S. Kuikka et al., Modeling environmentally driven uncertainties in Baltic cod (Gadus morhua)management by Bayesian influence diagrams, CAN J FISH, 56(4), 1999, pp. 629-641
Citations number
50
Categorie Soggetti
Aquatic Sciences
Journal title
CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES
The large variability in Baltic cod (Gadus morhua) recruitment has been att
ributed both to environmental factors dependent on the inflow of saline wat
er (oxygen and salinity in spawning deeps) and to the size of the spawning
stock. Due to the complex interactions between hydrographic and biological
processes, future recruitment levels of cod will remain highly uncertain an
d increase uncertainties in stock predictions and management advice. We ass
essed the effects of the exploitation level and mesh size used by a trawl f
ishery on some variables of management interest under different environment
al conditions. The modeling consisted of three separate steps: (i) modeling
of selectivity, (ii) estimation of uncertainties by Monte Carlo simulation
s, and (iii) decision analysis by Bayesian influence diagrams, focusing on
the structural uncertainties and model selection. Realistic assumptions of
environmental conditions and present fishing mortality rates suggest that t
he current Baltic cod fishery is unsustainable. We use our approach to iden
tify robust management measures that reduce the risk of overfishing and the
sensitivity to management information. The value of information analysis d
emonstrates the advantages of a larger mesh size as a management measure.