Terms of Reference
Assess whether conservation, technical and management measures
are compatible for the purpose of stock conservation and management of
targeted fish stocks and bycatch fish stocks in their entirety. Where
possible given available data, consider also the impact of damage caused
to individual fish passing through the collecting bag gear.
This work builds on analyses from the Workshop on the use of
Collecting bags in shrimp fisheries (WKCB) [@ICES2022].
Background
Sorting grids implementation is mandatory across NEAFC shrimp trawl
fisheries, however, collecting bag regulations vary by flag state
creating compatibility issues and discrepancies in bycatch management.
Some target species lack formal stock assessments, and there is
incomplete observer coverage across fisheries. There is also limited
quantitative data on the survival of fish that pass through the sorting
grids.
WKCB1 evaluated the compatibility of conservation, technical and
management measures for Barents Sea fish stock management, focusing on
the effectiveness of sorting grids and collecting bags in shrimp trawl
fisheries.
Regulatory differences were foubnd across NEAFC member states
regarding collecting bag regulations, creating inconsistent conservation
outcomes that undermine the effectiveness of technical measures.
Collecting bags demonstrate problematic impacts on juvenile fish
retention, with 1.1% retention for cod and 12% for halibut, directly
contradicting conservation goals and rebuilding plans for key stocks.
Furthermore, the analysis is constrained by limited quantitative data on
individual fish impacts and sublethal effects of gear passage,
representing a critical knowledge gap for comprehensive impact
assessment. Additionally, several target species lack formal stock
assessments, necessitating alternative approaches based on life history
traits and ecosystem-based frameworks.
Stock Assessments
This analysis covers eight key species: cod, Greenland halibut,
redfish (beaked and golden), capelin, northern shrimp, American plaice,
wolffish, and snow crab.
The target stock Northern shrimp (Pandalus borealis) in the
Barents Sea is assessed annually by IMR/PINRO. Following Russia’s
suspension from ICES, most Barents Sea bycaught stocks are now assessed
by the Joint Russian Norwegian Arctic Fisheries Working Group
(JRN-AFWG).
Data Sources: ICES Stock Information Database (SID),
JRN-AFWG assessments, stockassessment.org, and regional fisheries
reports.
Stock Assessment Status
| Northern shrimp (Pandalus
borealis) |
pra.27.1-2 |
JRN-AFWG 2024 |
Full assessment |
| Cod (Gadus morhua) |
cod.27.1-2 |
JRN-AFWG 2025 |
Full assessment |
| Haddock (Melanogrammus
aeglefinus) |
had.27.1-2 |
JRN-AFWG 2024 |
Full assessment |
| Greenland halibut (Reinhardtius
hippoglossoides) |
ghl.27.1-2 |
JRN-AFWG 2024 |
Full assessment |
| Beaked redfish (Sebastes
mentella) |
reb.27.1-2 |
JRN-AFWG 2024 |
Full assessment |
| Golden redfish (Sebastes
norvegicus) |
reg.27.1-2 |
JRN-AFWG 2024 |
Full assessment |
| Capelin (Mallotus
villosus) |
cap.27.1-2 |
JRN-AFWG 2024 |
Full assessment |
| American plaice (Hippoglossoides
platessoides) |
ple.27.1-2 |
Limited |
Ecosystem overview |
| Wolffish (Anarhichas
lupus) |
No SID |
None |
Bycatch species |
| Snow crab (Chionoecetes
opilio) |
No SID |
None |
Ecosystem studies |
Assessment Methods
The analysis employs quantitative age-based assessments for data-rich
stocks including cod, haddock, redfish, capelin, and northern shrimp,
providing comprehensive estimates of recruitment, spawning stock biomass
(SSB), catch, and fishing mortality. For species lacking formal
assessments such as American plaice, wolffish, and snow crab, the
approach utilizes life history traits and selectivity information to
construct operating models that enable conservation measure evaluation.
Reference cases represent idealized scenarios where conservation
measures are perfectly implemented, serving as benchmarks for evaluating
current management effectiveness and providing forward projections of
sustainable catch levels under optimal conservation conditions.
Management Measures
The Barents Sea fisheries operate under a complex management
framework involving multiple regulatory bodies and technical measures
designed to balance conservation objectives with fishing
opportunities.
Current Technical Measures Implementation
All flags in the NEAFC shrimp trawl fisheries have adopted mandatory
sorting grids to reduce bycatch, including cod, Greenland halibut,
redfish, and plaice, covering both domestic and international waters.
The use of collecting bags—an additional codend mounted ahead of the
grid to retain fish that would otherwise escape—varies significantly by
country. This practice is permitted in some countries such as the EU,
UK, and Iceland (south of 62°N) but prohibited by others, notably
Norway, Russia, and the Faroe Islands within the Barents Sea.
The technical specifications of these measures show considerable
variation across jurisdictions. Grid bars are generally set between
19–22 mm, while collecting bag mesh sizes range from 130–140 mm.
However, mesh sizes, bar spacings, and Minimum Conservation Reference
Sizes (MCRS) vary by country, creating regulatory fragmentation that
complicates management effectiveness.
Summary Table: Conservation and Technical Measures
Compatibility
| Cod |
Full assessment (JRN-AFWG) |
High |
Negative (1.1% juvenile retention) |
Partial |
Conflicts with rebuilding plans |
| Greenland Halibut |
Full assessment (JRN-AFWG) |
High |
Negative (12% juvenile retention) |
Partial |
Undermines conservation goals |
| Redfish |
Full assessment (JRN-AFWG) |
Moderate |
Moderate impact |
Partial |
Size selectivity issues |
| Capelin |
Full assessment (JRN-AFWG) |
High |
Minimal |
Compatible |
Clear size selectivity |
| Northern Shrimp |
Full assessment (JRN-AFWG) |
High |
Minimal |
Compatible |
Target species |
| American Plaice |
No formal assessment |
Moderate |
Unknown |
Data limited |
Assessment gaps |
| Wolffish |
No formal assessment |
Moderate |
Unknown |
Data limited |
Bycatch species |
| Snow Crab |
No formal assessment |
Moderate |
Unknown |
Data limited |
Assessment gaps |
Compatibility Legend - Compatible:
Measures work effectively together for conservation -
Partial: Some compatibility issues that can be
addressed - Data Limited: Insufficient data for full
assessment
Overall Assessment The current conservation,
technical, and management measures show partial
compatibility across the Barents Sea ecosystem, with
compatibility issues primarily related to collecting bag implementation
and data limitations for some species.
Conservation and Management Measures Analysis
Sorting grids exhibit varying effectiveness across stocks. They are
highly effective for shrimp, capelin and species with clear size
selectivity, they are moderately effective for groundfish species, but
show only limited effectiveness where collecting bags are used.
The implementation of collecting bags is variable and creates several
compatibility issues, i.e. i) Regulatory Inconsistency due to
different rules across NEAFC member states; ii) Bycatch
Management increased retention of juvenile fish underming
conservation goals; iii) Quota Allocation inconsistent
reporting and allocation of bycatch catches; and iv) Stock
Rebuilding, conflicts with rebuilding plans for key stocks.
Compatibility Assessment for Stock Conservation
The compatibility of current technical measures presents significant
challenges for stock management. While collecting bags increase the
retention of larger and commercially valuable groundfish that would
otherwise escape via the grid, thereby raising both bycatch and revenue,
they also retain a measurable proportion of juvenile fish. Based on
observer and research data, approximately 1.1% of cod and 12% of halibut
below MCRS are retained in collecting bag operations.
Major coastal states Norway and Russia consider the collecting bag
practice incompatible with joint rebuilding plans for stocks like cod
and halibut. These countries have implemented strict regulations
prohibiting collecting bag use, viewing such practices as undermining
decades of conservation efforts. The compatibility of current measures
is therefore partial at best—while required technical measures reduce
juvenile bycatch through grids and MCRS requirements, the optional use
of collecting bags introduces significant regulatory discrepancies.
Bycatch Impact Assessment
The impact on bycatch stocks reveals concerning patterns in
collecting bag fisheries. Mean bycatch ratios reach approximately 13.6%
for cod and 10.9% for halibut, representing substantial retention of
non-target species. Discard rates vary considerably, with mean discard
rates for cod in collecting bag fisheries reaching approximately 3.3% in
2020, while Greenland halibut discard rates were lower at around
0.7%.
Limited quantitative data exists regarding physical damage or
sublethal effects on fish passing through the grid and collecting bag
system. This data gap represents a significant challenge for
comprehensive impact assessment and management decision-making.
Technical Measures Framework
Mandatory Sorting Grids
Sorting grids are required across all NEAFC shrimp trawl fisheries,
covering both domestic and international waters in the Barents Sea.
These grids serve to reduce bycatch of groundfish species including cod,
Greenland halibut, redfish, and plaice. Technical specifications include
grid bar spacing of 19–22 mm (varying by country), integration into
trawl gear design, and subjection to regular inspection and compliance
monitoring.
Collecting Bags
Collecting bags represent an additional codend mounted ahead of the
sorting grid, designed to retain fish that would otherwise escape
through the grid. The regulatory status of these devices varies
dramatically across NEAFC member states. They are permitted in the EU,
UK, and Iceland (south of 62°N) but prohibited by Norway, Russia, and
the Faroe Islands within the Barents Sea. Technical specifications
typically include 130–140 mm mesh size, with the primary impact being
increased retention of larger, commercially valuable groundfish.
Conservation Reference Sizes
Minimum Conservation Reference Sizes aim to protect juvenile fish
from exploitation, though implementation varies by species and country.
Despite these measures, juvenile retention rates remain significant,
with 1.1% for cod and 12% for halibut, indicating limited effectiveness
in current configurations.
Stock Rebuilding and Management Coordination
Norway and Russia coordinate joint rebuilding plans for key stocks,
primarily targeting cod and Greenland halibut with objectives to restore
stocks to sustainable levels. However, collecting bag usage conflicts
with these rebuilding objectives, creating tension between coastal state
management efforts and international fishing practices. The Joint
Norwegian-Russian Fisheries Commission serves as the bilateral platform
for discussing and deciding on management issues, including technical
measures.
Bycatch Management and Monitoring
Observer programs provide essential data on bycatch rates, with
quantified cod bycatch at approximately 13.6% and Greenland halibut
bycatch at 10.9% in collecting bag fisheries. Discard rates show cod at
3.3% and Greenland halibut at 0.7% based on 2020 data. However,
monitoring systems face challenges from inconsistent reporting standards
and limited coverage of sublethal effects on discarded fish.
Regulatory Framework Challenges
NEAFC Coordination Issues
The North East Atlantic Fisheries Commission manages international
waters but faces significant challenges from variable implementation of
technical measures across member states. Harmonization needs include
standardized regulations for collecting bags, mesh sizes, and reporting
requirements. The current fragmented approach creates compliance
complications and undermines conservation effectiveness.
Quota Management Problems
Shared quotas between coastal states face issues from inconsistent
reporting and allocation of bycatch catches. A persistent problem
involves retained bycatch not being properly deducted from quotas,
creating accountability gaps in the management system.
Assessment Integration
The Joint Russian Norwegian Arctic Fisheries Working Group (JRN-AFWG)
currently provides stock assessments, utilizing MSY-based reference
points for sustainable management. However, data integration challenges
exist in incorporating stock assessments with technical measure
effectiveness evaluation.
Management Effectiveness Evaluation
Current management measures demonstrate partial effectiveness in
achieving conservation objectives. The system shows high effectiveness
for mandatory sorting grids applied to species with clear size
selectivity, moderate effectiveness for groundfish species where size
overlap occurs, and limited effectiveness where collecting bags are
used, as they reduce grid effectiveness.
The variable implementation of collecting bag regulations creates
significant compatibility issues that fundamentally limit the overall
effectiveness of the management framework. These discrepancies
particularly impact the achievement of comprehensive stock conservation
and management objectives, highlighting the need for more harmonized
approaches across the NEAFC regulatory area.
Methods
Current Assessment Status
The latest ICES assessments were conducted in 2021 by AFWG or WGPAND.
Since Russia was suspended from ICES, most of the Barents Sea stocks are
assessed by the Joint Russian Norwegian Arctic Fisheries Working Group
(JRN-AFWG), largely based on assessments benchmarked in ICES.
Assessed Stocks: Cod, Greenland halibut, redfish,
capelin, and northern shrimp. Cod has a new assessment in 2025.
Unassessed Stocks: For American plaice, wolffish and
snow crab there have never been ICES stock assessments, nor have they
been assessed elsewhere.
Since we are not trying to provide short term advice in this request,
these assessments can still potentially be used to assess the long term
impact of these technical measures.
Stock database keys are sourced from ICES Stock Information Database
(SID) and assessment reports, providing standardized access to
comprehensive stock assessment data. Some species such as wolffish and
snow crab are not assigned dedicated stock IDs in ICES, as they are
included in ecosystem, bycatch, or regional scientific reports rather
than formal stock assessments. Each SID link provides direct access to
the official ICES page for the respective assessed stock, facilitating
transparent data access and verification.
Reference Cases
Data-Rich Stock Analyses
This section presents comprehensive analyses for the three data-rich
stocks (cod, haddock, and redfish) that have quantitative assessments.
Each analysis follows a systematic approach: i) assessment summary, ii)
stock-recruitment relationships (SRR), iii) production functions, and
iv) FMSY simulations.
Cod (Gadus morhua)
Assessment Authority: JRN-AFWG 2025 | Stock
ID: cod.27.1-2 | Latest Assessment: Available
via stockassessment.org
The cod stock has the most comprehensive assessment data enabling
detailed conservation analysis with quantitative age-based assessment
featuring recruitment, SSB, catch, and fishing mortality estimates. The
stock is currently in a rebuilding phase with strong recruitment
patterns observed in recent years.
Conservation Effectiveness: Grid implementation
shows high effectiveness for size selectivity. Collecting bag results in
1.1% juvenile retention - detrimental to rebuilding. Optimal fishing
mortality (~0.3) for sustainable harvest while maintaining stock
rebuilding goals.
Haddock (Melanogrammus aeglefinus)
Assessment Authority: JRN-AFWG 2024 | Stock
ID: had.27.1-2 | Latest Assessment: 2024 via
stockassessment.org
Haddock stock provides robust assessment data allowing comprehensive
conservation evaluation with full quantitative assessment structure. The
stock shows strong recruitment variability and is managed under
precautionary approach principles.
Haddock Conservation: Complete framework enables
detailed conservation evaluation with strong recruitment patterns
allowing precise MSY-level calculations. Optimal grid sizing enables
sorting of juvenile haddock, strengthening rebuilding efforts.
Beaked Redfish (Sebastes mentella)
Assessment Authority: JRN-AFWG 2024 | Stock
ID: reb.27.1-2 | Latest Assessment: Barents
Sea redfish
Quantitative assessment with stock structure analysis enabling
comprehensive conservation framework. The redfish stock shows complex
population dynamics with multiple spawning components.
Redfish Conservation: Complex stock structure
requires careful management of collecting bag operations to avoid
problematic juvenile retention. Compatible conservation path requires
limiting collection bag operations.
Golden Redfish (Sebastes norvegicus)
Assessment Authority: JRN-AFWG 2024 | Stock
ID: reg.27.1-2 | Latest Assessment: Golden
redfish assessment
Assessment Summary
Golden redfish assessment provides quantitative framework for
conservation evaluation with detailed stock structure analysis and
recruitment patterns.
Golden Redfish Conservation: Similar to beaked
redfish, requires careful management of technical measures to ensure
conservation compatibility.
Stock recruitment relationships
Production Functions
Reference Cases: FMSY Simulations
Methodology and Conditioning
The FMSY simulations represent idealized reference scenarios where
conservation measures are perfectly implemented, providing critical
benchmarks for evaluating current management effectiveness. These
reference cases are conditioned using the following methodology:
Model Conditioning: Each FMSY simulation is based on
Beverton-Holt stock-recruitment relationships fitted to historical
assessment data, with parameters estimated through maximum likelihood
estimation. The models incorporate age-specific natural mortality,
growth, maturity, and selectivity patterns derived from the most recent
stock assessments.
Reference Point Derivation: The simulations utilize
MSY-based reference points (FMSY, BMSY) calculated from the fitted
stock-recruitment relationships. These reference points represent the
fishing mortality and biomass levels that would produce maximum
sustainable yield under optimal conditions.
Projection Framework: Forward projections are
conducted over 25-year time horizons using the Fmsy()
function, which applies FMSY-level fishing mortality with stochastic
recruitment deviates based on historical patterns. The simulations
include bias correction to account for model uncertainty and ensure
realistic stock trajectories.
Conservation Scenarios: These reference cases assume
perfect implementation of technical measures, including optimal sorting
grid effectiveness, zero juvenile retention from collecting bags, and
ideal size selectivity. This provides a theoretical maximum for
conservation effectiveness against which current measures can be
evaluated.
Purpose and Applications
These FMSY reference cases serve multiple critical purposes in the
conservation assessment:
Benchmark Evaluation: They provide quantitative
benchmarks for comparing current management effectiveness against
optimal conservation scenarios, enabling identification of performance
gaps and improvement opportunities.
Management Guidance: The projections inform
decision-making by showing sustainable catch levels and stock rebuilding
trajectories that could be achieved with optimal conservation measure
implementation.
Regulatory Framework Evaluation: These reference
cases enable assessment of how current regulatory fragmentation and
collecting bag inconsistencies prevent achievement of optimal
conservation outcomes.
Cod FMSY Reference Case
Haddock FMSY Reference Case
Beaked Redfish FMSY Reference Case
Golden Redfish FMSY Reference Case
#> [1] "maxfbar has been changed to accomodate new plusgroup"
ICES Stock Assessment Graphs
Data-Limited Stock Analyses
American Plaice (Hippoglossoides platessoides)
American plaice receives limited formal assessment coverage, being
primarily included in ecosystem overviews rather than dedicated stock
assessments. The conservation approach for this species relies on life
history traits derived from FishBase, biological parameter estimates,
and operating models to evaluate technical measure effectiveness and
conservation compatibility.
Wolffish (Anarhichas lupus)
Wolffish lacks formal assessment status and is treated as a bycatch
species in the Barents Sea ecosystem. The conservation approach
incorporates bycatch considerations within ecosystem models, utilizing
available life history information to assess the impacts of technical
measures on this species and inform management decisions.
Snow Crab (Chionoecetes opilio)
Snow crab has no formal ICES assessment and is evaluated based on
scientific studies and ecosystem research. The conservation approach
employs ecosystem-based frameworks and literature-derived life history
characteristics to understand the species’ response to technical
measures and inform conservation strategies.
