What is the highest population of Trondra Island in the Scalloway Islands?
CREATE TABLE "main_list" (
  "island" text,
  "location" text,
  "area_ha" real,
  "population" real,
  "height_m" real
);
SELECT MAX("population") FROM "main_list" WHERE "location"='scalloway islands' AND "island"='trondra';