It is impossible to estimate the quantity of small fish that is destroyed since it is impossible to estimate the amount that is shovelled overboard, dead or dying.
Discards are that portion of the total catch which is dumped or thrown overboard at sea. Discards are generally considered a waste of fish resources and inconsistent with responsible fisheries. However, while technically a discard, the return of an egg-bearing lobster to the sea is clearly supportive of responsible fisheries.
WHY IS AN UPDATE OF GLOBAL DISCARDS NEEDED?
FAO is required to report periodically to the United Nations General Assembly (UNGA) on progress with regard to UN resolutions on fisheries. A number of these resolutions (see Section 4.2.1) make reference to monitoring bycatch and discards, including provisions on bycatch and discards in international fisheries instruments, and reviewing the impact of bycatch and discards on the sustainable use of living marine resources.
This update helps to quantify the scale of discards in different types of fishing operations and in different regions and provides an indication of the progress made in reducing discards and wastage in the worlds capture fisheries. These trends are of interest for the design of national and multilateral initiatives to promote responsible fishing operations and utilization of the catch. Estimating discards also raises practical issues with regard to the interpretation, application and monitoring of the Code of Conduct for Responsible Fisheries (CCRF).
In 1994 FAO published an estimate of global discards in marine fisheries (Alverson et al.) indicating that 27 million tonnes, or approximately 27 percent of the global catch, were discarded annually. The initial estimate was a major achievement, providing the order of magnitude for the estimate of global discards and illustrating the difficulty in estimating global discards, as indicated by the wide range of the estimate (17.9-39.5 million tonnes). In particular, the Alverson assessment helped to reduce global discards by focusing attention on the potential magnitude of the discard problem.
The 1994 estimate was based on data from the 1980s and early 1990s and cannot accurately reflect the changes that have occurred in world fisheries. However, the estimate continues to be cited in support of particular policies and actions. The Alverson assessment was also subject to criticism with respect to aspects of the estimation method, including the assumptions on which the assessment was based and the limited geographical coverage of the available discard information.
The objectives of the current study were to develop an improved and more robust and transparent method for estimating discards at the global level, and to use the method to re-estimate discards in the worlds marine capture fisheries.
The approach used in this study differs substantially from that used in the Alverson assessment, which was based on discard/catch ratios determined by species or species group. These ratios were then applied to FAOs Fishstat nominal catch statistics for the 1988-1990 period in order to derive the global estimate.
In contrast, the current study compiled an inventory of the worlds fisheries and their respective catches. Information on the quantity of discards or the proportion of discards in the catch was obtained from available discard studies. As discard studies were not available for all fisheries, in some cases the ratio of discards to catch was assumed, based on information from similar fisheries. The total quantity of discards for the fishery was calculated by raising (extrapolating) the results of the discard studies to the total recorded landings for the fishery, as extracted from national fisheries statistics and other sources.
The fishery-by-fishery approach offers the possibility of verification and periodic updating of the discard estimates at the country or regional level in consultation with national fisheries authorities and regional fisheries organizations.
While it is unlikely that a definitive estimate of discards at the global level can be made, the re-estimate is seen as a contribution to an ongoing FAO process to focus attention on the scale of discards, trends in discarding and on fisheries management issues and practices associated with discards.
 UN General Assembly
Resolution 49/118 (UNGA, 1994). There are numerous references to discards in the
Code of Conduct for Responsible Fisheries (CCRF).|
 Alverson et al., 1994 (referred to hereafter as the Alverson assessment). While the primary author made subsequent revisions of the estimate, the 1994 estimate is that which is most frequently cited in the literature. A previous estimate was also made by Saila (1983).
 See UN resolutions, Section 4.2.1.