BIRD DEPREDATION RESEARCH AND MANAGEMENT ON AQUACULTURE: AN OVERVIEW

Aquaculture in the United States is very diverse with respect to species cultured, annual production, size, complexity, and spatial arrangement of facilities. Similarly, species of predacious birds using aquaculture facilities also vary with many of these industry characteristics. Fish eating birds are highly adaptable, and relatively common throughout the aquaculture industry, and are often associated with fish depredation problems. Suitability of information regarding the impacts of birds to aquaculture varies dramatically by depredating species and industry sector and changes over time.

For example research has shown that Little Blue Herons (Egretta caerulea) can negatively impact baitfish aquaculture but more recently scaup (Aythya spp.) have become a primary species of concern. Impacts of Double-crested Cormorants (Phalacrocorax auritus; Figure 1) to catfish aquaculture are well documented and have been estimated to range between $6-12 million annually, but the industry has changed dramatically in recent years. Early research indicated Great Blue Heron (Ardea herodias) depredations on catfish aquaculture caused significant damage. Newer research however, initiated a paradigm shift in management by demonstrating that some wading birds like the Great Blue Heron and Great Egret (Ardea alba) largely eat diseased catfish and consumption of healthy catfish can be limited by specific management efforts. However, disease transmission is still an important but poorly understood issue with these species and others such as the American White Pelican (Pelecanus erythrorhynchos). For some aquaculture products such as crawfish, there is little information regarding bird species and their impacts.

These issues highlight the fact that bird depredations are dynamic and evolve with changing demographics of both the aquaculture industry and bird populations. As bird populations and aquaculture change, it is imperative that research identify where and how aquaculture production losses occur and guide science-based management plans to abate production loss.