Collected Evidence: Collected Evidence: Cease or prohibit all types of fishing in a marine protected area Seventy-nine studies examined the effects of ceasing or prohibiting all types of fishing in a marine protected area on fish populations. Fifteen studies were in the Indian Ocean (Kenya, Tanzania, South Africa, Mozambique, Madagascar, multiple African countries, Australia). Twelve studies were in the Mediterranean Sea (Spain, France, Italy). Ten studies were in the Pacific Ocean (New Zealand, USA, Hawaii, New Caledonia, Costa Rica, Tonga, Vanuatu, Solomon Islands). Seven studies were in each of the Coral Sea (Australia, Vanuatu), the Tasman Sea (New Zealand, Australia) and the Atlantic Ocean (Brazil, USA, Puerto Rico, Argentina, South Africa, UK, Canary Islands, Portugal, Turks and Caicos Islands). Four studies were in the Philippine Sea (Philippines). Three studies were in the Caribbean Sea (Belize, Puerto Rico). One study was in each of the Gulf of Mexico (USA), the Java Sea (Indonesia), the Pacific and Indian Oceans (multiple countries), the Sulu Sea (Malaysia) and the North Sea (Norway). Six studies were reviews of marine reserves (New Zealand, Latin America/Caribbean, regions unspecified and across the world).  COMMUNITY RESPONSE (26 STUDIES)  Community composition (7 studies): Seven site comparison studies (two replicated, and one before-and-after) in the Mediterranean Sea, Indian Ocean, Philippine Sea and the Atlantic Ocean found that protected areas where all fishing had been prohibited for between three and 16 years, had a different fish community composition, compared to fished areas.  Richness/diversity (22 studies): Fourteen of 20 site comparison studies (eight replicated, one replicated and paired, and one before-and-after) in the Indian Ocean, Mediterranean Sea, Philippine Sea, Tasman Sea, Atlantic Ocean, Caribbean Sea, Coral Sea and the Pacific Ocean, found that marine protected areas that had prohibited all fishing for between one to more than 25 years, had higher fish species/richness compared to fished areas. Six studies found similar fish species/richness between one and 20 years after all fishing was banned in protected areas, compared to fished areas. One systematic review in the Atlantic and Pacific Oceans found no difference in species richness between unfished protected areas and fished areas. One replicated, site comparison study in the Indian Ocean found that the effects of prohibiting all fishing on fish species richness/diversity after 15 years varied with the sampling method used. POPULATION RESPONSE (66 STUDIES) Abundance (64 studies): Thirty of 54 site comparison studies (18 replicated, eight replicated and paired, two before-and-after, one paired and before-and-after, and one replicated and before-and-after) in the Indian Ocean, Atlantic Ocean, Mediterranean Sea, Pacific Ocean, Tasman Sea, Coral Sea, Philippine Sea, Caribbean Sea, Gulf of Mexico, and the Sulu Sea, found that marine protected areas that had been prohibiting all fishing for up to 25 years or more, had higher abundances (density and/or biomass) of all fish (total fish biomass, total fish density), fishery targeted fish species, non-fishery targeted fish species and all or most of the individual fish species/groups monitored, except fish densities (all or most) and non-fishery targeted species, compared to unprotected fished areas and/or partly-fished protected areas. The studies also found that in some cases where the total fish biomass or densities were higher in no-fished areas, the effect varied between individual groups of fish based on species family and/or position in the food chain, commercial target and non-target species, fish sizes, depth and habitat types. Eight studies found that inside protected areas prohibiting all fishing there were similar abundances of all fish, and all or most of the individual fish species/groups monitored, compared to fished areas between one and 20 years after implementation. The other sixteen studies found that the effect of prohibiting fishing in protected areas for three to 20 years on fish abundance varied between fish species or groups and on their fished status (fishery target or non-target) and/or position in the food chain. One also found that the effect varied with size or age of the protected areas. Five of six reviews (three systematic) across the world, in the Pacific and/or Atlantic Oceans and in unreported regions found that non-fished marine reserves with one to 27 years of protection had higher abundances of all fish, all fish and invertebrates combined and blue cod compared to fished areas, but there were differences between species/groups and fishing intensity outside reserves. The other review found that fish abundance varied between species in no-take marine reserves between one and 25 years old, and was affected by food chain position, level of exploitation and duration of protection. One replicated study in the Pacific Ocean found a long-term decline in the abundance/presence of eight of 12 shark and ray species inside an established (>15 years) no-fishing protected area, however enforcement was poor. One before-and after, site comparison study in the Pacific Ocean, found no differences in overall fish abundance between a marine reserve closed permanently to fishing for five years and a closed area that was harvested for two years during the same period. One site comparison study in the Coral Sea found that in a no-take zone of an area protected for at least 10 years, fish abundance of four of six fish groups were similar to no-entry and fished zones, but two had lower abundance than the no-entry zone. One replicated, paired, site comparison study in the Tasman Sea found that in a non-fished marine park zone abundance of commercially targeted fish was higher than partly fished zones but lower than unprotected areas after four to eight years. Reproductive success (1 study): One site comparison study in the Mediterranean Sea found more eggs of four commercially targeted fish species inside a non-fished marine reserve enforced for three years than in fished areas outside the reserve. Survival (1 study): One site comparison study in the Atlantic Ocean found that prohibiting all fishing in a marine protected area for three years resulted in similar survival of red hind grouper, compared to fished areas. Condition (20 studies): Two global review studies (one systematic) and two systematic reviews in the Pacific Ocean and the Atlantic and Pacific Oceans found that prohibiting all fishing in marine protected areas for one to 27 years resulted in larger fish overall and larger blue cod compared to fished areas, but there were differences between individual fish families or species. Eight of 11 site comparison studies (four replicated, one before-and-after, one paired, and one replicated and paired) in the Tasman Sea, Pacific Ocean, Indian Ocean, Mediterranean Sea, Atlantic Ocean, Java Sea and the Philippine Sea, found that non-fished protected areas had larger fish overall and larger individuals of all or most of the fish species/groups monitored, compared to fished areas, after one to 22 years. The other three studies found similar fish sizes of all or all but one species, compared to fished areas one to 16 years after all fishing was prohibited. Three site comparison studies (one replicated) in the Coral Sea, Caribbean Sea and the Atlantic Ocean found that fish size in protected areas that had not been fished for six to more than 20 years, varied between fish species or food chain groups. One site comparison study in the Atlantic Ocean found that red hind grouper were larger, but had similar growth, in an area protected from fishing for three years compared to fished areas. One site comparison study in the Atlantic Ocean found that young lemon sharks in areas protected from fishing for 20 years had similar growth rates, but lower condition, than sharks in unprotected fished areas. BEHAVIOUR (2 STUDIES)  Behaviour change (2 studies): One replicated, site comparison study in the Pacific and Indian Oceans found that surgeonfish and parrotfish inside established protected areas where fishing was prohibited, showed a similar avoidance response to fishing gears as in fished areas, and this increased with increasing fishing intensity outside the protected areas. One replicated, site comparison study in the Indian Ocean found that in non-fished areas protected for one and 24 years, fish grazing rates were higher compared to fished areas.  OTHER (15 STUDIES) Use (7 studies): Four of six site comparison studies in the Pacific Ocean, Atlantic Ocean and the Tasman Sea found that marine protected areas where all fishing had been prohibited for at least five to 15 years, were used for a large proportion of time by shark and ray species and commercially important reef fish species, compared to fished areas, thus were provided protection from fishing. Two other studies found that time spent inside areas closed to all fishing for 20 years and over 30 years, varied between species and with size for three shark species and with size for giant trevally. One replicated study in the Indian Ocean found that most individuals of five fish species remained inside a marine reserve zone closed to fishing over a nine-year period. Catch abundance (2 studies): One of two site comparison studies in the Mediterranean Sea and Pacific Ocean found that commercial fish catch rates in small-scale traditional fisheries were highest closest to a marine reserve closed to all fishing for 22 years, and decreased with increasing distance from the reserve. The other study found that there was no increase in fish catch rates in commercially landed catch in the five years after a no-fishing zone was implemented in a co-managed protected area. Stock biomass (1 study): One replicated, site comparison study in the Indian Ocean found that the stock biomass (the harvested portion of the population) of reef fish species was highest in enforced protected areas closed to all fishing, compared to various other area management regimes.  Fishing mortality (2 studies): Two site comparison studies in the North Sea and Pacific Ocean found that prohibiting fishing in protected areas resulted in reduced commercial fishing mortality of corkwing wrasse tagged inside non-fished marine reserves compared to fished areas, and that the overall fishing mortality of grey reef sharks tagged inside protected areas was low.  Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2682https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2682Sat, 28 Nov 2020 14:35:06 +0000Collected Evidence: Collected Evidence: Deploy fishing gear at selected depths to avoid unwanted species Five studies examined the effect of deploying fishing gear at selected depths to avoid unwanted species on marine fish populations. Three studies were in the Atlantic Ocean (Florida, Brazil, Canary Islands), and one study was in each of the Pacific Ocean (Hawaii) and the Tasman Sea (Australia). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (5 STUDIES) Reduction of unwanted catch (5 studies): Four of five replicated studies (three controlled, one paired and controlled) in the Pacific Ocean, Atlantic Ocean and the Tasman Sea found that deploying fishing gear (longlines, handlines and traps) at selected depths, including above the seabed instead of on it, reduced the unwanted catches of five of 17 fish species, three of eight shark/ray species, non-commercially targeted fish species and Harrison’s dogfish, compared to depths usually fished. The other study found that different shark species were hooked at different depths in the water column during bottom-set longlining deployments.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2683https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2683Mon, 30 Nov 2020 16:26:13 +0000Collected Evidence: Collected Evidence: Deploy fishing gear at selected times (day/night) to avoid unwanted species Two studies examined the effect of deploying fishing gear at selected times on marine fish populations. Both studies were in the South Pacific Ocean (Lake Wooloweyah, Australia).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (2 STUDIES)   Reduction of unwanted catch (2 studies): One of two replicated, controlled studies in the South Pacific Ocean found that trawling for prawns during the day reduced the overall catch of unwanted fish by number, but not weight, compared to usual night trawling, and the effect differed by species. The other study found that powered handlining in the day avoided catches of Harrison’s dogfish at shallower, but not deeper seamounts, compared to the night.    Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2684https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2684Mon, 30 Nov 2020 16:40:44 +0000Collected Evidence: Collected Evidence: Selectively avoid unwanted fish based on temperature distribution We found no studies that evaluated the effects of selectively avoiding fish by their temperature distributions on marine fish populations. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2685https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2685Mon, 30 Nov 2020 16:56:00 +0000Collected Evidence: Collected Evidence: Reduce duration of fishing gear deployments Four studies examined the effects of reducing the duration of time that fishing gear is deployed in the water on marine fish populations. Two studies were in the North Sea. One study was in the Atlantic Ocean (USA) and one was in both the Barents Sea and Atlantic Ocean (Norway/USA).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (2 STUDIES)  Survival (2 studies): Two replicated, controlled studies in the North Sea found that survival of unwanted plaice and/or sole released after capture in beam or pulse trawls was higher after shorter duration trawl deployments, but that the opposite was true for plaice captured in otter trawls, over tow durations of between one and two hours.  BEHAVIOUR (0 STUDIES) OTHER (2 STUDIES)  Reduction of unwanted catch (1 study): One of two replicated studies (one paired and controlled) in the Barents Sea/Atlantic Ocean and the Atlantic Ocean found that catch rates of unwanted sharks caught in longline gear decreased with decreasing time the gear was deployed in the water, over durations of up to 10 hours. The other study found that shorter tow durations caught similar amounts of small haddock, but more small cod, than longer durations, in bottom trawls fished for between five minutes and one hour. Improved size-selectivity of fishing gear (1 study): One replicated, paired, controlled study in the Barents Sea/Atlantic Ocean found that varying bottom trawl fishing durations between five minutes and two hours had no effect on the size-selectivity of Atlantic cod, haddock or long rough dab. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2686https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2686Mon, 30 Nov 2020 17:00:02 +0000Collected Evidence: Collected Evidence: Change the towing speed of a trawl net One study examined the effect of changing the towing speed of a trawl net on catch of marine fish. The study was in the North Sea (Norway).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (1 STUDY) Improved size-selectivity of fishing gear (1 study): One replicated, paired study in the North Sea found that changing the towing speed of a bottom trawl net did not increase the size selectivity of small cod and haddock. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2687https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2687Wed, 02 Dec 2020 10:42:04 +0000Collected Evidence: Collected Evidence: Reduce the hauling speed of a trawl net We found no studies that evaluated the effects of reducing the hauling speed of a trawl net on marine fish populations.  ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2688https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2688Wed, 02 Dec 2020 10:47:28 +0000Collected Evidence: Collected Evidence: Use a different method to sort or bring catch onboard We found no studies that evaluated the effects of using different methods to sort or bring catches onboard vessels on marine fish populations.  ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2689https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2689Wed, 02 Dec 2020 14:45:13 +0000Collected Evidence: Collected Evidence: Reduce the duration of exposure to air of captured fish before release Three studies examined the effect of reducing the duration of exposure of fish to air on marine fish populations. One study was in each of the Bay of Biscay (Spain), Gulf of Alaska (Canada) and Coral Sea (Australia).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (2 STUDIES) Survival (1 study): One replicated study in the Bay of Biscay found that reducing air exposure before release did not increase the survival of small-spotted catshark caught during commercial trawling. Condition (1 study): One replicated study in the Gulf of Alaska found that shorter durations of air exposure before release improved the physical condition and reduced the amount of injury to discarded chum salmon caught in purse seine nets.  BEHAVIOUR (1 STUDY) Behaviour change (1 study): One study in the Coral Sea found that minimal exposure to air and handling resulted in improved overall behaviour after release (activity and ability to return to reef) of reef fish, compared to fish exposed to air and handling for longer duration. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2690https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2690Wed, 02 Dec 2020 14:47:25 +0000Collected Evidence: Collected Evidence: Release protected or species of concern alive after capture Six studies examined the effects of releasing protected or species of concern alive after capture on marine fish populations. Two studies were in the Atlantic Ocean (USA and Canada), and one was in each of the Coral Sea (Australia), Tasman Sea (New Zealand), Cantabrian Sea (Spain) and the Pacific Ocean (USA).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (6 STUDIES) Survival (6 studies): Four of six replicated studies in the Atlantic Ocean, Tasman Sea, Cantabrian Sea and the Pacific Ocean found that the majority (76–92%) of unwanted (discarded or protected) small-spotted catshark, thorny skate, pearl perch and Atlantic wolffish, but less than half of smooth skate, survived for at least 1 h–5 days after capture and/or release, and survival was reduced by hooking/capture depth injuries and longer tow durations. One study found that nearly all yelloweye rockfish survived for four days after capture and release, but canary rockfish survival decreased with increasing capture depth. The other study found that all spinetail devilrays brailed aboard from purse seine nets survived but not those brought aboard entangled in the net. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2691https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2691Wed, 02 Dec 2020 14:55:19 +0000Collected Evidence: Collected Evidence: Establish handling and release protocols in non-recreational fisheries Two studies examined the effects of establishing handling and release protocols in non-recreational fisheries on marine fish populations. One study was in the Atlantic Ocean (West Africa) and one was in the South Pacific Ocean (Australia).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Survival (1 study): One study in the Atlantic Ocean reported that tracked whale sharks released from purse seines using an enhanced protocol survived for at least 21 days, and post-release movements appeared normal. BEHAVIOUR (2 STUDIES) Behaviour change (2 studies): One study in the Pacific Ocean found that after release protocols (minimal handling and air exposure), reef fish returned more quickly to a reef or the seabed after release, compared to higher stress handling and longer air exposure. One study in the Atlantic Ocean reported that the post-release movements of tracked whale sharks released from purse seines using an enhanced protocol appeared normal. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2692https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2692Wed, 02 Dec 2020 15:51:06 +0000Collected 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: Legislate to oblige fishers to retain and land all catch of species managed by quotas We found no studies that evaluated the effects of legislating to oblige fishers to retain and land all catch of quota species on marine fish populations. ‘We found no studies’ means that we have not yet found any studies that have directly evaluated this intervention during our systematic journal and report searches. Therefore, we have no evidence to indicate whether or not the intervention has any desirable or harmful effects.Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2694https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2694Wed, 02 Dec 2020 16:24:14 +0000Collected Evidence: Collected Evidence: Use artificial light on fishing gear Two studies examined the effects of using artificial light on fishing gear on marine fish populations. One study was in the Pacific Ocean (USA) and one in the Barents Sea (Norway).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (2 STUDIES) Reduction of unwanted catch (1 study): One replicated, paired, controlled study in the Pacific Ocean found that shrimp trawl nets with artificial lights caught fewer unwanted fish when they were fitted to the fishing line, but not to a size-sorting grid, compared to a conventional trawl. Improved size-selectivity of fishing gear (1 study): One replicated, controlled study in the Barents Sea found that size-selectivity of long rough dab, Atlantic cod, haddock and redfish was not improved by the presence of LED lights on a size-sorting grid. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2695https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2695Wed, 02 Dec 2020 17:04:07 +0000Collected Evidence: Collected Evidence: Attach an electropositive deterrent to fishing gear Nine studies examined the effect of attaching an electropositive deterrent to fishing gear on marine fish populations. Three studies were in the Atlantic Ocean (USA, Canada, Bahamas). One study was in each of the Gulf of Alaska (USA), the South Pacific Ocean (Australia) and the Tasman Sea (Australia). One study was a global systematic review and two studies were in laboratory facilities (USA).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (4 STUDIES) Behaviour change (4 studies): Three of four replicated studies (one paired and controlled, one randomized and controlled, one randomized, and one controlled) in the Atlantic Ocean, Tasman Sea, and in laboratory conditions, found that the presence of potentially deterrent materials attached near the bait reduced the frequency of feeding attempts and bait consumption of spiny dogfish, great hammerhead and draughtboard sharks compared to the absence of deterrent materials. The other study found that a potentially deterrent material did not reduce bait consumption by bonnethead and young lemon sharks compared to non-deterrents. One of the studies also found that the bait consumption behaviour of commercially valuable Pacific halibut was unaffected by deterrent materials. OTHER (5 STUDIES) Reduction of unwanted catch (5 studies): Two of four replicated, controlled studies (one randomized) in the Gulf of Alaska, the Pacific Ocean and the Atlantic Ocean found that fishing gear (longlines and traps) fitted with electropositive deterrent materials caught fewer unwanted spiny dogfish, longnose skate, sharks and rays, and fewer undersized halibut, compared to standard fishing gear or gears with non-deterrent materials. The other two studies, and a global systematic review found that electropositive deterrents on fishing gear resulted in similar catches of unwanted spiny dogfish, sharks (total catch), blue shark and sharks and rays (total catch), compared to gear with no deterrents. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2696https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2696Thu, 03 Dec 2020 12:05:21 +0000Collected Evidence: Collected Evidence: Use a larger mesh size Forty-two studies examined the effects of using a larger mesh size of fishing net on marine fish populations. Ten studies, and one review, were in the Atlantic Ocean (UK, Portugal, USA). Eight studies were in the Aegean Sea (Greece, Turkey). Five studies were in the North Sea (UK, Netherlands, France, North Europe) and three were in the Tasman Sea (Australia). Two studies were in each of the Mediterranean Sea (Italy, Turkey), the Pacific Ocean (USA, Chile), the Skagerrak and Kattegat (Northern Europe) and the Gulf of Mexico (Mexico). One study was in each of the English Channel (UK), the Bering Sea (USA), the Baltic Sea (Finland), the Caribbean Sea (Barbados), the Persian Gulf (Kuwait), the Bristol Channel (UK), the Barents Sea (Norway) and the Arabian Sea (India).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (3 STUDIES) Survival (3 studies): One of three controlled studies (one replicated and paired, and one replicated) in the Atlantic Ocean, Baltic Sea and Bristol Channel found that larger mesh sizes improved the post-capture survival of skates and rays compared to smaller meshes. The other two found similar post-capture survival in haddock, whiting and small herring between trawl nets with larger mesh and nets of smaller mesh size. Condition (1 study): One replicated, paired, controlled study in the Bristol Channel reported that the condition of skates and rays at capture was better with a larger trawl codend mesh size compared to a smaller mesh. BEHAVIOUR (0 STUDIES) OTHER (41 STUDIES) Reduction of unwanted catch (21 studies): Fifteen of 20 replicated studies (five controlled, two paired, eight paired and controlled, one randomized and one randomized and controlled) in the North Sea, Skagerrak/Kattegat, Aegean Sea, Caribbean Sea, Mediterranean Sea, Atlantic Ocean, Tasman Sea, Gulf of Mexico, Pacific Ocean, Bering Sea and the Bristol Channel found that using a larger mesh size in a fishing net (various trawls, gillnets, seines and trammel nets) reduced the catches of unwanted (small/undersized, non-commercial, discarded) fish or fish and invertebrates combined, compared to nets with standard/smaller mesh sizes. One study found that amounts of unwanted fish were reduced with larger mesh at smaller catch sizes but were similar between large and small meshes at larger catch sizes, and one found that increasing a trawl codend mesh size reduced the unwanted catch of one of two fish species compared to a standard mesh. Three found that larger mesh sized fishing nets did not typically reduce the unwanted fish catch compared to nets of smaller mesh sizes. One study found that increasing both the mesh size and minimum size limit reduced catches of the youngest fish. Improved size-selectivity of fishing gear (23 studies): Nineteen of 21 replicated studies (eight controlled, four paired and controlled, three randomized and controlled, and one paired) and one review, in the North Sea, Aegean Sea, Baltic Sea, Pacific Ocean, Atlantic Ocean, Gulf of Mexico, Tasman Sea, Arabian Sea, Persian Gulf, Barents Sea and the Mediterranean Sea found that larger mesh sizes (both diamond and square) of the netting of various gear types improved the size-selectivity for all fish species assessed and in one, for two of three fish species, compared to smaller mesh sizes. One study found that size-selectivity for fish was not improved with larger mesh size in the netting of fish traps. The other found that increasing the codend mesh size of trawls fitted with size-sorting escape grids resulted in similar size-selectivity of the codend for fish compared to smaller codend mesh sizes. One controlled study in the English Channel found that a trawl net codend with a larger size of square mesh had similar size-selectivity for Atlantic mackerel as a smaller diamond mesh codend. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2697https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2697Thu, 03 Dec 2020 19:56:32 +0000Collected Evidence: Collected Evidence: Use a different hook type Twenty-five studies examined the effect of using a different hook type on marine fish populations. Nine studies were in the Atlantic Ocean (Portugal, South Africa, USA, Brazil, Portugal, Iceland), six studies were in Pacific Ocean (New Zealand, Japan, Costa Rica, Hawaii, Fiji) and two studies were in the Mediterranean Sea (Spain, Italy). One study was in each of the Barents Sea (Norway), the Denmark Strait (Greenland), the Coral Sea (Australia) and the Strait of Gibraltar (Spain/Morocco). Four studies were reviews (worldwide, Atlantic and Pacific Oceans). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (10 STUDIES) Survival (10 studies): Four of seven replicated, controlled studies in the Atlantic Ocean, Pacific Ocean and Coral Sea and two of three worldwide systematic reviews, found that using different hook types in longline or recreational fisheries, including sizes, styles and other modifications to hooks, reduced the incidence of fish hook injuries (associated with higher post-release mortality), and reduced the capture mortality of some species of unwanted sharks and rays and non-target billfish species, compared to conventional hooks or other hook types. The other four studies found that using a different hook type did not reduce the post-release mortality of young sea breams, or the capture mortality of sharks species and non-target fish species, but did reduce the incidence of deep-hooking in some cases. BEHAVIOUR (0 STUDIES) OTHER (23 STUDIES) Reduction of unwanted catch (20 studies): Eight of 16 replicated studies (13 controlled, one randomized) in the Atlantic Ocean, Pacific Ocean, Barents Sea, Mediterranean Sea, Denmark Strait and Coral Sea, found that using a different hook type, including different sizes, styles and hook modifications, reduced the unwanted catch in longline and recreational hook fisheries of non-commercially targeted and targeted fish species, small non-target fish species, overall fish catch, overall discarded bony fish catch but not sharks and rays, undersized haddock, two of three unwanted fish species, non-target sharks and rays and non-target rays and sailfish, compared to standard hooks or hooks of other types. Seven studies found that changing hook type did not reduce the unwanted catch of young or non-target fish species, unwanted sharks and rays, unwanted blue shark, unwanted roughhead grenadier or non-target pelagic stingray and silky shark, compared to standard or other hook types. The other study found that catch rates of young groupers, and non-target fish and shark species varied with hook design, and larger hooks caught fewer non-target fish species overall, but more undersized grouper and sharks compared to other hook types. Four global systematic reviews found that hook style did not affect the unwanted catch of billfish species, sharks and rays or sharks, compared to standard styles. Improved size-selectivity of fishing gear (3 studies): Two of three replicated studies in the Atlantic Ocean and Strait of Gibraltar, found that increasing hook sizes improved the size-selectivity (by increasing the average catch length) of hottentot and black spot seabream compared to smaller hook sizes. The other study found that a different hook size improved size selectivity for two of five commercially targeted fish species and was also affected by bait size. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2698https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2698Tue, 08 Dec 2020 15:46:56 +0000Collected Evidence: Collected Evidence: Modify longline configuration Four studies examined the effects of modifying longline configuration on marine fish populations. One study was in each of the Norwegian Sea (Norway) and Atlantic Ocean (Brazil). Two were global reviews.  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (2 STUDIES) Survival (2 studies): One global review found that survival of unwanted sharks and rays at retrieval of longline gear was higher on nylon hook attachment lines instead of wire for two of three species and lower for one. One replicated, controlled study in the Atlantic Ocean found that survival of unwanted sharks caught on tuna longlines was reduced with nylon hook lines compared to wire. BEHAVIOUR RESPONSE (0 STUDIES) OTHER (4 STUDIES) Reduction of unwanted catch (4 studies): One of two replicated, controlled studies in the Norwegian Sea and Atlantic Ocean and one of two reviews of worldwide longline fisheries found that modifying longline configuration (increasing the lead weight on mid-water longlines to increase the sinking rate or using nylon instead of wire hook attachments) reduced the catches of unwanted sharks and/or rays compared to standard longlines. One review found that longline modifications reduced unwanted shark/ray catches in one of two cases. The other study found that modified longlines did not reduce catches of undersized haddock compared to standard longlines. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2699https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2699Wed, 09 Dec 2020 16:42:33 +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: Modify gillnet or entangling (trammel/tangle) net configuration Four studies examined the effects of modifying gillnet or entangling (trammel or tangle) net configuration on marine fish populations. One study was in each of the Gulf of Maine (USA), the Atlantic Ocean (USA) and the Adriatic Sea (Italy), and one study was in two estuaries in North Carolina (USA).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (4 STUDIES) Reduction in unwanted catch (4 studies): Three of four replicated studies (one controlled, two paired and controlled) in the Gulf of Maine, Atlantic Ocean, Adriatic Sea and estuaries in the USA, found that modifications to the configuration of gillnets, including reduced height, increased tension twine diameter and mesh size and orientation, reduced the unwanted catch of cod in one of two net designs, discarded fish of commercial and non-commercial species, and the discards of non-commercial, but not commercial species (fish and invertebrates), compared to conventional configurations. The other study found that gillnet modification did not typically reduce unwanted shark catches compared to unmodified gillnets. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2701https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2701Fri, 11 Dec 2020 11:55:00 +0000Collected Evidence: Collected Evidence: Modify fishing trap/pot configuration Twenty-three studies examined the effects of modifying fishing trap or pot configuration on marine fish populations. Five studies were in the Atlantic Ocean (USA, Brazil, Canary Islands, Canada). Three studies were in each of the Bothnian Sea (Sweden), the Baltic Sea (Poland, Sweden), the Tasman Sea (Australia) and the Indian Ocean (Kenya, South Africa). One study was in each of the Kattegat (Denmark), the Mediterranean Sea (Spain), the Adriatic Sea (Italy), the Southern Ocean (Australia), the Pacific Ocean (Canada) and the Barents Sea (Norway).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Survival (1 study): One replicated, controlled study in the Bothnian Sea found that survival of small herring escaped from a pontoon fish trap through a size-sorting grid was similar to trap-caught herring that did not pass through a grid. BEHAVIOUR (0 STUDIES) OTHER (22 STUDIES) Reduction of unwanted catch (20 studies): Sixteen of 20 replicated studies (11 controlled, one randomized, paired and controlled, one randomized and controlled, two paired and controlled and one randomized) and one before-and-after study in the Atlantic Ocean, Baltic Sea, Mediterranean Sea, Southern Ocean, Tasman Sea, Adriatic Sea, Bothnian Sea, Indian Ocean, Pacific Ocean, the Kattegat and the Barents Sea, found that modifications to trap configuration (various, including using a different trap type, increased mesh size and fitting an escape device) reduced the unwanted (undersized, discarded or non-commercial target) catches of fish (overall, or all of multiple study species), brown trout, black sea bass, herring, bluethroat wrasse and leatherjacket, cod, protected rockfishes, whitefish, black sea bass, American eel and winter flounder, sharks/rays and of salmon and rainbow trout in one of two cases, compared to unmodified conventional traps or traps of other designs. One of these also found that the number of unwanted species (fish and invertebrates) was lower in modified traps. Three other studies, found that trap modification or type had no effect on unwanted catches of white croaker, non-commercial fish or undersized Atlantic cod, and non-target haddock catches were increased. However, one of these also reported that traps (creels) did not catch high proportions of immature fish, unlike bottom trawls. Improved size-selectivity of fishing gear (4 studies): Three of four replicated studies (two controlled and one randomized, paired and controlled) in the Baltic Sea, Tasman Sea, Indian Ocean and Atlantic Ocean found that traps or pots modified with a square mesh escape window or larger mesh sizes improved the size-selectivity of Atlantic cod, black sea bass and most fish species compared to smaller mesh and/or standard gear. The other found that increasing mesh size of a trap escape panel had no effect on size-selectivity of panga. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2702https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2702Mon, 14 Dec 2020 10:32:58 +0000Collected Evidence: Collected Evidence: Fit escape devices (panels/grids) to encircling nets Three studies examined the effect of fitting fish escape devices (panels or size-sorting grids) to encircling nets on marine fish populations. One study was in the Tasman Sea (Australia), one was in the North and Norwegian Seas (Norway) and one was in the Atlantic Ocean (Portugal).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Survival (1 study): One replicated, controlled study in the North and Norwegian Seas reported no difference in the survival of saithe, but reduced survival of mackerel, between fish that had passed through a rigid size-sorting escape grid in a purse seine net and those that had not, after one month. BEHAVIOUR (0 STUDIES) OTHER (2 STUDIES) Reduction of unwanted catch (2 studies): Two replicated studies (one controlled) in the Tasman Sea and Atlantic Ocean found that transparent panels of net and a large-diamond mesh escape panel fitted to fish seine nets, reduced the catches of unwanted small individuals of one of four commercially targeted fish and unwanted or undersized fish, compared to conventional seine nets. Improved size-selectivity of fishing gear (1 study): One replicated, controlled study in the Tasman Sea found that size-selectivity of one of four commercial fish species was improved in seine nets with transparent netting panels compared to without. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2703https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2703Mon, 14 Dec 2020 14:09:11 +0000Collected Evidence: Collected Evidence: Modify the design or configuration of trawl gear (mixed measures) Nineteen studies examined the effects of modifying the design or configuration of trawl gear on marine fish populations. Seven studies were in the Clarence River estuary (Australia), three studies were in each of the Mediterranean Sea (Turkey) and North Sea (UK), two studies were in the North Pacific Ocean (USA), and one study was in each of the South Pacific Ocean, the Skagerrak and Baltic Sea (Denmark/Sweden), the Atlantic Ocean (USA) and the Coral Sea (Australia).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (19 STUDIES) Reduce unwanted catch (16 studies): Twelve of 16 replicated studies (seven paired and controlled, five controlled, and two paired) in the Clarence River estuary, South Pacific Ocean, North Pacific Ocean, Mediterranean Sea, Skagerrak and Baltic Sea, Atlantic Ocean, North Sea and the Coral Sea, found that various modifications to trawl gear, including changes to the trawl wires, number of nets, codend number, footrope configuration, front trawl body panels, codend netting layers, spreading mechanism, method of weaving, knot orientation or using a new overall trawl design, resulted in reduced unwanted catches of non-target and/or discarded fish species or sizes, and of all sizes of four of seven commercial species, compared to standard unmodified trawl gear or other trawl designs. One of these also found increased catch rate of one commercial species and for another two species the effect varied with fish size. Two studies found that modified trawl gear reduced the unwanted catch of only a small proportion of the number of individual fish species caught compared to other trawl configurations, and also that unwanted fish catches varied between day/night. One study found that different trawl configurations had mixed effects on the numbers and sizes of non-target fish catch. The other study found no reduction in catches of discarded finfish between a modified and standard trawl codend. Improved size-selectivity of fishing gear (5 studies): Five replicated, controlled studies in the North Sea and Mediterranean Sea found that various modifications to trawl gear, including changes to the length of the extension piece, the codend strengthening bag, the method of weaving, the number of codend layers and overall design improved the size-selectivity for unwanted (non-target/discarded) fish species or sizes, and annular seabream in one of two cases, compared to unmodified standard trawl gear or other design configurations. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2704https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2704Thu, 17 Dec 2020 11:29:15 +0000Collected Evidence: Collected Evidence: Change the size of the main body of a trawl net One study examined the effects of changing the size of the main body of a trawl net to reduce unwanted catch on marine fish populations. The study was in the North Sea (Norway). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (1 STUDY) Improved size-selectivity of fishing gear (1 study): One replicated study in the North Sea found that reducing the size of the main body of a trawl net did not improve the size-selection of cod and haddock. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2705https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2705Thu, 17 Dec 2020 12:05:11 +0000Collected Evidence: Collected Evidence: Decrease the circumference or diameter of the codend of a trawl net Thirteen studies examined the effects of decreasing the circumference or diameter of a trawl codend on marine fish populations. Four studies were in the Tasman Sea (Australia) and three studies were in the North Sea (UK, Norway). Two studies were in the Adriatic Sea (Italy) and two were in the Baltic Sea (Denmark/ Germany). One study and one review were in the Northeast Atlantic Ocean (Northern Europe).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (13 STUDIES) Reduction of unwanted catch (6 studies): Two of six replicated, controlled studies (three paired, and one randomized and paired) in the Tasman Sea, Adriatic Sea and Northeast Atlantic Ocean found that bottom trawl nets of smaller circumferences reduced discarded catch of fish in three of five cases and of total discarded catch (fish and invertebrates) in one of two areas, but not overall, compared to standard trawls. Two studies found that reduced circumference codends reduced non-target or discarded fish catch in three of 12 cases and for one of four species. The two other studies found that discarded fish catch was not reduced in smaller circumference codends. Improve size-selectivity of fishing gear (8 studies): Four of eight replicated, controlled studies (one paired) in the North Sea, Adriatic Sea and Baltic Sea, and one review in the Northeast Atlantic Ocean, found that decreasing the circumference or diameter of the codend of trawl gear (bottom trawls and seines) improved the size-selectivity of haddock, Atlantic cod, whiting and European hake and red mullet, compared to larger circumferences/diameters. One also found the effect was the same across two codend mesh sizes, and one also found the effect was greater in diamond mesh with the netting orientation turned by 90° compared to standard diamond mesh. Two studies found that a decrease in codend circumference/diameter improved size-selectivity of haddock and saithe in one of two cases, and of one of three fish species. The other study found that a smaller circumference codend reduced size-selectivity of the gear for one of three fish species and was similar for the other two. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2706https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2706Thu, 17 Dec 2020 14:51:11 +0000
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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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