Dr Robin Cook, who also worked on the research, said: "Our results highlight the importance of considering the broader ecosystem consequences of fishery management. Policy changes to reduce discards affect the food web and, without careful consideration, may dissipate or negate intended benefits.
"Inflating landing quotas to accommodate the entire catch is an inadequate solution with few conservation benefits. On the other hand, the effective reductions in harvest rates resulting from changes in fishing practices to eliminate the capture of unwanted fish can deliver conservation benefits, especially in heavily exploited systems.
"These ecological effects need to be considered alongside the practical, societal and economic issues in developing a sustainable policy."
Discarding of undersize and low-value fish by commercial fisheries is not a new problem. UK Parliamentary debates in the 1890s condemned the quantities of plaice thrown away by fishing fleets in the North Sea because they were too small to be sold.
Today, the waste of living resources due to discarding is considered unacceptable. For this reason, the EU has reformed the Common Fisheries Policy in an effort to eradicate the practice by obliging fishing vessels to land all of their catch.
The key issue for the policy is the extent to which the landing obligation is compensated by an increase in quotas. The Strathclyde research shows that full compensation, in which quotas are raised by an amount equivalent to the quantity of fish currently discarded, negates any conservation benefits. On the other hand, forcing improvements in the selectivity of fisheries by offering no compensation has dramatic conservation benefits; hence there is a trade-off between practicality and ecological benefit.
|Contact: Lachlan Mackinnon|
University of Strathclyde