Impact study of technical measures in the Swedish Baltic Sea cod fishery (Collaboration between the scientific community and the fishing sector to minimize discards in the Baltic cod fisheries. European Commission MARE/2010/11 – Lot1)

Authors: Hans Nilsson  Joakim Hjelm  Massimiliano Cardinale  Staffan Waldo 

Discard is the practice of returning unwanted catches of fish to the sea. In this report we analyse and discuss the effect of four different factors (gear selectivity, minimum landing size (MLS), a discard ban, and the size distribution of cod in the stock) affecting discards in the Baltic Sea cod fishery. We present both a short-term analysis, where we analyse the economic effects of these factors, and a biological medium-term forecast where the effects on stock development is taken into account. The results are:

  • If a discard ban would be introduced today, with current fish size distribution (period 2010) and with the current legislation (MLS 38cm, Bacoma 120/105 or T90 120), it would result in deceased economic performance (about 20%).
  • A reduced minimum landing size (MLS: from 38 to 35cm) is a possible way to minimize the negative economic effect of a discard ban.
  • The most important single factor affecting the industry’s economic performance was the size distribution of the cod stock, but management only indirectly influences this factor.
  • The economic performance is in most cases lower when using selective gear compared to the Bacoma 120/105 reference trawl, but the differences in economic performance tends to be smaller when a discard ban is introduced.
  • The industry’s short term economic loss for increasing selectivity is smaller when the size distribution of cod is “good” (i.e. more large cod is present in the stock), irrespectively of a discard ban is introduced or not.
  • The payback time in terms of catch of improved selectivity in the current state of the ecosystem is approximately a year given the current growth rate of the cod stock.


Hans Nilsson

Joakim Hjelm

Massimiliano Cardinale

Staffan Waldo