Threespine Stickleback Gasterosteus aculeatus in Thingvallavatn: Habitat and Food in a Lake Dominated by Arctic Charr Salvelinus alpinus

Abstract

In the large and deep Lake Thingvallavatn, Iceland, threespine stickleback were restricted to the Nitella opaca vegetation found in the deep littoral zone (10-20 m). The stickleback matured during their third year, and reached an average asymptotic length of 57 mm. The diet consisted mainly of benthic cladocerans, ostracods and chironomid larvae. Some copepods were also eaten by fish of age 1 and older in August and September. There were some differences in food choice between the size groups of stickleback present, as older fish ate more large zoobenthos, like snails and water bugs