Environment Food and Rural Affairs written question – answered at on 13 January 2011.
To ask the Secretary of State for Environment, Food and Rural Affairs what assessment she has made of the effects on the marine environment of the practice of discard in each region in each year since 1997-98.
The ecological impacts of discarding on the ecosystem include the direct effects of discard mortality on fish stocks and the effects of population growth in species that utilise these discards.
The direct ecological effects of discard mortality are inextricably linked to overall fishing mortality. In the North Sea, excessive fishing mortality has been shown to:
reduce potential yield from the stocks; reduce species diversity; change predator-prey interactions; change the relative abundance of species.
Several seabed dwelling species utilise discards. However, evidence for expansion of these populations, as a response to discards, is weak. In general, the full impacts of discarding on marine communities are not well understood, and neither are the consequences of reducing the amount of discarded material. However, it is recognised that removing non-marketable marine organisms from the ecosystem will reduce its health, and is therefore not consistent with good ecosystem management.
A wide range of scavengers, including seabirds and fishes, are also known to feed on discards. In the North Sea, discarding is estimated to account for up to 10% of the overall annual food consumption of scavengers. This level of contribution is probably sufficient to allow larger populations of these scavenging species to exist than would otherwise be possible. For instance, seabirds are estimated to consume 50% of discarded material; enough to potentially support over 6 million birds.
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