Fig. 4

The coefficient of variations (CVs) of the survey indices of 11 stocks estimated with the spring and fall survey in 2011. a and b are based on the survey indices in number (\( \widehat{Y_s} \)) while c and d are based on them in biomass (\( \widehat{B_s} \)). The shaded bars are the CVs estimated under the assumption of the simple random sampling whereas the blank bars are those under the assumption of the systematic sampling. Those 11 stocks are as follows: 1 = Pacific cod (Gadus macrocephalus); 2 = White croaker/Silver jewfish (Argyrosomus argentatus); 3 = Pacific herring (Clupea pallasii); 4 = Red tilefish (Branchiostegus japonicus); 5 = Blackfin flounder (Glyptocephalus stelleri); 6 = Yellow croaker (Larimichthys polyactis); 7 = Gazami crab (Portunus trituberculatus); 8 = Mottled skate (Raja pulchra); 9 = Chub mackerel (Scomber japonicus); 10 = Black scraper (Thamnaconus modestus); 11 = Largehead hairtail (Trichiurus lepturus)