Fine-scale data supplied to CCAMLR for 1987/88 showed that the catches of Patagonotothen brevicauda guntheri were five times greater in the South Georgia area than at Shag Rocks. Previous survey data and reports to the CCAMLR Working Group on Fish Stock Assessment indicated that this species was only ever caught at Shag Rocks. Therefore the South Georgia catches were almost certainly of another species. The small size of P.b. guntheri means that they can only be caught with net meshes so small that they would also catch undersized individuals of other, larger species. Survey results suggest that such fishing is likely to have a significant effect on other species. P.b. guntheri has been reported as a by-catch of other fisheries; this suggests that illegal nets were used.