Collected 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%2Fconservationevidencejournal.com%2Factions%2F3559https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3559Wed, 08 Dec 2021 14:21:43 +0000Collected Evidence: Collected Evidence: Use non-offset hooks Two studies evaluated the effects of using non-offset hooks on reptile populations. One study was off the Pacific coast of Costa Rica and one was in the north-east Atlantic. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Survival (1 study): One replicated, controlled, paired study in the north-east Atlantic Ocean found that mortality of leatherback turtles was similar when caught with non-offset hooks or offset hooks. BEHAVIOUR (0 STUDIES) OTHER (2 STUDIES) Unwanted catch (2 studies): One of two replicated, paired studies (including one controlled study) off the Pacific coast of Costa Rica and in the north-east Atlantic found that non-offset circle hooks caught a similar number of olive ridley and green turtles compared to offset circle hooks in a shallow-set longline fishery. The other study found that non-offset G-style circle hooks caught fewer leatherback and hard-shell turtles compared to offset Gt-style circle hooks or offset J-hooks in a longline swordfish fishery. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3571https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3571Wed, 08 Dec 2021 15:13:12 +0000Collected Evidence: Collected Evidence: Use non-ringed hooks One study evaluated the effects of using non-ringed hooks on reptile populations. This study was in the Mediterranean. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (1 STUDY) Unwanted catch (1 study): One replicated, paired study in the Mediterranean found that when non-ringed circle hooks were used in a swordfish longline fishery fewer loggerhead turtles were caught compared to when ringed hooks were used. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3576https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3576Wed, 08 Dec 2021 15:18:56 +0000Collected Evidence: Collected Evidence: Use larger hooks Two studies evaluated the effects of using larger hooks on reptile populations. One study was in the USA and one was in the Eastern Pacific Ocean. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (1 STUDY) Use (1 study): One study in the USA of captive loggerhead turtles found that turtles were less likely to attempt to swallow larger circle hooks than smaller ones. OTHER (1 STUDY) Unwanted catch (1 study): One replicated study in the Eastern Pacific Ocean found that olive ridley turtles were less likely to be caught by swallowing larger hooks than smaller ones. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3578https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3578Wed, 08 Dec 2021 15:21:29 +0000Collected Evidence: Collected Evidence: Modify number of hooks between floats on longlines One study evaluated the effects of modifying the number of hooks between floats on longlines on reptile populations. This study was in the Atlantic and North Pacific. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (1 STUDY) Unwanted catch (1 study): One replicated study in the Atlantic and North Pacific found that having fewer hooks between floats did not reduce turtle by-catch in the Pacific but had mixed effects in the Atlantic depending on the species. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3580https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3580Wed, 08 Dec 2021 15:25:39 +0000Collected Evidence: Collected Evidence: Use catch and hook protection devices We found no studies that evaluated the effects of using catch and hook protection devices on reptile populations. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2Fconservationevidencejournal.com%2Factions%2F3582https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3582Wed, 08 Dec 2021 15:27:59 +0000Collected Evidence: Collected Evidence: Install exclusion devices on fishing gear: Sea turtles Three studies evaluated the effects of installing exclusion devices on fishing gear on sea turtle populations. One study was in the Gulf of Mexico (USA), one was in the Mid-Atlantic (USA) and one was off the coast of Western Australia. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Survival (1 study): One replicated, before-and-after study in the Gulf of Mexico found that when exclusion grids with escape holes were used in a shrimp trawl fishery there were fewer lethal strandings of loggerhead turtles compared to when grids were not used. BEHAVIOUR (1 STUDY) Use (1 study): One controlled study in the Mid-Atlantic found that when exclusion devices were used on scallop dredges there were fewer interactions with sea turtles than when no devices were used. OTHER (1 STUDY) Unwanted catch (1 study): One replicated study off the coast of Western Australia found that exclusion grids with escape hatches prevented sea turtles entering trawl nets. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3584https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3584Wed, 08 Dec 2021 15:30:20 +0000Collected Evidence: Collected Evidence: Install exclusion devices on fishing gear: Tortoises, terrapins, side-necked & softshell turtles Thirteen studies evaluated the effects of installing exclusion devices on fishing gear on tortoise, terrapin, side-necked & softshell turtle populations. Ten studies were in the USA, two were in Canada and one was in Australia. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Survival (1 study): One replicated, randomized, paired, controlled study in the USA found that fewer turtles died in hoop nets with an exclusion device than in unmodified traps. BEHAVIOUR (1 STUDY) Use (1 study): One randomized, controlled trial in the USA found mixed effects of crab pot exclusion devices on use of pots by diamondback terrapins depending on the device design. OTHER (13 STUDIES) Unwanted catch (13 studies): Eight of 13 controlled studies (including seven replicated, paired studies) in the USA, Australia and Canada found that crab pots, fyke nets, hoop nets and eel traps with exclusion devices caught fewer turtles, diamond back terrapins and short-necked turtles than unmodified gear. Two studies also found that modified gear caught smaller short-necked turtles and diamondback terrapins than unmodified gear. Three studies found mixed effects of exclusion devices on unwanted catch of turtles and diamondback terrapins depending on the device design. The other two studies found that that crab pots with wire exclusion devices or magnetized exclusion devices caught a similar number of diamondback terrapins compared to unmodified pots. One study also found that crab pots with wire exclusion devices caught larger diamondback terrapins than pots with plastic exclusion devices. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3590https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3590Wed, 08 Dec 2021 16:11:04 +0000Collected Evidence: Collected Evidence: Install exclusion devices on fishing gear: Snakes & lizards One study evaluated the effects of installing exclusion devices on fishing gear on snake and lizard populations. This study was in Australia. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (1 STUDY) Unwanted catch (1 study): One replicated study off the coast of Western Australia found that exclusion grids did not prevent sea snakes from entering trawl nets. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3599https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3599Wed, 08 Dec 2021 16:47:50 +0000Collected Evidence: Collected Evidence: Install exclusion devices on fishing gear: Crocodilians We found no studies that evaluated the effects of installing exclusion devices on fishing gear on crocodilian populations. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2Fconservationevidencejournal.com%2Factions%2F3600https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3600Wed, 08 Dec 2021 16:50:30 +0000Collected Evidence: Collected Evidence: Install escape devices on fishing gear: Sea turtles One study evaluated the effects of installing escape devices on fishing gear on sea turtle populations. This study was in the Gulf of Carpentaria (Australia). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (1 STUDY) Unwanted catch (1 Study): One randomized, paired, controlled study in the Gulf of Carpentaria found that trawl nets with escape devices caught a similar number of sea turtles compared to unmodified nets. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3601https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3601Wed, 08 Dec 2021 17:09:33 +0000Collected Evidence: Collected Evidence: Install escape devices on fishing gear: Tortoises, terrapins, side-necked & softshell turtles Three studies evaluated the effects of installing escape devices on fishing gear on tortoise, terrapin, side-necked & softshell turtle populations. One study was in each of Australia, the USA and Canada. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Survival (1 study): One replicated, randomized, paired, controlled study in the USA found that a lower percentage of turtles died in hoop nets with escape devices than in unmodified nets. BEHAVIOUR (0 STUDIES) OTHER (3 STUDIES) Unwanted catch (3 Studies): One replicated, controlled study in Australia found that most short-necked turtles escaped from a carp trap with an escape ring. One replicated, randomized, controlled, paired study in the USA found that hoop nets with escape devices caught fewer turtles than unmodified nets. One replicated, randomized, paired, controlled study in Canada found that more painted turtles escaped from fyke nets with an escape device than from unmodified nets after being placed in the net. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3602https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3602Thu, 09 Dec 2021 09:55:00 +0000Collected Evidence: Collected Evidence: Install escape devices on fishing gear: Snakes & lizards Three studies evaluated the effects of installing escape devices on fishing gear on snake and lizard populations. All three studies were in the Gulf of Carpentaria (Australia). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (3 STUDIES) Unwanted catch (3 Studies): One of two paired, controlled studies (including one randomized and one replicated study) in the Gulf of Carpentaria found that trawl nets with escape devices caught a similar number of sea snakes compared to unmodified nets. The other study found that trawl nets with an escape device caught fewer sea snakes compared to unmodified nets. One replicated, paired, controlled study in the Gulf of Carpentaria found that the placement of escape devices trawl nets affected the number of sea snakes caught compared to unmodified nets. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3603https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3603Thu, 09 Dec 2021 10:08:51 +0000Collected Evidence: Collected Evidence: Install escape devices on fishing gear: Crocodilians We found no studies that evaluated the effects of installing escape devices on fishing gear on crocodilian populations. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2Fconservationevidencejournal.com%2Factions%2F3604https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3604Thu, 09 Dec 2021 10:16:43 +0000Collected Evidence: Collected Evidence: Install exclusion and escape devices on fishing gear Six studies evaluated the effects of installing exclusion and escape devices on fishing gear on reptile populations. Two studies each were off the coast of Australia, in the Gulf of Carpentaria (Australia) and in the Adriatic Sea. COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (2 STUDIES) Use (2 studies): Two replicated studies (including one controlled study) in the Adriatic Sea found that one or two loggerhead turtles were able to escape from a trawl net with an exclusion and escape device. OTHER (5 STUDIES) Unwanted catch (5 studies): Four studies (including two replicated, paired, controlled studies) off the coast of Australia and in the Gulf of Carpentaria (Australia) found that that trawl nets with an exclusion and escape device caught fewer loggerhead turtles or sea turtles and sea snakes compared to unmodified nets. One replicated study in the Adriatic Sea found that no loggerhead turtles were caught by a trawl net with an exclusion and escape device. Collected Evidencehttps%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3605https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3605Thu, 09 Dec 2021 10:22:38 +0000Collected Evidence: Collected Evidence: Use sinking lines instead of floating lines We found no studies that evaluated the effects on reptile populations of using sinking lines instead of floating lines. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2Fconservationevidencejournal.com%2Factions%2F3606https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3606Thu, 09 Dec 2021 10:36:58 +0000Collected Evidence: Collected Evidence: Use stiffened materials or increase tension of fishing gear We found no studies that evaluated the effects on reptile populations of using stiffened materials or increasing tension of fishing gear. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2Fconservationevidencejournal.com%2Factions%2F3607https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3607Thu, 09 Dec 2021 10:39:10 +0000Collected Evidence: Collected Evidence: Modify mesh sizes used in fishing gear We found no studies that evaluated the effects on reptile populations of modifying mesh sizes used in fishing gear. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2Fconservationevidencejournal.com%2Factions%2F3608https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3608Thu, 09 Dec 2021 10:40:41 +0000Collected Evidence: Collected Evidence: Use lower profile gillnets with longer/no tie-downs We found no studies that evaluated the effects on reptile populations of using lower profile gillnets with longer/no tie-downs. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2Fconservationevidencejournal.com%2Factions%2F3609https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3609Thu, 09 Dec 2021 10:42:43 +0000Collected Evidence: Collected Evidence: Use bindings to keep trawl nets closed until they have sunk below the water surface We found no studies that evaluated the effects on reptile populations of using bindings to keep trawl nets closed until they have sunk below the water surface. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated 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%2Fconservationevidencejournal.com%2Factions%2F3610https%3A%2F%2Fconservationevidencejournal.com%2Factions%2F3610Thu, 09 Dec 2021 10:45:18 +0000
What Works 2021 cover

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.

More about What Works in Conservation

Download free PDF or purchase
The Conservation Evidence Journal

The Conservation Evidence Journal

An online, free to publish in, open-access journal publishing results from research and projects that test the effectiveness of conservation actions.

Read the latest volume: Volume 21

Go to the CE Journal

Discover more on our blog

Our blog contains the latest news and updates from the Conservation Evidence team, the Conservation Evidence Journal, and our global partners in evidence-based conservation.

Who uses Conservation Evidence?

Meet some of the evidence champions

Endangered Landscape ProgrammeRed List Champion - Arc Kent Wildlife Trust The Rufford Foundation Save the Frogs - Ghana Mauritian Wildlife Supporting Conservation Leaders
Sustainability Dashboard National Biodiversity Network Frog Life The international journey of Conservation - Oryx Cool Farm Alliance UNEP AWFA Bat Conservation InternationalPeople trust for endangered species Vincet Wildlife Trust
For a full list of, and information about, our champions:
All Evidence Champions
About our champions, why and how to become one:
Become an Evidence Champion

This website uses Cookies

We use limited Cookies to run the site and to analyse our traffic (none for site vendors). By using this site, you will be providing your consent to our use of Cookies.

Accept & continue