|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|||||||||
|
|
||||||||||
|
|
|
|||||||||
|
|
|
|
|
|
|
|
|
|
||
|
|
|
|
|
|||||||
|
|
||||||||||
|
Use Of Windrow Composting To Effectively
Discard Fish Carcasses And Contain Bacterial Pathogens Clifford E.
Starliper and Emmett B. Shotts, Jr. USGS, Leetown
Science Center, National Fish Health Research Laboratory, 1700 Leetown Road,
Kearneysville, WV 25430 During the summer of 1998, an epizootic
occurred in Atlantic salmon (Salmo salar)
being reared as part of a genetics research program at the Leetown Science
Center, Kearneysville, WV. Furunculosis was diagnosed as the cause. The
strategy for disease control was integrated and included chemical and
antimicrobial therapy and depopulation of affected lots of fish that were not
essential for success of the genetics program. This resulted in about 4600 kg
of fish (25,000 carcasses) to be discarded. It was imperative to dispose of the
carcasses and not contaminate underground water or surrounding streams with A. salmonicida. Windrow composting was
chosen as the method to dispose of the carcasses. The compost pile was
constructed on a concrete pad using a rubber tire loader; it was shaped as a
windrow that formed a peak along its longitudinal axis to facilitate the
chimney effect. Carcasses were mixed one part plus ten parts of a bulking
material consisting of spent, horse stable and cow barn bedding. In addition to
this (large) pile, a smaller pile (250 kg of fish) was constructed in the fall
of 1998 to again determine the fate of A.
salmonicida and of equal importance to evaluate the killing effect on
potential human pathogenic coliform bacteria (e.g. Escherichia coli) that originated from the manure in the bulking
material. Bacterial analyses of the kidneys of infected fish just prior to
construction of the pile showed a 30% prevalence having an average of 8.43 X 107
cfu/g of A. salmonicida and 8 of 8
bulk samples were positive for, and contained an average of 2.18 X 106
cfu E. coli per g. Temperature
cycling was monitored and the pile was mixed and turned and reformed into the
windrow shape following each decline. The process was considered complete and
the material “field ready” in about 1 year (5 cycles). With each turn, samples
of the compost material were subjected to bacterial isolation. Composting of
the diseased fish carcasses proved to be extremely effective in achieving
containment and killing of A. salmonicida
and E. coli. After only one temperature
cycle (36 days) no A. salmonicida or E. coli were isolated and in fact, 38%
(6 of 16) of the compost samples were sterile. Pathogen killing was a result of
the sustained high temperatures in the piles (e.g. above 60°C (140°F) for 3 wks).
Environmental bacteria were isolated (i.e. Bacillus,
Klebsiella). Some of the numerous
positive benefits of composting will be discussed.
Return to 25th Annual Eastern Fish Health WorkshopReturn to Leetown Science Center Home Page |