Limit fishing activity by vessel size and/or engine power

How is the evidence assessed?
  • Effectiveness
    not assessed
  • Certainty
    not assessed
  • Harms
    not assessed

Study locations

Key messages

  • One study examined the effects of limiting fishing activity by vessel size and/or engine power on marine fish populations. The study was in the North Sea (Northern Europe).




  • Abundance (1 study): One before-and-after study in the North Sea found that after vessels with a higher engine power were excluded from an area for half of each year there was a higher abundance of commercially targeted fish, but no difference in the overall abundance of non-commercially targeted fish over five years. In addition, for all fish, abundance was higher for two of eight size-groups.


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

  1. A before-and-after study in 1985–1994 of an extensive area of seabed in the North Sea, northern Europe (Piet & Rijnsdorp 1998) found that excluding fishing vessels (large beam trawlers) with an engine power >221kW from an area for six months a year resulted in increased abundance of commercially targeted but not non-commercially targeted fish over five years, and of two of eight size-groups for both commercial and non-commercial fish overall. In the period after the exclusion (1989–1994), there was no difference in the total abundance of non-commercially targeted fish compared to the period before (1985–1988) (data reported as statistical results). However, total abundance of commercial fish was higher. Numbers of two of eight size groups for both commercial (30–35 and 35–40 cm) and non-commercial fish (25–30 and 30–35 cm) increased after compared to before (see original paper for data/size group). In 1989, an area of 42,000 km2 in the eastern North Sea (“plaice box”) was closed to vessels >221kW engine power from April-September. Fishing with other gear types of <221kW engine power was permitted. Data were collected from beam trawl surveys (8 m beam, eight tickler chains, 40 mm mesh codend) in July-September each year. Trawls were towed for 30 minutes at 4 knots in the periods before (1985–1988) and after (1989–1994) the exclusion.

    Study and other actions tested
Please cite as:

Taylor, N., Clarke, L.J., Alliji, K., Barrett, C., McIntyre, R., Smith, R.K., and Sutherland, W.J. (2021) Marine Fish Conservation: Global Evidence for the Effects of Selected Interventions. Synopses of Conservation Evidence Series. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

All the journals searched for all synopses

Marine Fish Conservation

This Action forms part of the Action Synopsis:

Marine Fish Conservation
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