Conservation Evidence: Evidence Data

Collected 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: 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: 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 +0000Collected Evidence: Collected Evidence: Fit a size-sorting escape grid (rigid or flexible) to a fish trawl net Eighteen studies examined the effects of fitting size-sorting escape grids to a fish trawl net on marine fish populations. Six studies were in the North Sea (France, Norway, Scotland), three were in the North Atlantic Ocean (Portugal, USA), and two were in the Norwegian Sea (Norway). One study was in each of the Barents Sea (Norway), the South Atlantic Ocean (Namibia), the Mediterranean Sea (Spain), the Adriatic Sea (Italy), the Gulf of Maine (USA), and the Baltic Sea (northern Europe). One study was in a laboratory (Japan). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (1 STUDY) Use (1 study): One replicated study in a laboratory in Japan found that masu salmon were able to actively escape through a rigid escape grid, irrespective of grid orientation and towing speed, but escape was reduced in dark conditions compared to light. OTHER (17 STUDIES) Reduction of unwanted catch (14 studies): Eleven of 14 replicated studies (three paired and controlled) in the North Sea, North Atlantic Ocean, Barents Sea, South Atlantic Ocean, Mediterranean Sea, Adriatic Sea, Gulf of Maine and Baltic Sea found that fitting size-sorting escape grids of various types and configurations to fish trawl nets reduced the catches of unwanted small mackerel, small monkfish, non-target whiting and haddock, small hake, unwanted spiny dogfish, non-target herring, prohibited halibut, unwanted sizes of cod and other non-target fish, relative to the retained codend catch or compared to trawls without grids. One study found that fitting size-sorting escape grids of three designs to fish trawl nets reduced the discarded catch of nine of 12 fish species and the overall amount of discarded catch (fish and invertebrates combined), relative to the retained codend catch. One study found that fitting size-sorting escape grids had a mixed effect on the reduction of unwanted and/or undersized fish catch relative to the retained codend catch depending on fish ecological group. The other study found that, compared to standard trawl nets without escape grids, trawls with size-sorting escape grids reduced the overall catch of whiting, but not of undersized whiting. Improved size-selection of fishing gear (3 studies): Two of three replicated studies (two paired and controlled and one controlled) in the North Sea and Norwegian Sea, found that a size-sorting escape grid fitted to trawl nets improved the size-selection of haddock, but not saithe or cod, compared to standard nets without grids. One study found that trawl nets fitted with an escape grid did not improve the size-selection of cod and haddock compared to trawl nets fitted with square mesh escape windows. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2720https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2720Fri, 08 Jan 2021 16:54:19 +0000Collected Evidence: Collected Evidence: Fit a size-sorting escape grid (rigid or flexible) to a prawn/shrimp trawl net Thirty studies examined the effects of fitting size-sorting escape grids to prawn/shrimp trawl nets on marine fish populations. Five studies were in the North Sea (Scotland/Norway, Belgium/Netherlands, UK, Scotland), four were in the Coral Sea (Australia) and two were in each of the Gulf of Carpentaria (Australia), the Indian Ocean (Australia, Mozambique), the North Atlantic Ocean (Portugal, USA), the Pacific Ocean (Chile, USA), the Skagerrak and Kattegat (northern Europe) and the South Atlantic Ocean (Brazil). One study was in each of the Tasman Sea (Australia), the Greenland Sea (Svalbard), the Bay of Biscay (France), the Gulf of Maine (USA), the Gulf of Thailand (Vietnam), the Tyrrhenian Sea (Italy), the Gulf of St Vincent (Australia), the Persian Gulf (Iran) and the Northeast Atlantic Ocean (Norway). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (30 STUDIES) Reduction of unwanted catch (30 studies): Seven of seven replicated studies (including one controlled) in the northeast Atlantic Ocean, North Sea, North Atlantic Ocean, Greenland Sea, Gulf of Thailand, Tyrrhenian Sea and the Skagerrak and Kattegat found that fitting rigid or flexible size-sorting escape grids, of various types and configurations, to prawn/shrimp trawl nets reduced unwanted fish catches (non-commercial species and discarded commercial species/sizes) by allowing the escape of unwanted sharks and the other fish species monitored. Two of two before-and-after studies in the Gulf of Maine and Pacific Ocean found that after the introduction of size-sorting escape grids to trawl nets in fisheries for shrimp, the capture of non-target and unwanted fish was reduced compared to before grids were used. Eleven of 20 replicated studies (including one controlled and 19 paired and controlled) in the Tasman Sea, Coral Sea, Gulf of Carpentaria, North Sea, Indian Ocean, Bay of Biscay, Skagerrak and Kattegat, Pacific Ocean, South Atlantic Ocean, Gulf of St Vincent and Persian Gulf found that prawn/shrimp trawls with size-sorting escape grids, of various types and configurations, had lower catches of all or all but one undersized or otherwise unwanted fish and shark/ray species monitored, and unwanted total catch (fish and invertebrates), compared to trawl nets without escape grids. Two found that escape grids reduced non-target catches of most sizes of whiting and plaice and larger sizes of total fish, but increased the retention of small cod and haddock. Three studies found a variable effect of fitting escape grids to shrimp/prawn trawl nets on unwanted fish catch compared to nets with no grids, and the effect varied with year, site and grid type. Three found that grids had no effect on the reduction of unwanted fish and catches were similar for all or most of the unwanted non-commercial and commercial fish species/groups and for the total unwanted catch (fish and invertebrates). The other study found that fewer unwanted fish of 10 of 11 species/groups were retained in a shrimp/prawn trawl net with an escape grid used in combination with a diamond mesh codend with the mesh orientation turned by 90°, compared to a conventional diamond mesh net with no grid. One replicated, randomized study in the North Atlantic Ocean found that the reduction in catch of unwanted sharks depended on the type of escape grid and shrimp/prawn trawl net used. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2721https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2721Mon, 18 Jan 2021 16:42:48 +0000Collected Evidence: Collected Evidence: Fit a size-sorting mesh funnel (a sieve net) to a prawn/shrimp trawl net Three studies examined the effects of fitting a size-sorting mesh funnel (sieve net) to a prawn/shrimp trawl net on marine fish populations. All three studies were in the North Sea (Belgium, UK). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR RESPONSE (0 STUDIES) OTHER (3 STUDIES) Reduction of unwanted catch (3 studies): Three replicated, paired, controlled studies in the North Sea found that shrimp trawls fitted with a mesh size-sorting funnel, a sieve net, reduced the catches of unwanted (non-commercial or discarded) fish, compared to standard trawls. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2722https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2722Wed, 20 Jan 2021 12:16:50 +0000Collected Evidence: Collected Evidence: Fit a size-sorting escape grid (rigid or flexible) to trawl nets and use a square mesh instead of a diamond mesh codend Three studies examined the effects of fitting a size-sorting escape grid (rigid or flexible) to trawl nets and using a square mesh instead of a diamond mesh codend on marine fish populations. The studies were in the North Sea (UK), the Kattegat and Skagerrak (Sweden/Denmark) and the Coral Sea (Australia). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR RESPONSE (0 STUDIES) OTHER (3 STUDIES) Reduction of unwanted catch (3 studies): Three replicated, paired, controlled studies (one randomized) in the North Sea, Kattegat and Skagerrak and Coral Sea found that trawl nets with an escape grid and a square mesh codend caught fewer unwanted whiting, plaice, cod, haddock and unwanted catch of the most frequently caught fish species, but not hake or less frequently caught species compared to a diamond mesh codend with no grid. One also found that catch rates of most fish species were similar compared to a square mesh codend alone. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2725https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2725Thu, 21 Jan 2021 16:59:21 +0000Collected Evidence: Collected Evidence: Fit a size-sorting escape grid (rigid or flexible) and large, supported escape openings to trawl nets Four studies examined the effect of fitting trawl nets with a size-sorting escape grid and large, supported escape openings for fish escape on marine fish populations. Two studies were in the Gulf of Carpentaria (Australia), one study was in the Atlantic Ocean (USA) and one study was in the Persian Gulf (Iran). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (4 STUDIES) Reduction of unwanted catch (4 studies): Three of four replicated studies (three paired and controlled) in the Gulf of Carpentaria, the Atlantic Ocean and the Persian Gulf, found that trawl nets fitted with a both a size-sorting escape grid and a large supported escape opening reduced the catches of unwanted fish and sharks and rays, but not sawfish, compared to standard trawl nets. The other study found that trawl nets with an escape grid/opening caught similar amounts of unwanted sharks to trawl nets without. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2726https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2726Fri, 22 Jan 2021 13:26:19 +0000Collected Evidence: Collected Evidence: Fit a moving device to a trawl net to stimulate fish escape response (stimulator device) Three studies examined the effects of fitting a moving device to a trawl net to stimulate fish escape response (stimulator device) on marine fish populations. Two studies were conducted in laboratory facilities (South Korea) and one study was in the Baltic Sea (Northern Europe). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (3 STUDIES) Reduction of unwanted catch (2 studies): Two replicated, controlled studies in a laboratory found that trawl nets fitted with moving devices to stimulate fish escape response increased the escape of young red seabream compared to without devices, but for young olive flounder moving devices were only effective at increasing escape when used in combination with another novel device that made the net shake. Improved size-selectivity of fishing gear (1 study): One replicated, controlled study in the Baltic Sea found that only one of three types of moving stimulator devices fitted in conjunction with square mesh escape panels improved the size selectivity for cod, compared to without devices. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2729https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2729Tue, 26 Jan 2021 14:04:39 +0000