Bad fish arithmetic: government reports and actual catches don’t add up

Dirk Zeller is an organizer and speaker for the AAAS Symposium Underreported Yet Overoptimistic: Fisheries Catch Reconstructions and Food Security, Sunday, Feb. 19, 10 – 11:30 a.m.

More than 12,000 people live along the Alaskan coast and have a long history of catching and eating fish. They catch nearly 1,000 metric tonnes of fish annually. I helped document this in a scientific study published in the journal Polar Biology in 2011 titled Arctic fisheries catches in Russia, USA and Canada: Baselines for neglected ecosystems..

Yet, the U.S. has been reporting zero fisheries catches from that part of their waters to the United Nations Food and Agriculture Organization (FAO), which assembles the only global database on fisheries catches. Many countries, largely inadvertently, underreport how many fish are being caught in their waters.

Much of the catch data reported to the FAO is substantially incorrect

As part of the Sea Around Us Project ( at the UBC Fisheries Centre, our team has demonstrated over the last decade that much of the data on fisheries catches reported by countries to the FAO are often substantially incorrect. Therefore, we have developed and applied a methodology for ”reconstructing” real catch histories from coastal countries based on detailed analysis of the academic literature and data from other sources including government, businesses and industry, combined with local expert knowledge and the use of assumption-based interpolations.

This provides a more comprehensive picture of fisheries catches for all fisheries sectors than what is otherwise available. Such reconstructions have shown, for example, that Tanzania’s official reported fisheries data in the past excluded all catches for Zanzibar, despite this island group having a dedicated fisheries agency collecting data. Due to such underreporting, actual total catches taken by Tanzanian fishers are around 70 per cent higher than official statistics lead one to believe, as documented in another study led by my colleague Jennifer Jacquet.

The Sea Around Us project reconstructs real catch histories

Incomplete catch data are also an issue in other parts of the world. In another study published recently,  we show that the fisheries of the nine highly developed coastal countries surrounding the Baltic Sea in north-eastern Europe appear to catch over 30 per cent more than is reported.

Our approach to deriving more accurate total catch estimates incorporates historical anecdotes (i.e., isolated observations) and local studies in catch reconstructions, which can provide crucial baselines of knowledge. By using better fish arithmetic, the Sea Around Us Project aims to set a new basis for policies related to global fisheries.

By 2012 we will quantify the actual contribution of fisheries to world food security

With the completion of our coverage of all maritime countries and territories in the world by 2012, we will be finally able to quantify the actual contribution of fisheries to food security of the world, examine region-specific trajectories of fisheries catches (likely to strongly differ from those derived from the FAO database), and jointly with our new global database on fishing capacity help settle issues of the impact of fisheries on living fish in the sea.

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