Abstract-Atlantic halibut (Hippoglossus hippoglossus) is an increasingly valued commercial fish and its recent population growth has attracted the attention of fisheries scientists and managers both within and outside Canada. With renewed transnational interests in this species, fishery managers have relied on existing, but limited, ecological information for multilateral discussions on shared allocations of catch. To address this dearth of information, we modeled species distribution using maximum entropy, where by survey catch data were related to environmental data to quantify habitat suitability. We then calculated

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Monthly count of sample sets from trawl surveys conducted during 2001-2013 in the northwest Atlantic Ocean by gear type and responsible agency. Collectively, surveys sample at all times of the year.

Data from trawl surveys conducted during [2001][2002][2003][2004][2005][2006][2007][2008][2009][2010][2011][2012][2013] in the northwest Atlantic Ocean were grouped geographically. For each grouping, habitat suitability for Atlantic halibut (Hippoglossus hippoglossus) was modeled by using maximum entropy, and the 3 outputs were then combined, creating a composite probability distribution layer. Model evaluations: high values of area under the omission curve (AUC) reflect the strength of each model in differentiating between sites with presence and absence of Atlantic halibut in its region: (A) Nova Scotia and U.S. waters (NS/U.S.), (B) Newfoundland and Labrador (NF), and (C) the northern and southern Gulf of St. Lawrence (GSL). The color scale represents probability distribution values on a scale of 0-1, with 1 being the most suitable, 0 the least, and 0.5 representing environments where conditions are typical for presence. Covariate contribution plots showing the varying levels (percentage) at which each variable contributed to each regional model: (D) NS/U.S., (E) NF, and (F) GSL. When prediction values were assigned to test data, presence locations were more prevalently associated with high probability distribution values and absence locations with low ones in all 3 regions: (G) NS/U.S., (H) NF, and (I) GSL. BT=bottom temperature.

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