Case studies of Harvest Strategies in global fisheries

Explore the diversity of harvest strategies around the globe

Case studies world map

 Stocks with active harvest strategies

 Stocks with harvest strategies in development

1

1

 

Southern Bluefin Tuna

Case Studies - Southern Bluefin Tuna

Managed by:

CCSBT

Adoption Year:

Adopted in 2001; updated in 2019

See full information
2

2

 

North Atlantic Albacore

Case Studies - North Atlantic Albacore

Managed by:

ICCAT

Adoption Year:

2017/2021

See full information
3

3

 

Greenland Hallibut

Case Studies - Greenland Hallibut

Managed by:

NAFO

Adoption Year:

Adopted in 2010; Updated in 2017

See full information
4

4

 

Indian Ocean Skipjack Tuna

Case Studies - Indian Ocean Skipjack Tuna

Managed by:

IOTC

Adoption Year:

2016

See full information
5

5

 

Tiger Flathead

Case Studies - Tiger Flathead

Managed by:

Australia (domestic)

Adoption Year:

2009

See full information
6

6

 

Deep-water and Shallow-water Hake

Case Studies - Deep-water and Shallow-water Hake

Managed by:

South Africa (domestic)

Adoption Year:

1990; Updated in 2018

See full information
7

7

 

British Columbia Sablefish

Case Studies - British Columbia Sablefish

Managed by:

Canada (domestic)

Adoption Year:

2010

See full information
8

8

 

Rock Lobster

Case Studies - Rock Lobster

Managed by:

New Zealand (domestic)

Adoption Year:

1997

See full information
9

9

 

Atlantic Herring

Case Studies - Atlantic Herring

Managed by:

United States Domestic Fisheries

Adoption Year:

2019

See full information
10

10

 

North Pacific Albacore

Case Studies - North Pacific Albacore

Managed by:

WCPFC / IATTC

Expected Adoption Year:

2022

See full information
11

11

 

Pacific Bluefin Tuna

Case Studies - Pacific Bluefin Tuna

Managed by:

WCPFC / IATTC

Expected Adoption Year:

2024

See full information
12

12

 

Indian Ocean Yellowfin Tuna

Case Studies - Indian Ocean Yellowfin Tuna

Managed by:

IOTC

Expected Adoption Year:

2023

See full information
13

13

 

Indian Ocean Albacore Tuna

Case Studies - Indian Ocean Albacore Tuna

Managed by:

IOTC

Expected Adoption Year:

2024

See full information
14

14

 

Indian Ocean Swordfish

Case Studies - Indian Ocean Swordfish

Managed by:

IOTC

Expected Adoption Year:

2024

See full information
15

15

 

Indian Ocean Bigeye Tuna

Case Studies - Indian Ocean Bigeye Tuna

Managed by:

IOTC

Adoption Year:

2022

See full information
16

16

 

North Atlantic Swordfish

Case Studies - North Atlantic Swordfish

Managed by:

ICCAT

Expected Adoption Year:

2023

See full information
17

17

 

Western and Eastern Atlantic Bluefin Tuna

Case Studies - Western and Eastern Atlantic Bluefin Tuna

Managed by:

ICCAT

Expected Adoption Year:

2022

See full information
18

18

 

WCPO Skipjack Tuna

Case Studies - WCPO Skipjack Tuna

Managed by:

WCPFC

Expected Adoption Year:

2022

See full information
19

19

 

South Pacific Albacore

Case Studies - South Pacific Albacore

Managed by:

WCPFC

Expected Adoption Year:

2023

See full information
20

20

 

EPO Bigeye Tuna

Case Studies - EPO Bigeye Tuna

Managed by:

IATTC

Expected Adoption Year:

2024

See full information
21

21

 

Pacific Halibut

Case Studies - Pacific Halibut

Managed by:

IPHC

Adoption Year:

2020

See full information
22

22

 

Norwegian Spring Spawning Herring

Case Studies - Norwegian Spring Spawning Herring

Managed by:

NEAFC

Expected Adoption Year:

2023

See full information
23

23

 

Blue Whiting

Case Studies - Blue Whiting

Managed by:

NEAFC

Expected Adoption Year:

2023

See full information
24

24

 

Western Atlantic Skipjack Tuna

Case Studies - Western Atlantic Skipjack Tuna

Managed by:

ICCAT

Expected Adoption Year:

2023

See full information
25

25

 

WCPO Bigeye Tuna

Case Studies - WCPO Bigeye Tuna

Managed by:

WCPFC

Expected Adoption Year:

2024

See full information
26

26

 

WCPO Yellowfin Tuna

Case Studies - WCPO Yellowfin Tuna

Managed by:

WCPFC

Expected Adoption Year:

2023

See full information
27

27

 

Pacific Saury

Case Studies - Pacific Saury

Managed by:

NPFC

Expected Adoption Year:

2023

See full information
28

28

 

Atlantic Mackerel

Case Studies - Atlantic Mackerel

Managed by:

NEAFC

Expected Adoption Year:

2022

See full information

Tuna

Swordfish

Bottomfish

Forage Fish

Lobster

Harvest strategies are a tool that is being used successfully around the world for all different types of fisheries – predators and prey, surface species and bottomfish, international and domestic. This interactive map showcases the global breadth of harvest strategies, including both active harvest strategies (in teal) and those in development (in orange). Navigating this interactive is easy- click on any silhouette to view the details of a that fish’s harvest strategy in that particular location.


Is your stock missing from the map? We want to include you!


FACTSHEET: Case Studies of Harvest Strategies in Global Fisheries; Language Options: Español 🇪🇸 • Français 🇫🇷 • 日本 🇯🇵 • ไทย 🇹🇭

1Active Harvest Strategy

Southern Bluefin Tuna

Case Studies - Southern Bluefin Tuna
 
Case Studies - Southern Bluefin Tuna map

Management Authority:

Commission for the Conservation of Southern Bluefin Tuna

Adoption Year:

Adopted in 2001; updated in 2019

Management Objectives:

  • Convention objective: “Ensure, through appropriate management, the conservation and optimum utilization of southern bluefin tuna”
  • Harvest strategy objectives: See target reference points below

Reference Points:

  • Limit Reference Point: 24% SSB0
  • Target Reference Point (long-term): 30% SSB0 by 2035, with a 50% chance of success

*SSB0 = spawning stock size that would exist in the absence of fishing

Harvest Strategy:

Fully-specified ‘Cape Town Procedure’ adopted in 2019 was tested through comprehensive MSE process.

Specifications:

  • Type:Empirical
  • Management cycle: 3 years
  • Data inputs: Longline catch per unit effort index, gene tagging, close-kin genetics
  • Management output: Quota
  • Harvest control rule: Hybrid rule that increases or decreases quota using model-based log-linear trend in adult biomass inferred by an age-structured model using genetic data and an empirical-based-staged response to CPUE.
  • Other:
    Maximum quota change = 3000 t (~15-20%)
    Minimum quota change = 100 t

Outcome:

Quotas have increased each management cycle since the harvest strategy was adopted (an 87% increase between 2011 and 2020). The number of adult fish increased from 5% SSB0 in 2010 to 20% SSB0 in 2020.

Link to relevant policy document or update:

2Active Harvest Strategy

North Atlantic Albacore

Case Studies - North Atlantic Albacore
 
Case Studies - North Atlantic Albacore map

Management Authority:

International Commission for the Conservation of Atlantic Tunas

Adoption Year:

2017/2021

Management Objectives:

  • Maintain stock in green quadrant of Kobe plot with at least 60% probability while maximizing long-term yield
  • Rebuild to or above SSBMSY with at least 60% probability within as short a time as possible, while maximizing average catch and minimizing TAC changes

Reference Points:

  • B-Threshold Reference Point (interim): BMSY
  • B-Limit Reference Point (interim): 40% BMSY
  • F-Target Reference Point (interim): 80% FMSY
  • F- Minimum Reference Point (interim): 10% FMSY

Harvest Strategy:

Adopted in 2021, ICCAT successfully converted the HCR into a full harvest strategy through the addition of an exceptional circumstances protocol and the specification of the data collection and assessment methods needed to apply the HCR.

Specifications:

  • Type: Model-based
  • Management cycle: 3 years
  • Data inputs: Stock assessment estimates of current stock biomass (Bcurr) with respect to BMSY, stock biomass at maximum sustainable yield (BMSY), fishing mortality at MSY (FMSY)
  • Management output: Quota
  • Harvest control rule:
    If B>BTHRESHOLD (BMSY), fish at FTARGET (80%FMSY)
    If BLIM<B<BTHRESHOLD, reduce F linearly as specified in HCR
    If B<BLIM, suspend fishery and initiate scientific monitoring at FMIN (10% FMSY)
  • Other:
    Maximum catch limit: 50,000t
    Maximum quota change: +25%/-20% if current biomass is above BTHRESHOLD

Outcome:

The stock was declared recovered in 2016, a year before the HCR was adopted. The 2018-20 quota set by the HCR was limited by the 20% maximum change clause included in the original HCR. Using the 2020 stock assessment, the HCR recommended a TAC increase for the 2021-23 management period which was agreed to by all parties without controversy, despite the virtual meeting necessitated by COVID-19.

3Active Harvest Strategy

Greenland Hallibut

Case Studies - Greenland Hallibut
 
Case Studies - Greenland Hallibut map

Management Authority:

North East Atlantic Fisheries Commission

Adoption Year:

Adopted in 2010; Updated in 2017

Management Objectives:

  • Restore to within a prescribed period of time or maintain at BMSY (chance of B2037<BMSY is ≤ 50%)
  • The risk of failure to meet the BMSY target and interim biomass targets within a prescribed period of time should be kept moderately low
  • Low risk (<30% chance) of exceeding FMSY
  • Very low risk (<10%) of going below an established threshold [e.g. Blim or Blim proxy]
  • Maximize yield in the short, medium and long term (5,10, 20 years, respectively)
  • The risk of steep decline of stock biomass should be kept moderately low
  • Keep inter annual TAC variation below “an established threshold” (i.e., 15%)

Reference Points:

  • Target reference point: BMSY
  • Proxy limit reference point: 30%BMSY

Harvest Strategy:

The original HCR adopted in 2010 proved unsuccessful and was modified in 2017. The current harvest strategy will be implemented until 2024, so a new one will be adopted in 2023. If circumstances occur outside the ranges tested by the MSE, the exceptional circumstances protocol will be triggered, possibly changing the HCR.

Specifications:

  • Type: Empirical
  • Management cycle: 3 years
  • Data inputs: Five survey-based abundance indices
  • Management output: Quota
  • Harvest control rule: Combination of a target-based and slope-based rule that increases or decreases quota depending on the current TAC and recent trends in survey biomass
  • Other:
    Maximum quota change: +/- 10%

Outcome:

Greenland halibut are considered overfished. The initial HCR adopted in 2010 had to be revised in 2017 as the exceptional circumstance protocol was triggered in 4 out of 6 years, likely due to annual catch estimates far exceeding the TAC. The TAC based on the current HCR increased in 2019 to 16521 t but decreased for 2022 to 15,864 t.

Link to relevant policy document or update:

4Active Harvest Strategy

Indian Ocean Skipjack Tuna

Case Studies - Indian Ocean Skipjack Tuna
 
Case Studies - Indian Ocean Skipjack Tuna map

Management Authority:

Indian Ocean Tuna Commission

Adoption Year:

2016

Management Objectives:

  • Maintain stock at levels that can produce MSY, as qualified by relevant environmental and economic factors
  • Use HCR to maintain stock at or above the target and well above the limit

Reference Points:

  • Target/Threshold Reference Point: 40%B0
  • Limit Reference Point: 20%B0
  • Safety Reference Point: 10%B0

*B0 = stock size that would exist in the absence of fishing

Harvest Strategy:

The current HCR is slated to be expanded to a fully specified harvest strategy in 2023 or 2024.

 

Harvest control rule specifications:
  • Type: Model-based
  • Management cycle: 3 years
  • Data inputs: Stock assessment estimates of current spawning stock biomass (Bcurr); unfished stock biomass (B0); equilibrium exploitation rate (Etarg) associated with sustaining the stock at Btarg
  • Management output: Quota
  • Harvest control rule: Reduces catch linearly from the threshold level (0.4B0) to the safety level (0.1B0); zero catch below safety level, except for subsistence fisheries
  • Other:
    Maximum catch limit: 900,000t
    Maximum quota change: +/- 30%

Outcome:

Based on the 2020 stock assessment, the stock is currently not overfished or experiencing overfishing. Current spawning stock biomass is estimated to be at 0.45B0, above the target reference point. However, because there is no allocation key, the HCR-associated TAC has been exceeded by up to 30% in every year since adoption. Overages are expected to continue until the quota is allocated. Regardless, the TAC was increased by almost 10% to 513,572 t for the 2021-2023 period as the skipjack stock continues to be productive regardless of these overages, likely due to favorable environmental conditions.

5Active Harvest Strategy

Tiger Flathead

Case Studies - Tiger Flathead
 
Case Studies - Tiger Flathead map

Management Authority:

Australia (domestic)

Adoption Year:

2009

Management Objectives:

Biological

  • To maintain stocks at (on average), or return to, a target biomass point BTARG or equivalent proxy (e.g. FTARG or CPUETARG) equal to the stock size that aims to maximise net economic returns for the fishery as a whole
  • To maintain stocks above the limit biomass level, or an appropriate proxy, at least 90% of the time
  • A reduced level of fishing if a stock is below BTARG but above BLIM (or an appropriate proxy)
  • To implement rebuilding strategies, no-targeting and incidental bycatch TACs if a stock moves below BLIM (or an appropriate proxy)
  • To ensure the sustainability of fisheries resources, including consideration of the individual fishery circumstances and individual species or stock characteristics, when developing a management approach

Socio-economic

  • To maintain stocks at (on average), or return to, a target biomass point BTARG equal to the stock size that aims to maximise net economic returns for the fishery as a whole
  • To maximise the profitability of the fishing industry and the net economic returns to the Australian community
  • To minimise costs to the fishing industry, including consideration of the impacts on the industry of large or small changes in TACs and the appropriateness of multi-year TACs

Ecosystem

  • To be consistent with the principles of ecologically sustainable development, including the conservation of biological diversity, and the adoption of a precautionary risk approach

Reference Points:

  • Limit Reference Point: 20%B0
  • Trigger Reference Point: 35%B0
  • Target Reference Point: 120%BMSYand 48%B0

*B0 = stock size that would exist in the absence of fishing
*120%BMSY is a proxy for BMEY, the biomass that will produce maximum economic yield

Harvest Strategy:

This fully specified, MSE-tested harvest strategy framework applies to the Southern and Eastern scalefish and shark fishery, with each stock applying one of four different HCRs included in the harvest strategy.

Specifications:

  • Type: Empirical
  • Management cycle: 3 years
  • Data inputs: CPUE, indices of abundance, size and age data
  • Management output: Quota
  • Harvest control rule: If B is below limit, no targeted fishing and a rebuilding strategy will be developed; if below trigger, TAC declines linearly toward the target to allow stock to rebuild to target level; if above target, fish at F that produces target biomass (i.e., F48); if between trigger and target, also fish at F48to account for uncertainty in status

Outcome:

According to the most recent 2019 assessment, the stock is considered sustainable at 34% of unfished spawning stock biomass, above Bmsy but below the TRP. The current level of fishing pressure under the HCR is unlikely to deplete the stock or impair recruitment.

Link to relevant policy document or update:

6Active Harvest Strategy

Deep-water and Shallow-water Hake

Case Studies - Deep-water and Shallow-water Hake
 
Case Studies - Deep-water and Shallow-water Hake map

Management Authority:

South Africa (domestic)

Adoption Year:

1990; Updated in 2018

Management Objectives:

Maintain both stocks about BMSY and balance trade-offs between catch, effort and inter-annual variability in TAC

Reference Points:

Target Reference Point: BMSY

Harvest Strategy:

A fully specified harvest strategy that has been tested via MSE. It includes rules for Exceptional Circumstances for when certain key indices drop below pre-determined threshold values, or when further observations fall outside the range tested within the MSE. Operating models for the MSE continue to be updated, most recently in 2021, to account for new data.

Specifications:

  • Type: Empirical
  • Management cycle: Annual
  • Data inputs: Commercial CPUE and survey abundance indices.
  • Management output: Quota
  • Harvest Control Rule: TAC recommendations are based on the output of the harvest strategy formula

Outcome:

The 2021 assessment showed both hake stocks above the B-based target reference points. While the TAC trend has been downwards since 2020, the harvest strategy is responding properly to some recent recruitments lower than average to ensure the stocks are maintained near or above BMSY. The harvest strategy will be revised in 2022.

7Active Harvest Strategy

British Columbia Sablefish

Case Studies - British Columbia Sablefish
 
Case Studies - British Columbia Sablefish map

Management Authority:

Canada (domestic)

Adoption Year:

2010

Management Objectives:

  • Maintain female spawning stock biomass above the LRP of 0.4BMSY in 95% of years measured over two sablefish generations (36 years)
  • When in the Cautious Zone (i.e., 0.4BMSY<B<0.8BMSY), limit the probability of decline over the next 10 years to very low (5%) at the LRP, increasing linearly to moderate (50%) at the TRP
  • Maintain the female spawning biomass above BMSY, or 0.8BMSY when rebuilding from the Cautious Zone, in the year 2052 with 50% probability
  • Minimize probability that annual TAC levels are below 1,992 tonnes measured over two Sablefish generations
  • Maximize the average annual catch over 10 years, subject to meeting the four objectives above

Reference Points:

  • Upper Stock Reference Point: 0.8BMSY
  • Limit Reference Point: 0.4BMSY
  • Target Reference Point: BMSY or 0.8BMSY (when rebuilding from the Cautious Zone)

Harvest Strategy:

A fully specified harvest strategy that has been tested via MSE. Operating models for the MSE continue to be updated, most recently in 2019, to account for new data.

Specifications:

  • Type: Model-based
  • Management cycle: Annual
  • Data inputs: Stock assessment using a surplus production model
  • Management output: Quota
  • Harvest Control Rule: A harvest control rule in which the harvest rate on legal-sized sablefish is reduced linearly from UMSY (maximum sustainable yield), when the estimated stock is above 0.6BMSY, to zero when the estimated stock size is less than 0.4BMSY

Outcome:

A 2019 update found that sablefish have now recovered to or above 0.8BMSY with 50% probability, so are now outside of the Cautious Zone. The 2019-2020 TAC was the highest TAC recommenced thus far by the HCR.

8Active Harvest Strategy

Rock Lobster

Case Studies - Rock Lobster
 
Case Studies - Rock Lobster map

Management Authority:

New Zealand (domestic)

Adoption Year:

1997

Management Objectives:

Per New Zealand’s Harvest Strategy Standard:

  • Achieve the MSY-compatible target or better with at least 50% likelihood
  • Limit the risk of breaching the soft limit to no more than 10%
  • Limit the risk of breaching the hard limit to no more than 2%

Reference Points:

  • Target Reference Point: BMSYor BREFa historical stock size proxy from when the stock had” good productivity and was demonstrably safe”; BREFis always ≥ BMSY
  • Soft Limit:20%SSB0or 50%BREF
  • Hard Limit:10%SSB0or 25%BREF

*SSB0 = spawning stock size that would exist in the absence of fishing

Harvest Strategy:

  • Type: Empirical
  • Management cycle: 5 years
  • Data inputs: CPUE
  • Management output: Quota
  • Harvest control rule: There are 4 different rock lobster stocks that have an HCR, and each is slightly different. They include step and sliding rules.
  • Other: Varies by stock, but most set a minimum quota change.

Outcome:

All but one of the ten lobster stocks in New Zealand are above the target. The single stock considered overfished is still above both the soft and hard limits, according to a 2018 assessment. While the 2022 assessment has yet to be completed for the stock, initial information suggests abundance may be increasing for the stock under current management controls. In 2019, the MPs for two management areas recommended increases in TAC. Two management areas are no longer managed by harvest strategies due to a loss of some of the catch/ effort data, which had been used as the basis for the harvest strategies.

Link to relevant policy document or update:

Operational management procedures of New Zealand rock lobster stocks for 2020–21: Describes performance of harvest strategies and recommendations

9Active Harvest Strategy

Atlantic Herring

Case Studies - Atlantic Herring
 
Case Studies - Atlantic Herring map

Management Authority:

United States Domestic Fisheries

Adoption Year:

2019

Management Objectives:

  • SSB/SSBMSY = 100%, with an acceptable level as low as 85%;
  • Variation in annual yield is <10%, with an acceptable level as high as 25%;
  • Probability of overfished 0%, with an acceptable level as high as 25%;
  • Probability of herring fishery closure between 0-10%.

Reference Points:

Upper biomass parameter (overfished threshold): 50%SSBMSY
Lower biomass parameter (closes fishery): 10%SSBMSY
Maximum fishing mortality: 80%FMSY

Harvest Strategy:

Measure includes only a harvest control rule as opposed to a full harvest strategy.

Specifications:

  • Type: Model-based
  • Management cycle: 3 years, but quota may be different each year
  • Data inputs: Recruitment estimates derived from 1995 VPA, mean weights at age, surplus production model
  • Management output: Quota
  • Harvest control rule: When biomass is greater than 50% of SSB/SSBMSY, the maximum
    fishing mortality allowed is 80% of FMSY, so 20% of FMSY is left for herring predators. As biomass declines further, fishing mortality declines linearly, and if biomass falls below 10% of SSB/SSBMSY, the fishery closes.

Outcome:

The MSE-tested HCR was implemented for the first time in 2019. Following accounting of the 2020 catches, catch limits decreased for 2022 and 2023 due to overages in 2020.

10Harvest Strategy in development

North Pacific Albacore

Case Studies - North Pacific Albacore
 
Case Studies - North Pacific Albacore map

Management Authority:

Western and Central Pacific Fisheries Commission/ Inter-American Tropical Tuna Commission

Expected Adoption Year:

2022

Management Objectives:

WCPFC Interim Management Objective:

  • Maintain the biomass, with reasonable variability, around its current level in order to allow recent exploitation levels to continue and with a low risk of breaching the limit reference point

MSE Candidate Management Objectives:

  • Maintain spawning biomass above the limit reference point
  • Maintain depletion of total biomass around historical average depletion
  • Maintain catches by fishery above average historical catch
  • Change in total allowable catch between years should be relatively gradual
  • Maintain fishing intensity (F) at the target value with reasonable variability

Reference Points:

WCPFC:

  • Limit Reference Point: 20%SSBcurrent F=0
  • Target Reference Point: To be determined based upon socioeconomic factors

Ranges for proposed reference points for new harvest strategy:

  • Target Reference Point: F40-F50
  • Threshold Reference Point: 14-30% SSB0
  • Limit Reference Point: 7%-20% SSB

*SSBcurrent F=0 = stock size that would exist in absence of fishing

Candidate Harvest Strategies:

MSE evaluated numerous sliding, “hockey-stick,” model-based harvest control rules that decrease F from Ftarget once the spawning stock biomass drops below SSBthreshold toward SSBlimit. The fishery is closed at SSBlimit.

  • Sets total allowable catch for longlines or total allowable effort for surface fleets

Progress Update & Workplan:

2021: Final MSE results presented
2022: 
Adoption of a final harvest strategy

Link to relevant policy document or update:

11Harvest Strategy in development

Pacific Bluefin Tuna

Case Studies - Pacific Bluefin Tuna
 
Case Studies - Pacific Bluefin Tuna map

Management Authority:

Western and Central Pacific Fisheries Commission/ Inter-American Tropical Tuna Commission

Expected Adoption Year:

2024

Management Objectives:

WCPFC Interim Management Objective:

  • Support thriving Pacific bluefin tuna fisheries across the Pacific Ocean while recognizing that the management objectives of the WCPFC are to maintain or restore the stock at levels capable of producing maximum sustainable yield
  • Maintain an equitable balance of fishing privileges among countries
  • Seek cooperation with IATTC to find an equitable balance between the fisheries in the western and central Pacific Ocean (WCPO) and those in the eastern Pacific Ocean (EPO).

Reference Points:

  • Initial Rebuilding Target: historical median biomass (equivalent to 6.4%SSB0) by 2024
  • Second Rebuilding Target: 20% SSBF=0by 2034
  • Candidate Limit Reference Points: 5%SSBF=0, 7.7%SSBF=0, 15%SSBF=0, 20%SSBF=0
  • Candidate Threshold Reference Points: 15%SSBF=0, 20%SSBF=0, 25%SSBF=0
  • Candidate Target Reference Points: 10%FSPR, 15%FSPR, 20%FSPR, 30%FSPR, 40%FSPR
  • Candidate Fmin: 5%Ftarget, 10%Ftarget

*SSBF=0 = spawning stock size that would exist in the absence of fishing

*SPR = Spawning Potential Ratio, or the lifetime spawning output that a young fish is expected to produce under current fishing mortality compared to what it would produce in the absence of fishing.

Candidate Harvest Strategies:

Model-based, sliding HCRs are being explored in the initial MSE work, with a view to develop a comprehensive harvest strategy.

Progress Update & Workplan:

2022-2023: Operationalize management objectives, develop MSE
2024: Provide feedback on MSE, adopt harvest strategy

Link to relevant policy document or update:

12Harvest Strategy in development

Indian Ocean Yellowfin Tuna

Case Studies - Indian Ocean Yellowfin Tuna
 
Case Studies - Indian Ocean Yellowfin Tuna map

Management Authority:

Indian Ocean Tuna Commission

Expected Adoption Year:

2023

Management Objectives:

Tuning Objectives (for MSE purposes):

  • Pr(B(2029)>=B(MSY) ) = 0.5 (SB in 2029 exceeds SBMSY in exactly 50% of the simulations)
  • Pr(B(2034)>=B(MSY) ) = 0.6 (SB in 2034 exceeds SBMSY in exactly 50% of the simulations)

Reference Points:

  • Interim Limit Reference Point: 40% BMSY and 140% FMSY
  • Interim Target Reference Point: BMSY and FMSY

Candidate Harvest Strategies:

Comprehensive harvest strategy proposed by Australia. MSE evaluating model-based HCRs with these candidate constraints:

  • Total Allowable Catch (TAC) to be set every 3 years (and held constant between settings)
  • A maximum of 15% change to the TAC (increase or decrease) relative to the previous TAC

Progress Update & Workplan:

Evaluation of candidate harvest strategies underway via MSE. Reference set of operating models were revised in 2021 due to concerns about uncertainty in the stock assessment on which the operating models are based, strengthening the MSE.

  • 2022: Refine and further develop MSE and candidate harvest strategies
  • 2023: Adopt final harvest strategy

 

13Harvest Strategy in development

Indian Ocean Albacore Tuna

Case Studies - Indian Ocean Albacore Tuna
 
Case Studies - Indian Ocean Albacore Tuna map

Management Authority:

Indian Ocean Tuna Commission

Expected Adoption Year:

2024

Management Objectives:

Tuning Objectives (for MSE purposes):

  • Pr(mean(SB(2019:2038)>=SB(MSY)) = 0.5. Average SB over the period 2030-2034 exceeds SBMSYin exactly 50% of the simulations)
  • Pr(Kobe green zone 2019:2038) = 0.5. The stock status is in the Kobe green quadrant over the period 2019-2038 exactly 50% of the time (averaged over all simulations)
  • Pr(Kobe green zone 2019:2038) = 0.6. The stock status is in the Kobe green quadrant over the period 2019-2038 exactly 60% of the time (averaged over all simulations)
  • Pr(Kobe green zone 2019:2038) = 0.7. The stock status is in the Kobe green quadrant over the period 2019-2038 exactly 70% of the time (averaged over all simulations)

Reference Points:

Interim Limit Reference Point: 40% BMSY and 140% FMSY
Interim Target Reference Point: BMSY and FMSY

Candidate Harvest Strategies:

Both model-based and empirical, CPUE-based harvest strategies are being tested via MSE. Harvest control rules are being tested with the following constraints:

  • Total Allowable Catch (TAC) to be set every 3 years (and held constant between settings)
  • A maximum of 15% change to the TAC (increase or decrease) relative to the previous TAC

Progress Update & Workplan:

Evaluation of candidate harvest strategies underway via MSE.

  • 2022: Refine and further develop MSE and candidate harvest strategies
  • 2023 or 2024: Adopt final harvest strategy

Link to relevant policy document or update:

 

14Harvest Strategy in development

Indian Ocean Swordfish

Case Studies - Indian Ocean Swordfish
 
Case Studies - Indian Ocean Swordfish map

Management Authority:

Indian Ocean Tuna Commission

Expected Adoption Year:

2024

Management Objectives:

Tuning Objectives (for MSE purposes):

  • Pr(Kobe green zone 2030:2034) = 0.5. The stock status is in the Kobe green quadrant over the period 2030:2034 exactly 50% of the time (averaged over all simulations)
  • Pr(Kobe green zone 2030:2034) = 0.6. The stock status is in the Kobe green quadrant over the period 2030:2034 exactly 60% of the time (averaged over all simulations)
  • Pr(Kobe green zone 2030:2034) = 0.7. The stock status is in the Kobe green quadrant over the period 2030:2034 exactly 70% of the time (averaged over all simulations)

Reference Points:

  • Interim Limit Reference Point: 40% BMSY and 140% FMSY
  • Interim Target Reference Point: BMSY and FMSY

Candidate Harvest Strategies:

Both model-based and empirical, CPUE-based harvest strategies are being tested via MSE. Harvest control rules are being tested with the following constraints:

  • TAC setting every 3 years
  • 15% TAC change limits
  • 3 year lag between data and TAC implementation

Progress Update & Workplan:

Evaluation of candidate harvest strategies underway via MSE

  • 2022: Refine and further develop MSE and candidate harvest strategies
  • 2023 or 2024: Adopt final harvest strategy

Link to relevant policy document or update:

 

15Active Harvest Strategy

Indian Ocean Bigeye Tuna

Case Studies - Indian Ocean Bigeye Tuna
 
Case Studies - Indian Ocean Bigeye Tuna map

Management Authority:

Indian Ocean Tuna Commission

Adoption Year:

2022

Management Objectives:

General: Maintain the stock biomass in the green zone of the Kobe plot (not overfished and not subject to overfishing) while maximizing the average catch from the fishery and reducing the variation in the total allowable catch (TAC) between management periods.

  • The bigeye tuna spawning stock has a 60% probability of achieving the target reference point of SBMSY by 2034-2038;
  • The bigeye tuna spawning stock biomass avoids breaching the interim limit reference point of 50%BMSY with a high probability

Reference Points:

  • Interim Limit Reference Point: 50% BMSY and 130% FMSY
  • Interim Target Reference Point: BMSY and FMSY

Harvest Strategy:

Adopted in 2022, IOTC adopted a fully specified harvest strategy. An exceptional circumstances protocol still needs to be specified.

Specifications:

  • Type: Model-based
  • Management cycle: 3 years
  • Data inputs: Total catches of bigeye tuna, longline CPUE data
  • Management output: Quota
  • Harvest control rule:
    The MP uses a hockey-stick HCR that constructs a harvest rate based on biomass depletion (measured relative to carrying capacity) from a simple biomass dynamic model. The pivot points are at 40% and 10% of carrying capacity, with the HCR multiplier linearly decreasing from 1 to almost zero between those pivot points.
  • Other:
    Maximum quota change:
    +/- 15%

Outcome:

The harvest strategy-derived TAC will first be implemented in 2024. A mechanism to control catch will be developed in 2025 if an allocation scheme has not yet been agreed.

Link to relevant policy document or update:

16Harvest Strategy in development

North Atlantic Swordfish

Case Studies - North Atlantic Swordfish
 
Case Studies - North Atlantic Swordfish map

Management Authority:

International Commission for the Conservation of Atlantic Tunas

Expected Adoption Year:

2023

Management Objectives:

Conceptual Management Objectives:

  • Greater than [___]% probability of occurring in the green quadrant of the Kobe matrix
  • Less than [___]% probability of the stock falling below BLIM
  • Maximize overall catch levels
  • Any increase or decrease in TAC between management periods should be less than [___]%.

Reference Points:

  • Interim Limit Reference Point: 0.4BMSY
  • Interim Target Reference Point: BMSY based on convention objective

Candidate Harvest Strategies:

Using MSE to evaluate both constant and threshold model-based harvest strategies.

Progress Update & Workplan:

MSE process began in 2018, currently developing MSE framework and operating models

  • 2021-2022: Adopt reference set of OMs, adopt operational management objectives, and test candidate harvest strategies
  • 2023: Finalize MSE and adopt final harvest strategy

Link to relevant policy document or update:

17Harvest Strategy in development

Western and Eastern Atlantic Bluefin Tuna

Case Studies - Western and Eastern Atlantic Bluefin Tuna
 
Case Studies - Western and Eastern Atlantic Bluefin Tuna map

Management Authority:

International Commission for the Conservation of Atlantic Tunas

Expected Adoption Year:

2022

Management Objectives:

Conceptual Management Objectives:

  • Greater than [___]% probability of occurring in the green quadrant of the Kobe matrix
  • Less than [___]% probability of the stock falling below BLIM
  • Maximize overall catch levels
  • Any increase or decrease in TAC between management periods should be less than [___]%.

Reference Points:

  • Interim Target Reference Point: B1and F0.1
  • Interim Biomass Limit Reference Point: 40% dynamic SSBMSY 

Candidate Harvest Strategies:

Using MSE to evaluate several empirical harvest strategies

Progress Update & Workplan:

MSE process began in 2014; Currently finalizing MSE framework and evaluating candidate harvest strategies

  • 2021: Adopt reference set of OMs, test candidate harvest strategies
  • 2022: Finalize MSE and operational management objectives, adopt final harvest strategy

Link to relevant policy document or update:

18Harvest Strategy in development

WCPO Skipjack Tuna

Case Studies - WCPO Skipjack Tuna
 
Case Studies - WCPO Skipjack Tuna map

Management Authority:

Western and Central Pacific Fisheries Commission

Expected Adoption Year:

2022

Management Objectives:

Interim Objective:

  • The spawning biomass of skipjack tuna is to be maintained on average at a level consistent with the interim target reference point of 50% of the spawning biomass in the absence of fishing

Draft performance indicators:

  • Maintain skipjack, yellowfin, and bigeye biomass at or above levels that provide fishery sustainability throughout their range
  • Be above limit reference point (proposed: with an >80% probability)
  • Rebuild stock to the average SB/SBF=0 in selected reference period, a proxy for the target reference point
  • Maximise economic yield from the fishery (average expected catch, and relative to a reference period)
  • Maintain acceptable catch per unit effort for purse seines (relative to a reference period)
  • Catch stability
  • Stability and continuity of market supply (effort variation relative to a reference period)
  • Stability and continuity of market supply (probability of and deviation from SB/SBF=0>50%)

Reference Points:

  • Interim Limit Reference Point: 20%SBrecent,F=0
  • Interim Target Reference Point: 50%SBF=0

*SBF=0 = spawning stock size that would exist in the absence of fishing

Candidate Harvest Strategies:

Using MSE to evaluate several model-based harvest strategies with threshold (i.e., hockey stick), stepped and asymptotic harvest control rules; HS must have <20% chance of breaching the limit reference point.

Progress Update & Workplan:

Evaluation of candidate harvest strategies underway via MSE

  • 2020-21: Refine and further develop MSE and candidate harvest strategies
  • 2022: Adopt final harvest strategy

Link to relevant policy document or update:

19Harvest Strategy in development

South Pacific Albacore

Case Studies - South Pacific Albacore
 
Case Studies - South Pacific Albacore map

Management Authority:

Western and Central Pacific Fisheries Commission

Expected Adoption Year:

2023

Management Objectives:

Interim Objective:

  • Achieve an 8% increase in catch per unit of effort (CPUE) for the southern longline fishery as compared to 2013 levels

Draft performance indicators:

  • Maintain biomass at or above levels that provide fishery sustainability throughout their range
  • Maximise economic yield from the fishery (average expected catch)
  • Maintain acceptable CPUE
  • Catch stability

Reference Points:

  • Interim Limit Reference Point: 20%SBF=0 and FX%SPR, with X TBD
  • Interim Target Reference Point: 56% SBF=0

*SBF=0 = spawning stock size that would exist in the absence of fishing

Candidate Harvest Strategies:

Using MSE to evaluate several harvest strategies with model-based and empirical harvest control rules using CPUE data; HS must have <20% chance of breaching the limit reference point

Progress Update & Workplan:

Evaluation of candidate harvest strategies underway via MSE

  • 2020-22: Refine and further develop MSE and candidate harvest strategies
  • 2023: Adopt final harvest strategy

South Pacific albacore is also being incorporated in the mixed fishery MSE framework for the Western and Central Pacific in which the harvest strategies for bigeye, skipjack, yellowfin, and South Pacific albacore will overlap.

Link to relevant policy document or update:

20Harvest Strategy in development

EPO Bigeye Tuna

Case Studies - EPO Bigeye Tuna
 
Case Studies - EPO Bigeye Tuna map

Management Authority:

Inter-American Tropical Tuna Commission

Expected Adoption Year:

2024

Management Objectives:

In development and not officially adopted, but often assumed to be BMSY based on Article VII(1)c of the Antigua Convention.

Reference Points:

Reference points being developed as part of current MSE process.

  • Interim Limit Reference Point: F0.5R0 and SSB0.5R0, where steepness = 0.75 (this is equivalent to 8%SSB0)
  • Interim Target Reference Point:FMSY, SSBMSY

*SSB0 = spawning stock size that would exist in the absence of fishing
*R0 = recruitment (i.e., number of young fish) that would exist in the absence of fishing
*steepness – the fraction of virgin recruitment obtained when a stock is at 20% of its unfished size. A steepness of 0.75 indicates that a stock is productive enough to still produce 75% of its maximum reproductive output, even when it is depleted to just 20% of its initial population size.

Candidate Harvest Strategies:

Candidate model-based harvest strategies are being developed as part of current MSE process.

Current interim HCR developed without MSE testing:

  • F should not exceed FMSY
  • If >10% chance that F>Flimit, reduce F to ≤FMSY with a 50% probability and a <10% chance of F>Flimit
  • If >10% chance that SSB<SSBlimit, take action to get SSB≥SSBMSY with a 50% probability and a <10% chance of SSB<SSBlimit within 2 generations or 5 years, whichever is greater

Progress Update & Workplan:

  • 2020-23: MSE framework development and refinement; testing of candidate harvest strategies
  • 2024: Finalize MSE; adopt HCR/HS

21Active Harvest Strategy

Pacific Halibut

Case Studies - Pacific Halibut
 
Case Studies - Pacific Halibut map

Management Authority:

International Pacific Halibut Commission

Adoption Year:

2020

Management Objectives:

  • Maintain Pacific halibut, on average, at a target (fixed or dynamic) female spawning biomass equal to the stock size required to produce maximum net economic returns on a spatial and temporal scale relevant to the fishery
  • Maintain Pacific halibut, above a female spawning biomass limit where the risk to the stock is regarded as unacceptable (SBLIM), at least 90% of the time

Reference Points:

  • Target Reference Point: 45% SSB0 and 120%SSBMSY
  • Interim Trigger Reference Point: 30% SSB0
  • Interim Limit Reference Point: 20% SSB0and 50%SSBMSY

*SSB0 = spawning stock size that would exist in the absence of fishing

Harvest Strategy:

Using MSE to evaluate several model-based harvest strategies; HS must have ≥ 50% chance of achieving the target and ≤10% chance of breaching the limit

Interim harvest control rule:

  • The harvest control rules relies on the spawning potential ratio (SPR) of 46% (FSPR=46%). The SPR is adjusted to reduce the fishing intensity at low levels of spawning biomass by linearly increasing the SPR (i.e reducing the fishing intensity) if the estimated stock status is less than a trigger at 30% SSB0, to zero fishing intensity (SPR=100%) when the estimated stock status is less than the limit at 20% SSB0(i.e., a 30:20 control rule).

*SPR = Spawning Potential Ratio, or the lifetime spawning output that a young fish is expected to produce under current fishing mortality compared to what it would produce in the absence of fishing.

Outcome:

Interim harvest strategy in place since 2020 to set the allowable coastwide catch, but adoption of a final, formal harvest strategy has yet to occur, in part due to ongoing negotiations about how to allocate the catch among Alaska, Canada, and the U.S. West Coast. Final mortality limits are determined based on the previous year’s limits, the interim harvest strategy, and social and economic considerations. MSE development continues and is exploring size limits and stock assessment frequency as part of the harvest strategy.

Link to relevant policy document or update:

 

22Harvest Strategy in development

Norwegian Spring Spawning Herring

Case Studies - Norwegian Spring Spawning Herring
 
Case Studies - Norwegian Spring Spawning Herring map

Management Authority:

North East Atlantic Fisheries Commission/ North-East Atlantic Coastal States

Expected Adoption Year:

2023

Management Objectives:

Aiming at ensuring harvest rates within safe biological limits, and consistent with the precautionary approach* and the maximum sustainable yield (MSY) approach.

*ensure with a high probability (95%) that the size of the stock is maintained above Blim

Reference Points:

  • Interim Target Fishing Mortality Reference Point: Fmgt (0.14F) / FMSY (0.157F)
  • Interim Biomass Trigger Reference Points: Bpa/MSY Btrigger (3,184,000 tonnes)
  • Interim Limit Reference Points: Flim (0.291F) and Blim (2,500,000 tonnes)

*Bpa = A stock size above which the stock is considered to have full reproductive capacity. Pa stands for precautionary approach.

Candidate Harvest Strategies:

A few harvest control rule (HCR) options were explored by ICES (2018). A HCR and Reference Points were adopted that set a total allowable catch (TAC) when biomass is above/below biological reference points (Bpa, Blim, etc.)

  • If SSB≥Bpa, the TAC shall be fixed to a fishing mortality of Fmgt.
  • Maximum TAC change: +25%, -20%
  • If Blim<SSB<Bpa, the TAC shall be fixed at a level that is consistent with a fishing mortality given by: Target F = 0.05 + [(SSB – Blim)*(Fmgt – 0.05) / (Bpa– Blim)]
  • If SSB<Blim, the TAC will be fixed corresponding to a fishing mortality F=0.05.

Noted Constraints:

  • There are mechanisms for banking up to 10% of unutilized quota and borrowing up to 10% beyond the quota allocated subject to stock status.
  • Development of only an HCR, as opposed to a full harvest strategy.

Progress Update & Workplan:

  • 2022: The HCR based on ICES evaluation (2018) has been in place since 2019 and should be reviewed after 5 years (no later than December 2023).
  • 2022: The interim long-term management strategy may no longer be precautionary in the long term. There have been consistent deviations from the HCR (overshooting catch advice) due to an allocation dispute. During the evaluation of the management strategy, the implementation error in the form of a consistent overshoot of the TAC was not included.
  • 2023: Refine and further develop management strategy evaluation (MSE) and candidate harvest control rules in collaboration with ICES
  • 2024: Adopt a full harvest strategy or updated harvest control rule.

23Harvest Strategy in development

Blue Whiting

Case Studies - Blue Whiting
 
Case Studies - Blue Whiting map

Management Authority:

North-East Atlantic Fisheries Commission/ North-East Atlantic Coastal States

Expected Adoption Year:

2023

Management Objectives:

Aiming at ensuring harvest rates within safe biological limits, and consistent with the precautionary approach* and the maximum sustainable yield (MSY) approach.

*ensure with a high probability (95%) that the size of the stock is maintained above Blim

Reference Points:

  • Interim Target Fishing Mortality Reference Point: FMSY(0.32F)
  • Interim Biomass Trigger Reference Point: Bpa/MSY Btrigger(2,250,000 tonnes)
  • Interim Biomass Limit Reference Point: Blim(1,500,000 tonnes)

*Bpa = A stock size above which the stock is considered to have full reproductive capacity. Pa stands for precautionary approach.

Candidate Harvest Strategies:

An interim harvest control rule (HCR) has previously been explored by ICES that sets a total allowable catch (TAC) when biomass is above/below biological reference points (Bpa,Blim, etc.)

  • If SSB≥Bpa, the TAC shall be fixed to a fishing mortality of FMSY
  • Maximum TAC change: +/- 20%
  • If Blim<SSB<Bpa, the TAC shall be fixed that is consistent with a fishing mortality given by the following formula: Target F = 0.05 + [(SSB – Blim)*(FMSY – 0.05) / (Bpa– Blim)]
  • If SSB<Blim, the TAC will be fixed corresponding to a fishing mortality F=0.05

Noted Constraints:

  • There are mechanisms for banking up to 10% of unutilized quota and borrowing up to 10% beyond the quota allocated subject to stock status.
  • The HCR since 2017 has an annual TAC change rule different from the one evaluated: Maximum TAC change: +25%, -20%
  • Development of only an HCR, as opposed to a full harvest strategy.

Progress Update & Workplan:

  • 2021: The HCR based on ICES evaluation (2016) has been in place since 2017 and should have been reviewed after 5 years (no later than December 2021).
  • 2021: The interim long-term management strategy may no longer be precautionary in the long term. There have been consistent deviations from the HCR (overshooting catch advice) due to an allocation dispute. During the evaluation of the management strategy, the implementation error in the form of a consistent overshoot of the TAC was not included.
  • 2022: Refine and further develop management strategy evaluation (MSE) and candidate harvest control rules in collaboration with ICES.
  • 2023: Adopt a full harvest strategy or updated harvest control rule.

24Harvest Strategy in development

Western Atlantic Skipjack Tuna

Case Studies - Western Atlantic Skipjack Tuna
 
Case Studies - Western Atlantic Skipjack Tuna map

Management Authority:

International Commission for the Conservation of Atlantic Tunas

Expected Adoption Year:

2023

Management Objectives:

Management objectives have not yet been agreed, but the scientists are preliminarily using performance statistics corresponding to status, safety, yield, and stability objectives.

Reference Points:

None have been adopted but the scientists proposed the following:

  • Target Reference Point: BMSY or 40%B0
  • Limit Reference Point: 40%BMSY or 20%B0

Candidate Harvest Strategies:

Testing a variety of harvest control rules, including constant catch and hockey stick harvest control rules (i.e., that adjust the total allowable catch up and down as the population size increases and decreases, respectively).

Progress Update & Workplan:

Initial MSE testing complete, looking to recondition operating models with 2022 assessment data, initiate robustness tests, and introduce implementation error into the MSE. Need input from managers on management objectives and performance statistics.

Link to relevant policy document or update:

Collective Volumes of Scientific Papers: Paper not yet available in ICCAT database

25Harvest Strategy in development

WCPO Bigeye Tuna

Case Studies - WCPO Bigeye Tuna
 
Case Studies - WCPO Bigeye Tuna map

Management Authority:

Western and Central Pacific Fisheries Commission

Expected Adoption Year:

2024

Management Objectives:

Initial proposals for the Southern longline, tropical longline, and tropical purse seine fishery include biological, economic, social, and ecosystem objectives.

Reference Points:

  • Limit Reference Point: 20%SBF=0
  • Target Reference Point: Pending agreement on a target reference point the spawning biomass depletion ratio (SB/SBF=0) is to be maintained at or above the average SB/SBF=0 for 2012-2015

Candidate Harvest Strategies:

Evaluating a harvest control rule and harvest strategy through a mixed fishey modelling framework that develops model-based harvest strategies for bigeye, but is set up to achieve objectives across multiple species, including yellowfin, skipjack, and South Pacific albacore.

Progress Update & Workplan:

Initial mixed fishery framework explored via MSE; Next steps include operating model conditioning, the development of candidate management procedures for bigeye for the tropical longline fishery, and the development of mixed fishery, multi-species performance indicators. Input needed from managers on management objectives and target reference points.

Link to relevant policy document or update:

26Harvest Strategy in development

WCPO Yellowfin Tuna

Case Studies - WCPO Yellowfin Tuna
 
Case Studies - WCPO Yellowfin Tuna map

Management Authority:

Western and Central Pacific Fisheries Commission

Expected Adoption Year:

2023

Management Objectives:

Tuning Objectives (for MSE purposes):

  • Pr(B(2029)>=B(MSY) ) = 0.5 (SB in 2029 exceeds SBMSY in exactly 50% of the simulations)
  • Pr(B(2034)>=B(MSY) ) = 0.6 (SB in 2034 exceeds SBMSY in exactly 50% of the simulations)

Reference Points:

  • Interim Limit Reference Point: 40% BMSY and 140% FMSY
  • Interim Target Reference Point: BMSY and FMSY

Candidate Harvest Strategies:

Comprehensive harvest strategy proposed by Australia. MSE evaluating model-based HCRs with these candidate constraints:

  • Total Allowable Catch (TAC) to be set every 3 years (and held constant between settings)
  • A maximum of 15% change to the TAC (increase or decrease) relative to the previous TAC

Progress Update & Workplan:

Evaluation of candidate harvest strategies underway via MSE. Reference set of operating models were revised in 2021 due to concerns about uncertainty in the stock assessment on which the operating models are based, strengthening the MSE.

  • 2022: Refine and further develop MSE and candidate harvest strategies
  • 2023: Adopt final harvest strategy

Link to relevant policy document or update:

  • WCPFC Harvest Strategies: Navigate to ‘Bigeye and Yellowfin Tunas in the WCPO’ to read an overview of the current work going towards the harvest strategy

27Harvest Strategy in development

Pacific Saury

Case Studies - Pacific Saury
 
Case Studies - Pacific Saury map

Management Authority:

North Pacific Fisheries Commission

Expected Adoption Year:

2023

Management Objectives:

Initial Options:

  • The annual probability that the stock drops below Blim should not exceed “X” probability; or the annual probability that the fishing mortality exceeds Flim should not exceed “X” probability
  • Catch is high and stable as much as possible
  • Maximum interannual variation of TAC over yy period should be less than xx%.

Reference Points:

Initial biomass target and limit reference points will be based on either BMSY or carrying capacity (K), and will include multipliers yet to be defined (e.g., X%*BMSY and Y%*K). Fishing mortality target and limit reference points will be based on FMSY (e.g., Z%*FMSY).

Candidate Harvest Strategies:

Evaluating empirical or model-based harvest control rules that reduce the target harvest rate and total allowable catch when biomass falls below its target level. Currently, only a harvest control rule is being developed, as opposed to a full harvest strategy.

Progress Update & Workplan:

Plan is to use the current interim stock assessment model to evaluate a short-term harvest control rule, then move on to a full MSE proccess to evaluate a comprehensive management procedure.

28Harvest Strategy in development

Atlantic Mackerel

Case Studies - Atlantic Mackerel
 
Case Studies - Atlantic Mackerel map

Management Authority:

North East Atlantic Fisheries Commission

Expected Adoption Year:

2022

Management Objectives:

  • Maximum long-term yield
  • A maximum annual probability of SSB falling below the limit reference point is less than 5% for all years.

Reference Points:

  • Fishing mortality target = 26%FMSY
  • Bpa (MSY Biomass trigger value) = 2.58 metric tons
  • Biomass limit reference point = 2.00 metric tons

*Bpa: biomass below which action should be taken, (pa= precautionary approach)

Candidate Harvest Strategies:

Explored 5 harvest control rules that derive a target fishing mortality based on spwaning stock biomass, including combinations of limitations on interannual variability in total allowable catch (aka stability), and various catch banking and borrowing schemes (e.g 10% banking of total allowable catch and 10% borrowing applied in alternate years, suspended when SSB is below the biomass trigger value)

Progress Update & Workplan:

Full MSE completed by ICES. Coastal States of NEAFC must evaluate MSE results to select final elements of the management strategy.

Link to relevant policy document or update: