Antarctic krill breeding facilities at port of nagoya public aquarium

Abstract

Antarctic fishes and invertebrates, including Antarctic krill, are generally stenothermal, and it is necessary to maintain water temperature about 0°C to keep them in good condition. Because the effects of nitrifying bacteria are limited by the extremely low temperature of about 0°C, biological filtration does not keep up with the deterioration of water quality resulting from the excrement of animals and un-eaten food. It is therefore necessary to exchange seawater frequently in our present cold-water aquarium.

We developed a new system at Port of Nagoya Public Aquarium (PNPA) that keeps Antarctic marine animals in good condition. The improved system increases the temperature of sea water to 10°C prior to biological filtration and thereby increases the effectiveness of the biological filter. The krill-rearing container was constructed inside the main tank so that the water flow inside the rearing container could be stopped. This avoids a rapid reduction of phytoplankton feed due to turnover of the seawater in the system while krill were fed. As a result of these improvements, long-term rearing, mass culture and reproduction of Antarctic krill are possible. We have exhibited Antarctic marine animals since the opening of PNPA in 1992, and we have exhibited Antarctic krill continuously since 1997. In this article, we detail the Antarctic krill breeding facilities at PNPA.

Keywords:

• Krill
• Holding facilities
• Water quality
• Bacterial control
• Long-term viability
• Aquaculture

Acknowledgements

We wish to express our gratitude to Dr. Stephen Nicol and Dr. Graham Hosie of the Australian Antarctic Division for kindly offering us Antarctic krill that were our first krill to rear. And we also deeply appreciate Dr. Taro Ichii and Dr. So Kawaguchi of the National Research Institute of Far Seas Fisheries for offering us Antarctic krill that led to our success in establishing mass rearing of krill. We thank Dr. Itaru Uchida, director of PNPA, for giving us the opportunity to rear krill at PNPA. We thank Kakuro Watanabe and other staff of PNPA for some advice and help with krill rearing. Sincere gratitude is expressed to reviewers Dr. Jonathan L. Watkins of the British Antarctic Survey and Mr. Robert King of the Australian Antarctic Division for critical and constructive comments that increase the quality of this paper.

Notes

(ND: not detected).