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What Works in Conservation 2017

 | 
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

Based on the collated evidence, what is the current assessment of the effectiveness of interventions for reducing exploitation and conflict?

Beneficial

● Use legislative regulation to protect wild populations

Likely to be beneficial

● Use wildlife refuges to reduce hunting disturbance

Unknown effectiveness (limited evidence)

● Employ local people as ‘biomonitors’
● Increase ‘on-the-ground’ protection to reduce unsustainable levels of exploitation
● Introduce voluntary ‘maximum shoot distances’
● Mark eggs to reduce their appeal to collectors
● Move fish-eating birds to reduce conflict with fishermen
● Promote sustainable alternative livelihoods
● Provide ‘sacrificial grasslands’ to reduce conflict with farmers
● Relocate nestlings to reduce poaching
● Use education programmes and local engagement to help reduce persecution or exploitation of species

No evidence found (no assessment)

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

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%).
http://www.conservationevidence.com/​actions/​271

Likely to be beneficial

Use wildlife refuges to reduce hunting disturbance

3Three 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%).
http://www.conservationevidence.com/​actions/​278

Unknown effectiveness (limited evidence)

Employ local people as ‘biomonitors’

4A 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%).
http://www.conservationevidence.com/​actions/​275

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

5Two 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%).
http://www.conservationevidence.com/​actions/​272

Introduce voluntary ‘maximum shoot distances’

6A 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%).
http://www.conservationevidence.com/​actions/​279

Mark eggs to reduce their appeal to collectors

7A 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%).
http://www.conservationevidence.com/​actions/​276

Move fish-eating birds to reduce conflict with fishermen

8A 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%).
http://www.conservationevidence.com/​actions/​281

Promote sustainable alternative livelihoods

9A 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%).
http://www.conservationevidence.com/​actions/​273

Provide ‘sacrificial grasslands’ to reduce conflict with farmers

10Two 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%).
http://www.conservationevidence.com/​actions/​280

Relocate nestlings to reduce poaching

11A 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%).
http://www.conservationevidence.com/​actions/​277

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

12Six 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%).
http://www.conservationevidence.com/​actions/​274

No evidence found (no assessment)

13We have captured no evidence for the following interventions:

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

3.7.2 Reducing fisheries bycatch

Based on the collated evidence, what is the current assessment of the effectiveness of interventions for reducing fisheries bycatch?

Beneficial

● Use streamer lines to reduce seabird bycatch on longlines

Likely to be beneficial

● Mark trawler warp cables to reduce seabird collisions
● Reduce seabird bycatch by releasing offal overboard when setting longlines
● Weight baits or lines to reduce longline bycatch of seabirds

Trade-off between benefit and harms

● Set lines underwater to reduce seabird bycatch
● Set longlines at night to reduce seabird bycatch

Unknown effectiveness (limited evidence)

● Dye baits to reduce seabird bycatch
● Thaw bait before setting lines to reduce seabird bycatch
● Turn deck lights off during night-time setting of longlines to reduce bycatch
● Use a sonic scarer when setting longlines to reduce seabird bycatch
● Use acoustic alerts on gillnets to reduce seabird bycatch
● Use bait throwers to reduce seabird bycatch
● Use bird exclusion devices such as ‘Brickle curtains’ to reduce seabird mortality when hauling longlines
● Use high visibility mesh on gillnets to reduce seabird bycatch
● Use shark liver oil to deter birds when setting lines

Likely to be ineffective or harmful

● Use a line shooter to reduce seabird bycatch

No evidence found (no assessment)

● 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

Beneficial

Use streamer lines to reduce seabird bycatch on longlines

14Ten 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%).
http://www.conservationevidence.com/​actions/​285

Likely to be beneficial

Mark trawler warp cables to reduce seabird collisions

15A 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%).
http://www.conservationevidence.com/​actions/​305

Reduce seabird bycatch by releasing offal overboard when setting longlines

16Two 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%).
http://www.conservationevidence.com/​actions/​299

Weight baits or lines to reduce longline bycatch of seabirds

17Three 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%).
http://www.conservationevidence.com/​actions/​296

Trade-off between benefit and harms

Set lines underwater to reduce seabird bycatch

18Five 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%).
http://www.conservationevidence.com/​actions/​288

Set longlines at night to reduce seabird bycatch

19Six 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%).
http://www.conservationevidence.com/​actions/​283

Unknown effectiveness (limited evidence)

Dye baits to reduce seabird bycatch

20A 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%).
http://www.conservationevidence.com/​actions/​293

Thaw bait before setting lines to reduce seabird bycatch

21A 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%).
http://www.conservationevidence.com/​actions/​298

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

22A 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%).
http://www.conservationevidence.com/​actions/​284

Use a sonic scarer when setting longlines to reduce seabird bycatch

23A 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%).
http://www.conservationevidence.com/​actions/​295

Use acoustic alerts on gillnets to reduce seabird bycatch

24A 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%).
http://www.conservationevidence.com/​actions/​301

Use bait throwers to reduce seabird bycatch

25A 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%).
http://www.conservationevidence.com/​actions/​291

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

26A 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%).
http://www.conservationevidence.com/​actions/​302

Use high visibility mesh on gillnets to reduce seabird bycatch

27A 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%).
http://www.conservationevidence.com/​actions/​303

Use shark liver oil to deter birds when setting lines

28Two 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%).
http://www.conservationevidence.com/​actions/​297

Likely to be ineffective or harmful

Use a line shooter to reduce seabird bycatch

29Two 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%).
http://www.conservationevidence.com/​actions/​290

No evidence found (no assessment)

30We 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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