Fish Stocks in Rebuilding Plans: A Trend Analysis

 

Introduction

 

            The control of fishing mortality (F) is essential to rebuilding stocks that have been overfished.  The Magnuson-Stevens Fishery Conservation and Management Act (sec. 304(e)(4)) mandates the National Oceanic Atmospheric Administration (NOAA) and the National Marine Fisheries Service (NMFS) to end overfishing immediately and to rebuild stocks within 10 years.  Overfished stocks can rebuild when overfishing is ended and favorable environmental conditions increase biomass (B).  Rebuilt stocks offer a sustainable and stable seafood supply for fishermen and consumers.

 

            Understanding how total mortality, including F, affects B is essential to rebuilding an overfished stock.  Rebuilding of a stock will generally occur if more fish survive to maturity than are lost to mortality.  There are several types of mortality including natural and fishing mortality.  Natural mortality, such as through predation, occurs regardless of management control.  Fishing mortality (F) can be directly controlled through the management measures of Regional Fisheries Management Councils (RFMC). Management measures to protect essential fish habitats may also help to increase the survival of stock members at critical life stages where natural mortality is higher than at other life stages. 

 

            Using the best available science, rebuilding plans are developed by the RFMCs and approved by NMFS to control F so that a stock can rebuild to sustainable levels.  When F is controlled, more members of the stock can survive and spawn, thus increasing the probability of a stock rebuilding.  NMFS conducts stock assessments to determine the current levels of F and B for the stock, and to estimate, or re-estimate, sustainable values of F (Fmsy) and B (Bmsy) levels for each stock.  Rebuilding plans use these values to predict the time it will take for B to rebuild.  Generally, where F is less than Fmsy, B will increase, approaching Bmsy. However, there are cases where controlling F does not result in increased B.  There are several reasons rebuilding may not occur.  Biomass is affected by a number of factors in addition to fishing, including habitat loss, environmental variability, and community dynamics such as disease outbreaks and predator-prey interactions.   If these factors are not accounted for in the rebuilding plan, it may take longer to rebuild the stock than anticipated; therefore, control of F is necessary for rebuilding but cannot guarantee rebuilding. 

 

Methods and Results

 

  Trends in B and F can demonstrate a rebuilding plan’s progress in achieving targets for overfished stocks.  NMFS reviewed 59 stocks that have at one time been declared overfished (Table 1) to determine if they were candidates for inclusion in a trends analysis. This analysis included stocks that are currently not overfished, but are still rebuilding.  NMFS examined B and F trends in relation to a stock’s biological reference points (B/Bmsy, F/Fmsy).  The latest stock assessment data were used to create figures of a stock’s trends prior to and following an overfished declaration.  Due to the periodic recalculation of F and B by stock assessment scientists, in many figures, the initial estimates of F and B used in the overfished declaration are included to illustrate the uncertainty of stock assessment estimates.  Many stocks have been in rebuilding plans prior to the Sustainable Fisheries Act of 1996 (Table 1) but these initial estimates do not appear in the figures; only estimates for the current overfished declaration are in this analysis. 

 

There are several reasons why some of the (59) stocks were not appropriate for the NMFS analysis. Stocks that were not good candidates for this analysis include: 1) the stock has been recently declared overfished, so a rebuilding plan has not yet been implemented; 2) the rebuilding plan has only recently been adopted and the most recent scientific assessment does not yet reflect its measures; 3) the stock will have its rebuilding plan revised in 2008 because current rebuilding plans have not been successful; 4) the stock has insufficient data to develop a rebuilding plan; 5) the stock does not have reliable estimates of biomass and/or fishing mortality; and 6) stocks whose assessment reports do not reflect the current state of knowledge because biomass and fishing mortality reference points are in the process of being revised. Of the 55 stocks in rebuilding plans, 34 stocks were considered appropriate for the analysis and their F status and B trends are shown in Table 2.

 

Discussion

 

Using data from the most recent stock assessment, figures were created to illustrate the trends in F and B for the 34 stocks.  For most stocks, this time series extends to four years prior to the overfished declaration.  The control of F was evaluated prior to the categorizing of the B trends for each stock.  For this discussion, F is considered controlled if it is reduced or is kept under the overfishing level (F/Fmsy <1). If F is controlled, one would expect B to increase )if conditions are favorable; therefore we evaluated the recent trends based on two criteria: B is increasing or B is not increasing.  In many cases B showed no clear trend in biomass or the biomass is stagnating.  These stocks, such as windowpane flounder, are included in the B is not increasing category.

 

Of the 34 rebuilding stocks that were evaluated, 24 stocks (71%) had F controlled by the end of the time series (Table 2). For these 24 stocks, 18 stocks (75%) show increases in biomass and 6 stocks (25%) show declines or flat trends in biomass. For the remaining 10 stocks where F has not been adequately controlled, 7 (70%) show declines or flat trends in biomass. These results demonstrate the importance in controlling F in order to achieve rebuilding.

 

The seven Northwest (NW) region stocks in this analysis have both controlled overfishing and have increasing biomass.  Most of the NW region stocks are long-lived fish and biomass rebuilds slowly; therefore the rebuilding plan periods are protracted.  The cowcod is estimated to rebuild biomass over a 38 year period.  Despite the slight apparent increase in biomass in the figure, the cowcod has increased B/Bmsy from 0.056 at the overfished declaration to 0.094 at the end of the time series, an increase of 68%.

 

Northwest Region

Stock

F Controlled/ Biomass Increasing

F Controlled/ Biomass Not Increasing

F Not Controlled/ Biomass Increasing

F Not Controlled/ Biomass Not Increasing

bocaccio

 

 

 

canary rockfish

 

 

 

cowcod

 

 

 

darkblotched rockfish

 

 

 

Pacific ocean perch

 

 

 

widow rockfish

 

 

 

yelloweye rockfish

 

 

 

Percentage of Stocks in Category

100%

 

 

 

 


 

 

            The Northeast (NE) region had 19 stocks in rebuilding plans that were evaluated.  Of these, 12 (63%) have successfully controlled F during the available time series.  Of those 12 stocks, 8 (67%) are rebuilding biomass.  Of the 7 overfished NE stocks where overfishing was occurring, 6 (86%) have declining biomass.  Overfishing of summer flounder occurred throughout this time series yet biomass increased from the overfishing declaration until 2006.

           

Northeast Region

Stock

F Controlled/ Biomass Increasing

F Controlled/ Biomass Not Increasing

F Not Controlled/ Biomass Increasing

F Not Controlled/ Biomass Not Increasing

American plaice

 

 

 

barndoor skate

 

 

 

bluefish (except Gulf of Mexico)

 

 

 

cod – Georges Bank

 

 

 

cod – Gulf of Maine

 

 

 

golden tilefish

 

 

 

haddock – Georges Bank

 

 

 

haddock – Gulf of Maine

 

 

 

ocean pout

 

 

 

pollock

 

 

 

redfish

 

 

 

spiny  dogfish

 

 

 

summer flounder

 

 

 

thorny skate

 

 

 

white hake

 

 

 

windowpane flounder – SNE/MA

 

 

 

winter flounder – SNE/MA

 

 

 

yellowtail flounder – CC/GoM

 

 

 

yellowtail flounder – SNE/MA

 

 

 

Percentage of Stocks in Category

42%

21%

5%

32%

 

The South Atlantic (SA) region has controlled overfishing in 2 out of the 3 stocks in this evaluation.  As expected, king mackerel gulf group and red porgy, where overfishing has ended, are rebuilding biomass.  However, despite ongoing overfishing, greater amberjack Gulf of Mexico continued to build biomass every year after the overfished declaration, except for 2005.

 

Southeast Region

Stock

F Controlled/ Biomass Increasing

F Controlled/ Biomass Not Increasing

F Not Controlled/ Biomass Increasing

F Not Controlled/ Biomass Not Increasing

greater amberjack – Gulf of Mexico

 

 

 

king mackerel – Gulf group

 

 

 

red porgy

 

 

 

Percentage of Stocks in Category

67%

 

33%

 

 

 

 

            The Highly Migratory Species management program has 5 stocks that were evaluated.  Of these 5 stock, 3 (60%) have successfully controlled F; only 1 of these 3 stocks, swordfish – North Atlantic has increasing biomass, as one would expect with lower fishing mortality.  The 2 HMS stocks where overfishing is occurring are responding in different ways: Bluefin tuna with decreasing biomass as one would expect and albacore – North Atlantic with increased biomass.

 

Highly Migratory Species Division

Stock

F Controlled/ Biomass Increasing

F Controlled/ Biomass Not Increasing

F Not Controlled/ Biomass Increasing

F Not Controlled/ Biomass Not Increasing

swordfish – North Atlantic

 

 

 

bigeye tuna - Atlantic

 

 

 

albacore - North Atlantic

 

 

 

sandbar shark

 

 

 

bluefin tuna – West Atlantic

 

 

 

Percentage of Stocks in Category

20%

40%

20%

20%

 

 

 


Table 1.  Northeast region stocks that have been declared overfished and have rebuilding plans.  The rationale for exclusion from the analysis is provided.  *These stocks are part of the Northeast Multispecies FMP and have been in a rebuilding plan since 1986.

 

 

Stock

Jurisdiction

Rebuilding Program Progress

Status of Analysis

Northeast Region

 

Cod - Gulf of Maine*

NEFMC

4/10-year plan

Included in Analysis

Cod - Georges Bank*

NEFMC

4/22-year plan

Included in Analysis

Haddock - Gulf of Maine*

NEFMC

4/10-year plan

Included in Analysis

Haddock - Georges Bank*

NEFMC

4/10-year plan

Included in Analysis

American Plaice*

NEFMC

4/10-year plan

Included in Analysis

Redfish*

NEFMC

4/47-year plan

Included in Analysis

Yellowtail Flounder - Georges Bank

NEFMC

2/8-year plan

2) The rebuilding plan has only recently been adopted and the most recent scientific assessment does not yet reflect its measures

Yellowtail Flounder - Southern New England/Middle Atlantic*

NEFMC

4/10-year plan

Included in Analysis

Yellowtail Flounder - Cape Cod / Gulf of Maine*

NEFMC

4/19-year plan

Included in Analysis

White Hake*

NEFMC

4/10-year plan

Included in Analysis

Pollock*

NEFMC

4/10-year plan

Included in Analysis

Windowpane Flounder - Southern New England /Middle Atlantic*

NEFMC

4/10-year plan

Included in Analysis

Winter Flounder - Southern New England / Middle Atlantic*

NEFMC

4/10-year plan

Included in Analysis

Ocean Pout*

NEFMC

4/10-year plan

Included in Analysis

Atlantic Halibut

NEFMC

N/A

4) the stock has insufficient data to develop a rebuilding plan

Winter Skate

NEFMC

N/A

1) the stock has been recently declared overfished, so a rebuilding plan has not yet been implemented

Barndoor Skate

NEFMC

year 5 of plan

Included in Analysis

Thorny Skate

NEFMC

year 5 of plan

Included in Analysis

Monkfish - North

NEFMC / MAFMC

8/10-year plan

6) stocks whose assessment reports do not reflect the current state of knowledge because biomass and fishing mortality reference points are in the process of being revised.  NOTE: When these new reference points are adopted in 2008, the stocks will be declared rebuilt

Monkfish - South

NEFMC / MAFMC

8/10-year plan

6) stocks whose assessment reports do not reflect the current state of knowledge because biomass and fishing mortality reference points are in the process of being revised.  NOTE: When these new reference points are adopted in 2008, the stocks will be declared rebuilt

Spiny Dogfish

NEFMC / MAFMC

8/5-year plan

Included in Analysis

Summer Flounder

MAFMC

8/13-year plan

Included in Analysis

Scup

MAFMC

N/A

2) The rebuilding plan has only recently been adopted and the most recent scientific assessment does not yet reflect its measures.  NOTE: The rebuilding plan will be implemented on 1/1/08.

Black Sea Bass

MAFMC

8/10-year plan

5) the stock does not have reliable estimates of biomass and/or fishing mortality

Bluefish (except Gulf of Mexico)

MAFMC

7/9-year plan

Included in Analysis

Butterfish (Atlantic)

MAFMC

N/A

1) the stock has been recently declared overfished, so a rebuilding plan has not yet been implemented.  NOTE: The rebuilding plan is expected to be implemented by 1/1/09

Golden Tilefish (except South Atlantic and Gulf of Mexico)

MAFMC

7/10-year plan

Included in Analysis

* These stocks are part of the Northeast Multispecies FMP and have been in a rebuilding plan since 1986.


Table 1 continued.  South Atlantic, Northwest, and Pacific Island region stocks that have been declared overfished and have rebuilding plans.  The rationale for exclusion from the analysis is provided.

 

South Atlantic Region

 

Snowy Grouper

SAFMC

15/15-year plan

3) the stock will have its rebuilding plan revised in 2008 because current rebuilding plans have not been successful

Black Sea Bass

SAFMC

7/10-year plan

3) the stock will have its rebuilding plan revised in 2008 because current rebuilding plans have not been successful

Red Porgy

SAFMC

9/18-year plan

Included in Analysis

King Mackerel - Gulf Group

SAFMC / GMFMC

year 20 of plan

Included in Analysis

Red Snapper

GMFMC

7/31-year plan

5) the stock does not have reliable estimates of biomass and/or fishing mortality

Greater Amberjack

GMFMC

5/10-year plan

Included in Analysis

Grouper Unit 1

CFMC

3/25-year plan

5) the stock does not have reliable estimates of biomass and/or fishing mortality

Grouper Unit 2

CFMC

3/30-year plan

5) the stock does not have reliable estimates of biomass and/or fishing mortality

Grouper Unit 4

CFMC

3/10-year plan

5) the stock does not have reliable estimates of biomass and/or fishing mortality

Queen Conch

CFMC

3/30-year plan

5) the stock does not have reliable estimates of biomass and/or fishing mortality

Northwest Region

 

Pacific Ocean Perch

PFMC

8/18-year rebuilding plan

Included in Analysis

Bocaccio

PFMC

8/27-year rebuilding plan

Included in Analysis

Canary Rockfish

PFMC

7/63-year rebuilding plan

Included in Analysis

Darkblotched Rockfish

PFMC

6/10-year rebuilding plan

Included in Analysis

Cowcod

PFMC

7/39-year rebuilding plan

Included in Analysis

Yelloweye Rockfish

PFMC

5/82-year rebuilding plan

Included in Analysis

Widow Rockfish

PFMC

6/14-year rebuilding plan

Included in Analysis

Pacific Islands Region

 

Seamount Groundfish Complex - Hancock Seamount

WPFMC

in progress

5) the stock does not have reliable estimates of biomass and/or fishing mortality

* These stocks are part of the Northeast Multispecies FMP and have been in a rebuilding plan since 1986.


Table 1 continued.  Alaska region and Highly Migratory stocks that have been declared overfished and have rebuilding plans.  The rational for exclusion from the analysis is provided.

 

Alaska Region

 

Blue King Crab - Pribilof Islands

NPFMC

4/10-year plan

6) stocks whose assessment reports do not reflect the current state of knowledge because biomass and fishing mortality reference points are in the process of being revised.

Blue King Crab - Saint Matthews Island

NPFMC

8/10-year plan

6) stocks whose assessment reports do not reflect the current state of knowledge because biomass and fishing mortality reference points are in the process of being revised.

Snow Crab - Bering Sea

NPFMC

8/10-year plan

6) stocks whose assessment reports do not reflect the current state of knowledge because biomass and fishing mortality reference points are in the process of being revised.

Highly Migratory Species

 

Blue Marlin - Atlantic

HMS

Phase I implemented

5) the stock does not have reliable estimates of biomass and/or fishing mortality

White Marlin - Atlantic

HMS

Phase I implemented

5) the stock does not have reliable estimates of biomass and/or fishing mortality

Sailfish - West Atlantic

HMS

not internationally implemented

5) the stock does not have reliable estimates of biomass and/or fishing mortality

Bigeye Tuna - Atlantic

HMS

not internationally implemented

Included in Analysis

Albacore - North Atlantic

HMS

not internationally implemented

Included in Analysis

Bluefin Tuna - West Atlantic

HMS

10/20-year plan

Included in Analysis

Swordfish - North Atlantic

HMS

8/10-year plan

Included in Analysis

Sandbar Shark

HMS

4/26-year plan

Included in Analysis

Large Coastal Shark Complex

HMS

4/26-year plan

5) the stock does not have reliable estimates of biomass and/or fishing mortality.  NOTE: Although this stock complex is currently listed as overfished, it is still managed under a rebuilding plan

Porbeagle Shark

HMS

N/A

1) the stock has been recently declared overfished, so a rebuilding plan has not yet been implemented

Dusky Shark

HMS

N/A

1) the stock has been recently declared overfished, so a rebuilding plan has not yet been implemented

* These stocks are part of the Northeast Multispecies FMP and have been in a rebuilding plan since 1986.


Table 2.  Quad chart containing all overfished stocks evaluated in this document.  The green and red colors highlight stock that have biomass (B) responding as expected to fishing mortality (F).  The yellow color indicates the stocks are not responding to F status as expected. 

 


 

F is controlled (Slides)

F/FMSY >1 (Overfishing)

B/BMSY

increasing

barndoor skate

bluefish (except Gulf of Mexico)

bocaccio

canary rockfish

cowcod

darkblotched rockfish

golden tilefish

haddock – Georges Bank*

haddock – Gulf of Maine*

king mackerel – gulf group

Pacific ocean perch

pollock*

red porgy

redfish*

Spiny  dogfish

swordfish – North Atlantic

widow rockfish

yelloweye rockfish

albacore - North Atlantic

greater amberjack - GoM

summer flounder

 

 Slides

 

B/BMSY

Not increasing

American plaice*

bigeye tuna - Atlantic

ocean pout*

sandbar shark

thorny skate

windowpane flounder – SNE/MA*

Slides

bluefin tuna – West Atlantic

cod – Georges Bank*

cod – Gulf of Maine*

white hake*

winter flounder – SNE/MA*

yellowtail flounder – SNE/MA*

yellowtail flounder – CC/GoM*

Slides

* These stocks are part of the Northeast Multispecies FMP and have been in a rebuilding plan since 1986.