2 SCIENTIFIC REPORTS
2.2.1 THE COMPOSITION; DEMOGRAPHY AND BIOLOGY OF THE DEMERSAL FISH FAUNA IN THE ELEPHANT ISLAND - SOUTH
SHETLAND ISLAND REGION AND AT THE TIP OF THE ANTARCTIC PENINSULA
Karl-Hermann Kock1, Markus Busch2, Malte Holst1, Sven Klimpel2, Dietmar Pietschok1, Leonid Pshenichnov3, Rüdiger Riehl2, Susanne Schöling1
1 Bundesforschungsanstalt für Fischerei, Hamburg, Germany
2 Heinrich-Heine-Universität, Düsseldorf, Germany
3 Southern Scientific Research Institute of Marine Fisheries and Oceanography, Kerch, Ukraine
Objectives
The aims of the survey were threefold:
• to estimate the biomass of the most abundant fish stocks in CCAMLR Subarea 48.1
• to study the demography of the most abundant fish species, and
• to collect additional information on reproduction and food and feeding of all abundant fish species
Work at sea
Our survey was based on the same stratified random survey design as utilized during surveys conducted in collaboration with the Southwest Fisheries Science Centre of the National Marine Fisheries Survey of the US in 1998 – 2006 with RV Yuzhmorgeologiya and RV Polarstern. A total of 85 hauls were carried out around Elephant Island, in a ‘box of 8 x 10 nautical miles west of Elephant Island, off the South Shetland Islands and the tip of the Antarctic Peninsula from 19 December 2006 to 6 January 2007 (Table 2.24).
Table 2.24 Number of hauls conducted around Elephant Island, in a ‘box’ west of Elephant Island, off the South Shetland Islands and at the northern tip of the Antarctic Peninsula.
ANT-XXIII/8, Scientific reports
As during previous surveys with RV Polarstern in the 1980’s, 1990’s and in 2002 a 140’ (= 42.67m) commercially sized two-panel bottom trawl was used.
The width of the trawl was 17–18m between the tips of the upper wings and net height was 3.1–3.4m. Trawling was conducted from 50 to 500m depth.
Fishing time was 30 minutes net on the bottom. In order to minimize destruction of benthos communities within the path of the doors and the net and reduce the by–catch of benthos without reducing the catchability of the trawl we used the same ground tackle as in 2002 (Kock, 2002).
More survey effort was concentrated on the 100–400m depth range in order to cater for the higher abundance of fish in this depth zone. The location of fishing stations is provided in Fig. 2.22. Trawling was only conducted during daylight hours.
Fig. 2.22 Stations of the fish survey west of the Antarctic Peninsula (CCAMLR).
Catch composition of each tow was recorded in terms of weight and number of individuals per species. The by-catch of benthos was recorded in terms of weight. The qualitative composition of the benthos was noted. At least 49 fish species were caught in the 85 hauls (Table 2.25). Species identification in some genera, such as Pogonophryne and Paraliparis, was preliminary and still incomplete.
CCAMLR and related topics
Table 2.25 List of species caught in the course of the bottom trawl survey in the Elephant Island – South Shetland Island region and at the tip of the Antarctic Peninsula.
Family Species Elephant Isl.
and the South Shetland Isl.
Tip of the Antarctic Peninsula
Nototheniidae Dissostichus mawsoni + +
Aethotaxis mitopteryx +
Notothenia rossii +++ +
N. coriiceps +++ +++
Gobionotothen gibberifrons +++ +++
Lepidonotothen larseni +++ +++
L. nudifrons +++ +++
L. squamifrons ++ +
Trematomus bernacchii + +
T. eulepidotus +++ +++
T. hansoni + +
T. loennbergii +
T. scotti +
Pleuragramma antarcticum + +++
Harpagiferidae Harpagifer antarcticus + Artedidraconidae Artedidraco skottsbergi + ++
Pogonophryne phyllopogon +
Pogonophryne sp. + +
Bathydraconidae Parachaenichthys charcoti +++ +++
Gerlachea australis + +
Gymnodraco acuticeps ++ ++
Racovitzia glacialis +
Prionodraco evansii +
Channichthyidae Champsocephalus gunnari +++
Chaenocephalus aceratus +++
Pseudochaenichthys georgianus
+++
Chionodraco rastrospinosus +++ +++
Chionodraco myersi +
Cryodraco antarcticus +++ +++
Chaenodraco wilsoni + +++
Pagetopsis macropterus + +++
Neopagetopsis ionah + +
Rajidae Bathyraja maccaini +++ +++
Bathyraja sp. 2 +++ +++
Muraenolepidae Muraenolepis microps +++
Gempylidae Paradiplospinus gracilis + Myctophidae Electrona antarctica +++
E. carlsbergi ++
Protomyctophum bolini +
Krefftichthys anderssoni +
Gymnoscopelus nicholsi +++
G. braueri +
Anotopteridae Anotopterus pharao + Zoardidae Ophthalmolycus amberensis +++
Pachycara brachycephalum +++
Lycodichthys antarcticus + +
Liparididae Paraliparis sp. +
Macrouridae Macrourus holotrachys +
Carapidae sp. +
ANT-XXIII/8, Scientific reports
Our catches in the Elephant Island – South Shetland Islands demonstrated that Notothenia rossii and N. coriiceps were more abundant than during previous cruises while ice fish, such as Champsocephalus gunnari and Chaenocephalus aceratus were much less common.
No recruitment has been observed in Gobionotothen gibberifrons since a number of years while juvenile fish were still common in catches in the area in the 1980’s and 1990’s. N. coriiceps and G. gibberifrons were the most abundant nototheniids along the tip of the Antarctic Peninsula while Chaenodraco wilsoni, Chionodracorastrospinosus and Cryodraco antarcticus were the most common ice fish. The reproductive state of the most abundant fish species is provided in Table 2.26.
Table 2.26 Reproductive state and estimated spawning time in some abundant nototheniids and channichthyids.
Species Reproductive state Estimated start of spawning Champsocephalus gunnari First spawners, start of
gonad development, older fish more advanced
April
Chaenocephalus aceratus Gonad development more
advanced than C. gunnari March Cryodraco antarcticus,
Chionodraco rastrospinosus
Gonad development
advanced February Chaenodraco wilsoni Gonads in regression state October Notothenia rossii, Notothenia
coriiceps
Gonad development started End of April/beginning of March
Gobionotothen gibberifrons Gonads in resting stage August-September Lepidonotothen nudifrons Gonads developing Early April
Lepidonotothen larseni Gonads in resting stage or
early stage of development July - August
These observations confirmed findings from previous cruises and helped to complete the annual reproductive cycle of the abundant species. Information is now available for the most common species from late November to June.
Food composition. The food composition of the abundant species was analysed in 4483 fish in the Elephant Island – South Shetland Islands – Joinville Island area. An overview of the number of stomachs investigated per species was provided in Table 2.27. Our study confirmed results from previous investigations that krill is paramount for the feeding of many Antarctic fish species.
References
Kock K-H 2002. Investigation on Antarctic fish. In: DK Fütterer, A Brandt, GCB Poore (eds), The Expedition Antarktis – XIX/3-4 of the Research Vessel Polarstern in 2002, Ber.
Polarforsch. 470: 17
CCAMLR and related topics
Table 2.27 Number of stomachs investigated per species in the Elephant Island – South Shetland Islands – Joinville Island area.
Species
Elephant Island
South Shetland
Islands Joinville Island
Aethotaxis mitopteryx 55
Artedidraco skottsbergi 25
Bathyraja maccaini 4 1
Chaenocephalusaceratus 284 26
Chaenodraco wilsoni 1 1 176
Champsocephalus gunnari 624 53
Chionodraco myersi 1
Chionodraco rastrospinosus 81 85 235
Cryodraco antarcticus 36 14 61
Dissostichus mawsoni 27 6 4
Electrona antarctica 2 2
Gerlachea australis 2 2
Gobinotothen gibberifrons 272 86 396
Gymnodraco acuticeps 3 5 54
Krefftichthys anderssoni 3
Lepidonotothen larseni 149 31 79
Lepidonotothen nudifrons 34 53 222
Lepidonotothen squamifrons 81 72 9
Muranolepis microps 10 6
Neopagepopsis ionah 2 1 4
Notothenia coriiceps 152 92 66
Notothenia rossii 226 87 8
Ophthalmoclycus amberensis 15 2
Pachycara barchycephalum 1
Pagetopsis macropterus 2 49
Parachaenichthys charcoti 14 2 11
Peuragramma antarcticum 1 12
Pogonophryne phyllopogon 1
Prionodryco evansii 2
Protomyctophum sp. 1
Pseudochaenichthys geogianus 8 32
Racovitzia glacialis 4 1
Trematomus bernacchii 6 5
Tremtomus eulepidotus 20 166
Trematomus hansoni 4 32
Trematomus newnesi 45
Trematomus nicolai 8
Trematomus scotti 28
total 2124 669 1690
ANT-XXIII/8, Scientific reports
2.2.2 ANTARCTIC FISH PARASITE FAUNA: LIFE-CYCLE PATTERNS AND