FEEDING ECOLOGY OF SOME FISHES OF THE ANTARCTIC PENINSULA 



Robert A. Daniels 2 



ABSTRACT 



Feeding ecology of 19 species of Antarctic fishes is examined. All species are carnivorous; the most 

 important prey are amphipods, polychaetes, and isopods. Seven of the species examined (Notothenia 

 neglecta, N. gibberifrons, N. nudifrons, N. larseni, N. kempi, Trematomus seotti, and T. bernacehii) 

 are feeding generalists with diets varying with size of fish, season, and locality of capture. Seven 

 other species (Trematomus newnesi, Pleuragramma antarcticum, Cryothenia peninsulae, 

 Artedidraco skottebergi, Harpagifer bispinis, Prionodraco evansii, and Parachaenichthys charcoti) 

 are specialists, feeding predominantly upon prey either from a single taxon or from very few taxa. 

 Five species {Notothenia rossii, Trematomus eulepidotus, Cryodraco antarcticus, Pagetopsis 

 maeropterus, and Chaenocephalus aceratus) were not well represented in the samples, but a 

 qualitative description of their diet is included. The fishes studied consume a wide variety of food 

 types and use several feeding behaviors. Based on field and laboratory observations, most species are 

 ambush predators. However some species use an indiscriminant slurp method, grazing, or a search 

 and capture form of feeding. Some species switch feeding behaviors seasonally or with locality. Diet 

 similarity is high only in morphologically similar species. Where a high degree of diet similarity 

 occurs, overlap in distribution tends to be low. Although most species are high-level carnivores and 

 at least some occur sympatrically, direct competition for food among the species does not appear to 

 exist. This partitioning of food resources adds to the complexity of the structure of Antarctic 

 communities. The position of these fishes in the Antarctic trophic structure should be further 

 examined and considered before extensive exploitation is begun. 



Feeding ecology in Antarctic fishes has, until 

 recently, attracted little attention. Richardson 

 (1975) described the diets of four species of fish 

 found along the Antarctic Peninsula and 

 discussed diet overlap. In a thorough study, 

 Targett (1981) examined the trophic structure of 

 five demersal fish communities off Antarctic 

 and sub-Antarctic islands. Permitin and 

 Tarverdiyeva (1972, 1978) examined degree of 

 diet similarity among 10 fishes from the sub- 

 Antarctic island, South Georgia, and in noto- 

 theniids and channichthyids collected from the 

 South Orkney Islands, an archipelago north of 

 the Antarctic Peninsula. Moreno and Osorio 

 (1977) examined diet changes with depth in one 

 species, and Wyanski and Targett (1981) 

 reported on diets of nine harpagiferids. Others 

 (Arnaud and Hureau 1966; Holloway 1969; 

 Arnaud 1970; Hureau 1970; Everson 1970; 

 Permitin 1970; Meier 1971; Yukov 1971; DeWitt 

 and Hopkins 1977; Moreno and Zamorano 1980; 

 Duarte and Moreno 1981) described one com- 

 ponent of the diet of various fishes, the diet of one 



■Science Service Journal Series No. 337, New York State 

 Museum, Albany, N.Y. 



2 New York State Museum, Biological Survey, Cultural 

 Education Center, Room 3132, Albany, NY 12230. 



Manuscript accepted December 1981. 

 FISHERY BULLETIN: VOL. 80, NO. 3, 1982. 



species or qualitative descriptions of stomach 

 contents. This study examines several aspects of 

 feeding ecology of Antarctic fishes, including 

 seasonal, spatial, and size-related changes. With 

 increasing interest in the exploitation of 

 Antarctic resources (Lyubimova et al. 1973), the 

 need to understand the feeding ecology of these 

 fishes and their position in Antarctic communi- 

 ties has become important. 



STUDY AREA 



The Antarctic Peninsula reaches north from 

 the continent to lat. 63°18'S, long. 55°02'W. Its 

 west coast is flanked by numerous islands which 

 create many bays, inlets, straits, and small coves. 

 Weather conditions and longevity and distribu- 

 tion of fast and brash ice vary along the penin- 

 sula seasonally, yearly, and with area. Water 

 temperatures at Palmer Station (lat. 64°46'S, 

 long. 64°04'W) fluctuate approximately 2°C 

 from 0°C; salinities range from 32.2%« to 

 33.5%o except immediate to shore and in surface 

 waters during the spring thaw; dissolved oxygen 

 remains near saturation at 6-10 cc/1; pH ranges 

 from 7.9 to 8.5 (Krebs 1974; Showers et al. 1977). 

 Primary productivity varies greatly along the 

 peninsula (Krebs 1974) and in the Antarctic in 



575 



