Use stiffened materials or increase tension of fishing gear

Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 1
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How is the evidence assessed?

Effectiveness

0%
Certainty

28%
Harms

10%

Calculating overall effectiveness category

Background information and definitions

Using stiffened materials or increasing the tension of fishing nets, ropes or lines may reduce the risk of marine and freshwater mammals becoming entangled. However, tensioned vertical ropes may cause injuries to mammals that come into contact with them (Baldwin et al. 2012).

For another intervention that may involve stiffened gear, see Use acoustically reflective fishing gear materials.

Baldwin K., Byrne J. & Brickett B. (2012) Taut vertical line and North Atlantic right whale flipper interaction: experimental observations. University of New Hampshire and Blue Water Concepts.

Study locations

Key messages

One study evaluated the effects on marine mammals of using stiffened materials in fishing nets. The study was in the South Atlantic Ocean (Argentina).

COMMUNITY RESPONSE (0 STUDIES)

POPULATION RESPONSE (0 STUDIES)

BEHAVIOUR (0 STUDIES)

OTHER (1 STUDY)

Reduction in entanglements/unwanted catch (1 study): One controlled study in the South Atlantic Ocean found that using stiffened fishing nets did not reduce the number of Franciscana dolphin entanglements.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A controlled study in 2009–2010 of a pelagic area in the South Atlantic Ocean, off the coast of Buenos Aires, Argentina (Bordino et al. 2013) found that using stiffened fishing nets did not reduce the number of Franciscana dolphin Pontoporia blainvillei entanglements compared to conventional nets. Entanglement rates of Franciscana dolphins did not differ between stiffened and conventional nets (both 0.08 dolphins/haul). Catch rates of the three main target fish species also did not differ between net types (whitemouth croaker Micropogonias furnieri, striped weakfish Cynoscion guatucupa, king weakfish Macrodon ancylodon; see original paper for data). Monofilament nylon gill nets of two types (nets made from a stiff grade of nylon and conventional nets; number of each not reported) were deployed in 150 locations by a fishery. The nets were sampled 1–19 times resulting in 273 hauls of stiffened nets and 279 hauls of conventional nets. An observer on board each of three fishing vessels retrieving the nets recorded the number of entangled dolphins within each of 552 hauls between October 2009 and March 2010.
Study and other actions tested
Referenced paper
Bordino P., Mackay A.I., Werner T.B., Northridge S.P. & Read A.J. (2013) Franciscana bycatch is not reduced by acoustically reflective or physically stiffened gillnets. Endangered Species Research, 21, 1-12.

Please cite as:

Berthinussen, A., Smith, R.K. and Sutherland, W.J. (2021) Marine and Freshwater Mammal Conservation: Global Evidence for the Effects of Interventions. Conservation Evidence Series Synopses. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

This Action forms part of the Action Synopsis:

Marine and Freshwater Mammal Conservation

Related Actions

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Use acoustic devices on fishing gear Action Link	Trade-off between benefit and harms	33	Synopsis Link
Finance low interest loans to convert to fishing gear that reduces unwanted catch of mammals Action Link	No evidence found (no assessment)	0	Synopsis Link
Involve fishers in designing and trialling new fishing gear types to encourage uptake of gear that reduces unwanted catch of mammals Action Link	No evidence found (no assessment)	0	Synopsis Link