WWW.WAS.ORG • WORLD AQUACULTURE • SEPTEMBER 2013 43 and dispersion of otter populations suggests that these ponds act as steppingstone ecosystems, promoting population development. The otter is an energy-efficient hunter and carp ponds are ideal hunting grounds. Inevitably the current expansion of otter populations leads to conflicts between carp producers and otters. Compensation for Financial Damage A widely adopted strategy to deal with the negative economic impacts of predatory species is to establish compensation schemes for financial damage. In Lower Austria, the first claim for compensation of losses caused by otter was raised in 1984 and US$ 3,840 of the claimed US$ 4,326 have been paid. From 1984 to 1990, 31 claims were raised and 60-80 percent of the claimed compensations have been paid by the Provincial Government, the Hunters Association of Lower Austria and two NGOs. Since 1994 the compensation was solely covered by the Government of Lower Austria. The claims asserted by carp producers reached US$ 469,742 in 2005. From 2003 to 2005, payments decreased to 6065 percent of claimed compensations, reflecting the growing experience (1,725 handled cases between 1984 and 2005) in separating losses caused by otter from other causes. In 2010, a new compensation strategy, emphasizing promotion of preventive measures, was established. As a consequence, compensations declined to US$ 35,855 (Fig. 4). According to the new rules, many farmers can no longer apply for compensation. At present large-scale carp farmers must tolerate predation by otters to get funds from agricultural programs, angling ponds cannot claim compensation at all and neither can the managers of running waters. Small-scale carp farmers (≤ 0.65 ha) get no compensation for losses caused by otter but are granted financial aid for protecting their ponds with electric fences (50 percent of the installation costs, with a maximum of US$ 960). The increasing number of cases since 2010 (Fig. 5) is a consequence of the newly established compensation strategy that encourages owners of large ponds to report their damages to get funds from agricultural programs (ÖPUL). Requirements for Compensation To get financial compensation for losses caused by otter, several conditions must be fulfilled. First, the presence of the otter at the pond must be verified (spraints, tracks, carcass of captured fish). To evaluate the impact of otter on the fish stock and to exclude other possible causes of fish loss, the fish producer must provide detailed data on stocking, husbandry and expected harvest of the pond, such as invoices and management records. The date of harvesting has to be announced well in advance to enable verification by public authorities, which is done randomly. There is no legal title for compensation. The burden of proof rests with the carp farmer. There is no compensation for angling ponds, illegal ponds or ponds that are not harvested on a regular basis, at least once within two years. The type of financial support depends on pond size. For ponds smaller than 0.65 ha, preventive measures (electric fences) are subsidized, if possible. Owners of larger ponds (>0.65 ha) or small ponds where fencing is not feasible can apply for compensation for losses caused by otter. Calculating Compensation Claims To calculate the losses caused by otters, the difference between number and weight of stocked and harvested fish is used. Natural losses are taken into account at a specific rate. For carp, natural losses between 5 and 25 percent, depending on size, are estimated. For predatory species such as pike perch Sander lucioperca or pike Esox lucius, natural losses are estimated at up to 80 percent, depending on species and size class. Furthermore, it is assumed that, as the stock is reduced by otter, the remaining fish show increased growth because of FIGURE 4. Compensation paid to carp breeders for losses caused by otters from 19912011. The high compensation in 1997 and 2002 may not have been caused by otter alone (hard winter, flooding). This gives an idea of how difficult it can be to separate the impact of otters from other causes. In 2010 a new strategy was established and compensations declined. FIGURE 5. The number of registered cases of damages caused by otter from 1991-2011. The rising number of cases in 2010 and 2011 is a consequence of the newly established compensation strategy that encourages owners of large ponds to report their damages to get funds from agricultural programs (ÖPUL). (CONTINUED ON PAGE 42)
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