Environmental and Fisheries Related Effects on Cod Catches in a Pot Fishery in the Baltic Sea

Along with the increasing grey seal population, the seal-fishery conflict in the Baltic cod fishery has increased dramatically. Due to this conflict cod pots has been evaluated as an alternative to traditional fishing-gear. In a three year study from 2009 to 2011 carried out by the Institute of Coastal Laboratories, cod pots were used by commercial fishermen in two areas in the south Baltic. We evaluated pot catches in relation to environmental and fisheries related variables. By using generalized additive models, we showed that catch per unit effort (CPUE) of large cod were affected by water depth, time of year, soak days and the direction of the water current. The CPUE of small cod were affected by topographic variables such as the slope and complexity of the bottom, in addition to water depth, month and soak days.

In 2012 to 2013 test fishing with cod pots was again conducted in the southern Baltic. Results of the pot´s catchability from 2009 until 2013, shows that catchability varies over year and area. The pot´s catchability decreases with increasing latitude. However results from southern Baltic indicate that pots can be an alternative gear in the cod fishery in the Baltic Sea.