Download Fishing Mortality - Measuring the Effects of Catch Shares

Northeast Groundfish: Ecological Indicators
Updated Results - Version: June 2015
Has the status of fish stocks changed?
Indicator: Fishing Mortality
This indicator shows the rate at which fishing removed fish from stocks.
Additional charts provided below. The images in this downloadable fact sheet may not show all the components
within each indicator. To work with an interactive display of the data underlying this indicator, go to:
http://www.catchshareindicators.org/results/northeast/ecological/fishery-stock-status-fishing-mortality/
Northeast: Fishery Stock Status – Fishing Mortality
Updated June 2015
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Key Terms and Definitions:
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Maximum sustainable yield (MSY): The largest long-term average catch or yield that can be taken from a stock
or stock complex under prevailing ecological and environmental conditions. This is often used as a management
goal.
Fishing Mortality (F): A measurement of the rate of removal of fish from a population by fishing. Fishing
mortality can be reported as either annual or instantaneous. Annual mortality is the percentage of fish dying in
one year. Instantaneous is that percentage of fish dying at any one time. The acceptable rates of fishing
mortality may vary from stock to stock.
FMSY: The rate of fishing mortality that, if applied constantly, would result in maximum sustainable yield (MSY).
F/FMSY: The ratio of actual fishing mortality (F) in a given year to the current estimate of the level that would
provide maximum sustainable yield (FMSY); overfishing is occurring when F/FMSY ≥ 1.
Maximum Fishing Mortality Threshold (MFMT): The threshold above which a stock is said to be experiencing
overfishing, typically set at FMSY.
Overfishing: A rate or level of fishing mortality that jeopardizes the capacity of a fishery to produce the
maximum sustainable yield on a continuing basis (F>FMSY).
High Fishing Mortality Rate: The actual fishing mortality (F) exceeds the overfishing limit (F>1.5FMSY).
Overview
On average, fishing mortality rate (F), defined as fish removed through fishing as opposed to predation or
other causes of death, remained above the rates that would produce maximum sustained yields (FMSY)
throughout the extended baseline. The average generally declined through time, eventually reaching
levels near FMSY in recent years. The average ratio of F to FMSY (F/FMSY, see Key Terms and Definitions)
remained above one (with overfishing occurring across stocks on average) until 2007, declined through the
first year of the Northeast Multispecies Sector Program (2010), and gradually increased in recent years,
though remained below one. In any given year, overfishing was occurring on some stocks (where fishing
mortality exceeded levels that produce maximum sustainable yield). The proportion of stocks with high
fishing mortality (levels that exceed FMSY by 50 percent or more) peaked at 82 percent in 1992-93 and
during the project’s eight-year baseline period reached a high of 71 percent in 2003. It declined to 18
percent in 2013.
Baseline Period
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 86 to 303 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 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), with Cape Cod/Gulf of Maine (CC/GOM) yellowtail flounder experiencing the most
pronounced reduction from 849 percent of FMSY in 2000 to 173 percent of FMSY in 2007.
Northeast: Fishery Stock Status – Fishing Mortality
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The proportion of stocks that experienced overfishing (F>FMSY) declined from approximately 71 percent in
2002 to between 35 and 53 percent in the period from 2006 through 2009. Only two stocks—Western
Georges Bank (GB) haddock and Acadian redfish—did not experience overfishing at any point.
The proportion of stocks experiencing high fishing mortality rates (F>1.5FMSY) declined from 71 to 35
percent between 2003 and 2009. In all, 12 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 776 percent in the worst case (GB yellowtail flounder in 2004), but
average fishing mortality ratios declined during the project baseline. Six 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. 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.
Catch Share Program
The analysis includes data for the first four years of the Northeast Multispecies Sector Program (20102013). The average ratio of fishing mortality to FMSY declined slightly in the first year of the sector program
from 86 percent in 2009 to 69 percent in 2010, but then it increased to 74 percent in 2013. However, there
were variable trends in fishing mortality on an individual species basis. For example, average F/FMSY on
GOM haddock increased by 35 percent following implementation of the catch share program from 2009 to
2013. In contrast, fishing mortality ratios on CC/GOM yellowtail flounder and GB yellowtail flounder
declined by 52 and 53 percent, respectively, following implementation of the Northeast Multispecies
Sector Program. In many stocks, changes in fishing mortality ratios were smaller. GOM cod continues to be
exploited well in excess of FMSY; this persistent overfishing is largely a result of updated stock assessments
in 2011 and 2012 that revealed the stock to be in worse condition than previously estimated. In the first
year of the Northeast Multispecies Sector Program, fishing mortality ratios of six stocks were less than 50
percent of FMSY, and the proportion of stocks with high fishing rates was the lowest of any year through the
project baseline and sector program years. These instances of low fishing mortality may have been a
consequence of species with low ACLs constraining catches of other target species (Ratio of Catch to
Quota). The proportion of stocks with overfishing or high fishing mortality fell from 35 to 20 percent from
2010 to 2013.
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.
Northeast: Fishery Stock Status – Fishing Mortality
Updated June 2015
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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. F MSY
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.
Information Sources
Brooks, E.N., Sutherland, S., Van Eeckhaute, L., and Palmer, M.C. 2012. Georges Bank Haddock Assessment
Update. National Marine Fisheries Service, Northeast Fisheries Science Center Groundfish Assessment
Updates 12-06.
Group, N.D.W. 2010. Stock Assessment of Pollock in US Waters for 2010. National Marine Fisheries Service,
Northeast Fisheries Science Center Stock Assessment Workshop 10-17.
Legault, C., Alade, L., Emery, S., King, J., and Sherman, S. 2012a. Cape Cod-Gulf of Maine Yellowtail Flounder
Groundfish Assessment Update. National Marine Fisheries Service, Northeast Fisheries Science Center
Groundfish Assessment Updates 12-06.
Legault, C., Alade, L., Stone, H.H., and Gross, W.E. 2012b. Stock Assessment of Georges Bank Yellowtail
Flounder for 2012. Transboundary Resources Assessment Committee.
Miller, T.J. 2012. Gulf of Maine-Georges Bank Acadian Redfish. Northeast Fisheries Science Center
Groundfish Assessment Updates 12-06.
Northeast Fisheries Science Center. 2011. 52nd Northeast Regional Stock Assessment Workshop (52nd
SAW): Northeast Fisheries Science Center Reference Document 11-17.
Northeast Fisheries Science Center. 2012a. Gulf of Maine Atlantic Cod (Gadus morhua) Stock Assessment
for 2011, Updated through 2010. Stock Assessment Workshop 12-05: 1–369.
Northeast Fisheries Science Center. 2012b. Southern New England Mid-Atlantic Yellowtail Flounder
(Limanda ferruginea) Stock Assessment for 2012, Updated through 2011. Stock Assessment Workshop 1218: 1–246.
Northeast Fisheries Science Center. 2013a. Stock Assessment of Georges Bank Atlantic Cod (Gadus morhua)
for 2012. Stock Assessment Workshop 13-11: 1–206.
Northeast Fisheries Science Center. 2013b. Gulf of Maine Atlantic Cod (Gadus morhua) Stock Assessment
for 2012, Updated through 2011. Northeast Fisheries Science Center Stock Assessment Workshop 13-11.
Northeast: Fishery Stock Status – Fishing Mortality
Updated June 2015
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Northeast Fisheries Science Center. 2014a. Gulf of Maine Atlantic Cod (Gadus morhua) Stock Assessment
for 2014, Updated through 2013. Scientific and Statistical Committee 14-10.
Northeast Fisheries Science Center. 2014b. Operational Assessments and Peer Review Reports for Georges
Bank winter flounder, Gulf of Maine Winter Flounder, and Pollock. Groundfish Plan Development Team 1410.
O’Brien, L., and Dayton, J. 2012. Gulf of Maine-Georges Bank American Plaice Assessment for 2012.
National Marine Fisheries Service, Northeast Fisheries Science Center Groundfish Assessment Updates 1206.
Palmer, M.C., Sutherland, S., and Brooks, E.N. 2012. 2012 Update of the Gulf of Maine haddock
(Melanogrammus aeglefinus) stock assessment: an update of the resource through calendar year 2010.
National Marine Fisheries Service, Northeast Fisheries Science Center Groundfish Assessment Updates 1206.
Shepherd, G., Sosebee, K., and Brooks, L. 2013. Gulf of Maine/Georges Bank White Hake (Urophycis tenuis)
Stock Assessment for 2013, Updated through 2011. National Marine Fisheries Service, Northeast Fisheries
Science Center Reference Documents 13-10.
Van Eeckhaute, L., Brooks, E.N., and Hansen, S.C. 2012. Assessment of Eastern Georges Bank Haddock for
2012. Transboundary Resources Assessment Committee.
Wang, Y., and O’Brien, L. 2012. Assessment of Eastern Georges Bank Atlantic Cod for 2012. Transboundary
Resources Assessment Committee: 1–88.
Wigley, S.E., and Emery, S. 2012. Witch Flounder. National Marine Fisheries Service, Northeast Fisheries
Science Center Groundfish Assessment Updates 12-06.
Northeast: Fishery Stock Status – Fishing Mortality
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Charts
Proportion of Stocks with high Fishing Mortality
Northeast: Fishery Stock Status – Fishing Mortality
Updated June 2015
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Northeast: Fishery Stock Status – Fishing Mortality
Updated June 2015
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F/FMSY Ratios for Allocated Stocks
Northeast: Fishery Stock Status – Fishing Mortality
Updated June 2015
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