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Eight years of freshwater crayfish (Paranephrops zealandicus (White)) harvest from one New Zealand pond: comments on the resulting population structure
Hollows J, Song T and Kyle C 
Published Online: 4/15/2020
Abstract
A 100 m2 forestry pond was stocked with 65 crayfish (Paranephrops zealandicus (White, 1847)), weighing approximately 35 g, in 2010. Sampling was undertaken at the end of each growing season (March-April) from 2012 to 2019. All crayfish > 45 g were harvested from the population; from 2015 between 1.84 kg and 3.65 kg of crayfish < 45 g were harvested (11 to 24% of the < 45 g population). In 2014, refuge (Cytisus scoparius) for the crayfish was added to the pond. The following year there was a noticeable increase in crayfish biomass, particularly those 45 g or less. In 2018, eight kg of lime was added to the pond. This did not greatly change the pH or calcium in the pond water when measured 10 months later, but there was a corresponding increase in total biomass and biomass of crayfish > 45 g. Crayfish biomass ranged from 2.76 kg (2012) to 17.71 kg (2017). Harvests of crayfish > 45 g ranged from 1.1 kg (2012) to 3.98 kg (2019) and for crayfish < 45 g from 1.84 kg (2018) to 3.65 kg (2016). Our findings suggest that habitat modification and harvesting a range of crayfish size classes can increase total biomass, but not necessarily the biomass of larger crayfish.
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How to Cite
Hollows J, Song T and Kyle C. (2020). Eight years of freshwater crayfish (Paranephrops zealandicus (White)) harvest from one New Zealand pond: comments on the resulting population structure. Freshwater Crayfish 25(1):7-12. doi: 10.5869/fc.2020.v25-1.007
Author Information
John W. Hollows,* , KEEWAI, 15 Wales Street, Maori Hill,Dunedin, Opoho, New Zealand9010. E-mail: john@keewai.co.nz
Thomas Song, , Ernslaw One Ltd., Cemetry Road, Tapanui, otago, New Zealand9542. E-mail:
Callum Kyle, , Ernslaw One Ltd., Cemetry Road, Tapanui, Otago, New Zealand9542. E-mail: callum.kyle@ernslaw.co.nz
Corresponding Author indicated by an *.
Publication History
Manuscript Submitted: 10/28/2019
Manuscript Accepted: 3/24/2020
Published Online: 4/15/2020
Published in Print: 4/30/2020
Funding Information
No specific funding statement is available for this article.