BIOLOGIYA MORYA, 2004, Vol. 30, No. 2, pp. 131-137

Feeding of pollack Theragra chalcogramma larvae of different size on the western Kamchatka shelf

© 2004 K. M. Gorbatenko¹, A. Yu. Merzlyakov¹, S. Yu. Shershenkov²

¹Pacific Fisheries Research Center, Vladivostok 690600;
²Magadan Research Institute of Fisheries and Oceanography, Magadan 685000

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Samples were collected with a Bongo net in the western Kamchatka shelf region in the summer 2002. 373 stomachs of pollack larvae of different size were examined. The diet of pollack larvae included more than 20 plankters of different size. Phytoplankton was the major food source of larvae of size 4-6 mm. The proportion of phytoplankton in the larval diet decreased as larvae grew, and the late larval stages shifted to the consumption of zooplankton. As larvae increased in size, the food organisms changed from smaller to larger ones. In larvae of size 4 to 31 mm, the length of prey varied from 0.1 (Coscinodiscus) to 6.0 mm (Neocalanus plumchrus). The average daily repleteness of pollack larvae varied from 32 to 210^o/_ooo. Minimum repleteness was found for larvae of size 4-6 mm with mixed feeding (endogenous and exogenous), and repleteness was highest in fish 30-35 mm long. Daily food rations calculated for the most abundant size groups of larvae varied from 4.3 to 6.6% of the body mass.

Key words: feeding, pollack larvae, spatial distribution, dietary components, daily food consumption.