Fishery Stock Status Fishing Mortality

Transcription

1 Northeast Groundfish Interim Findings: Ecological Indicators Version: February 2014 Fishery Stock Status Fishing Mortality This indicator measures the rate at which fishing removed fish each stock. This is a component of fishery stock status (Fishery Stock Status: Introduction). 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: Overview Fishing mortality (or the fish removed through fishing as opposed to predation or other causes of death) remained above the rate that would produce maximum sustained yields (FMSY) for the first half of the baseline period. The rate subsequently declined to levels near maximum sustainable yield throughout the rest of the period covered by the available data. Average fishing mortality rate dropped slightly in the first year of the sector program (2010) to 88 percent of FMSY. The proportion of stocks with very high fishing mortality (levels that exceed MSY by 50 percent or more) has declined from its peak in 2003 to 40 percent Northeast: Fishery Stock Status Fishing Mortality February

2 in In any given year, some stocks experienced levels of fishing mortality greater than levels that produce maximum sustainable yield. Baseline Period In the baseline period from 2002 through 2009, the average fishing mortality across the 16 allocated stocks ranged from 145 to 101 percent of the level that would produce maximum sustainable yield (FMSY). Three-quarters of these stocks experienced a declining trend in exploitation rates during the baseline period, with American plaice experiencing the sharpest reduction from 300 percent of FMSY in 2002 to 63 percent of FMSY in The percentage of stocks experiencing high fishing mortality rates declined from 70 to 38 percent between 2003 and In all, 12 of the 16 stocks allocated in the Sector Program experienced a high level of fishing mortality at some point during the baseline period, with F/FMSY equaling 770 percent in the worst case (GB yellowtail flounder). Six stocks experienced high fishing mortality in every year of the baseline period, while only two stocks Western Georges Bank (GB) haddock and Acadian redfish did not experience overfishing at any point in the baseline period. The percentage of stocks that experienced overfishing (F>FMSY) declined from roughly 70 percent in 2002 to between 45 and 50 percent in the period from 2006 through Some of the high exploitation rates were a result of earlier stock assessments that overestimated stock abundance. This led to overly high target catches, such as in the case of Gulf of Maine (GOM) cod stocks. Catch Share Program The analysis includes only data for the first year of the sector program (2010) because too few assessments covering fishing mortality for 2011 are currently available. Average fishing mortality over all stocks declined from 101 percent in 2009 to 88 percent in But that trend varied from species to species. For example, fishing mortality on GOM haddock increased from 115 percent of FMSY to 178 percent of FMSY from 2009 to Meanwhile, fishing mortality on Cape Cod/ GOM yellowtail flounder and GOM haddock declined from 234 and 196 percent of FMSY in 2009 to 111 and 124 percent of FMSY in 2010, respectively. Other stocks showed smaller changes in exploitation rate. The continued high fishing mortality rate on GOM cod was a result of the previously mentioned revisions to the stock assessment in 2011 and Fishing mortality on five stocks were less than 50 percent of FMSY in the first year of the catch share program, which was the largest number of stocks with low fishing rates of any year of the time series. These instances of low fishing mortality may have been a consequence of constraints on fishing because of the likelihood of incidental takes of species with low ACLs. The percentage of stocks with overfishing or high fishing mortality was relatively unchanged, however. Data Gaps and Limitations Data were available from recent stock assessments for all stocks, but there was no 2010 estimate of fishing mortality for Atlantic pollock. Northeast: Fishery Stock Status Fishing Mortality February

3 The main data limitation for this indicator is that not all stocks are assessed on an annual basis. For that reason, 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. Another limitation is that the fisheries exploitation rate was measured differently for different stocks. For many fisheries, F=catch/(summary biomass), while F MSY =MSY/(summary biomass at MSY). F MSY was sometimes based on a proxy, such as F40% (the fishing mortality that reduces spawning stock biomass to 40 percent). Differences in the way that F MSY 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 Georges Bank Haddock Assessment Update. Northeast Fisheries Science Center Groundfish Assessment Updates Group, N.D.W Stock Assessment of Pollock in US Waters for Northeast Fisheries Science Center Stock Assessment Workshop Legault, C., Alade, L., Emery, S., King, J., and Sherman, S. 2012a. Cape Cod-Gulf of Maine Yellowtail Flounder Groundfish Assessment Update. Northeast Fisheries Science Center Groundfish Assessment Updates Legault, C., Alade, L., Stone, H.H., and Gross, W.E. 2012b. Stock Assessment of Georges Bank Yellowtail Flounder for Transboundary Resources Assessment Committee. Miller, T.J Gulf of Maine-Georges Bank Acadian Redfish. Northeast Fisheries Science Center Groundfish Assessment Updates Northeast Fisheries Science Center nd Northeast Regional Stock Assessment Workshop (52nd SAW): Northeast Fisheries Science Center Reference Document Northeast Fisheries Science Center. 2012a. Gulf of Maine Atlantic Cod (Gadus morhua) Stock Assessment for 2011, Updated through Stock Assessment Workshop 12-05: Northeast Fisheries Science Center. 2012b. Southern New England Mid-Atlantic Yellowtail Flounder (Limanda ferruginea) Stock Assessment for 2012, Updated through Stock Assessment Workshop 12-18: Northeast Fisheries Science Center. 2013a. Stock Assessment of Georges Bank Atlantic Cod (Gadus morhua) for Stock Assessment Workshop 13-11: Northeast Fisheries Science Center. 2013b. Gulf of Maine Atlantic Cod (Gadus morhua) Stock Assessment for 2012, Updated through Northeast Fisheries Science Center Stock Assessment Workshop O Brien, L., and Dayton, J Gulf of Maine-Georges Bank American Plaice Assessment for Northeast Fisheries Science Center Groundfish Assessment Updates Northeast: Fishery Stock Status Fishing Mortality February

4 Palmer, M.C., Sutherland, S., and Brooks, E.N Update of the Gulf of Maine haddock (Melanogrammus aeglefinus) stock assessment: an update of the resource through calendar year Northeast Fisheries Science Center Groundfish Assessment Updates Shepherd, G., Sosebee, K., and Brooks, L Gulf of Maine/Georges Bank White Hake (Urophycis tenuis) Stock Assessment for 2013, Updated through Northeast Fisheries Science Center Reference Documents Van Eeckhaute, L., Brooks, E.N., and Hansen, S.C Assessment of Eastern Georges Bank Haddock for Transboundary Resources Assessment Committee. Wang, Y., and O Brien, L Assessment of Eastern Georges Bank Atlantic Cod for Transboundary Resources Assessment Committee: Wigley, S.E., and Emery, S Witch Flounder. Northeast Fisheries Science Center Groundfish Assessment Updates Northeast: Fishery Stock Status Fishing Mortality February

5 Charts Proportion of Stocks with Experiencing Overfishing and with High Fishing Mortality Fishing Mortality for Allocated Stocks Northeast: Fishery Stock Status Fishing Mortality February