This paper examines the links between scientific activities and territorial development. For a territory, particularly a metropolitan area, an economic development strategy including scientific activities focuses on two objectives: on the one hand, international scientific networking (ISN), and on the other hand, local fertilization (LF). After reviewing of the different potential ISN-LF combinations, we empirically test one specific configuration, the ISN-LF coexistence. The analysis is based on a double case study, both thematic and geographical: the Brest (France) and Bergen (Norway) sites in the field of marine sciences. Three methods are successively implemented: two combined and comparative methods (spatialized bibliometrics and interview survey) and a regionalized input-output modelling. The different results are contrasted in order to appreciate how ISN can exist and develop while strengthening the LF dynamics, and to identify the nurturing conditions, or conversely the drags. Several conclusions are drawn: first, the ISN-LF articulation scheme appears to be different in the two territories studied, despite a similar ISN performance. Secondly, the significant and actual performing of an ISN-LF coexistence scheme where ISN strengthens the LF (Bergen case) seems to be a stabilizing factor, or even improving factor for the ISN performance, and not a deteriorating factor. Recommendations are suggested: relying on the effectiveness of incentive funding mechanisms for researchers and firms; acting firstly on future researchers, by learning, in order to increase the propensity to collaborate and to develop a common collaborative culture; the need for a stronger presence of transfer organizations within the local scientific community; and finally the need for a matching and an intentional adaptation of the research and innovation policies to the main local economic sectors.