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Cephalopod Populations in Antarctic Waters

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Cephalopod Populations in Antarctic Waters Cephalopod populations in Antarctic waters Uwe Piatkowski There are ca. 800 cephalopod amounting to a total estimate of ca. 34 Of the ca. 20 squid species which species worldwide but relatively few of million t annually (Clarke 1983). Bio- regularly appear south of the Antarctic these species occur in polar seas in mass and total annual production are Polar Front, only a few are considered comparison to the rich squid popu- unknown and probably much higher as being truly Antarctic. Of those, only lations in subpolar and adjacent seas. but no Antarctic cephalopods have been two species are endemic: the Antarctic In the Southern Ocean, there are exploited commercially. However, major neo-squid Alluroteuthis antarcticus and fewer than 50 species of squids and cephalopod jigging and trawl fisheries the glacial squid Psychroteuthis glacialis octopodes. However, several squid exist nearby e.g. around the Falkland (Fig. 1). They are of pivotal importance species occur in large numbers and are Islands and off New Zealand (see Pütz in the high-Antarctic food web. Both consumed by seabirds, seals and whales and Poncet, this book). species prey on krill and myctophids Figure 1. Left: Psychroteuthis glacialis. Early life stage, mantle length 15 mm. Right: Pareledone felix. Female, mantle length 45 mm. 171 (lanternfish) and are known to be the mation about species composition, size during the past decade we described major prey of emperor penguins and and distribution of Antarctic cepha- twelve new octopod species from bottom elephant seals (see Zimmer and Wilson, lopods which are otherwise inaccessible trawl samples taken during several this book). to scientific sampling. In contrast to expeditions with the RV Polarstern in the As Antarctic top predators accumu- squid, information on Antarctic octo- vicinity of the Antarctic Peninsula (e.g. late the indigestible cephalopod beaks podes has grown considerably recently Allcock et al. 2007) (Fig. 1). The samples in their guts, studies of the top predators’ as they can easily be sampled by illustrate a higher than expected octopod stomach contents yield valuable infor- scientific bottom trawling. In fact, species diversity and supply new in- formation on their distribution patterns and ecological aspects. The samples also confirm that the isolation of the South- ern Ocean and the Antarctic continental slope and shelf over the past 35-40 million years has contributed to the evo- lution of a rich endemic fauna and the radiation of Southern Ocean octopodes into the deep sea (Strugnell et al. 2008). Furthermore, the trawl samples show that during recent years, octopus populations have gained significantly higher abundances around the Ant- arctic Peninsula than in similar areas nearby. This elevated abundance oc- curred after the rapid depletion of de- mersal fish stocks and may indicate a possible shift in the structure of the eco- system (Vecchione et al. 2009). Bilöd Todarodes philippovae and T. sagittatus in Antarctic and Arctic waters. The species name in the Antarctic stamp is incorrect. Collection: U. Piatkowski. 172.
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