Influence of management practices and of scavenging seabirds on availability of fisheries discards to benthic scavengers

There is great variation in discarding practice among fisheries in different parts of the world. Management systems result in some fisheries discarding mostly fish offal, much of which is macerated into small chunks, while other fisheries discard large (ca. 25 cm) whole fish. Scavenging seabirds consume high proportions of most categories of discarded fish and offal (typically 60 to 80% of discarded roundfish, 70 to 95% of discarded offal), but tend to avoid discarded benthic invertebrates and fish that are difficult to swallow, such as species with long spines or large flatfish. Amounts and composition of fishery discards and offal reaching benthic scavenging communities are clearly very strongly influenced by the intense but selective consumption by seabirds, and this alteration will depend strongly on details of the fishery management regulations and customs, such as whether or not waste is macerated. There is scope to adjust fisheries management practices to reduce the impact of offal and discards on scavenger communities.