Did the status of fish stocks change?
Indicators: Biomass | Fishing Mortality
Short Answer: No (when considering fishing mortality; see also biomass). Average fishing mortality was low in the nine baseline years before catch shares, and it continued to be low and constant in the first six years of catch shares.
- Catch shares did not affect fishing mortality rates, which were low both before and after catch share implementation. Average fishing mortality rate was between 0.119 and 0.2 during the baseline period, and between 0.119 and 0.125 under catch shares.
- The biggest changes in fishing mortality rates occurred in the 1990s, when fishery managers reduced catch limits for many stocks that were being overfished.
- Long-term efforts to reduce fishing mortality of overfished stocks have shown success. As of June 2017, 6 of 9 rebuilding stocks had been declared rebuilt.
Interactive Chart Story
Fishing mortality rate: The proportion of a fish stock removed by fishing (as opposed to predation or other causes of death) compared to the proportion that would achieve the maximum sustainable yield (MSY), or a proxy for MSY, for that stock. Fishing mortality rate is abbreviated as F, and the fishing mortality rate for maximum sustainable yield is abbreviated as FMSY. Average fishing mortality rate: The average of the fishing mortality rates of all the stocks. Percentage of stocks experiencing overfishing: The percentage of fish stocks in which fishing mortality exceeded the level for MSY (or a proxy) for that stock. (F>FMSY) Percentage of stocks experiencing very high overfishing: The percentage of fish stocks in which fishing mortality exceeded by more than fifty percent the level needed to achieve MSY, or a proxy, for that stock. (F>1.5FMSY)
Average fishing mortality rate: The average of the fishing mortality rates of all the stocks.
Percentage of stocks experiencing overfishing: The percentage of fish stocks in which fishing mortality exceeded the level for MSY (or a proxy) for that stock. (F>FMSY)
Percentage of stocks experiencing very high overfishing: The percentage of fish stocks in which fishing mortality exceeded by more than fifty percent the level needed to achieve MSY, or a proxy, for that stock. (F>1.5FMSY)
Baseline: Before Catch Share Program
Extended Baseline Period (1980—2001): The fishing mortality rate was variable and often very high during the extended baseline period (Chart 1). Dramatic declines in fishing mortality ratios occurred in the 1990s, a time when fishery managers reduced catch limits for many stocks because rockfish were found to reproduce at a lower rate than previously thought (Ralston 2011). The long-term trends were most pronounced for stocks that historically had been overfished and then entered into rebuilding plans. A majority of the stocks now designated as “rebuilding” were subjected to very high overfishing (F / FMSY > 1.5) from 1980 to 1994, and their average fishing mortality rate peaked in 1988 at 2.48. For all stocks, the period from 1992 to 2001 was marked by gradual but substantial reduction in average fishing mortality rate from a peak greater than 1.0 to less than 0.27. Ooverfishing occurred on more than 50 percent of all stocks from 1980 to 1993, before declining to 46 percent in 1994 and 8 percent in 2001 (Chart 2a). During that period, in 1989 and 1990, more than 50 percent of stocks experienced very high overfishing (Chart 2b).
Baseline Period (2002–2010): In the nine years prior to catch shares, fishing mortality rates were low, typically at or below the level that would maximize sustainable yield. The average fishing mortality rate for all stocks fluctuated between 0.119 and 0.20 (Chart 1). Stocks that were under rebuilding plans also had low average fishing mortality ratios, ranging from 0.094 to 0.198 (Chart 1; click Rebuilding Species button). High-value stocks such as Pacific whiting, petrale sole, and sablefish had somewhat higher fishing mortality rates that exceeded FMSY (Chart 4). Overall, the baseline period from 2002 to 2010 was characterized by low fishing rates, in part because of rebuilding plans for overfished stocks but also as a result of previous management reforms like implementation of limited entry in 1993, declaration of federal disaster in 2000, and establishment of Rockfish Conservation Areas in 2002. For more information, see West Coast fishery history.
During Catch Share Program
The average fishing mortality rate remained low and had little variability in the first six years of the catch share program (Chart 1). The rate was steady at approximately 0.119 to 0.125 for all stocks, and at 0.081 to 0.090 for rebuilding species. Sablefish, one of the most valuable stocks in the fishery, was the only stock to experience overfishing, which occurred in 2011, 2015, and 2016. Sablefish overages were small and ranged from 1% to 4% over the reference level (Chart 4). Four stocks had fishing mortality ratios greater than 0.5 in at least three years of the catch share period: Petrale sole, sablefish, Pacific whiting, and South Vancouver yellowtail rockfish.
The low fishing mortality rates from 2011 to 2016 cannot be attributed to the catch share program, as decreases had occurred throughout the 1990s. While catch shares brought more individual accountability and provided more individual flexibility for fishermen—including longer fishing seasons and the ability to lease or sell unused quota—the shift to catch shares did not result in decreases in fishing mortality as might have been expected. The constant average fishing mortality rates do not mean that individual fishermen or vessels were catching constant amounts of fish. Rather, the fleet likely became more efficient, which is expected under catch shares, and fewer individual vessels were catching larger amounts of fish (Ratio of Catch to Quota). Decreases observed in average fishing mortality were driven largely by a small number of stocks (Chart 3), some of which experienced decreased catch-to-quota ratios.
The reduced variability at a fishery-wide level and high fishing mortality rates for valuable species suggest that fishermen were not able to increase their catches of many different stocks—which would have increased fishing mortality rates for those stocks—but only did so for a few high-value stocks. Low annual catch limits and the nonselective nature of trawl gear likely interacted to limit fishermen’s abilities to increase fishing rates on stocks with moderate value.
The catch share program is one component of a long-term effort by fishery managers to limit fishing mortality in order to rebuild overfished stocks. These efforts have been effective. As of June 2017, 6 of 9 rebuilding stocks had been declared rebuilt. Only 3 stocks—Pacific ocean perch, yelloweye rockfish, and cowcod—were still under rebuilding plans.
Data Gaps and Limitations
Available data from the stock assessments conducted by the NOAA National Marine Fisheries Service (NMFS) dictated the methods that we used for measuring fishing mortality rates. For almost all stocks, we used a proxy of F40% for the fishing mortality rate that is expected to achieve the MSY (FMSY). F40% represents the Spawning Potential Ratio at 40%, which is the fishing mortality that reduces spawning stock biomass to 40 percent of pre-fishing levels. We used a proxy because there was insufficient information for most Pacific Coast groundfish stocks to establish a species-specific FMSY.
In our analysis, the most important limitation was that data were not yet available for all stocks for all years of the catch share program. Stock assessment reports are not produced by NMFS annually for all stocks. It may take several more years after the conclusion of this study until assessments are available for all stocks for 2011 to 2016. For some stocks, the most recent assessments were from 2007 or 2008, prior to the catch share program. In these cases, we made the assumption, for analytical purposes, that fishing mortalities remained constant after the most recent assessment. The widow rockfish assessment only reported values from 2001 to 2010, so we assumed that the 2001 fishing mortality value applied retrospectively to all earlier years of the extended baseline period.
We excluded yellowtail rockfish from analysis because the assessments reported fishing mortality values for three regions but only a stock-wide reference point, so it was not possible to accurately calculate the fishing mortality ratio.
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Updated: May 2018
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