The recent development of models for precautionary-approach management systems has, for the Barents Sea cod fishery, led to a sophisticated set of harvest control rules (HCR) based on core indicators. In Arctic animal populations, behaviour and human activities reflect adaptation to significant fluctuations among and within years. The later HCR development in the above mentioned cod fishery aims to reduce fluctuations in the fishery. Economically this may be less beneficial, as proven in several studies (Hannesson, 1975; Eide 2007) where pulse fisheries, taking advantage on natural environmental fluctuations, are shown to produce more economic rent than stable catches. The ecosystem may also be less vulnerable by choosing pulse fishing strategies, as it may lead to a lower fishing pressure when stock levels are low.
The new prognostic element in HCR rules
demands better and more accurate ecosystem models in a period of global
climatic change, with uncertainties related to ecosystem capability of
adapting to environmental changes and increased probability of
significant shifts in ecosystem structure. A stochastic ecosystem model
based on cellular automata principles (Wolfram, 2002) will represent
real systems, where the probability spaces are defined through the
findings of other ATP workpackages. Cellular automata ecosystem
modelling includes various types of spatial distribution of harvest
activities, which may facilitate studies of the impact of changes in
spatial distribution of species and economic activities.
The HCR
concept also allows for meta-rules, which are rules on how HCR are
changed as functions of new knowledge gained over time. Such dynamic
HCR-rules may be studied through scenario-modelling as described by
Hagen et al. (1998). The fleet model EconMult (Eide and Flaaten, 1998)
is suitable as an object of HCR management in such a scenario model,
covering natural fluctuations and possible impact of global warming,
including abrupt changes. Stochastic representations of the Barents Sea
commercial fish species, including a possible existence of system
tipping points, will be utilised in a bio-economic study of different
HCR systems. The HCR systems link to political decisions and the
capacity of management institutions in the region (Action 3 in WP6), and
to the work carried out in other work packages.
