Journal of Environmental Science and Engineering A 4 (2015) 401-419 doi:10.17265/2162-5298/2015.08.003 Age, Growth and Distribution of the Antarctic Fish Chaenocephalus Aceratus Based on Otoliths Ryszard Jacek Traczyk Department of Oceanography and Geography, University of Gdansk, Gdynia 81378, Poland Abstract: The Chaenocephalus aceratus were sampled in summers between 1979 and 1990. Their otoliths show pattern of daily microincrements as otoliths of similar species—Pseudochaenichthys georgianus and fishes both temperate and tropical waters. Changes of the microincrements growth pattern and otolith shape are described in relation to larval, hatching and metamorphosis stages have similar patterns for Ps. georgianus and Champsocephalus gunnari, reflecting similar habitats in their early life. Width of larvae-postlarvae daily increments are: (1.0-1.6) × 10 -3 SSI, (1.8-2.8) × 10 -3 SGI and (1.5-2.4) × 10 -3 ANI. They were search and chosen automatically from density profiles of otolith tissues. Tissues were prepared by new saving time and materials way—one time up to 40 ones per microscopic glass. Age of fish estimated from microincrements was alike to that inferred from the body length distribution, otoliths mass (age (years) = 140.82 OM (g) + 0.8546) and otolith shape changes—large in length and surface on medial plane. Those parameters create age groups of close neighbours. They have different environments. C. aceratus due to its adaptation to cold water, attain rapidly large body according to a growth equation: L t = 75.1 × (1–e -0.26(t – 0.51) ). Among large fishes there were only females. Key words: Chaenocephalus aceratus, otolith shape, age of icefish, Antarctic fish. 1. Introduction Age determination of individual fishes can provide basic information about fish ecology such as population structures or changes in population growth due to environmental changes. The problems of ageing Antarctic fish Channichthyidae are commonly known [1-4], they have not scales and their bones undergo constant and large reduction [5]. In published papers, it deals with age of C. aceratus based on growth of otolith in some stated age up to 12 years. However, North [6] found that otoliths of icefish have sequences of 4 marks—complete seasonal marks per year (not as 2 marks per year). Since that, all age estimates based on yearly marks should have half a year less. Kompowski [7] former age reader for this species, estimate the year increments from number of hills (personal information). Corresponding author: Ryszard Jacek Traczyk, master, research field: biological oceanography. E-mail: ryszardtraczyk@gmail.com. The main aim of this study was obtaining data on C. aceratus age from otoliths and catch observation and comparing them to similar species. The changes in otolith shape were linked to life stages. C. aceratus is a cold adapted fish living exclusively in Antarctic waters on the shelf of Bouvier, South Georgia, South Sandwich, South Orkneys, South Shetlands and Palmer Archipelago in range of depth from 5 m to more than 770 m. Its different life history stages live at different mean depths and distance from the shore, as their diet varied for them [8], and their time development are likely to be broadly synchronized with the life cycles of their food species. So, that young hatch and develop during period elevated production [9]. At South Georgia, egg (4.4 mm in diameter) laid demersal inshore (to 240 m depth) in late summer from February or March to May and at Elephant I. from May to June. Larvae (after 1-2 month development in egg [8, 10]) hatch at about 11-17 mm TL during four months in winter from June up to spring—November [10]. Hatched larvae create D DAVID PUBLISHING