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NOAA Fisheries Reviewing Method of Estimating Discarded Fish

Fisheries management aims to make sure that fish stocks are not overharvested. To do that, we set caps on the total amount of fish caught. The caps include both landed fish (fish brought to port) and fish discarded at sea. We keep track of landed fish through a number of sources: we get reports from fishermen and from the dealers who buy the fish. Much harder to estimate is the amount of fish thrown overboard. These fish may be too small, they may be a species they are not allowed to keep, or they may be a species that is hard to sell.

Right now, most of our discard data comes from the subset of commercial fishing trips that carry fisheries observers. Because we don’t observe every trip (only approximately 14% of groundfish trips, for example), we have to estimate the fishery-wide discards. We know our estimates of discards can have big consequences. An overestimate can result in early fishery closures, while an underestimate can result in catches that exceed quotas.

At the Greater Atlantic Regional Fisheries Office, our challenge was greatly increased in 2010, when groundfish sectors were established. We had to develop a way to calculate discards for each of 19 sectors rather than fishery-wide. Working with other fishery scientists, we developed the “peer-reviewed cumulative discard methodology.” Since 2010, we have expanded our use of this method to estimate discard in other fisheries besides groundfish. This includes discards of yellowtail flounder in the scallop fishery, haddock in the herring fishery, butterfish in the longfin squid fishery, and river herring in the herring and mackerel fisheries.

Graph for 2014 showing amounts of observed versus unobserved discards of groundfish species are percentage of Sub-ACLFishing Year 2014 Allocated Groundfish Discards as a Percentage of Sub-ACL

Considering Modifications and Fishermen’s Concerns

When we adopted the new methodology in 2010, the peer reviewers suggested that we should evaluate our methods after several years and consider possible modifications. In addition, fishermen and other stakeholders have identified concerns or suggested ways to modify the method. For example:

Using Independent Experts for Review

The Center for Independent Experts (CIE) has obtained the services of two scientists who will conduct an independent peer review. We are pleased to announce the reviewers will be:

We have been archiving weekly catch data and discard rates since January 2014 so that the analyses supporting the review can use the actual information available to us for in-season monitoring. We will use this database to test the various revised approaches, and see how they perform in comparison to the current methodology.

We are opening the review process up to the public through a webinar on October 31 and a three-day workshop November 7-9.Anyone is welcome to attend the meeting in person at 55 Great Republic Drive, as well.  Background information on our discard methodology is available, and will be updated with peer review materials on or about October 27.

Find out how to participate.