Conservation Evidence: Evidence Data

Collected 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 large, supported escape openings (such as Fisheyes, Bigeyes and radial escape sections) to trawl nets Eight studies examined the effects of fitting large, supported escape openings (such as Fisheyes, Bigeyes and radial escape sections) to trawl nets on marine fish populations. Three studies were in the northwest Atlantic Ocean (USA) and three were in the Gulf of Carpentaria (Australia). One study was in the north Pacific Ocean (USA) and one was in the Coral Sea (Australia). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (8 STUDIES) Reduction of unwanted catch (8 studies): Six of seven replicated studies (five paired and controlled, and one randomized, paired and controlled) in the Atlantic Ocean, Gulf of Carpentaria, Pacific Ocean and the Coral Sea found that fitting large, supported escape openings (various designs including Fisheyes, Bigeyes and radial escape sections) to trawl nets reduced the overall catches of unwanted fish, immature red snapper and total unwanted catch (fish and invertebrates combined) compared to standard nets. The other study found that there were fewer unwanted Chinook salmon in catches with two of two designs of escape openings, but only one of the designs caught fewer widow rockfish. One replicated, paired and controlled study in the Gulf of Carpentaria found that trawl nets fitted with either large escape openings or a square mesh escape panel reduced unwanted shark catch but not unwanted ray or sawfish catches, compared to standard nets. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2723https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2723Wed, 20 Jan 2021 16:58:00 +0000Collected Evidence: Collected Evidence: Fit mesh escape panels/windows to a trawl net and use square mesh instead of diamond mesh codend One study examined the effects of fitting mesh escape panels to a trawl net and using a square mesh instead of a diamond mesh codend on marine fish populations. The study was in the English Channel (UK). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (1 STUDY) Reduction of unwanted catch (1 study): One replicated, paired, controlled study in the English Channel found that using a trawl net with square mesh escape panels and a square mesh codend reduced the numbers of discarded finfish compared to a diamond mesh codend with no panels. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2724https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2724Thu, 21 Jan 2021 16:56:46 +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 mesh escape panels/windows and a size-sorting grid (rigid or flexible) to a trawl net Six studies examined the effects of fitting trawl nets with mesh escape panels or windows and a size-sorting grid on marine fish populations. Two studies were in the Atlantic Ocean (Portugal, Suriname), two were in the Indian Ocean (Australia, Mozambique), one study was in the Gulf of Carpentaria (Australia) and one was in the English Channel (UK). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) BEHAVIOUR (0 STUDIES) OTHER (6 STUDIES) Reduce unwanted catch (5 studies): Four of five replicated studies (four paired, controlled) in the Gulf of Carpentaria, Indian Ocean and Atlantic Ocean, found that bottom trawl nets fitted with square mesh escape panels and size-sorting grids of various types reduced the unwanted catch (non-target or undersized) of fish, sharks and stingrays, rays and total discarded catch (fish and invertebrates), compared to standard unmodified trawl nets, and that fish escape through either the panel/window, grid, or both varied between fish species or sizes. The other study found that the escape of non-target fish from the combined use of a square mesh panel and grid depended on the position of the panel in the net. Improved size-selectivity of fishing gear (1 study): One replicated, paired, controlled study in the English Channel found that size-selectivity of whiting was increased in bottom trawl nets fitted with square mesh escape panels or cylinders in combination with one or two size-sorting grids of different types, compared to standard nets. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2727https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2727Fri, 22 Jan 2021 15:52:49 +0000Collected Evidence: Collected Evidence: Use a different design or configuration of size-sorting escape grid/system in trawl fishing gear (bottom and mid-water) Twenty-three studies examined the effects of using a different design or configuration of size-sorting escape grid/system in trawl fishing gear on marine fish populations. Ten studies were in the Atlantic Ocean (Canada, USA, Brazil, Spain, Norway). Five studies were in the Barents and/or Norwegian Sea (Norway). Two studies were in the Kattegat and Skagerrak (Denmark/Sweden). One study was in each of the Arafura Sea (Australia), the Greenland Sea (Norway), the North Sea (Norway), the North Pacific Ocean (USA) and the Indian Ocean (Australia). One study was in a laboratory (Japan). COMMUNITY RESPONSE (0 STUDIES) POPULATION RESPONSE (0 STUDIES) OTHER (23 STUDIES) Reduction of unwanted catch (17 studies): Six of 16 replicated studies (eight paired and controlled, three controlled, one randomized and controlled, and one paired) in the Atlantic Ocean, a laboratory, Arafura Sea, Barents Sea, Kattegat and Skagerrak, Greenland Sea, North Sea, Pacific Ocean and the Indian Ocean, and one controlled study in the Barents Sea found that using a different design or configuration of size-sorting escape grid/system in trawl nets reduced the unwanted (undersized, non-target, discarded) catches of all or most of the fish species assessed, compared to standard or other grid designs/configurations. Four studies found that the effect of using different escape grids on the reduction of unwanted catch varied with fish species, light conditions, and the type of trawl net used. The other six found that, overall, using a different escape grid did not reduce unwanted fish catch. Improve size-selectivity of fishing gear (7 studies): Three of seven replicated studies (three controlled, one paired and controlled) in the Barents/Norwegian Sea, the Atlantic Ocean and the Greenland Sea found that different types or configurations of size-sorting escape grid systems in trawl nets resulted in better size-selectivity for unwanted redfish and Greenland halibut and of commercial target hake compared to other designs or configurations. Three studies found that the effect of using a different design or configuration of size-sorting escape grid/system on improving the size-selectivity of trawls varied between fish species compared to standard or other escape grid designs. The other study found that a new design of grid system did not improve the size-selectivity of unwanted redfish compared to an existing system. Collected Evidencehttps%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2728https%3A%2F%2Fwww.conservationevidence.com%2Factions%2F2728Mon, 25 Jan 2021 16:30:19 +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