks. One before-and-after study off the coast of Hawaii found that fish-baited circle hooks caught fewer loggerhead and leatherback turtles compared to compared to squid-baited J-hooks. One replicated study in the Gulf of Garbes found that hooks baited with stingray caught fewer loggerhead turtles compared to fish-baited hooks. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3612https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3612Thu, 09 Dec 2021 12:02:07 +0000Collected Evidence: Collected Evidence: Release accidentally caught (‘bycatch’) reptiles Three studies evaluated the effects on reptile populations of releasing accidentally caught reptiles. One study was in each of the Caribbean Sea, Costa Rica and the Republic of Korea. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (2 STUDIES) Survival (2 studies): One replicated study in the Caribbean Sea found that from a released group of green turtles that included some accidentally caught and some head-started individuals, some survived for at least several months in the wild. One replicated study in the Republic of Korea found that green turtles caught in pound nets all survived for at least two weeks to a year after release. BEHAVIOUR (1 STUDY) Behaviour change (1 study): One controlled study off the Pacific coast of Costa Rica found that the behaviour of longline-caught sea turtles following release was broadly similar to free-swimming turtles. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3624https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3624Thu, 09 Dec 2021 13:37:44 +0000Collected Evidence: Collected Evidence: Set catch shares by species One study examined the effects of setting catch shares by species on marine fish populations. The study was in the Pacific Ocean (Canada).   COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (1 STUDY) Reduction of unwanted catch (1 study): One before-and-after study in the Pacific Ocean found that after a species-specific catch share was set (Individual Vessel Bycatch Quota) unwanted halibut catch in a multi-species fishery was reduced, whereas it was higher under a previous catch share system (Individual Transferable Quota) based on all species in the catch. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3814https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3814Fri, 27 May 2022 08:31:55 +0100
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What Works in Conservation

What Works in Conservation provides expert assessments of the effectiveness of actions, based on summarised evidence, in synopses. Subjects covered so far include amphibians, birds, mammals, forests, peatland and control of freshwater invasive species. More are in progress.

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