Post-harvest weight loss has important implications for abalone quota management

摘要

Regulations forming part of the abalone quota management system in Victoria, Australia require that abalone processors notify fisheries authorities of quantities of abalone consigned from commercial divers within 25 h of landing. The regulations also require that the abalone are to be landed whole in the shell, and transported and stored in sealed bins until confirmation of official notification. Although the bins cannot be opened before notification, the 25-h limit for notification provides a window of opportunity to make potential gains through weight loss in those abalone destined for canning. This arises because notified weights, rather than weights estimated upon landing, are used to decrement the quota allocations of individual divers. I investigated the potential for post-harvest weight loss by subjecting abalone to three experimental treatments selected to simulate a range of possible transport and storage regimes. My results demonstrate that substantial weight loss can occur in whole abalone during both ambient and refrigerated storage. Loss of weight in abalone during storage results from the release of water and body fluid associated with physiological responses to hypoxic stress caused by exposure to air. In Victoria, about 60 percent of the landed catch is used to produce canned product. Because of the observed weight losses during storage, divers supplying abalone for canning have to harvest more abalone to achieve their quotas than those supplying abalone for live export. Lossesin weight of 10-20 percent observed during this study equate to a harvest of 6-12 percent (350,000-700,000 abalone) more than the total allowable catches. Harvesting these additional quantities of abalone may exceed desired fishing mortalities for long-term population sustainability. If beach weights were deducted from quotas, then this problem could be resolved.