Piscivore food presentation in BIAZA collections: exploring future options to limit risk of ingestion of microplastics

Abstract

The impacts of marine plastic debris on wildlife have largely been considered by zoos as an in situ conservation issue rather than having a direct impact on zoo animals. However, marine plastic debris has been found in the gastrointestinal tracts of fish species that are used by zoos as animal feed. Microplastics (<5 mm) have been observed in scats of captive pinnipeds fed wild-caught fish. Safeguarding fish-eating species kept in captivity, particularly those involved in the European Association of Zoos and Aquaria’s (EAZA) Ex-situ Programmes (EEPs), from potential long-term negative effects of plastic marine pollution is important. To explore options to reduce risks of plastic ingestion that complement current husbandry decisions, this study aimed to identify priorities for presenting whole or chopped fish in BIAZA collections as well as identify key Taxon Advisory Groups (TAGs) that may be most affected. The Penguin and Small Carnivore TAGs recorded the most common presentations of whole fish items. The Small Carnivore TAG and Fish and Aquatic Invertebrate TAG were routinely presented chopped or processed fish in the highest number of collections. Contaminant removal was low priority for chopped fish items, suggesting that mitigation of microplastic ingestion has not been widely considered. Options to reduce risk of plastic ingestion from prey stomach contents include: evisceration of fish for collections already presenting chopped fish, with stomach flushing of prey potentially more suitable for those wishing to present whole, intact feed items. Screening of prey items presents an opportunity to all collections to monitor risk and intervene where necessary.