title: Spatio-temporal dynamics of a fish predator: Density-dependent and hydrographic effects on Baltic Sea cod population.
abstract: Understanding the mechanisms of spatial population dynamics is crucial for the successful management of exploited species and ecosystems. However, the underlying mechanisms of spatial distribution are generally complex due to the concurrent forcing of both density-dependent species interactions and density-independent environmental factors. Despite the high economic value and central ecological importance of cod in the Baltic Sea, the drivers of its spatio-temporal population dynamics have not been analytically investigated so far. In this paper, we used an extensive trawl survey dataset in combination with environmental data to investigate the spatial dynamics of the distribution of the Eastern Baltic cod during the past three decades using Generalized Additive Models. The results showed that adult cod distribution was mainly affected by cod population size, and to a minor degree by small-scale hydrological factors and the extent of suitable reproductive areas. As population size decreases, the cod population concentrates to the southern part of the Baltic Sea, where the preferred more marine environment conditions are encountered. Using the fitted models, we predicted the Baltic cod distribution back to the 1970s and a temporal index of cod spatial occupation was developed. Our study will contribute to the management and conservation of this important resource and of the ecosystem where it occurs, by showing the forces shaping its spatial distribution and therefore the potential response of the population to future exploitation and environmental changes.
authors.affiliation: Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Marine Research, Lysekil, Sweden.
authors.forename: Valerio
authors.initials: V
authors.lastname: Bartolino
authors.affiliation: Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Marine Research, Lysekil, Sweden.
authors.forename: Huidong
authors.initials: H
authors.lastname: Tian
authors.affiliation: Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Coastal Research, Öregrund, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Bergström
authors.affiliation: Natural Resources Institute Finland (Luke), Turku, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Jounela
authors.affiliation: Puolipäivänkatu 4 A 6, Helsinki, Finland.
authors.forename: Eero
authors.initials: E
authors.lastname: Aro
authors.affiliation: Swedish Meteorological and Hydrological Institute, Research Department, Norrköping, Sweden.
authors.forename: Christian
authors.initials: C
authors.lastname: Dieterich
authors.affiliation: Swedish Meteorological and Hydrological Institute, Research Department, Norrköping, Sweden.|Leibniz Institute for Baltic Sea Research Warnemünde, Department of Physical Oceanography and Instrumentation, Rostock, Germany.
authors.forename: H E Markus
authors.initials: HE
authors.lastname: Meier
authors.affiliation: Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Marine Research, Lysekil, Sweden.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Cardinale
authors.affiliation: Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Marine Research, Lysekil, Sweden.
authors.forename: Barbara
authors.initials: B
authors.lastname: Bland
authors.affiliation: Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Marine Research, Lysekil, Sweden.
authors.forename: Michele
authors.identifier: http://orcid.org/0000-0003-4910-5236
authors.initials: M
authors.lastname: Casini
mesh_terms: D000818:Animals; D001454:Baltic States; D017753:Ecosystem; D005399:Fishes / Q000502:physiology*; D008962:Models, Theoretical; D009792:Oceans and Seas; D011156:Population Density; D011157:Population Dynamics