DETERRING PISCIVOROUS BIRDS FROM AQUACULTURE OPERATIONS
The cost of bird damage to aquaculture is hard to quantify. In addition to predation, fish stock might be related to cultural, mechanical, or environmental elements. The costs of control, however, are becoming available from grower surveys, and estimates of loss can be projected from food habit studies. The damage to aquaculture in Europe and North America, based on average food intake of fish-eating birds, are tens of millions of dollars per year; and in Israel, a few millions of dollars per year. Adding to the direct damage from predation, there is a potential spread of disease by birds. However, there is not sufficient information because the complexity of the different facilities and their setting of the average aquaculture operation that prevent a controlled disease studies. Taking it all together, the damage caused by these fish-eating birds can cause the Israeli pond-base aquaculture sector to crash.
As a result of tens of years of urbanization while drying large areas or shallow water bodies, causing the loss of natural habitats for the fish-eating birds, the aquaculture earthen ponds became a rescue haven for the migrating birds. Meanwhile, as a result of people awareness and the increasing value of the bird-watcher tourism there is a significant increase in the fish-eating birds' populations. Israel's unique location on the path of global bird migration between the Europe and Africa intensifies the conflict between aquaculture and fish-eating birds because in the transition seasons the population of fish-eaters has increased significantly.
Many ways to deal with the fish-eater birds were tried, both in Israel and in the world by a) prevention such as nets and cable stretched over the fish ponds, which are costly; b) direct human presence by ground harassment with vehicle patrols, dogs, destroying nesting colonies and disrupting birds at their resting sites during the day and night; c) using devices such as reflecting tapes, lights, eyespot balloons, scarecrows made of hunting birds, pop-up scarecrows with exploders, water spray devices, pyrotechnics, automatic exploders, alarm or distress calls,. These methods, most of the time, had only a short-term success. With the time, the use of traps and firearms has become illegal as a result of bird-watchers and public pressuring the governments to protect the birds.
Therefore, it became obvious that more research needs to be done, for example, the necessity to consider aspects such as the species, species and size of the fish, the size and depth of the pool, and the environment. More studies have been carried out in an attempt to implement technologies for the removal of harmful birds and advanced means of observation and monitoring to cope with the habituation of birds. These systems are based on computing technologies, image processing, and robotics. A review of the latest use of these advanced technologies that was introduced lately to the aquaculture industry in Israel will be presented.