Wading bird predation at tropical aquaculture facilities in central Florida

In 1995 and 1996, fish loss due to bird predation was documented at 18 pond s at seven aquaculture facilities in central Florida. Losses in ponds from which birds were excluded with netting averaged 11.1%, whereas losses in un netted ponds averaged 37.6%. Populations of wading birds varied among facil ities, but the snowy egret Egretta thula, green-backed heron Butorides stri atus, tricolored heron E. tricolor, and little blue heron E. caerulea were the principal depredating species. Field observations revealed feeding rate s by little blue herons as high as 4 fish/min. Estimated monetary losses at unnetted study ponds averaged US$1,360/pond compared with average losses o f $589 at netted ponds. Currently, exclusion is the only technique that is consistently reliable, and it appears that netting ponds to control bird de predations is economically feasible, particularly with high-value fish.