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January 25, 2015

New Zealand

Research—Pollution from Lobster Farms

 

From Abstract: This study quantifies the production of dissolved inorganic nitrogen (DIN) from the red spiny lobster, Jasus edwardsii, in the laboratory and then uses the data in a numerical model to predict the dispersal pattern of DIN from a hypothetical commercial spiny lobster farm.  Modeling scenarios were set up with combinations of two different stocking densities (3 and 5 kg m−3), two different diets (mussels and a moist artificial diet) and three different feed conversion ratios (FCR = 3, 5 and 28).  DIN excretion rate from unfed lobsters in the laboratory on average was 1.10 ± 0.12 μg N g−1 h−1 while feeding lobsters on mussels and artificial diet increased DIN excretion significantly by around eightfold and twofold, respectively.  Ammonia was consistently the dominant contributor to measured DIN output from lobsters.  Modeling results indicated that the mean elevated DIN from a hypothetical farm where the lobsters were fed with mussels ranged from 7 up to 20 μg N L−1 with increasing stocking density and FCR and was 30–150% higher than the mean elevated DIN resulting from lobsters fed with artificial diet.  Overall, the results indicated that DIN output from the hypothetical spiny lobster sea-cage farming is unlikely to be problematic using the FCR, stocking density, and the number of cages modeled at the coastal site in this study.  Furthermore, feeding lobsters with artificial diet can help maintain a lower DIN output than seafood, such as mussels or trash fish.

 

Source: Environmental Science and Pollution Research.  Characterizing the Fate of Nitrogenous Waste From the Sea-Cage Aquaculture of Spiny Lobsters Using Numerical Modeling.  Soxi Lee (email soxi@yahoo.com, Leigh Marine Laboratory, Institute of Marine Science, University of Auckland, P.O. Box 349, Warkworth, New Zealand), Neil D. Hartstein and Andrew Jeffs.  Published online, January 21, 2015.

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