返回Google圖書搜尋

Considerations in the Transport and Captive Management of Lowland Longjaw Galaxias (Galaxias Cobitinis)

出版	Publishing Team, Department of Conservation, 2018
ISBN	19885147899781988514789
URL	http://books.google.com.hk/books?id=WycsygEACAAJ&hl=&source=gbs_api

註釋Lowland longjaw galaxias (Galaxias cobitinis; Threatened: Nationally Critical) only occur in the Kakanui River catchment in North Otago, New Zealand, which can experiance reduced surface flow conditions during summer and early autumn. To guide conservation options during future low flow events, studies of the optimum conditions for holding G. cobitinis in captivity for periods of up to 3 months were undertaken. Methods were also developed to transport G. cobitinis, hold fish in temporary facilities, feeding, and the treatment of parasitic, fungal and bacterial infections. Investigations focussed on growth rates, and relative condition of G. cobitinis held at (i) different densities and (ii) in differing substratum treatments, with or without additional water current. We found that G. cobitinis can be successfully held in captive conditions for several months with low mortality, even at densities of > 50 fish/m2. Galaxias cobitinis readily adapted to a diet of frozen bloodworms and any incidences of disease were readily treated with standard off-the-shelf preparations. Our studies indicated that characteristics of the holding tanks were important. Galaxias cobitinis held in tanks with angled substratum, imitating riffle habitat, had higher growth and relative condition, and less ectoparasites, than those in tanks with a flat layer of substratum. These results were possibly influenced by the differing amounts of cover, potentially affecting stress levels and susceptibility to disease; and that deeper water required greater energy expenditure in the flat substratum treatment. Furthermore, supplying additional water current with submersible pumps reduced fish condition, likely due to additional energy demands. Optimal conditions for holding G. cobitinis likely involve shallow water levels in tanks with abundant cover, and water current supplied by aeration only. These findings may also be useful for the captive management of other, small, range restricted, non-migratory fish species that are threatened by drought disturbance or water abstraction.