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Fishery and Sea ResourcesFigure 2: Three different age of Post-Ovulatory Follicles (POFs).Year POF0 POF1 POF21998 41 40 531999 55 34 702001 9 4 172005 0 22 1042006 1 18 38Table 1: Total number of each age POF.the POF 0 remain in the ovary about sixhours after deposition. To reduce the mistake,with new method S was evaluated byPOFs 2 which should be equivalent to thesum of POFs 0+POFs 1, because the POF0 are always subsampled and because thePOF 2 should correspond in number to thesum of the other two classes. The resultsobtained by old aging method were comparedwith the results by new aging system.3 ResultsAlmost all ovaries collected are in pre-,post- or spawning, confirming that the samplingwere conducted during the anchovyreproduction season. The abundant presenceof POFs in each year attests that thespawning occurred before the capture. Thetotal of postovulatory follicles of each ageclass is showed in Table 1.The values of AUC for the ROC curve,the estimates of sensitivity and specificityfor each examined year (2005 and 2006)show a high percentage of correct classificationwith the old method for both years.The sensitivity, that represents probabilityof correct classification of POF0-1, is 0.91in 2005 and 0.81 in 2006 and the specificity,that represent probability of correctclassification of POF2, is 0.75 in 2005 and0.88 in 2006. The proportion of correctlyclassified units (kappa) is 0.62 in 2005 and0.61 in 2006. The estimation of area underROC curve (AUC) is equal to 83.4% in2005 and 85% in 2006 (Table 2; Figure 3).So it was considered unnecessary to continuewith a second observation of histologicalsections for other years.Excluding 1998, in the study periodthe re-estimation of the spawning fractionincreases and consequently the stockbiomass decreases, when we used the newaging method (Table 3; Figures 4 and 5).2118