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Marine Ecology Progress Series

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MEPS 465:201-215 (2012)  -  DOI:

Physical and behavioural influences on larval fish retention: contrasting patterns in two Antarctic fishes

Emma F. Young1,*, Jennifer Rock2, Michael P. Meredith1, Mark Belchier1, Eugene J. Murphy1, Gary R. Carvalho3

1British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
2Department of Zoology, University of Otago, Dunedin 9054, New Zealand
3School of Biological Sciences, Bangor University, Bangor LL57 2UW, UK

ABSTRACT: Waters around South Georgia are amongst the most productive in the Southern Ocean, and support internationally important fisheries. However, there is significant inter-annual variability in fish stocks, and some species have failed to recover from historical overfishing. Dispersal and retention of the planktonic eggs and larvae of marine fish can play a key role in the maintenance of adult stocks. We use a numerical modelling approach to examine the influence of oceanographic and life-history variability on the dispersal and retention of 2 Antarctic fishes: Champsocephalus gunnari (mackerel icefish) and Notothenia rossii (marbled rockcod). Mean retention of N. rossii larvae was predicted to be 5.3%, considerably lower than that of C. gunnari (31.3%), a difference related to the longer planktonic period of the former. Such apparent loss of larvae from local recruitment grounds may contribute to the failure of the N. rossii population to recover from its collapse in the 1970s. However, retention of both species showed high inter-annual variability. Dispersal and retention of C. gunnari were strongly influenced by location of the spawning site, with the greatest contribution to overall retention from spawning sites on the southwest South Georgia shelf. In addition, a consistent feature in C. gunnari was a lack of larval exchange between the proximate South Georgia and Shag Rocks shelves, regions separated by only 240 km. Our findings provide insights into the demographic dynamics and connectivity of C. gunnari and N. rossii populations at South Georgia in relation to prospects for recovery and ongoing responses to environmental variability and change in the region.

KEY WORDS: Individual based model · Larval transport · Ocean circulation · Vertical migration · Fisheries management · Population connectivity

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Cite this article as: Young EF, Rock J, Meredith MP, Belchier M, Murphy EJ, Carvalho GR (2012) Physical and behavioural influences on larval fish retention: contrasting patterns in two Antarctic fishes. Mar Ecol Prog Ser 465:201-215.

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