PS 3-35 - Modeling Arctic char spawning habitat from Inuit knowledge, by using fuzzy logic

Background/Question/Methods

Anadromous Arctic char (Salvelinus Alpinus) is a cold water species, particularly vulnerable to the ongoing climate change and the modification undergone by its environment, especially the spawning sites located in rivers. The physical characteristics of spawning habitats used by Arctic char are scarcely described in the scientific literature and data available do not allow to build predictive model. However, as the species is culturally important for Inuit population in Canada for time immemorial, some Inuit hunters have a deep knowledge of this fish behaviour and habitat use. In the present study, we have worked in collaboration with three communities of Ungava Bay, in Nunavik, to collect information through interviews. Then we have applied an expert-model, based on fuzzy logic, to build spawning habitats of anadromous Arctic char informed only by Inuit knowledge. The model aims to predict the Habitat Suitability Index (HSI) given some physical characteristics (water depth, current velocity and type of bed material). The model was applied on 15 characterized sites in various rivers, identified to be spawning or non-spawning sites by Inuit experts.

Results/Conclusions

The knowledge of Inuit experts allowed insightful information for the characterization of spawning sites. The most suitable characteristics for spawning habitats were depths between 0.6 m and 1.5 m, in areas of flowing water with velocities > 0.1 m/s and any type of river bed material as long as the smallest grain-size is constituted of gravel or coarse sand. The fuzzy logic approach allowed to successfully assess the suitability of 12 of the 15 sites from the information given by Inuit experts. The best agreement with field data was reached when we used the information of the experts from three community together. The present study is, to our knowledge, the first fish habitat model based solely on Inuit knowledge and the first spawning habitat model for Arctic char. The methodology presented is well suited to formalize the description of local observations in a quantitative model and could be applied to other animal or plant species for which local and/or traditional knowledge exists.