INVESTIGADORES
CASAUX Ricardo Jorge
artículos
Título:
Analysis of the diet of Champsocephalus gunnari at South Georgia in late summer from 1994 to 1997, Dr. Eduardo L. Holmberg surveys.
Autor/es:
BARRERA-ORO E.; CASAUX R,; MARSCHOFF E.
Revista:
CCAMLR SCIENCE
Editorial:
C C A M L R TI
Referencias:
Año: 1998 vol. 5 p. 103 - 123
ISSN:
1023-4063
Resumen:
The diet
composition of mackerel icefish Champsocephalus
gunnari caught in Subarea 48.3
in late summer of years 1994-97 was analysed using
frequency of occurrence (F%) and coefficient Q (%) methods. Krill (Euphausia superba) followed by the
amphipod hyperiid Themisto gaudichaudii
was the main food item around South
Georgia and Shag Rocks in the period investigated, except in 1994, when the
order of importance of these two
organisms in the diet was inverted. The consumption of other prey items such as
mysids and Thysanoessa sp., which
are known as important alternative food in years of krill scarcity and fish,
was only occasional or in negligible amounts, showing interannual variation. The spatial distribution of the
main preys in the diet as well as of the proportions of stomachs with/without
food in the area of investigation didnt show a consistent pattern from year to
year. Likewise, in the four Holmberg 1994-1997
surveys, high proportions of fish exhibited empty stomachs, phenomenon which
could arise from several concurrent causes. The variation of the diet with
respect to the length of C. gunnari
didnt show a selectivity pattern for any of the prey items. The availability
of krill in the Statistical Subarea 48.3 in the period investigated can be defined
as low in 1994, equivalent to those years of krill scarcity; intermediate in
1995, below the historical years of high abundance; and high in 1996 and 1997, in line with the
years of krill richness. This information is well in accord with independent
information from acoustic surveys and krill dependent species monitored in the
CEMP.