A decision support tool for parasite management in fish aquaculture

Abstract

A decision support tool was developed to aid management of problematic parasites in marine fish aquaculture. The tool provides biologically relevant treatment intervals to interrupt the life cycle of ectoparasitic flatworms that occur in global kingfish and amberjack (Seriola spp.) aquaculture. Temperature‐dependent life cycle parameters for the ‘skin flukes’, Benedenia seriolae and Neobenedenia girellae, and the ‘gill fluke’, Zeuxapta seriolae, were derived from published data and modelled using non‐linear regressions. Increasing temperatures shortened the duration of most life cycle parameters of all parasites. Salinity had no effect on the timing of life cycle parameters but limited hatching success in hypo‐ and hypersaline conditions. The tool, named BeNeZe after the first two letters of each parasite genera, enables rapid determination of treatment intervals for two consecutive medicinal immersion or ‘bathing’ treatments—the first to kill adult flatworms attached to fish and the second to prevent maturity of new parasite recruits. As temperature increases, the interval between treatments and the ‘window’ within which the second treatment should be applied is reduced. The tool can be used for multi‐species infections. The inclusion of parasite taxonomy, biology and behaviour as part of an integrated management strategy is reviewed. Available through an open access app, BeNeZe is intended to be applied in conjunction with farm biosecurity, surveillance, management measures and recognition of independent management units. BeNeZe can be used to reduce infection burdens, improve fish welfare and production and reduce treatment number and frequency.

Temporal Change in the Swimming Ability and Infectivity of the Oncomiracidium of a Monogenean <i>Neobenedenia girellae</i>

“…The oncomiracidia of H. okamotoi, which belong to the same family as D. denticulata, swam for 3, 7, and 9 days at 25°C, 20°C, and 15°C, respectively, and H. okamotoi oncomiracidia had a much longer survival period (Ogawa, 1998). The lifespans of oncomiracidia have also been studied in other monogeneans: 80 h at 7°C for the capsalid Entobdella hippoglossi (Kearn, 1974); 5-6 h at 20°C-26°C for the pseudodactylogyrids Pseudodactylogyrus bini and 3-5 h at 20°C-22°C for P. anguillae (Buchmann et al, 1987); 96 h at 6°C and 26 h at 22°C for the discocotylid Discocotyle sagittata (Gannicott and Tinsley, 1998); 2-52 h at 20°C for the microcotylid Sparicotyle chrysophrii (Repullés-Albelda et al, 2012); 50-58 h at 24°C and 27°C for the ancyrocephalid Dawestrema cycloancistrium (Maciel et al, 2017); and approximately 4 days at 20°C for the heteraxinid Zeuxapta seriolae (Hutson et al, 2022). The lifespan of monogenean oncomiracidium varies greatly between species.…”