14.8.1 General

No evidence found (no assessment)

1We have captured no evidence for the following interventions:

• Add chemicals or minerals to sediment to remove or neutralize pollutants

• Establish pollution emergency plans

• Use ‘bioremediating’ organisms to remove or neutralize pollutants.

14.8.2 Domestic and urban wastewater

No evidence found (no assessment)

2We have captured no evidence for the following interventions:

• Limit the amount of storm wastewater overflow

• Limit, cease or prohibit dumping of sewage sludge

• Limit, cease or prohibit dumping of untreated sewage

• Set or improve minimum sewage treatment standards.

14.8.3 Industrial and military effluents

No evidence found (no assessment)

3We have captured no evidence for the following interventions:

• Cease or prohibit the disposal of drill cuttings at sea or in rivers

• Cease or prohibit the disposal of mining waste (tailings) at sea or in rivers

• Rehabilitate and release marine and freshwater mammals following oil spills

• Relocate marine and freshwater mammals following oil spills

• Remove or clean-up oil pollution following a spill

• Set regulatory ban on marine burial of nuclear waste

• Use double hulls to prevent oil spills.

14.8.4 Aquaculture effluents

No evidence found (no assessment)

4We have captured no evidence for the following interventions:

• Introduce and enforce water quality regulations for aquaculture systems

• Reduce the amount of antibiotics used in aquaculture systems

• Reduce the amount of pesticides used in aquaculture systems.

14.8.5 Agricultural and forestry effluents

No evidence found (no assessment)

5We have captured no evidence for the following interventions:

• Create artificial wetlands to reduce the amount of pollutants reaching rivers and the sea

• Establish aquaculture to extract the nutrients from run-offs

• Establish riparian buffers to reduce the amount of pollutants reaching rivers and the sea

• Reduce pesticide, herbicide or fertilizer use

• Treat wastewater from intensive livestock holdings.

14.8.6 Other pollution

No evidence found (no assessment)

6We have captured no evidence for the following interventions:

• Limit, cease or prohibit discharge of waste effluents overboard from vessels

• Remove and clean-up shoreline waste disposal sites

• Use methods to reduce sediment disturbance during dredging (e.g. curtains, screens)

• Use non-toxic antifouling coatings on surfaces.

14.8.7 Fishing gear

Beneficial

Remove derelict fishing gear from mammals found entangled

7Two studies evaluated the effects of removing derelict fishing gear from mammals found entangled. One study was in the North Pacific Ocean (USA) and one in the North Atlantic Ocean (USA).

8COMMUNITY RESPONSE (0 STUDIES)

9POPULATION RESPONSE (2 STUDIES)

10Reproductive success (1 study): One review in the North Pacific Ocean found that after removing derelict fishing gear from Hawaiian monk seals, along with at least seven other interventions to enhance survival, more than a quarter of the seals reproduced.

11Survival (2 studies): One review in the North Pacific Ocean found that removing derelict fishing gear from Hawaiian monk seals, along with at least seven other interventions to enhance survival, resulted in more than a quarter of the seals surviving. One review in the North Atlantic Ocean found that three common bottlenose dolphins survived for at least 1–4 years after they were disentangled from derelict fishing gear and released.

12BEHAVIOUR (0 STUDIES)

13Assessment: beneficial (effectiveness 70 %; certainty 70 %; harms 10 %).

https://www.conservationevidence.com/actions/2892

No evidence found (no assessment)

14We have captured no evidence for the following interventions:

• Equip ports with dedicated fishing gear disposal facilities

• Establish fishing gear registration programmes

• Improve methods for locating fishing gear

• Inform fishers of the impacts of derelict fishing gear on mammals to encourage responsible disposal

• Offer incentives to fishers for recovering, reusing or recycling fishing gear

• Recover lost or discarded fishing gear

• Use biodegradable fishing gear.

14.8.8 Other garbage and solid waste

No evidence found (no assessment)

15We have captured no evidence for the following interventions:

• Install stormwater traps or grids

• Limit, cease or prohibit discharge of solid waste overboard from vessels

• Remove litter from marine and freshwater environments.

14.8.9 Noise pollution

Trade-off between benefit and harms

Use acoustic devices to deter marine and freshwater mammals from an area to reduce noise exposure

16Four studies evaluated the effects of using acoustic devices to deter marine and freshwater mammals from an area to reduce noise exposure. Two studies were in the North Sea (Germany), one study was in the Great Belt (Denmark) and one was in Faxaflói Bay (Iceland).

17COMMUNITY RESPONSE (0 STUDIES)

18POPULATION RESPONSE (0 STUDIES)

19BEHAVIOUR (4 STUDIES)

20Behaviour change (4 studies): Three studies (including two controlled and one before-and-after study) in the North Sea and the Great Belt found that using acoustic devices to deter mammals from an area at a wind farm construction site or pelagic sites reduced the activity and sightings of harbour porpoises at distances of 1–18 km from the devices. One before-and-after study in Faxaflói Bay found that when an acoustic device was deployed from a boat, minke whales swam away from the device, increased their swimming speed, and swam more directly.

21Assessment: trade-off between benefit and harms (effectiveness 65 %; certainty 60 %; harms 20 %).

https://www.conservationevidence.com/actions/2896

Unknown effectiveness

Use methods to dampen underwater noise emissions (e.g. bubble curtains, screens)

22One study evaluated the effects on marine mammals of using bubble curtains or screens to dampen underwater noise emissions. The study was in the North Sea (Germany).

23COMMUNITY RESPONSE (0 STUDIES)

24POPULATION RESPONSE (0 STUDIES)

25BEHAVIOUR (1 STUDY)

26Behaviour change (1 study): One before-and-after, site comparison study in the North Sea found that using bubble curtains or screens during pile driving resulted in harbour porpoise detections within 15 km decreasing less compared to before pile driving than at sites without bubble curtains or screens.

27Assessment: unknown effectiveness (effectiveness 50 %; certainty 30 %; harms 0 %).

https://www.conservationevidence.com/actions/2901

Use ‘soft start’ procedures to deter marine and freshwater mammals to reduce noise exposure

28Three studies evaluated the effects of using ‘soft start’ procedures to deter marine and freshwater mammals to reduce noise exposure. One study was in each of the South Atlantic Ocean (Gabon), the South Pacific Ocean (Australia) and various water bodies (UK).

29COMMUNITY RESPONSE (0 STUDIES)

30POPULATION RESPONSE (0 STUDIES)

31BEHAVIOUR (3 STUDIES)

32Behaviour change (3 studies): One study in various water bodies around the UK found that a greater proportion of cetaceans (including whales, dolphins and porpoise) avoided or moved away from vessels during ‘soft start’ procedures with seismic airguns compared to when airguns were not firing. One study in the South Atlantic Ocean found that during ‘soft start’ procedures using seismic airguns, a pod of short-finned whales initially moved away but remained within 900 m of the vessel as it passed by. One study in the South Pacific Ocean found that during ‘soft-start’ procedures with a small experimental airgun array, migrating humpback whales slowed their speed towards the vessel but did not significantly alter their course. Assessment: unknown effectiveness (effectiveness 55 %; certainty 36 %; harms 10 %).

https://www.conservationevidence.com/actions/2897

No evidence found (no assessment)

33We have captured no evidence for the following interventions:

• Delay or cease operations if marine and freshwater mammals are detected within a specified zone

• Limit, cease or prohibit the use of sonars

• Limit, cease or prohibit the use of underwater explosives

• Modify vessels to reduce noise disturbance

• Reduce hammer energy during pile driving

• Use alternative methods instead of airguns for seismic surveys.

14.8.10 Thermal pollution

No evidence found (no assessment)

34We have captured no evidence for the following interventions:

35• Limit, cease or prohibit the discharge of cooling effluents from power stations.