July 12, 2017 — A paper published last week titled, Global marine fisheries discards: A synthesis of reconstructed data, concludes that commercial fishermen have thrown away (discarded) about 10% of catch over the past decade. Researchers, led by Dirk Zeller, used catch reconstructions – estimates of how many fish were caught – to approximate that around 10 million tons of fish are discarded at sea per year. This number is down from a high of 18 million tons in the 1990s.
Zeller et al. 2017 suggest that the decline in discards are a result of declining fish stocks, though they acknowledge that gear and management improvements could also play a role. Indeed, worldwide fish stocks have remained relatively stable since 1990s, indicating that perhaps management and gear technology have played a larger role in reducing discards than researchers propose.
Previously, we have featured an in-depth analysis of discard policy in the EU by Philip Taylor & Griffin Carpenter.
In the below comments we offer 3 different perspectives on fishing discards and the recent Zeller et al. 2017 paper.
Comment by Bill Karp, Affiliate Professor, University of Washington
The recent paper by Zeller et al highlights challenges associated with estimation of discards and interpretation of overall estimates and trends. Their work builds on an extensive body of research, most notably earlier global discard estimates published in 1994 and 2005, and relies heavily on the Sea Around Us database and catch and discard estimation methods outlined by the authors.
Unwanted fish results from almost all fishing . Fishers generally target a species or group of but fishing gear is not perfectly selective for species or size. Regulations may preclude landing of some species and sizes (usually smaller fish), or economic factors may favor retention of larger fish or higher-value species If the undesired fish are not retained and marketed in some form (e.g. as fish meal for aquaculture feed, or fertilizer) they are generally returned to the sea as discards. This issue is not unique to fishing, waste is a concern in all types of food production. In the United States, roughly 7% of all crops are wasted at the farm (i.e. never harvested), with estimates up to 40% of food waste through the supply chain.
In recent years, waste associated with fisheries discard has become a major public policy issue in some regions, with partial discard bans being implemented in Norway, the European Union, and elsewhere. At the same time, regulatory and operational innovations have resulted in lower discard rates in some fisheries, and demonstrated the potential for broader improvement. Fisheries discard can be reduced by development and use more selective fishing methods, developing markets for unfamiliar species or products, and by regulatory approaches which provide incentives for improved selectivity and/or utilization or even prohibit certain types of discarding.
Zeller et. al. argue that high-grading (discarding of lower-value in favor of higher-value fish) and regulatory discard are major problems and shortfalls of individual transferable quota (ITQ) fisheries. While high-grading and regulatory discarding are substantive causes of discarding, ITQ-type of programs (catch share, rights-based) may include provisions for transferring of quota among participants as well as sharing information that can improve selectivity. These types of programs also reduce or eliminate the race for fish and thereby reduce levels of unwanted fish. They can also encourage accountability, a key to improved catch and discard data. Examples can be found in Alaska and elsewhere.