Bathymetric Distribution of Fish in the Apostle Islands Region, Lake Superior

Abstract

Records of seasonal and “all-season” (April-December) bathymetric distribution are given for 17 species of fish taken in bottom trawls and experimental gill nets fished on the bottom in 1958–63 in the Apostle Islands region of Lake Superior. The data are based on catches from 578 trawl tows at 2–59 fathoms and 301,900 linear feet of gill nets fished at 2–89 fathoms. Size of the fish varied widely among different species from the same gear and the same species from different gears. Seasonal differences in depth distribution were greatest for lake trout, bloaters, round whitefish, and older smelt, which exhibited an inshore movement in the summer and fall, and for longnose suckers, which migrated to deeper water with progress of the seasons. The all-season bathymetric distributions varied considerably among species. Round whitefish, 0- and I-group smelt, longnose suckers, ninespine sticklebacks, and johnny darters were most abundant at < 10 fathoms. Concentrations of lake trout, lake herring, lake whitefish, older smelt, trout-perch, and burbot were greatest at 10–29 fathoms. Pygmy whitefish were most common at 30–39 fathoms, bloaters and spoonhead sculpins at 40–49 fathoms, and shortjaw ciscoes, slimy sculpins, and fourhorn sculpins at 50–59 fathoms. The kiyi was most abundant at 70–79 fathoms.