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Table 2

Results of the generalized additive models (GAMs) on the effects of depth, day of fishing, longitude and latitude (independent variables) on spotted flounder CPUE for the gears trawl, trammel net and gillnet. In trawl and trammel net the Delta-X-error method was employed; hence a different model was constructed for the presence–absence (PA) data and for the positive/non-zero abundance (NZA) data. All variables are denoted by s() as they were considered continuous and a spline was used for fitting. Chi-square values (presence–absence tests) or F-values of the analysis of deviance (NZA/abundance tests) are indicated for each independent (explanatory) variable. Variables denoted by “–” were not included according to the Akaike information criterion selection. Significant effects at the 0.05 confidence level are denoted by an asterisk and in bold typeface. The percentage of deviance explained by the final model (including only the variables with significant effects) is also indicated.

Sample Dependent variable Independent variables Deviance explained (%)

    s(date) s(depth) s(longitude) s(latitude)  
Trawl PA 5.05* 5.87* 16.30
NZA 1.51 2.90
Trammel net PA 3.87 0.02 2.65 9.20
NZA 4.83* 3.17* 63.30
Gillnet Abundance 3.03* 0.36 37.50

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