Has the status of fish stocks changed?
Indicators: Biomass | Fishing Mortality
- Fishing Mortality has decreased considerably since the 1990s, a trend that continued without discernible change since catch shares were implemented.
- Since 2010, average fishing mortality across all stocks has generally been below overfishing limits.
- While less widespread, overfishing on stocks has nonetheless continued since catch shares were implemented.
This indicator shows the rate at which fishing removed fish from stocks.
Baseline: Before Catch Share Program
Along with the project baseline beginning in 2002, an extended baseline beginning in 1980 illustrates longer-term trends in stock status. On average across the 16 allocated stocks, fishing mortality ranged from 131 to 289 percent of the levels that would produce FMSY between 1980 and 2001. The average ratio of fishing mortality rate to FMSY has been steadily declining since 1995, when the fishery resource was declared a disaster and stock rebuilding plans were first implemented (History of the Fishery). Three-quarters of those stocks experienced declines in fishing mortality rates during the most recent decades (of the extended baseline), and Cape Cod/Gulf of Maine (CC/GOM) yellowtail flounder experienced a pronounced reduction from 890 percent of FMSY in 1998 to 266 percent in 2009.
The proportion of stocks that experienced overfishing (F>FMSY) declined by 33 percent during the project baseline. Only three stocks—eastern GOM haddock , pollock, and Acadian redfish—did not experience overfishing at any point in the baseline period.
The proportion of stocks experiencing high fishing mortality rates (F>1.5FMSY) declined from 65 to 29 percent between 2003 and 2009. In all, 11 of the 16 stocks allocated in the Northeast Multispecies Sector Program experienced a high rate of fishing mortality at some point during the project baseline, with an average fishing mortality rate of 716 percent in the worst case (GB yellowtail flounder in 2004), but ratios declined during the project baseline. Five stocks experienced high fishing mortality in every year of the project baseline. Some of the high fishing mortality rates were a result of earlier stock assessments that overestimated stock abundance [do we need to cite?]. This led to overestimated target catches at the beginning of the catch share period, such as in the case of GOM cod until a new assessment was undertaken in 2011.
During Catch Share Program
The analysis includes data for the first seven years of the Northeast Multispecies Sector Program (2010-2016). Fishing rates fluctuated during the catch share program, but there was little consistent pattern across species. On average, the ratio of fishing mortality to FMSY fluctuated around 100 percent, reaching the highest value of 125 percent in 2012. Similarly, there was little trend in the proportion of stocks experiencing overfishing during the catch share program years, and remains at roughly 40 percent of stocks. This apparent stability in aggregate measures masks considerable variability in fishing rates on individual stocks. Fishing rates increased for several species (SNE/MA yellowtail flounder, SNE/MA winter flounder, GOM winter flounder, and GB winter flounder ), while decreased for others (GB cod, eastern GB cod, GOM cod, eastern GB haddock, CC/GOM yellowtail flounder, and witch flounder). Extreme overfishing (F/FMSY > 1.5) remained common for some species. For instance, eastern GB cod, GB cod, GOM cod, and witch flounder experienced extreme overfishing for all six years of the catch share period for eastern GB cod, GB cod, GOM cod, and witch flounder, while CC/GOM yellowtail flounder and SNE/ MA yellowtail flounder experiences extreme overfishing in 4 of the years. In contrast, Acadian redfish, all three winter flounder stocks, haddock, and Atlantic pollock were fished below overfishing limits for all six years of the catch share program.
Data Gaps and Limitations
Data were available from relatively recent stock assessments for most stocks, but not all stocks are assessed every year. As a result, annual data are typically not consistently available for any given stock. Therefore the analysis uses the dataset available on an individual stock basis; in the cases where years have not been assessed, stock fishing mortality from the most recently assessed year is used. It may be several years until all targeted stocks have been assessed for enough years of the catch share program to engage in a meaningful analysis.
Stock reference points are updated over time; calculations of fishing mortality ratios (F/FMSY) relied on yearly estimated fishing mortality compared to the current FMSY estimate. In order to track tends among groups of species, stocks that have required rebuilding plans are separated to observe trends in fishing mortality ratios among that group. These analyses are not intended as a measure of the appropriateness of management decisions at any point in time but rather an indicator of change.
Another limitation is that the fisheries exploitation rate was measured differently for different stocks. FMSY is typically estimated as FMSY=MSY/(summary biomass at MSY), or sometimes based on a proxy, such as F40% (the fishing mortality that reduces spawning stock biomass to 40 percent). Differences in the way that FMSY is estimated should be taken into account when comparing the performance of individual stocks.
Northeast Fisheries Science Center (2012). Assessment or Data Updates of 13 Northeast Groundfish Stocks through 2010. US Dept Commerce, Northeast Fish Sci Cent Ref Doc. 12-06; 789 p.
Northeast Fisheries Science Center (2015). Operational Assessment of 20 Northeast Groundfish Stocks, Updated Through 2014. US Dept Commerce, Northeast Fish Sci Cent Ref Doc. 15-24; 251 p.
Stone, HH, EN Brooks, D Busawon, Y Wang (2015). Assessment of Haddock on Eastern Georges Bank for 2015. Transboundary Resources Assessment Committee.
Wang, Y, L O’Brien, I. Andrushcheknko, KJ Clark (2015). Assessment of Eastern Georges Bank Atlantic Cod for 2015. Transboundary Resources Assessment Committee.
Updated: April 2018
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