Collected Evidence: Collected Evidence: Protect spawning fish from capture Four studies examined the effects of protecting spawning fish on marine fish populations. Two studies were in the North Atlantic Ocean (Canada, UK) and one study was in each of the Philippine Sea (Palau) and the Tasman Sea (Australia).  COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Abundance (1 study): One before-and-after, site comparison study in the Atlantic Ocean found no increase in the biomass of the spawning stock of Atlantic cod in the nine years following implementation of a seasonal fishery closure to protect spawning cod, compared to fished areas. Survival (1 study): One before-and-after, site comparison study in the Atlantic Ocean found no change in Atlantic cod survival in the nine years after a seasonal fishery closure to protect spawning cod was implemented, compared to fished areas. Condition (1 study): One before-and-after, site comparison study in the Atlantic Ocean found no change in the length composition of Atlantic cod in the nine years following a seasonal fishery closure to protect spawning cod, compared to fished areas. BEHAVIOUR (2 STUDIES) Use (2 studies): One site comparison study and one study in the Northeast Atlantic Ocean and Tasman Sea reported that spawning and/or nursery areas closed seasonally or permanently to fishing were used by tagged adult Atlantic cod for nearly a third of time during spawning, and by school sharks less than one year old for up to 80% of time, but by school sharks between one and two years old for 18% of time, compared to areas outside. OTHER (2 STUDIES) Commercial catch abundance (2 studies): One before-and-after, site comparison study in the Atlantic Ocean found no change over nine years in commercial catches of Atlantic cod following a seasonal fishery closure to protect spawning cod compared to fished areas. One replicated, controlled study in the Philippine Sea found that during seasonal closure of a grouper fishery to protect spawning individuals, the commercial catch numbers of other fish groups (herbivores) increased, indicating they were being targeted more by spear fishers compared to the open season. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2938https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2938Thu, 11 Feb 2021 16:13:52 +0000Collected Evidence: Collected Evidence: Limit the number of fishing days One study examined the effects of limiting the number of fishing days on marine fish populations. The study was in the Mediterranean Sea (Italy). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Abundance (1 study): One before-and-after study in the Mediterranean Sea reported that in the 10 years following a decrease in overall number of days fished by a bottom trawl fleet, there was a higher biomass of thornback and brown rays. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3804https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3804Thu, 26 May 2022 14:24:22 +0100Collected Evidence: Collected Evidence: Limit beam trawl width We found no studies that evaluated the effects of limiting beam trawl width 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%2F3805https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3805Thu, 26 May 2022 14:36:31 +0100Collected Evidence: Collected Evidence: Limit dredge width or number of dredges per vessel We found no studies that evaluated the effects of limiting dredge width or number of dredges per vessel 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%2F3806https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3806Thu, 26 May 2022 14:40:55 +0100Collected Evidence: Collected Evidence: Limit the number of traps or pots per vessel We found no studies that evaluated the effects of limiting the number of traps or pots per vessel 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%2F3807https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3807Thu, 26 May 2022 14:42:42 +0100Collected Evidence: Collected Evidence: Limit the number or length of static fishing nets in an area We found no studies that evaluated the effects of limiting the number or length of static fishing nets in an area 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%2F3808https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3808Thu, 26 May 2022 14:45:45 +0100Collected Evidence: Collected Evidence: Limit fishing activity by vessel size and/or engine power One study examined the effects of limiting fishing activity by vessel size and/or engine power on marine fish populations. The study was in the North Sea (Northern Europe).   COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Abundance (1 study): One before-and-after study in the North Sea found that after vessels with a higher engine power were excluded from an area for half of each year there was a higher abundance of commercially targeted fish, but no difference in the overall abundance of non-commercially targeted fish over five years. In addition, for all fish, abundance was higher for two of eight size-groups. BEHAVIOUR (0 STUDIES)Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3809https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3809Thu, 26 May 2022 14:53:03 +0100Collected Evidence: Collected Evidence: Prohibit certain gear types Two studies examined the effects of prohibiting certain gear types on marine fish populations. One study was in the Indian Ocean (Kenya) and one was in the Kattegat (Sweden/Denmark).   COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (1 STUDY) Abundance (1 study): One replicated, site comparison study in the Indian Ocean found that in an area where all but one gear type was prohibited there was a higher fish density compared to areas where just one gear type was prohibited and to unrestricted areas. BEHAVIOUR (0 STUDIES) OTHER (1 STUDY) Reduction of unwanted catch (1 study): One replicated, before-and-after study in the Kattegat found that a combination of areas in which non-selective gear types were prohibited and long-term fishery closures reduced unwanted catch of cod compared to before. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3810https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3810Thu, 26 May 2022 14:57:28 +0100Collected Evidence: Collected Evidence: Introduce an overall catch limit (quota cap or total allowable catch) by fishery or fleet Nine studies examined the effects of introducing overall catch limits by fishery or fleet on marine fish populations. Three studies were worldwide, two studies were in the South Atlantic Ocean (Namibia/South Africa), two studies were in the North Sea (Northern Europe), and one study was in each of the North Sea and Atlantic Ocean (Scotland) and the North Atlantic Ocean (Canada).   COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (6 STUDIES) Abundance (5 studies): Four before-and-after studies (two replicated) in the South Atlantic Ocean, the North Atlantic Ocean and the North Sea reported that following the introduction of overall catch limits for fish there was a higher abundance or biomass of hakes, Atlantic herring and Atlantic halibut, compared to before. One replicated, controlled study of fish stocks worldwide found that overfished stocks of tunas and billfishes had faster increases of biomass when managed using overall catch limits, compared to stocks with other types of control or no management. Reproductive success (1 study): A global review reported that after overall catch limits and minimum landing size were introduced there was strong recruitment of broadbill swordfish for one key stock, while recruitment for four other stocks could not be assessed due to limited data. Survival (2 studies): One before-and-after study and one replicated, controlled study in the North Atlantic Ocean and worldwide found that for fish species with overall catch limits there was a decrease or lower fishing mortality, compared either to before implementation or to stocks without catch limits and those with other controls. BEHAVIOUR (0 STUDIES) OTHER (3 STUDIES) Reduction of unwanted catch (1 study): One replicated, before-and-after study in the North Sea and North Atlantic Ocean found that overall catch limits did not reduce unwanted megrim catch despite a reduction in discards, however this was due to retention of more small but legal-sized megrim, previously discarded. Reduction of fishing effort (1 study): One replicated, before-and-after study in the North Sea found that when annual total allowable catch limits were changed (increased or decreased), half of the otter trawl fleet had corresponding changes in fishing effort (increased or decreased), but there were no changes for the beam trawl fleet. Stock status (1 study): One global systematic review found that in terms of reaching biomass-based management targets fisheries with fleet-wide catch quotas were no different to fisheries managed either by catch shares or effort controls. However, along with catch share fisheries, fewer catch quota stocks were over-exploited than those with effort controls. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3811https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3811Thu, 26 May 2022 15:07:14 +0100Collected Evidence: Collected Evidence: Introduce catch shares Two studies examined the effects of introducing catch shares on marine fish populations. Both were reviews of fisheries worldwide.   COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (2 STUDIES) Abundance (2 studies): One of two worldwide systematic reviews found that fisheries or stocks managed under catch shares were more likely to meet management target levels for biomass sustainability than those that did not meet targets. The other study found there was no difference in performance of biomass-based management targets between fisheries under catch shares, fleet-wide catch caps or fishing effort controls. BEHAVIOUR (0 STUDIES) OTHER (2 studies) Stock status (2 studies): Two worldwide systematic reviews found that catch share fisheries had lower rates of over-exploitation compared to non-catch share fisheries, and a higher proportion of fisheries managed under catch shares either met or exceeded management target levels for rates of exploitation than those that did not meet targets. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3812https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3812Fri, 27 May 2022 08:20:03 +0100Collected Evidence: Collected Evidence: Set catch shares by area We found no studies that evaluated the effects of setting catch shares by area 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%2F3813https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3813Fri, 27 May 2022 08:29:31 +0100Collected 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 +0100Collected Evidence: Collected Evidence: Establish move-on rules for temporary, targeted fishing restrictions or closures when a catch or unwanted catch threshold is reached Two studies examined the effects of establishing move-on rules for temporary, targeted fishing restrictions or closures when a catch or unwanted catch threshold is reached on marine fish populations. One study was in the North Atlantic Ocean and North Sea (Scotland) and one was in the North Atlantic Ocean (Scotland).   COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (2 STUDIES) Reduction of unwanted catch (1 study): One replicated, controlled, before-and-after study in in the North Atlantic Ocean/North Sea found that after move-on rules were established when a catch threshold limit triggered temporary fishing closures there were lower overall cod discards. Reduction of fishing effort (2 studies): Two before-and-after studies (one replicated and controlled) in the North Atlantic Ocean and North Sea found that after move-on rules were established for vessels when a catch threshold limit was reached fishing effort for cod and blue ling was reduced. Commercial catch abundance (2 studies): Two before-and-after studies (one replicated and controlled) in the North Atlantic Ocean and North Sea found that after move-on rules were established for vessels when a catch threshold limit was reached commercial landings of cod and blue ling were reduced. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3815https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3815Fri, 27 May 2022 08:36:34 +0100Collected Evidence: Collected Evidence: Introduce fishing permit/licence or charter schemes We found no studies that evaluated the effects of introducing fishing permit/licence or charter schemes 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%2F3816https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3816Fri, 27 May 2022 08:40:24 +0100Collected Evidence: Collected Evidence: Limit the number of fishing permits/licences to limit vessel or fisher numbers We found no studies that evaluated the effects of limiting the number of fishing licences or permits to limit vessel or fisher numbers 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%2F3817https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3817Fri, 27 May 2022 08:41:37 +0100Collected Evidence: Collected Evidence: Purchase fishing permits from fishers to limit vessel or fisher numbers We found no studies that evaluated the effects of purchasing fishing permits from fishers to limit vessel or fisher numbers 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%2F3818https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3818Fri, 27 May 2022 08:43:16 +0100Collected Evidence: Collected Evidence: Purchase fishing vessels from fishers to limit vessel numbers We found no studies that evaluated the effects of purchasing fishing vessels from fishers to limit vessel numbers 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%2F3819https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3819Fri, 27 May 2022 08:45:56 +0100Collected Evidence: Collected Evidence: Eliminate fisheries subsidies that encourage overfishing We found no studies that evaluated the effects of eliminating fisheries subsidies that encourage overfishing 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%2F3820https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3820Fri, 27 May 2022 08:47:44 +0100Collected Evidence: Collected Evidence: Implement vessel decommissioning schemes We found no studies that evaluated the effects of implementing vessel decommissioning schemes 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%2F3821https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3821Fri, 27 May 2022 08:48:57 +0100Collected Evidence: Collected Evidence: Prohibit the catching and/or landing of specific fish species We found no studies that evaluated the effects of prohibiting catching and/or landing of specific 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%2F3822https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3822Fri, 27 May 2022 08:51:56 +0100Collected Evidence: Collected Evidence: Prohibit high grading in which only the most profitable individuals or species are landed One study examined the effects of prohibiting high grading in which only the most profitable individuals or species are landed on marine fish populations. The study was in the North Sea/North Atlantic Ocean (UK).   COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (1 STUDY) Commercial catch abundance/landings (1 study): One replicated, before-and-after study in the North Sea/North Atlantic Ocean reported that a ban on high grading did not eliminate the discarding of legal-sized but unwanted common megrim Lepidorhombus whiffiagonis that were required to be landed. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3823https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3823Fri, 27 May 2022 08:55:44 +0100Collected Evidence: Collected Evidence: Implement multi-species management strategies We found no studies that evaluated the effects of implementing multi-species management strategies 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%2F3824https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3824Fri, 27 May 2022 09:02:14 +0100Collected Evidence: Collected Evidence: Implement multi-year or long-term management strategies One study examined the effects of implementing multi-year or long-term management strategies on marine fish populations. The study was worldwide.   COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (1 STUDY) Stock status (1 study): One worldwide study found that commercial fisheries with multi-year or long-term management plans in place, among other management and governance strategies, had stocks that were more likely to be sustainable and less likely to be in decline compared to fisheries typically without long-term objectives. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3825https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3825Fri, 27 May 2022 09:04:24 +0100Collected Evidence: Collected Evidence: Use technology to communicate near real-time catch information to fishers to enable avoidance of unwanted catchicate near real-time catch information to fishers to enable avoidance of unwanted catch One study examined the effects of using technology to communicate near real-time catch information to fishers to enable avoidance of unwanted catch on marine fish populations. The study was in the North Pacific and North Atlantic Oceans.   COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (1 STUDY) Reduction of unwanted catch (1 study): A review in the North Pacific and North Atlantic Oceans reported that where technology was used to provide near real-time catch information to fishers there were reductions of unwanted catch or discards in two of three cases. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3826https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3826Fri, 27 May 2022 09:38:00 +0100Collected Evidence: Collected Evidence: Employ adaptive management methods to achieve long-term goals We found no studies that evaluated the effects of employing adaptive management methods to achieve long-term goals 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%2F3827https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F3827Fri, 27 May 2022 09:41:07 +0100
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.

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