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What Works in Conservation 2018

 | 
William J. Sutherland
, 
Lynn V. Dicks
, 
Nancy Ockendon
, 
et al.

3. Bird conservation

3.7 Threat: Biological resource use

Texte intégral

3.7.1 Reducing exploitation and conflict

Scare fish-eating birds from areas to reduce conflict

1Studies investigating scaring fish from fishing areas are discussed in ‘Threat: Agriculture – Aquaculture’.

Beneficial

● Use legislative regulation to protect wild populations

2Five out of six studies from Europe, Asia, North America and across the world, found evidence that stricter legislative protection was correlated with increased survival, lower harvests or increased populations. The sixth, a before-and-after study from Australia, found that legislative protection did not reduce harvest rates. Assessment: beneficial (effectiveness 65%; certainty 65%; harms 0%).

3http://www.conservationevidence.com/​actions/​271

Likely to be beneficial

● Use wildlife refuges to reduce hunting disturbance

4Three studies from the USA and Europe found that more birds used refuges where hunting was not allowed, compared to areas with hunting, and more used the refuges during the open season. However, no studies examined the population-level effects of refuges. Assessment: likely to be beneficial (effectiveness 45%; certainty 45%; harms 0%).

5http://www.conservationevidence.com/​actions/​278

Unknown effectiveness (limited evidence)

● Employ local people as ‘biomonitors’

6A single replicated study in Venezuela found that poaching of parrot nestlings was significantly lower in years following the employment of five local people as ‘biomonitors’. Assessment: unknown effectiveness — limited evidence (effectiveness 50%; certainty 19%; harms 0%).

7http://www.conservationevidence.com/​actions/​275

● Increase ‘on-the-ground’ protection to reduce unsustainable levels of exploitation

8Two before-and-after studies from Europe and Central America found increases in bird populations and recruitment following stricter anti-poaching methods or the stationing of a warden on the island in question. However, the increases in Central America were only short-term, and were lost when the intensive effort was reduced. Assessment: unknown effectiveness — limited evidence (effectiveness 50%; certainty 25%; harms 0%).

9http://www.conservationevidence.com/​actions/​272

● Introduce voluntary ‘maximum shoot distances’

10A single study from Denmark found a significant reduction in the injury rates of pink-footed geese following the implementation of a voluntary maximum shooting distance. Assessment: unknown effectiveness — limited evidence (effectiveness 40%; certainty 20%; harms 0%).

11http://www.conservationevidence.com/​actions/​279

● Mark eggs to reduce their appeal to collectors

12A single before-and-after study in Australia found increased fledging success of raptor eggs in a year they were marked with a permanent pen. Assessment: unknown effectiveness — limited evidence (effectiveness 50%; certainty 35%; harms 0%).

13http://www.conservationevidence.com/​actions/​276

● Move fish-eating birds to reduce conflict with fishermen

14A single before-and-after study in the USA found that Caspian tern chicks had a lower proportion of commercial fish in their diet following the movement of the colony away from an important fishery. Assessment: unknown effectiveness — limited evidence (effectiveness 32%; certainty 24%; harms 0%).

15http://www.conservationevidence.com/​actions/​281

● Promote sustainable alternative livelihoods

16A single before-and-after study in Costa Rica found that a scarlet macaw population increased following several interventions including the promotion of sustainable, macaw-based livelihoods. Assessment: unknown effectiveness — limited evidence (effectiveness 30%; certainty 19%; harms 0%).

17http://www.conservationevidence.com/​actions/​273

● Provide ‘sacrificial grasslands’ to reduce conflict with farmers

18Two UK studies found that more geese used areas of grassland managed for them, but that this did not appear to attract geese from outside the study site and therefore was unlikely to reduce conflict with farmers. Assessment: unknown effectiveness — limited evidence (effectiveness 18%; certainty 20%; harms 0%).

19http://www.conservationevidence.com/​actions/​280

● Relocate nestlings to reduce poaching

20A single replicated study in Venezuela found a significant reduction in poaching rates and an increase in fledging rates of yellow-shouldered amazons when nestlings were moved into police premises overnight. Assessment: unknown effectiveness — limited evidence (effectiveness 50%; certainty 30%; harms 0%).

21http://www.conservationevidence.com/​actions/​277

● Use education programmes and local engagement to help reduce persecution or exploitation of species

22Six out of seven studies from across the world found increases in bird populations or decreases in mortality following education programmes, whilst one study from Venezuela found no evidence that poaching decreased following an educational programme. In all but one study reporting successes, other interventions were also used, and a literature review from the USA and Canada argues that education was not sufficient to change behaviour, although a Canadian study found that there was a significant shift in local peoples’ attitudes to conservation and exploited species following educational programmes. Assessment: unknown effectiveness — limited evidence (effectiveness 50%; certainty 30%; harms 0%).

23http://www.conservationevidence.com/​actions/​274

No evidence found (no assessment)

24We have captured no evidence for the following interventions:

25• Use alerts during shoots to reduce mortality of non-target species

3.7.2 Reducing fisheries bycatch

Beneficial

● Use streamer lines to reduce seabird bycatch on longlines

26Ten studies from coastal and pelagic fisheries across the globe found strong evidence for reductions in bycatch when streamer lines were used. Five studies from the South Atlantic, New Zealand and Australia were inconclusive, uncontrolled or had weak evidence for reductions. One study from the sub-Antarctic Indian Ocean found no evidence for reductions. Three studies from around the world found that bycatch rates were lower when two streamers were used compared to one, and one study found rates were lower still with three streamers. Assessment: beneficial (effectiveness 65%; certainty 75%; harms 0%).

27http://www.conservationevidence.com/​actions/​285

Likely to be beneficial

● Mark trawler warp cables to reduce seabird collisions

28A single replicated and controlled study in Argentina found lower seabird mortality (from colliding with warp cables) when warp cables were marked with orange traffic cones. Assessment: likely to be beneficial (effectiveness 54%; certainty 40%; harms 0%).

29http://www.conservationevidence.com/​actions/​305

● Reduce seabird bycatch by releasing offal overboard when setting longlines

30Two replicated and controlled studies in the South Atlantic and sub-Antarctic Indian Ocean found significantly lower seabird bycatch rates when offal was released overboard as lines were being set. Assessment: likely to be beneficial (effectiveness 51%; certainty 50%; harms 0%).

31http://www.conservationevidence.com/​actions/​299

● Weight baits or lines to reduce longline bycatch of seabirds

32Three replicated and controlled studies from the Pacific found lower bycatch rates of some seabird species on weighted longlines. An uncontrolled study found low bycatch rates with weighted lines but that weights only increased sink rates in small sections of the line. Some species were found to attack weighted lines more than control lines. Assessment: likely to be beneficial (effectiveness 46%; certainty 45%; harms 15%).

33http://www.conservationevidence.com/​actions/​296

Trade-off between benefit and harms

● Set lines underwater to reduce seabird bycatch

34Five studies in Norway, South Africa and the North Pacific found lower seabird bycatch rates on longlines set underwater. However, results were species-specific, with shearwaters and possibly albatrosses continuing to take baits set underwater. Assessment: trade-offs between benefits and harms (effectiveness 61%; certainty 50%; harms 24%).

35http://www.conservationevidence.com/​actions/​288

● Set longlines at night to reduce seabird bycatch

36Six out of eight studies from around the world found lower bycatch rates when longlines were set at night, but the remaining two found higher bycatch rates (of northern fulmar in the North Pacific and white-chinned petrels in the South Atlantic, respectively). Knowing whether bycatch species are night-or day-feeding is therefore important in reducing bycatch rates. Assessment: trade-offs between benefits and harms (effectiveness 60%; certainty 70%; harms 48%).

37http://www.conservationevidence.com/​actions/​283

Unknown effectiveness (limited evidence)

● Dye baits to reduce seabird bycatch

38A single randomised, replicated and controlled trial in Hawaii, USA, found that albatrosses attacked baits at significantly lower rates when baits were dyed blue. Assessment: unknown effectiveness — limited evidence (effectiveness 50%; certainty 20%; harms 0%).

39http://www.conservationevidence.com/​actions/​293

● Thaw bait before setting lines to reduce seabird bycatch

40A study from Australia found that longlines set using thawed baits caught significantly fewer seabirds than controls. Assessment: unknown effectiveness — limited evidence (effectiveness 50%; certainty 30%; harms 0%).

41http://www.conservationevidence.com/​actions/​298

● Turn deck lights off during night-time setting of longlines to reduce bycatch

42A single replicated and controlled study in the South Atlantic found lower seabird bycatch rates on night-set longlines when deck lights were turned off. Assessment: unknown effectiveness — limited evidence (effectiveness 51%; certainty 21%; harms 0%).

43http://www.conservationevidence.com/​actions/​284

● Use a sonic scarer when setting longlines to reduce seabird bycatch

44A single study from the South Atlantic found that seabirds only temporarily changed behaviour when a sonic scarer was used, and seabird bycatch rates did not appear to be lower on lines set with a scarer. Assessment: unknown effectiveness — limited evidence (effectiveness 2%; certainty 10%; harms 0%).

45http://www.conservationevidence.com/​actions/​295

Use acoustic alerts on gillnets to reduce seabird bycatch

46A randomised, replicated and controlled trial in a coastal fishery in the USA found that fewer guillemots (common murres) but not rhinoceros auklets were caught in gillnets fitted with sonic alerts. Assessment: unknown effectiveness — limited evidence (effectiveness 44%; certainty 21%; harms 0%).

47http://www.conservationevidence.com/​actions/​301

● Use bait throwers to reduce seabird bycatch

48A single analysis found significantly lower seabird bycatch on Australian longliners when a bait thrower was used to set lines. Assessment: unknown effectiveness — limited evidence (effectiveness 46%; certainty 30%; harms 0%).

49http://www.conservationevidence.com/​actions/​291

● Use bird exclusion devices such as ‘Brickle curtains’ to reduce seabird mortality when hauling longlines

50A single replicated study found that Brickle curtains reduced the number of seabirds caught, when compared to an exclusion device using only a single boom. Using purse seine buoys as well as the curtain appeared to be even more effective, but sample sizes did not allow useful comparisons. Assessment: unknown effectiveness — limited evidence (effectiveness 48%; certainty 30%; harms 0%).

51http://www.conservationevidence.com/​actions/​302

● Use high visibility mesh on gillnets to reduce seabird bycatch

52A single randomised, replicated and controlled trial in a coastal fishery in the USA found that fewer guillemots (common murres) and rhinoceros auklets were caught in gillnets with higher percentages of brightly coloured netting. However, such netting also reduced the catch of the target salmon. Assessment: unknown effectiveness — limited evidence (effectiveness 60%; certainty 30%; harms 0%).

53http://www.conservationevidence.com/​actions/​303

● Use shark liver oil to deter birds when setting lines

54Two out of three replicated and controlled trials in New Zealand found that fewer birds followed boats or dived for baits when non-commercial shark oil was dripped off the back of the boat. Assessment: unknown effectiveness — limited evidence (effectiveness 30%; certainty 25%; harms 0%).

55http://www.conservationevidence.com/​actions/​297

Likely to be ineffective or harmful

● Use a line shooter to reduce seabird bycatch

56Two randomised, replicated and controlled trials found that seabird bycatch rates were higher (in the North Pacific) or the same (in Norway) on longlines set using line shooters, compared to those set without a shooter. Assessment: likely to be ineffective or harmful (effectiveness 0%; certainty 50%; harms 40%).

57http://www.conservationevidence.com/​actions/​290

No evidence found (no assessment)

58We have captured no evidence for the following interventions:

  • Reduce bycatch through seasonal or area closures
  • Reduce ‘ghost fishing’ by lost/discarded gear
  • Reduce gillnet deployment time to reduce seabird bycatch
  • Set longlines at the side of the boat to reduce seabird bycatch
  • Tow buoys behind longlining boats to reduce seabird bycatch
  • Use a water cannon when setting longlines to reduce seabird bycatch
  • Use high-visibility longlines to reduce seabird bycatch
  • Use larger hooks to reduce seabird bycatch on longlines

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