The rise of syndrome sub-optimal growth disorders in farmed shrimp.

Abstract

The phenomenon of slow growth in farmed shrimp was observed for the first timein 1989 inPenaeus vannameias a clinical manifestation of runt deformity syn-drome caused by infectious hypodermal and hematopoietic necrosis virus. Subse-quently, it was recorded inPenaeus monodonduring 2001–2002. Since then, thecondition described as monodon slow growth syndrome (MSGS) has beenreported from many countries. Though not leading to mortality, retarded growthat the pond level results in significant economic losses. Several potential patho-gens have been identified from affected shrimp; however, no confirmed causalrelationship has yet been established. Initially,P. vannameifarmed alongside slowgrowth-affectedP. monodonwere unaffected by the condition. Further, experi-mental studies suggested thatP.vannameiwas not susceptible. However, inrecent years, increasing incidence of severe growth retardation has been reportedin farmedP. vannamei. Currently, slow growth is considered as one of the mostimpactful production-limiting conditions affecting shrimp farming across Asia.Similar to MSGS, many infectious agents have been detected in slow growth-affectedP. vannamei, especially the microsporidianEnterocytozoon hepatopenaei.Further, genetic and environmental factors have been suggested to play a role.However, the exact cause of slow growth remains elusive, proposing that it maybe a multi-factor syndrome. This review tracks the trajectory of the conditionover the period of significant expansion of shrimp farming and postulates thatconventional single pathogen/single disease paradigms are insufficient todeal with chronic yield-limiting syndromes. We suggest more realistic, multi-dimensional aetiological consideration of syndromic and emerging diseases inshrimp aquaculture.