Questionnaire Report for Atlantic Halibut

(MERA version 4.1.6)

2019-07-30


1 About this document

This is a prototype of an automatic report that documents how the user specified the operating model and their various justifications.


2 Introduction

  1. Describe the history and current status of the fishery, including fleets, sectors, vessel types and practices/gear by vessel type, landing ports, economics/markets, whether targeted/bycatch, other stocks caught in the fishery. Within the management unit 3NOPs4VWX5Zc, which encompasses the Scotian Shelf and southern Grand Banks, halibut is fished mostly along the edges of the continental shelf mainly by longliners using bottom hook-and-line gear. On the Scotian Shelf and the southern Grand Banks most of the landed halibut is from a directed longline halibut fishery. Halibut is also landed by other longline, trawl, gill net and handline fisheries

Until 1988, the halibut fishery was unregulated. In 1988, a total allowable catch (TAC) of 3,200 t was set for 3NOPs4VWX5Zc. The TAC was reduced to 1500 t in 1994, and was further reduced to 850 t in 1995. In 1999, recommendations made by the Fisheries Resource Conservation Council (FRCC) resulted in an increase in the TAC from 850 to 1000 t. Annual TACs have increased several times since 2000. Since 1994, management plans and license conditions require the release of halibut less than 81 cm. Average landings from 1960 to 2007 for this region have been approximately 1800 t annually, with a range of just under 1000 to approximately 4200 t. The management units 3NOPs4VWX5Zc and 4RST were established in 1987, based primarily on tagging studies demonstrating that halibut are highly mobile (McCracken 1958, Bowering 1986, Stobo et al. 1988).

  1. Describe the stock’s ecosystem functions, dependencies, and habitat types. Atlantic halibut are distributed widely throughout the northern Atlantic. In the northwestern Atlantic, populations are found from the coast of Virginia to as far north as the Arctic Circle. Significant numbers swim off the coasts of Greenland, Newfoundland and Labrador, the Gulf of St. Lawrence, and Nova Scotia. In the northeast, Atlantic halibut range from the Bay of Biscay to Spitsbergen and the Barents Sea. Atlantic halibut are fished commercially.

  2. Provide all relevant reference materials, such as assessments, research, and other analysis. https://dfo-mpo.gc.ca/species-especes/profiles-profils/atl-halibut-fletan-atl-eng.html


3 Fishery Characteristics

3.1 Longevity

Answered
Very short-lived (5 < maximum age < 7)
Short-lived (7 < maximum age < 10)
Moderate life span (10 < maximum age < 20)
Moderately long-lived (20 < maximum age < 40)
Long-lived (40 < maximum age < 80)
Very long-lived (80 < maximum age < 160)
Justification
A new statistical catch at length (SCAL) model was used to assess the stock status of Atlantic Halibut and the impact of the fishery on biomass/population trends. SCAL model estimates of spawning stock biomass (SSB) between 1970 and 2013 indicate that the halibut stock has increased from the depleted state of the early 1990s to the present. The spawning stock biomass in 2013 is estimated to be 6,668 (SE=234) mt; the highest in the time series (http://publications.gc.ca/collections/collection_2015/mpo-dfo/Fs70-6-2015-012-eng.pdf)

3.2 Stock depletion

Answered
Crashed (D < 0.05)
Very depleted (0.05 < D < 0.1)
Depleted (0.1 < D < 0.15)
Moderately depleted (0.15 < D < 0.3)
Healthy (0.3 < D < 0.5)
Underexploited (0.5 < D)
Justification
A new statistical catch at length (SCAL) model was used to assess the stock status of Atlantic Halibut and the impact of the fishery on biomass/population trends. SCAL model estimates of spawning stock biomass (SSB) between 1970 and 2013 indicate that the halibut stock has increased from the depleted state of the early 1990s to the present. The spawning stock biomass in 2013 is estimated to be 6,668 (SE=234) mt; the highest in the time series (http://publications.gc.ca/collections/collection_2015/mpo-dfo/Fs70-6-2015-012-eng.pdf)

3.3 Resilence

Answered
Not resilient (steepness < 0.3)
Low resilience (0.3 < steepness < 0.5)
Moderate resilence (0.5 < steepness < 0.7)
Resilient (0.7 < steepness < 0.9)
Very Resilient (0.9 < steepness)
Justification
The stock-recruit relationship for halibut could not be well described by the more commonly used models; therefore, interim reference points were chosen (http://publications.gc.ca/collections/collection_2015/mpo-dfo/Fs70-6-2015-012-eng.pdf)

3.4 Historical effort pattern

Answered
Stable
Two-phase
Boom-bust
Gradual increases
Stable, recent increases
Stable, recent declines
Justification
The stock-recruit relationship for halibut could not be well described by the more commonly used models; therefore, interim reference points were chosen (http://publications.gc.ca/collections/collection_2015/mpo-dfo/Fs70-6-2015-012-eng.pdf)

3.5 Inter-annual variability in historical effort

Answered
Not variable (less than 20% inter-annual change (IAC))
Variable (maximum IAC between 20% to 50%)
Highly variable (maximum IAC between 50% and 100%)
Justification
Both the halibut survey and the commercial index show a similar distribution for halibut catches over a decade of sampling. The halibut survey abundance index suggests a possible increase in catch rates in 4VWX in recent years and a relatively stable catch prior to 2003. The commercial index catch rates, however, are more variable and there is no indication of increasing catch rates in recent years. The most recent stock assessment for 3NOPs4VWX5Zc Atlantic halibut (https://dfo-mpo.gc.ca/species-especes/profiles-profils/atl-halibut-fletan-atl-eng.html)

3.6 Historical fishing efficiency changes

Answered
Declining by 2-3% pa (halves every 25-35 years)
Declining by 1-2% pa (halves every 35-70 years)
Stable -1% to 1% pa (may halve/double every 70 years)
Increasing by 1-2% pa (doubles every 35-70 years)
Increasing by 2-3% pa (doubles every 25-35 years)
Justification
No info was found

3.7 Future fishing efficiency changes

Answered
Declining by 2-3% pa (halves every 25-35 years)
Declining by 1-2% pa (halves every 35-70 years)
Stable -1% to 1% pa (may halve/double every 70 years)
Increasing by 1-2% pa (doubles every 35-70 years)
Increasing by 2-3% pa (doubles every 25-35 years)
Justification
from Fig 2 (age 5 is around 75 cm. Also see Appendix 1). from Figure 22 the selectivity at age is 5. (see Heyer et al (2015)) 200 cm (for females) So 75/200cm=0.375.

3.8 Length at maturity

Answered
Very small (0.4 < LM < 0.5)
Small (0.5 < LM < 0.6)
Moderate (0.6 < LM < 0.7)
Moderate to large (0.7 < LM < 0.8)
Large (0.8 < LM < 0.9)
Justification
0.595 = 119cm/200 cm (for females). see Figure 2. Length-at-age for male and female Atlantic halibut (from Trzcinski et al 2011a) in den Heyer et al (2015).
Atlantic Halibut grow rapidly (approximately 10 cm per year) until the age of maturity, which for this region is estimated to be at 77 cm for males (age 5-6) and 119 cm for females (age 9-10). Female halibut grow faster than the males and attain a much larger maximum size. den Heyer, C.E., Hubley, B., Themelis, D., Smith, S.C., Wilson, S., and Wilson, G. 2015. Atlantic Halibut on the Scotian Shelf and Southern Grand Banks: Data Review and Assessment Model Update. DFO Can. Sci. Advis. Sec. Res. Doc. 2015/051. v + 82 p.

3.9 Selectivity of small fish

Answered
Very small (0.1 < S < 0.2)
Small (0.2 < S < 0.4)
Half asymptotic length (0.4 < S < 0.6)
Large (0.6 < S < 0.8)
Very large (0.8 < S < 0.9)
Justification
In addition to the direct impact of the fishery on the stock, discarding may be a significant source of mortality. Since 1994, all fish caught less than 81 cm in length are required to be discarded. Illegal discarding of large ‘whale’ halibut, which have a lower value per pound, could also be occurring. Atlantic halibut are also caught and landed with other commercially-valuable groundfish species (see below). If there is limited halibut quota available, halibut caught during
fisheries directed for other species may be illegally discarded. In general, halibut are thought to be robust to handling relative to other groundfish. Neilson et al. (1989) found that 35% of otter trawl-caught halibut and 77% of longline-caught halibut survived
48 hours in holding tanks. Recent deployments of PSAT tags suggest that the survival of larger halibut caught by longline gear could be 100% (Armsworthy et al. 2014). Kaimmer and Trumble (1998) found that careful handling of Pacific halibut can increase discard survival and that even those fish with mild or moderate injuries have a higher than expected probability of survival. For example, 69% of Pacific halibut with moderate injuries survived and 43% of halibut with severe injuries survived (Heyer et al (2015) p4).

Assuming moderate survival (35-67%) of discarded, undersized fish and no change in the size composition of the fishery, Neilson and Bowering (1989) concluded that the introduction of a minimum size of 81 cm would have little effect on yield, unless natural mortality was low (M=0.1), but that the value of the fishery would increase, owing to the increased value per weight of midsized halibut. (Heyer et al (2015) p12).

3.10 Selectivity of large fish

Answered
Asymptotic selectivity (SL = 1)
Declining selectivity with length (0.75 < SL < 1)
Dome-shaped selectivity (0.25 < SL < 0.75)
Strong dome-shaped selectivity (SL < 0.25)
Justification
from Fig 2 (age 5 is around 75 cm. Also see Appendix 1). from Figure 22 the selectivity at age is 5. (see Heyer et al (2015)) 200 cm (for females) So 75/200cm=0.375.

3.11 Discard rate

Answered
Low (DR < 1%)
Low - moderate (1% < DR < 10%)
Moderate (10% < DR < 30%)
Moderate - high (30% < DR < 50%)
High (50% < DR < 70%)
Justification
In addition to the direct impact of the fishery on the stock, discarding may be a significant source of mortality. Since 1994, all fish caught less than 81 cm in length are required to be discarded. Illegal discarding of large ‘whale’ halibut, which have a lower value per pound, could also be occurring. Atlantic halibut are also caught and landed with other commercially-valuable groundfish species (see below). If there is limited halibut quota available, halibut caught during
fisheries directed for other species may be illegally discarded. In general, halibut are thought to be robust to handling relative to other groundfish. Neilson et al. (1989) found that 35% of otter trawl-caught halibut and 77% of longline-caught halibut survived
48 hours in holding tanks. Recent deployments of PSAT tags suggest that the survival of larger halibut caught by longline gear could be 100% (Armsworthy et al. 2014). Kaimmer and Trumble (1998) found that careful handling of Pacific halibut can increase discard survival and that even those fish with mild or moderate injuries have a higher than expected probability of survival. For example, 69% of Pacific halibut with moderate injuries survived and 43% of halibut with severe injuries survived (Heyer et al (2015) p4).

Assuming moderate survival (35-67%) of discarded, undersized fish and no change in the size composition of the fishery, Neilson and Bowering (1989) concluded that the introduction of a minimum size of 81 cm would have little effect on yield, unless natural mortality was low (M=0.1), but that the value of the fishery would increase, owing to the increased value per weight of midsized halibut. (Heyer et al (2015) p12).

3.12 Post-release mortality rate

Answered
Low (PRM < 5%)
Low - moderate (5% < PRM < 25%)
Moderate (25% < PRM < 50%)
Moderate - high (50% < PRM < 75%)
High (75% < PRM < 95%)
Almost all die (95% < PRM < 100%)
Justification
In addition to the direct impact of the fishery on the stock, discarding may be a significant source of mortality. Since 1994, all fish caught less than 81 cm in length are required to be discarded. Illegal discarding of large ‘whale’ halibut, which have a lower value per pound, could also be occurring. Atlantic halibut are also caught and landed with other commercially-valuable groundfish species (see below). If there is limited halibut quota available, halibut caught during
fisheries directed for other species may be illegally discarded. In general, halibut are thought to be robust to handling relative to other groundfish. Neilson et al. (1989) found that 35% of otter trawl-caught halibut and 77% of longline-caught halibut survived
48 hours in holding tanks. Recent deployments of PSAT tags suggest that the survival of larger halibut caught by longline gear could be 100% (Armsworthy et al. 2014). Kaimmer and Trumble (1998) found that careful handling of Pacific halibut can increase discard survival and that even those fish with mild or moderate injuries have a higher than expected probability of survival. For example, 69% of Pacific halibut with moderate injuries survived and 43% of halibut with severe injuries survived (Heyer et al (2015) p4).

Assuming moderate survival (35-67%) of discarded, undersized fish and no change in the size composition of the fishery, Neilson and Bowering (1989) concluded that the introduction of a minimum size of 81 cm would have little effect on yield, unless natural mortality was low (M=0.1), but that the value of the fishery would increase, owing to the increased value per weight of midsized halibut. (Heyer et al (2015) p12).

3.13 Recruitment variability

Answered
Very low (less than 10% inter-annual changes (IAC))
Low (max IAC of between 20% and 60%)
Moderate (max IAC of between 60% and 120%)
High (max IAC of between 120% and 180%)
Very high (max IAC greater than 180%)
Justification
No justification was provided

3.14 Size of an existing MPA

Answered
None
Small (A < 5%)
Small-moderate (5% < A < 10%)
Moderate (10% < A < 20%)
Large (20% < A < 30%)
Very large (30% < A < 40%)
Huge (40% < A < 50%)
Justification
No justification was provided

3.15 Spatial mixing (movement) in/out of existing MPA

Answered
Very low (P < 1%)
Low (1% < P < 5%)
Moderate (5% < P < 10%)
High (10% < P < 20%)
Fully mixed
Justification
Model assumes full mixing, but the management unit definition (3NOPs4VWX5Zc) is based largely on tagging results which indicate that Atlantic Halibut move extensively throughout the Canadian North Atlantic with smaller fish moving further than larger fish.

3.16 Size of a future potential MPA

Answered
None
Small (A < 5%)
Small-moderate (5% < A < 10%)
Moderate (10% < A < 20%)
Large (20% < A < 30%)
Very large (30% < A < 40%)
Huge (40% < A < 50%)
Justification
No justification was provided

3.17 Spatial mixing (movement) in/out of future potential MPA

Answered
Very low (P < 1%)
Low (1% < P < 5%)
Moderate (5% < P < 10%)
High (10% < P < 20%)
Fully mixed
Justification
No justification was provided

3.18 Initial stock depletion

Answered
Very low (0.1 < D1 < 0.15)
Low (0.15 < D1 < 0.3)
Moderate (0.3 < D < 0.5)
High (0.5 < D1)
Asymptotic unfished levels (D1 = 1)
Justification
The model was initialized in 1970 by estimating the number of age 1 fish. Ages 2 to 20 are then estimated using an assumed Z of 0.2 (Heyer et al 2015) , but landings records starts in 1960 (https://dfo-mpo.gc.ca/species-especes/profiles-profils/atl-halibut-fletan-atl-eng.html). from Figure 24 (Heyer et al 2015) initial SSB (7kt) is lower than present levels ,15kt (2013). The stock-recruit relationship for halibut could not be well described by the more commonly used models. No sure that to todo here. I assumed low regime.


4 Management Characteristics

4.1 Types of fishery management that are possible

Answered
TAC (Total Allowable Catch): a catch limit
TAE (Total Allowable Effort): an effort limit
Size limit
Time-area closures (a marine reserve)
Justification
1. Describe what, if any, current management measures are used to constrain catch/effort.
Since 1994, all fish caught less than 81 cm in length are required to be discarded. Until 1988, the fishery was unregulated. The first TAC of 3,200 mt was not captured for several years. In 1994, the TAC was reduced to 1,500 mt, and was further reduced to 850 mt in 1995, in response to a protracted decline in landings. In 1999, recommendations made by the Fisheries Resource Conservation Council resulted in an increase in the TAC for this stock from 850 mt to 1,000 mt. Since that time, both the TAC and landings hav been increasing (Figure 5b). The TAC in 2014 was 2,563 mt (den Heyer et al 2015, p5)

2. Describe historical management measures, if any.

3. Describe main strengths and weaknesses of current monitoring and enforcement capacity.

Until 1988, the halibut fishery was unregulated. In 1988, a total allowable catch (TAC) of 3,200 t was set for 3NOPs4VWX5Zc (see fishery for details). (https://dfo-mpo.gc.ca/species-especes/profiles-profils/atl-halibut-fletan-atl-eng.html)
Observer coverage is variable geographically and seasonally and is not well matched to the spatial and temporal distribution of the fishery. Estimates by quarter and NAFO area range from 0 to over 100% of landings (by weight) observed. Variable observer coverage contributes to uncertainty in the length composition of the fishery (a major input to the assessment model) and in the amount and species composition of the bycatch which is estimated from observed sets

4. Describe and reference any legal/policy requirements for management, monitoring and enforcement.


4.2 TAC offset: consistent overages/underages

Answered
Large underages (40% - 70% of recommended)
Underages (70% - 90% of recommended)
Slight underages (90% - 100% of recommended)
Taken exactly (95% - 105% of recommended)
Slight overages (100% - 110% of recommended)
Overages (110% - 150% of recommended)
Large overages (150% - 200% of recommended)
Justification
for the recent years see Figure 5b (den Heyer et al 2015)


4.3 TAC implementation variability

Answered
Constant (V < 1%)
Not variable (1% < V < 5%)
Low variability (5% < V < 10%)
Variable (10% < V < 20%)
Highly variable (20% < V < 40%)
Justification
for the recent years see Figure 5b (den Heyer et al 2015)


4.4 TAE offset: consistent overages/underages

Answered
Large underages (40% - 70% of recommended)
Underages (70% - 90% of recommended)
Slight underages (90% - 100% of recommended)
Taken exactly (95% - 105% of recommended)
Slight overages (100% - 110% of recommended)
Overages (110% - 150% of recommended)
Large overages (150% - 200% of recommended)
Justification
No justification was provided


4.5 TAE implementation variability

Answered
Constant (V < 1%)
Not variable (1% < V < 5%)
Low variability (5% < V < 10%)
Variable (10% < V < 20%)
Highly variable (20% < V < 40%)
Justification
No justification was provided


4.6 Size limit offset: consistent overages/underages

Answered
Much smaller (40% - 70% of recommended)
Smaller (70% - 90% of recommended)
Slightly smaller (90% - 100% of recommended)
Taken exactly (95% - 105% of recommended)
Slightly larger (100% - 110% of recommended)
Larger (110% - 150% of recommended)
Much larger (150% - 200% of recommended)
Justification
No justification was provided


4.7 Size limit implementation variability

Answered
Constant (V < 1%)
Not variable (1% < V < 5%)
Low variability (5% < V < 10%)
Variable (10% < V < 20%)
Highly variable (20% < V < 40%)
Justification
No justification was provided


5 Data Characteristics

5.1 Available data types

Answered
Historical annual catches (from unfished)
Recent annual catches (at least 5 recent years)
Historical relative abundance index (from unfished)
Recent relative abundance index (at least 5 recent years)
Fishing effort
Size composition (length samples)
Age composition (age samples)
Growth (growth parameters)
Absolute biomass survey
Justification
1. Provide the time series (specify years, if possible) that exist for catch, effort, and CPUE/abundance indices.
in 1998, the Industry-DFO Halibut Survey was initiated to provide a fishery-independent index of exploitable biomass throughout the management unit. Prior to 2010, science advice was provided based on the research vessel (RV) abundance indices, catch per unit effort and length composition of catch. The DFO summer RV survey in 4VWX and DFO Spring survey in 3NOPs provide fisheries-independent indices of abundance (den Heyer et la 2015 pag iv). The longest and most comprehensive fisheries-independent data on the distribution and abundance of halibut are from the DFO RV bottom trawl surveys. For the assessment, only the Spring RV survey in areas 3N, 3O and 3Ps, and the 4VWX summer RV survey have been included. Recognizing the limitations of the DFO RV surveys to provide indices of abundance for halibut, the joint Industry-DFO Halibut Survey using longline gear was initiated in 1998, to provide an index of biomass of the exploitable population. As with the 2010 model run, data on the length frequency in the otter
trawl catch starts in 1977, but sampling was very low in the first five years so only length frequency data starting in 1984 was used. Data on the length frequency in the longline catch starts in 1988 and the Industry-DFO Halibut Survey time series used for both an index of abundance and length composition begins in 1998.

2. Describe how these data collected (e.g., log books, dealer reporting, observers).
The groundfish port sampling program started in 1948, although halibut were not measured at that time since most fish were landed without a head. The first halibut length in the DFO Maritimes Port Sampling database was in 1989 (Table 8). Halibut have only been sampled from landings from longline and otter trawl gear. When shore sampling of halibut caught in the Commercial Index began in 1999, the number of halibut trips sampled increased to an average of 48 per year. The proportion at length was generated separately for otter trawl (sex=unknown) and longline gear (sex=male, female, combined=unknown, male and female). The samples sizes are presented in Tables 9 and 10. (den Heyer et la 2015 pag6).

At-sea observers monitor and record fishing activities in greater detail than can be obtained from fishery monitoring documents submitted by fishermen. The catches of all species, whether retained or discarded, are recorded. In addition to the information on the catch, at-sea observers also record information on the fishing practices, including nature and location of the fishing activity, and may sample fish to assess sex, weight, and maturity, collect otoliths and other samples or data. The at-sea observer data is maintained by the DFO Maritimes Region in the Industry Surveys Database (ISDB). Prior to 1988, there were a small number of sets observed at sea (Table 11). Observer
coverage increased in 1988 and increased again in 1999 with the beginning of the Commercial Index. The number of sets observed from the otter trawl fleet peaked during the collapse of the cod fishery and then rapidly declined, averaging 33 sets per year since 1994. Since 1995, the number of observed trips from the longline fleet has been over 300 in all but two years (2004 and 2006), and has averaged 595 sets since 1999. The sample sizes are presented in Tables 9 and 10. The proportion at length was generated separately for otter trawl and longline gear. Smaller halibut comprise a larger portion of the catch of male halibut than female.

3. Describe what types of sampling programs and methodologies exist for data collection, including the time-series of available sampling data and quality.
(1) a relative abundance index from the DFO 4VWX RV survey (RV_4VWX; 1970-2013)
(2) 3NOPs4VWX DFO-Industry Halibut Survey biomass CPUE (HS, 1998-2013), and
(3) male, female, and combined proportion-at-length data for longline commercial fisheries (1988-2013), RV_4VWX (1970-2013), and HS (1998-2013) surveys.
Cox, S.P., Benson, A., and den Heyer, C.E. 2016. Framework for the Assessment of Atlantic Halibut Stocks on the Scotian Shelf and Southern Grand Banks. DFO Can. Sci. Advis. Sec. Res. Doc. 2016/001. v + 57 p
4. Describe all sources of uncertainty in the status, biology, life history and data sources of the fishery. Include links to documentation, reports.
The stock-recruit relationship for halibut could not be well described by the more commonly used models; therefore, interim reference points were chosen.


5.2 Catch reporting bias

Answered
Strong under-reporting (30% - 50%)
Under-reporting (10% - 30%)
Slight under-reporting (less than 10%)
Reported accurately (+/- 5%)
Slight over-reporting (less than 10%)
Justification
Total removals were then assumed to be known without error (den Heyer et la 2015 pag13). A discard mortality of 23% was assumed based on the study by Neilson et al. (1989) and was applied within the model.


5.3 Hyperstability in indices

Answered
Strong hyperdepletion (2 < Beta < 3)
Hyperdepletion (1.25 < Beta < 2)
Proportional (0.8 < Beta < 1.25)
Hyperstability (0.5 < Beta < 0.8)
Strong hyperstability (0.33 < Beta < 0.5)
Justification
No justification was provided


5.4 Available data types

Answered
Perfect
Good (accurate and precise)
Data moderate (some what inaccurate and imprecise)
Data poor (inaccurate and imprecise)
Justification
The only data available on halibut abundance from 1970 to 1984 is the 4VWX summer RV survey data (abundance index and length composition), and the landings without length composition data. however, the fits to the abundance indices are shown in Figure 23. The fit to the DFO RV survey data was fairly good, with a short string of positive residuals in the late-1980s and early-90s. The updated DFO Summer RV (4VWX) survey and the 3NOPs4VWX5Zc Halibut Survey indices show that abundance of both pre-recruits and recruits continue to be high. The 2016 DFO Summer RV (4VWX) index remains above the long-term mean and suggests that the fishery will continue to benefit from high recruitment in the next couple of years (STOCK STATUS UPDATE OF ATLANTIC HALIBUT ON THE SCOTIAN SHELF AND SOUTHERN GRAND BANKS (NAFO DIVS. 3NOPS4VWX5ZC) Canadian Science Advisory Secretariat Science Response Science Response 2017/021
Survey standard errors estimated from these fits were 0.26 and 0.195, respectively, which are quite reasonable for fishery-independent survey data. Cox, S.P., Benson, A., and den Heyer, C.E. 2016. Framework for the Assessment of Atlantic Halibut Stocks on the Scotian Shelf and Southern Grand Banks. DFO Can. Sci. Advis. Sec. Res. Doc. 2016/001. v + 57 p.


6 Version Notes

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shiny-2019-07-30-19:55:32

Open Source, GPL-2 2019