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What Is This Indicator, and Why Is It Important? This indicator tracks the percentage of commercially important fish species, or “stocks,” that are increasing or decreasing in size. Only stocks whose population increased or decreased by at least 25% are reported. Trends are based on the estimated weight, or “biomass,” of the entire stock. Americans take large amounts of fish from U.S. waters (see Commercial Fish and Shellfish Landings. Landings of a given stock cannot be maintained indefinitely if that stock’s population declines. If declines persist, stocks can become too small to fish, with attendant economic and social consequences; declines may also lead to significant changes in the marine ecosystem. What Do the Data Show? The North/Mid-Atlantic region stands out as having, over time, more fish stocks with increasing populations and fewer stocks with declining populations. However, we know trends for only 20% of the stocks in this region. In contrast, the number of declining stocks went up in the Pacific Northwest, where we know trends for more than 40% of the stocks; by the 1990s, about 80% of Pacific Northwest stocks with known trends were declining. There are no clear trends in the other regions. However, when all five regions are considered together, about 40% of stocks had decreasing trends over the time period, while about 20% of stocks had increasing population trends. Discussion An increasing population trend may signal an increased ability of a stock to support commercial fishing, or it may reflect the recovery of an overfished stock. This latter case is likely in the Northeast, where strict catch restrictions have been imposed in response to severe stock declines. While the data presented here represent only about 25% of all commercial fish stocks, the stocks for which population trends do exist, and which are reported here, account for about 75% of the weight of fish caught each year in the United States. |
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