1-1 MID-ATLANTIC FISHERY MANAGEMENT COUNCIL Richard B. Robins, Jr. 800 North State Street, Suite 201 Christopher M. Moore, Ph.D. Chairman Dover, Delaware 19901-3910 Executive Director Tel: 302-674-2331 Lee G. Anderson Toll Free: 877-446-2362 Vice Chairman FAX: 302-674-5399 www.mafmc.org Bluefish Recommendation Summary Materials provided in this tab include the Bluefish Monitoring Committee Recommendations for annual catch targets (ACTs) and other commercial fishery management measures, a memo from Jim Armstrong to Chris Moore, and the Bluefish Assessment Update. The Scientific and Statistical Committee (SSC) recommendations for acceptable biological catch (ABC) are provided under Tab 3 (last document under that tab). A summary of the SSC and Monitoring Committee recommendations is provided below. The SSC recommended an ABC that is a reduction from OFL to address scientific uncertainty. The Bluefish Monitoring Committee recommended an ACT for each fishery that sum to the ACL. Please see the SSC and Monitoring Committee reports for additional details. Bluefish OFL 40.944 M lb ABC 32.044 M lb ACL 32.044 M lb Recreational Commercial ACTs 27.336 M lb 4.708 M lb TALs 17.194 M lb 10.500 M lb
Transcript
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MID-ATLANTIC FISHERY MANAGEMENT COUNCIL Richard B. Robins, Jr. 800 North State Street, Suite 201 Christopher M. Moore, Ph.D. Chairman Dover, Delaware 19901-3910 Executive Director Tel: 302-674-2331 Lee G. Anderson Toll Free: 877-446-2362 Vice Chairman FAX: 302-674-5399 www.mafmc.org
Bluefish Recommendation Summary
Materials provided in this tab include the Bluefish Monitoring Committee Recommendations for annual
catch targets (ACTs) and other commercial fishery management measures, a memo from Jim Armstrong
to Chris Moore, and the Bluefish Assessment Update. The Scientific and Statistical Committee (SSC)
recommendations for acceptable biological catch (ABC) are provided under Tab 3 (last document under
that tab).
A summary of the SSC and Monitoring Committee recommendations is provided below. The SSC
recommended an ABC that is a reduction from OFL to address scientific uncertainty. The Bluefish
Monitoring Committee recommended an ACT for each fishery that sum to the ACL. Please see the SSC
and Monitoring Committee reports for additional details.
Bluefish
OFL 40.944 M lb ABC 32.044 M lb ACL 32.044 M lb Recreational Commercial ACTs 27.336 M lb 4.708 M lb TALs 17.194 M lb 10.500 M lb
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July 29, 2011
Bluefish Monitoring Committee Recommendations
Attendees: John Maniscalco (NY-DEC), Jason McNamee (RI-DFW), Mark Terceiro (NEFSC), Tom Baum (NJ-DEP), Greg Wojcik (CT-DEEP), Chris Batsavage (NC-DMF), Rob O'Reilly (VMRC), Rich Wong (DNREC), Steve Doctor (MD-DNR), Mike Ruccio (NERO), Tobey Curtis (NERO), Jim Armstrong (Council Staff), Jessica Coakley (Council Staff), Jeff Kaelin (Lund's Fisheries), Lee Anderson (Council vice-chair), Eric Durell (MD-DNR), Toni Kerns (ASMFC), Mike Waine (ASMFC)
Discussion: The group received an overview of the presentation provided the SSC the prior day and was provided the SSC recommendations for ABC.
Consensus Recommendation:
Annual Catch Targets and Basis for Derivation
- The Bluefish Monitoring Committee recommends no adjustment was made to account for management uncertainty, due to the historic performance of the aggregate fishery (commercial and recreational catch) when compared to the total allowable catch (TAC). These recommendations are contingent on current fishery performance and present sources of management uncertainty.
- The Recreational ACT recommended is 27.336 million lb (12,399 mt). The Commercial ACT recommended is 4.708 million lbs (2,136 mt).
Relevant Sources of Management Uncertainty
- Forecast of recreational landings for upcoming year (used to establish transfer); assumes fishery will perform similar to the current year used in projection
- Past sector-specific landings performance can be used as a basis for quantifying management uncertainty (implementation error), and as an indicator of the future ability to achieve 2012 ACTs. Commercial fishery has never exceeded the commercial quota and typically underperforms relative to the commercial quota. Recreational fishery exceeded the harvest limit in 2006 (by 1%) and 2007 (by 11%); however, the recreational fishery typically results in landings less than the harvest limit.
- Recreational discard estimates (dead discards) have been increasing in recent years, and there is imprecision relative to the predicted and observed discards on the order of about 20% (underestimation). Commercial discard estimates are assumed negligible and no estimate is included in the assessment.
- The TAC has been exceeded once by approximately 7%.
Other Management Measures
- Transfer: The Bluefish MC recommends a transfer up to the maximum amount, which results in a commercial TAL of 10.500 million lb (4,763 mt) and a recreational TAL of 17.194 million lb (7,799 mt). If applied, RSA would be deducted to derive the commercial quota and recreational harvest limit.
- Recreational measures: The Bluefish MC recommends status quo recreational possession limit up to 15 fish.
- RSA: Up to 3%.
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Regulatory Review (Current Management Measures)
For the current 2011 fishing year, bluefish ABC (31.744 M lb; 14,399 mt) was based on Ftarget = Frebuild = FStatus Quo = 0.15, while OFL (39.621 M lb; 17,972 mt) was based on FMSY (0.19) as estimated in the ASAP model. Although the stock was officially declared rebuilt in 2009, the Council’s SSC chose to maintain Ftarget = FStatus Quo = Frebuild based on significant uncertainty in the assessment. Specific sources of uncertainty noted by the SSC include:
Missing data in the age-length keys (ALKs) Calibration of Albatross vs. Bigelow trawl catches Previously sampled near shore areas unavailable to the BIGELOW. Commercial discards assumed insignificant Significant population biomass (~40%) aggregated in the 6+ age group Weight at age assumed constant for period 2004+. Uncertainty in the MRFSS estimates, in general
For the current 2011 fishing year, the Council adopted a total allowable catch (TAC; landings + discards) equal to ABC (31.744 M lb; 14,399 mt), and total allowable landings (TAL; TAC - discards) of 27.293 M lb (12,380 mt). Based on the historic proportion of recreational and commercial landings for the period 1981-1989, 83% of the TAL is initially allocated as a recreational harvest limit (RHL) and 17% is allocated as a commercial quota. The FMP stipulates that if 17% of the TAL is less than 10.5 M lb (4,763 mt), then a transfer of landings could be made to increase the commercial quota to a limit of 10.5 M lb as long as the combined commercial and recreational landings would not exceed the TAL. In the final rule that established the 2011 management measures an estimate of recreational harvest for 2011 (16,851 M lb; 7,456 mt) was reported. Accordingly, a transfer of 4.772 M lb (2,164 mt) to the commercial fishery was made resulting in an adjusted commercial quota of 9.411 M lb (4,269 mt) and an adjusted RHL of 17.882 M lb (8,111 mt). A final adjustment allowed for two research projects to utilize 105,000 lb (48 mt) of bluefish RSA quota. The final commercial quota was 9.375 M lb (4.253 mt) and the final RHL was 17.813 M lb (8,080 mt).
Biological Reference Points
Bluefish biological reference points were established in the most recent benchmark assessment (41st SARC; NEFSC 2005). The reference points are based on output from the ASAP model, a forward projecting statistical catch-at-age model that is used to estimate current and historic population size and fishing mortality (Legault and Restrepo 1998). Overfishing is defined as occurring above FMSY is 0.19, which was determined internally to the ASAP model. The FMP prescribed Ftarget is 90% of FMSY (0.17). The estimate of BMSY is 147,051 mt (324.192 M lb), and the level at which the stock is determined to be overfished (½ BMSY) is 73,525.5 mt (162.096 M lb). BMSY was estimated in the 2005 assessment using SSB and recruit estimates from ASAP, fit externally to a Beverton-Holt stock-recruit model and subsequently using Thompson-Bell Yield and SSB/R.
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Stock Status and Projections
The ASAP estimate of fishing mortality for 2010 is 0.14, below the F threshold (FMSY = 0.19) and essentially equivalent to the specified 2010 F target (0.15). This outcome supports the statement that for 2010 overfishing was not occurring. Relative to fishing mortality targets, model estimates of annual F have been below threshold levels since 1997 (see Figure 2), consistent with catches that support growth in population biomass. Within the past 20 years, population abundance peaked in 2008 at 100 million fish, declined slightly in 2009 to 86 million fish and further to 72 million fish in 2010 (Table 10 in Attachment A). The declines are due to apparent weak 2009 and 2010 year classes, the two lowest in the time series. Retrospective analysis indicates no trend in updates to terminal year age-0 abundance estimates. These two year classes comprise the age-1 and 2 bluefish in 2011 and will be age-2 and 3 bluefish in 2012. Selectivity on age 1 and 2 bluefish is 100% and 94%, respectively, and 48% on age 3 bluefish. The time series of estimated stock biomass has increased by about 176% since 1996 (See Figure 3 below and Table 11 in attachment A). The current update on population biomass was complicated by alternative configurations of weight-at-age and updates in any year must contend with the models re-calculation of biological reference points. The final estimate of total biomass for 2010 that is comparable to the methods originally used to calculate BMSY (147,051 mt; 324.191 M lb) and annual biomass in previous years is 140,297 mt (309.302 M lb) which is 95.4% of BMSY and 190.8% of the ½ BMSY threshold. As such, the stock is not overfished. . Other changes in the model update (improved age-length key, estimated instead of constant weights-at-age for 2004 forward, among others) had relatively minor impacts on population estimates.
0.00
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Figure 2. Total bluefish abundance and fishing mortality as estimated in ASAP model. FMSY is indicated by the solid horizontal line.
Figure 3. Time series of bluefish total mean biomass (000s mt) and spawning stock biomass (000s mt) relative to Bmsy target and threshold (Source: 2011 Assessment Update).
ABC Recommendation
(Note: A concise presentation of the calculation of OFL, ABC, TAL and other management measures is provided in Table 1) The bluefish OFL for 2012 is the total catch at FMSY (0.19) which is estimated to be 40.944 M lb (18,572 mt). It has been noted in previous years that the metrics provided with the bluefish update do not adequately characterize the scope or level of scientific uncertainty associated with this assessment. In order to accommodate the uncertainty, the SSC has based ABC on Ftarget = FStatus Quo. There is increasing evidence that the stock has been rebuilt for several years such that the FMP-prescribed target F (0.17) could be used as the basis for ABC. Nevertheless, the appearance of the two lowest year classes in the time series in 2009 and 2010 suggests that increasing target F to 0.17 would not be appropriate at this time. As such, it is suggested that Ftarget = FStatus Quo be adopted for setting ABC for an additional year. This corresponds to Ftarget = 0.14 and ABC = 30.761 M lb (13,953 mt) which is 75% of ABC and 96.9% of the current year ABC. The SSC should determine if this ABC is consistent with the Council risk policy. Other Management Measures
Annual Catch Limit It is anticipated that the Bluefish FMP will be amended by the Omnibus ACL/AM Amendment in time
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for the 2012 fishing year. Under the Omnibus Amendment, total allowable catch (TAC) is replaced by annual catch limit ACL and is set equal to ABC (Figure 4; Table 2). Accordingly, the recommended ACL for bluefish for 2012 is 30.761 M lb (13,953 mt). Table 1. Recommended bluefish management measures for 2012.
Allowable Transfer Init RHL – Exp Rec Landings 4.423 2,006
Comm Quota Init Comm Quota + Transfer 8.778 3,982
RHL Init RHL - Transfer 16.841 7,639
FA
Figure 4. SpAmendment
pecification p(currently in
process for An rulemaking
Atlantic Blueg).
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efish as desccribed in the Omnibus AACL/AM
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Table 2. Specification terminology envisioned by the Omnibus ACL/AM Amendment.
Previous Term New Term Definition Use in Omnibus
Overfishing Limit (OFL)
Unchanged
The OFL is an estimate of the catch level above which overfishing is occurring. The amount of catch that corresponds to the estimate of MFMT applied to a stock and is expressed in terms of numbers or weight of fish.
OFL = catch level calculated
by MFMT
Acceptable Biological
Catch (ABC) Unchanged
The level of a stock’s annual catch that accounts for the scientific uncertainty in the estimate of OFL. May not exceed OFL.
ABC is established by
SSC
Total Allowable Catch (TAC)
Annual Catch Limit (ACL)
The level of annual catch of a stock that serves as the basis for invoking AMs. ACL may not exceed ABC. For Atlantic Bluefish ACL is set equal to ABC.
ACL = ABC
Fishery Sector Distinct user group to which separate management strategies and separate catch quotas apply. For bluefish, there are recreational and commercial sectors.
Recreational Sector,
Commercial Sector
Sector Annual Catch Target
(ACT)
An amount of annual catch of a stock that is the management target of the fishery, inclusive of discards, and accounts for management uncertainty in controlling the actual catch at or below ACL.
Recreational ACT,
Commercial ACT
Total Allowable Landings (TAL)
Sector Total Allowable
Landings (TAL)
Annual amount of total landings permitted by sector after removing estimated discards.
Sector TAL = sector ACT –
sector discards
Research Set-Aside (RSA)
Unchanged Amount of landings TAL up to 3 percent that may be set aside to fund research activities
TAL – X% (up to 3%) = RHL
and Commercial Quota
Recreational Harvest Limit
(RHL) Unchanged
Annual management target for the recreational sector after removing research set-aside.
RHL = Recreational Sector TAL-
RSA
Commercial Quota
Unchanged Annual management target for the commercial sector after removing research set-aside and receiving transfer from the recreational harvest limit.
Commercial Quota =
Commercial Sector TAL-
RSA
Optimum Yield (OY)
Unchanged The long-term average amount of desired yield from a stock or fishery. OY cannot exceed MSY.
OY
½ BMSY or BMSY
Proxy
Minimum Stock Size Threshold
(MSST)
Level of stock biomass below which the stock is considered to be overfished.
MSST = ½ BMSY
Proxy
FTHRESHOLD
(Also FMAX ,
FMSY)
Maximum Fishing
Mortality Threshold (MFMT)
The level of fishing mortality (F), on an annual basis, above which overfishing is occurring.
MFMT = FTHRESHOLD = FMSY = FMAX
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Considerations for ACT and TAL
Also according to the Omnibus Amendment, a reduction from ACL to the annual catch target (ACT) can be made in order to accommodate management uncertainty. The resulting ACT is further reduced by estimated discards to get total allowable landings (TAL) which is then divided among the recreational and commercial fisheries. The bluefish fishery (commercial + recreational) has exceeded the TAL once, in 2007 (Table 3) and has been below the TAL by an average of 5.422 M lb in the last three years (2008-2010) and under by 3.263 M lb in the last five years (2006-2010). Based on the historic performance of the bluefish fishery relative to specified management measures, no reduction from ACL is recommended and ACT is set equal to ACL. In other words, the buffer needed to assure that OFL is not exceeded is considered to be adequately accommodated by the 25% reduction from OFL to ABC. Reduction of the ACT to the TAL is calculated as ACT – discards, or 30.761 – 4.350 M lb = 26.411 M lb (11,980mt; Table 1). Research Set-Aside An adjustment allowing for research projects to utilize up to 3% of bluefish TAL is recommended as provided by the FMP. Full utilization of this allowance would result in a reduction of the initial TAL (26.411 M lb; 11,980 mt) by 0.792 M lb (359 mt) ending in an adjusted TAL of 25.619 M lb (11,621 mt). Recreational Harvest Limit and Commercial Quota Based on the historic proportion of commercial and recreational landings for the period 1981-1989 and according to the FMP, 17% of the TAL (now adjusted to 25.619 M lb; 11,621 mt; Table 1) is allocated to the commercial quota (4.355 M lb; 1,976 mt; Table 1) and 83% to the RHL is (21.264 M lb; 9,645 mt; Table 1). The FMP further stipulates that if 17% of the TAL is less than 10.5 M lb (4,763 mt), which it is (Table 1), then the commercial quota could be increased up to 10.5 M lb as long as the recreational fishery is projected to land less than 83% of the TAL for the upcoming year, i.e., the maximum transfer amount is the lesser of the amount that would result in a commercial quota of 10.5 M lb or an RHL consistent with expected recreational landings. Average recreational landings for 2008-2010 (7,639 mt; 16.842 M lb) are used for calculation of the initial recreational harvest limit (RHL). Accordingly, a transfer of 4.423 M lb (2,006 mt) to the commercial fishery is made resulting in an adjusted commercial quota of 9.411 M lb (4,269 mt) and an adjusted RHL of 16.841 M lb (7,639 mt; Table 1). The final RSA amount will likely be less than the full 3% such that these values could increase to a maximum of commercial quota of 9.050 M lb (4,105 mt) and an RHL of 17.361 M lb (7,875 mt) at zero RSA. Gear Regulations and Minimum Fish Size A 15 fish recreational possession limit was first implemented in 2001. Prior to that a 10 fish possession limit was in place since 1990, when the FMP was first implemented. There does not appear to be a compelling reason to deviate from the existing possession limits (15 fish) for the 2011 fishing season.
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Table 3. Summary of bluefish management measures, 2000 - 2011.
MID-ATLANTIC FISHERY MANAGEMENT COUNCIL Richard B. Robins, Jr. 800 North State Street, Suite 201 Christopher M. Moore, Ph.D. Chairman Dover, Delaware 19901-3910 Executive Director Tel: 302-674-2331 Lee G. Anderson Toll Free: 877-446-2362 Vice Chairman FAX: 302-674-5399 www.mafmc.org
M E M O R A N D U M
DATE: July 7, 2011
TO: Chris Moore, Executive Director
FROM: Jim Armstrong
SUBJECT: Addendum to Staff Memo on 2012 Bluefish Measures
Based on comments solicited through the distribution of meeting materials for the upcoming SSC and MC meeting, the following clarification is provided: 1. Determination of target F. During rebuilding, target F was defined as either, 1) the rebuilding plan's
prescribed F or, 2) status quo F, whichever was less in a given year, and where status quo was the realized F in the most recent year. Last year, the first post-rebuilding specification exercise, the SSC used status quo specified F (0.15), not status quo realized F (0.10) as target F for the 2011 fishing year. In identifying target F for 2012, I used the previous convention so that status quo F was realized F for 2010 (0.14). The same value would have been derived by applying the SSC’s risk policy for a Level 3 assessment (75% of Fmsy). The reduction from Fmsy (0.19) to status quo F (0.14) was meant to account for the existing assessment uncertainty as well as apparent poor 2009 and 2010 year classes. The designation of status quo F was not intended as a statement that the stock has not been rebuilt. There will be discussion at the upcoming meeting as to the magnitude of both current biomass and Bmsy. That discussion will likely inform the SSCs determination of an appropriate target F for 2010.
2. Process for determining commercial quota and RHL. According to the process envisioned in the Omnibus ACL/AM Amendment, the ACT is split 17%-83% between the commercial and recreational sectors, then discards are deducted separately from the separate ACTs resulting in recreational and commercial TALs. I made the 17%-83% split after deducting discards from a combined TAL as had been the convention. Because of the assumption that commercial discards are insignificant (zero) as well as the subsequent transfer of TAL from the recreational to the commercial sector, there is no difference in the final sector allocations.
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Bluefish 2011 Stock Assessment Update
Coastal/Pelagic Working Group
Northeast Fisheries Science Center
National Marine Fisheries Service
Woods Hole, MA
June 2011
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Executive Summary
The updated stock assessment was completed by adding catch and indices through
2010 to the previous 1982-2009 assessment. Catch information consisted of commercial
landings and length frequencies from Maine to Virginia collected by the Northeast
Fisheries Science Center, North Carolina landings and length information collected by
NC Division of Marine Fisheries, Florida landings and length information collected by
FL Fish and Wildlife Research Institute, and recreational landings and discards from
Maine to Florida collected in the NMFS recreational fisheries survey. The catch data
were combined with fisheries independent survey data from the Northeast Fisheries
Science Center, DE DNR, NJ DEP, CT DEP, coast-wide recreational catch per angler, as
well as juvenile indices from the SEAMAP program in the South Atlantic, in a forward
projecting catch at age model (ASAP). Fishery dependent and independent information
was partitioned into ages using a 2010 age-length key developed by Old Dominion
University.
The result of the analysis shows that bluefish is not overfished or experiencing
overfishing. Fishing mortality in 2010 was 0.14, below the biological reference point
(FMSY) of 0.19. Fishing mortality steadily declined from 0.34 in 1987 to 0.12 in 1999 and
has remained steady since 2000 with an average F=0.14. Recent total stock biomass
estimates peaked in 1982 at 318.2 thousand MT, then declined to 79.6 thousand MT by
1996 before increasing to the 2010 level of 140.3 thousand MT. Recruitment estimated
in the ASAP model has remained relatively constant since 2002 at around 21.4 million
age-0 bluefish, with the exception of a relatively large 2006 cohort estimated as 37.3
million fish. However, the 2009 and 2010 recruitment estimates were well below average
at 11.2 and 6.7 million fish, respectively. There was no significant retrospective bias in
the results. A projection of the abundance through 2013, under five different fishing
scenarios between F=0.10 and F=0.19, suggest that continue to biomass will decline due
to poor incoming year classes. Changes in the NMFS survey, limited age information,
discard size data and model configuration all contribute to the uncertainty in the
assessment.
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Introduction
The Atlantic coast stock of bluefish (Pomatomus saltatrix), distributed from
Maine through eastern Florida, is jointly managed by the Atlantic States Marine Fisheries
Commission (ASMFC) and the Mid-Atlantic Fishery Management Council (MAFMC). A
total annual quota is established and allocations given to commercial and recreational
fisheries. The management plan requires a distribution of 80% to recreational and 20% to
commercial, with provisions to shift unused recreational quota to commercial fisheries.
A bluefish stock assessment was presented for peer-review at the Northeast
Fisheries Science Center Stock Assessment Review Committee meeting (NEFSC SARC
41). The reviewers accepted the assessment for use in management decisions although
there were some reservations about the modeling approach. Since the review, the
bluefish stock assessment sub-committee (SASC) has produced annual updates while
maintaining the basic model settings from the approved assessment. The current
assessment is a continuation of the model update with the addition of 2010 catch at age
and indices at age information.
Life History
Bluefish, Pomatomus saltatrix, is a coastal, pelagic species found in temperate
and tropical marine waters throughout the world (Goodbred and Graves 1996; Juanes et
al. 1996). Bluefish spawn in offshore waters (Kendall and Walford 1979; Kendall and
Naplin 1981). Larvae develop into juveniles in continental shelf waters and eventually
move to estuarine and nearshore shelf habitats (Marks and Conover 1993; Hare and
Cowen 1994; Able and Fahay 1998; Able et al. 2003). Bluefish are highly migratory
along the U.S. Atlantic coast and seasonally move between the U.S. south Atlantic and
Middle-Atlantic, traveling as far north as Maine (Shepherd et al., 2006).
Several studies show bluefish to be a moderately long-lived fish with a maximum
age of 14 years (Hamer 1959; Lassiter 1962; Richards 1976; Barger 1990; Chiarella and
Conover 1990; Terceiro and Ross 1993; Austin et al. 1999; Salerno et al. 2001; Sipe and
Chittenden 2002). Bluefish up to 88 centimeter (cm) fork length (FL) have been aged
(Chiarella and Conover 1990; Salerno et al. 2001), although Terceiro and Ross (1993)
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noted considerable variation in mean bluefish size-at-age. Scale ages have been used to
estimate von Bertalanffy growth parameters (Lassiter 1962; Barger 1990; Terceiro and
Ross 1993; Salerno et al. 2001). The values for L∞ from these studies (87-128 cm FL)
match closely to the largest individuals in catch data and growth rates do not differ
between sexes (Hamer 1959; Salerno et al. 2001).
Bluefish grow nearly one-third of their maximum length in their first year
(Richards 1976, Wilk 1977). Variation in growth rates or sizes-at-age among young
bluefish is evident from the appearance of intra-annual cohorts. Lassiter (1962) identified
a spring-spawned cohort and a summer-spawned cohort from the bimodal appearance of
size at Annulus I for fish aged from North Carolina and the seasonal cohorts can differ in
age by two to three months. Summer-spawned larvae and juveniles grow faster than
spring-spawned larvae and juveniles (McBride and Conover 1991) although size
differences at annual age diminish greatly after three to four years (Lassiter 1962).
Spawning occurs offshore in the western North Atlantic Ocean, from
approximately Massachusetts to Florida (Norcross et al. 1974; Kendall and Walford
1979; Kendall and Naplin 1981; Collins and Stender 1987). Bluefish are characterized as
multiple spawners with indeterminate fecundity which spawn continuously during their
spring migration (Robillard et al. 2008). In addition to distinctive spring and summer
cohorts, Collins and Stender (1987) identified a fall-spawned cohort, demonstrating the
potential of an extended bluefish spawning season.
Bluefish in the western North Atlantic are managed as a single stock (NEFSC
1997; Shepherd and Packer 2006). Genetic data support a unit stock hypothesis (Graves
et al. 1992; Goodbred and Graves 1996; Davidson 2002). For management purposes, the
ASMFC and MAFMC define the management unit as the portion of the stock occurring
along the Atlantic Coast from Maine to the east coast of Florida.
Fisheries Dependent Data
Annual catch information was developed for five components of the commercial
fishery. Commercial landings from Maine to Virginia, North Carolina commercial
landings, Florida commercial landings, coast-wide recreational landings and coast-wide
recreational discards.
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Commercial fisheries from Maine to Virginia were sampled as part of the NEFSC
data collection program. Lengths were sampled from a variety of gears and market
categories. Expansion of length data was completed by market category and quarter of
the year, with the results merged into half year periods. In 2010 a total of 4,930
measurements from 91 samples were collected across all market categories from total
landings of 1,601 mt (50% of all commercial landings; Table 1). Market category/quarter
with inadequate length samples were filled with length information from adjacent
quarters within the same market category or from NC samples if necessary.
North Carolina commercial landings were expanded using length samples
collected by NC Division of Marine Fisheries. A total of 1,042 measurements from 24
samples were collected from landings of 1,463 mt (Table 1). Expansion of landings at
length were done by quarter, market category and gear type then combined into half year
totals. Length samples from Florida 2010 commercial landings were also available. A
total of 706 lengths from 53 samples were used to expand commercial landings of 143 mt
(Table 1). No landings were reported for South Carolina or Georgia. Total coast-wide
commercial landings in 2010 were 3,206 mt, an increase of 55 mt from 2009 (Figure 1).
Length frequencies from commercial fisheries are characterized by a multi-modal
distribution (Figure 2). In 2010 the distribution was strongly bimodal with one peak at 38
cm and a second around 70 cm. There were few fish below 25 cm. In comparison, the
2006 and 2008 distribution included a third mode around 55 cm. The 2009 distribution,
as well as previous years, was similarly bimodal.
Recreational landings are sampled for length as part of the MRFSS program. The
2010 recreational landings were 8,184 mt, an increase from 6,161 mt in 2009 (Table 2,
Figure 3). The MRFSS 2010 length samples (N=2,968) were used to expand recreational
landings per half year. Recreational discards in 2010 were estimated at 16,059 mt,
however after adjusting for a 15% mortality rate, the resulting discard loss was 2,409 mt.
A recent publication (Fabrizio et al 2008) shows that mortality may be higher and the
15% should be reevaluated in the next benchmark assessment. Length sampling for
bluefish discards in MRFSS at-sea sampling of recreational party boats provided lengths
of 195 discarded bluefish. In addition, lengths of bluefish tagged and released in the
American Littoral Society tagging program (by definition B2 catches) were included in
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the length distribution (n=960). Total combined (commercial and recreational) length
frequencies are presented in Figure 5.
Age data (n=393) were provided by Virginia Marine Resources Commission and
Old Dominion University ageing lab. Since the age key developed from the VA samples
was the only 2010 age information available, it was applied to both fishery dependent and
independent length data. Age data was provided by cm, fork length by half year. In
previous years the age key was provided for fish measured to total length, inches while
the length frequencies were measured in fork length to the nearest cm. Consequently,
previous length frequencies were converted to TL, inches using the following equation:
TL(in) = 0.245(FL(cm)) +0.440
For the assessment update, the age keys for 2004-2010 were made available in
FL, cm. Previous years data were updated (which included updating catch totals) and
length frequencies expanded using the revised age-length keys. In addition, the length
frequencies by age were converted to weight for calculation of annual weights at age
(beginning with 2004) (Table 3 Figure 6). Length-weight equations from the spring and
fall NEFSC bottom trawl survey were used for calculating weights at age. Due to low
sample size in spring surveys, all years beginning with 1993 were used in the equation
(n=205, a=-11.289, b=2.985). Fall equations were estimated from combined 2004-2010
length-weight data (n=3334, a=-11.621, b=3.096).
The previous catch at age through 2009 and the updated catch at age through 2010
are presented in table 4a and 4b. As in previous bluefish assessments the ages are
summarized in a plus category for ages 6 and above to reduce the effect of aging error.
Fisheries Independent Data
Survey indices as used in the previous bluefish assessment were updated for 2010.
These indices include SEAMAP juvenile (age 1) indices, Northeast Fisheries Science
Center (NEFSC) bottom trawl survey indices for ages 0 to 6+, NJ bottom trawl survey
indices of ages 0 to 2, DE bottom trawl survey indices for ages 0 to 2 and Marine
Recreational Fisheries Statistics Survey (MRFSS) recreational catch per angler trip
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(CPA) for ages 0 to 6+. The CT survey in 2008 and 2010 were not conducted during the
month of September, therefore these indices were treated as missing data. The NEFSC
survey in 2009 was modified by the replacement of the FV Albatross IV with the FSV
Henry B. Bigelow. The consequence of the replacement was a change in the areas
surveyed and the efficiency of the survey due to a change in net size and towing speed (as
well as other intangibles associated with a different vessel). Beginning in 2009 only the
outer third of the inshore strata set was sampled by the Bigelow. In addition, a conversion
coefficient of 1.16 was used to convert Bigelow mean number per tow into equivalent
Albatross units (Miller et al., 2010).
Among these survey indices, there were no consistent trends in total abundance.
The total NEFSC index (ln re-transformed stratified mean number per tow) declined to
6.66 in 2010 from 12.8 in 2008 (Table 5). The series arithmetic average index equaled
26.6 (geometric mean of 13.89). The 2010 Delaware survey index of ages 0 to 2 was
0.481 fish per tow, and below the time series average (0.520 per tow; Table 6). New
Jersey trawl survey indices of ages 0 to 2 for 2010 (1.64 fish/tow) was also below the
time series average of 6.3 per tow (Table 6). No indices of bluefish abundance in Long
Island Sound from the CT DEP survey were available from 2010 however, ages 0 to 6+
in 2009 (32.86 per tow) were about average for the series (33.42 per tow; Table 7).
Recreational catch per angler trip showed a small increase to 0.978 fish per angler trip in
2010, an increase from 0.832 in 2009 (Table 8). The recreational catch per angler was
modeled in a general linear model using a negative binomial error structure. The year
coefficient partitioned into ages (assuming the same proportion as the recreational catch)
was used in the ASAP model as a relative index of abundance.
Standardized recruitment indices (age 0) were developed using Z scores to
compare the relative 2010 indices to time series averages. Indices from NEFSC, DE, NJ,
and the Recreational CPA were all below average (Table 9, Figure 7).
ASAP Model
The initial ASAP model (version 2.0.20) was run with the previous 1982-2009
input file updated for 2010 total catch, catch at age, weight at age and indices at age. The
fishery was modeled as a single fleet with selectivity fixed as a bimodal pattern with full
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recruitment at age 1 (coded age 2). Model weighting factors remained the same as
previous assessments with the model heavily weighted towards the fishery total catch
rather than survey indices. Natural mortality was fixed at 0.2 and maturity at age was
held constant with full maturity at age 3. The updated model was run using the same
parameter settings while substituting the updated catch and weight at age matrices. The
modifications to the input matrices had little influence on the resulting trends in
population number or biomass (Appendix I).
The results of the updated ASAP model showed a decrease in total abundance
since 2006, declining from 97.9 million to 72.2 million fish (Table 10, Figure 8). The
decline is primarily the result of poor 2009 and 2010 year classes. Prior to 2009 and
2010, recruitment had remained relatively constant since 2000 at 21.4 million age-0
bluefish, with the exception of a large 2006 cohort estimated as 37.3 million fish. The
2009 recruitment estimate was below average at 11.2 million fish compared to the series
average of 22.8 million (Figure 9). Estimated recruitment in 2010 was the lowest in the
time series at 6.7 million. However among other age groups, the estimate of age 6-plus
bluefish continued to be large at 12.9 million, the second highest since 1990. Total mean
biomass in 2010 equaled 140,297 mt, a slight decrease since 2009. (Figure 10, Table 11).
Corresponding spawning stock biomass (SSB) in 2010 was 134,065 mt (Figure 10).
Updates to the mean weight at age has occurred in the current assessment, consequently
direct comparison of biomass estimates to previous bluefish assessments updates is not
appropriate.
Fishing mortality estimates in ASAP are based on a separability assumption with
F at age the product of FMULT and selectivity. Full selectivity is fixed at age 1. The 2010
FMULT value equals 0.14 (Figure 8). Fishing mortality steadily declined from 0.34 in 1987
to 0.12 in 1999 and has remained steady since 2000 with an average F=0.14.
Retrospective bias for the final model was examined for F, total abundance,
recruitment (age 0) and total biomass. The analysis shows little evidence of bias in the
estimates (Figure 11). The variation in the final model results for F and SSB was
determined using a Monte Carlo Markov chain with 1000 iterations and a thinning factor
of 100. The MCMC results of variation around F ranged from 0.114 to 0.159, with the
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80% CI between 0.128 and 0.147. Estimates for SSB ranged from 114,623 to 158,030
mt, with an 80% CI between 124,044 mt and 140,788 mt. (Figure 12).
Projections
Bluefish abundance and biomass through 2013 were examined for a range of
fishing scenarios with a stochastic projection in AGEPRO software. Weight at age in
2011-2013 was assumed equal to 2010, recruitment was derived from a random draw of
28 empirical estimates of age 0 abundance since 1982 and initial population size was
drawn from the output of the MCMC run. Fishing mortality for 2011 was assumed equal
to targeted F of 0.15. Five projection scenarios were examined: F =0.10, F=status quo
(0.14) (equivalent to F equal to 75% of FMSY (0.14) ), Ftarget (0.17) which equals 90% of
FMSY as defined in FMP, F0.1 (0.16) from the yield per recruit, and FMSY (0.19)
Results of the projections show a decrease in mean biomass and SSB for each
scenario including a reduced F (F=0.10) (Table 12, Appendix II). However, abundance
could continue to increase in all 5 cases. Yield through 2013 would be projected as lower
for F scenarios of status quo or less. Under status quo F (0.14), projected 2012 yield
would increase to 13,953 mt, which includes commercial and recreational landings as
well as recreational discards losses.
Biological Reference Points
The current biological reference points for bluefish were determined in SARC 41
and are FMSY (0.19) and BMSY (147,052 mt). The basis for the reference points was the
Sissenwine-Shepherd method using the Beverton-Holt stock recruitment parameters and
SSB per recruit results generated by the SARC 41 ASAP model results. BMSY was
calculated using mean weights at age and is therefore comparable to mean biomass in
year t. The 2010 estimate of mean total biomass is 140,297 mt (+1 std. dev. of 6,671 mt),
which is slightly below BMSY but well above ½ BMSY of 73,526 mt. The 2010 estimate
of fishing mortality (0.14) remains below FMSY. An alternative approach to estimating
BMSY is calculation of an equilibrium bluefish biomass when fished at FMSY, using a long
term projection. This biomass, determined from a 50 year projection with re-sampling of
Table 5. NEFSC bluefish indices by age using fall inshore strata and re-transformed loge stratified mean number per tow. * indices changed with conversion factor=1.16.
DRAFT ADDENDUM I TO AMENDMENT 1 TO THE BLUEFISH FISHERY MANAGEMENT PLAN
Biological Monitoring Program
This draft document was developed for Management Board review and discussion during
the August MAFMC meeting week. This document is not intended to solicit public comment as part of the Commission/State formal public input process. However, comments
on this draft document may be given at the appropriate time on the agenda during the scheduled meeting. Also, if approved, a public comment period will be established to solicit
input on the issues contained in the document.
ASMFC Vision Statement:
Healthy, self-sustaining populations for all Atlantic coast fish species or successful restoration well in progress by the year 2015.
August 2011
Draft Document for Board Review. Not for Public comment.
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PUBLIC COMMENT PROCESS AND PROPOSED TIMELINE This draft addendum presents the background on the Atlantic States Marine Fisheries Commission’s (ASMFC) management of bluefish, the addendum process and timeline, and a statement of the problem. This document also provides for public consideration and comment on the options presented. The public are encouraged to submit comments regarding this document at any time during the addendum process. Comments will be accepted until 5:00 pm on XXXX, 2011. Regardless of when they were sent, comments received after that time will not be included in the official record. Comments may be submitted by mail, email, or fax, as well as at public hearings. Dates, times, and locations for the public hearings are as follows: If you would like to submit comment in writing, please use the contact information below. Mail: Michael Waine Atlantic States Marine Fisheries Commission 1050 N. Highland St. Suite 200 A-N Arlington, VA 22201
If you have any questions or would like more information, please contact Mike Waine at 703-842-0740 ASMFC’s Addendum Process and Timeline The development of Addendum I to Amendment 1 to the Interstate Fishery Management Plan for Bluefish will follow the general process outlined in the figure below. Tentative dates are included to illustrate the timeline of the addendum process.
August 2011 Board Reviews Draft Addendum and Considers
Approval for Public Comment
Board Reviews Public Comment and Considers Final Approval of Options and Addendum
November 2011
Public Comment Period September - October 2011
Provisions of the Addendum are implemented January 2012
Draft Document for Board Review. Not for Public comment.
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1.0 Introduction The bluefish fishery management plan (FMP) was adopted by the Atlantic States Marine Fisheries Commission (ASMFC) and the Mid-Atlantic Fishery Management Council (MAFMC) in October 1989. It is a joint management plan and is the first FMP developed jointly by an interstate commission and a federal fishery management council. Bluefish is currently managed under Amendment 1 to the FMP approved in October 1998. Management authority in the Exclusive Economic Zone (EEZ, 3-200 miles from shore) lies with NOAA Fisheries. As defined by Amendment 1, the management unit is bluefish in U.S. waters of the western Atlantic Ocean. In 2005, the Stock Assessment Review Committee (SARC) approved the use of an age-structured assessment program (ASAP) for bluefish, replacing the previously used surplus production model. The bluefish stock successfully rebuilt under the management program in Amendment 1, but the Council and Commission are exploring uncertainties involved in the stock assessment. More specifically, the most recent benchmark assessment revealed gaps in age length keys used in the ASAP model, and therefore, the assessment results should be used with caution (NEFSC 2005). This draft addendum proposes to address the biological sampling protocols for bluefish relative to data needs for the stock assessment. 2.0 Management Program 2.1 Statement of the Problem A large part of the uncertainty in the stock assessment came from the age data used in the model (NEFSC 2005). The assessment used scale ages for the early part of the time series (1982 – 1997) and otolith ages for the later part (1998 – 2004). The SARC was concerned about discrepancies between scale and otolith ages and the general difficulties of ageing bluefish. The assessment was further hampered by gaps in the age-length keys resulting from a lack of samples for certain age and size classes (e.g., Figure 1); these gaps were filled by pooling samples across years, which increased uncertainty. Age samples were also geographically limited, coming only from Virginia and North Carolina. The panel recommended that ageing practices be standardized and sampling expanded to overcome these deficiencies in the assessment.
Draft Document for Board Review. Not for Public comment.
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Figure 1. Length frequencies of bluefish harvest and age samples for 2004.
In response to the SARC recommendations for the bluefish stock assessment, the 2011 ASMFC’s Action Plan included Task 2.4.4 to work with states on developing a cooperative program to collect otoliths to improve age data for assessments of several species including bluefish. Additionally, under this task, a bluefish ageing workshop was conducted in May 2011 to assess the need for bluefish biological monitoring and ensure that optimal and consistent sampling methods be established coast wide (ASMFC 2011). The recommendations from the SARC, and the bluefish ageing workshop, are the premise for the development of draft Addendum I to review the biological sampling protocols. 2.1.2 Background The most recent stock assessment of bluefish used age data from two states: North Carolina for the early part of the time series (1982 – 1997) and Virginia for the later part of the time series (1998 – 2004) (NEFSC 2005). Virginia accounted for approximately 4% of the total coastwide harvest of bluefish from 1998 – 2008 and yet supplied all of the age data for those years in the assessment. Additionally, the age-length keys used in the assessment had gaps due to a lack of samples in certain size classes. Fishery dependent length sampling of bluefish shows a bimodal pattern, with few samples in the 50-60cm size range, and the age samples used to develop age-length keys do not adequately cover the entire size range of the fisheries (e.g., Figure 1). These gaps had to be filled by pooling data across years. The 2005 peer review of the stock assessment highlighted both of these issues as sources of uncertainty. In 2010, the Bluefish Technical Committee (TC) recommended that a coastwide sampling program be developed to expand the geographical range of sampling and to fill in gaps in the age-length key. The TC identified the states that had accounted for more than 5% of the total bluefish harvest (commercial and recreational) from 1998 – 2008 (Massachusetts, Rhode Island, Connecticut, New York, New Jersey, and North Carolina) and recommended that they be responsible for providing a number of samples based on their contribution to the total landings. Bluefish ageing workshop participants revisited this issue, and recommended that a pilot program be developed to determine the optimum sample size for a coastwide age-length key and test the feasibility of state-level sampling combined with regional level ageing. Sampling allocation was reduced and simplified so that each of the key states plus Virginia would be responsible for providing 100 bluefish ages per year (50 from the spring and 50 from the fall). The importance of sampling from as wide a range of sizes as possible was stressed. Not all states have resources to age bluefish, but member states with ageing capabilities could cooperate to process and age the samples collected. This pilot study would also allow the states to determine the cost and feasibility of sharing ageing responsibilities, as well as explore options for funding mechanisms.
Draft Document for Board Review. Not for Public comment.
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2.1.3 Biological Monitoring Program The following options present possible changes to biological sampling protocols for bluefish. Option 1. Status quo. Biological sampling protocols are not explicit in the bluefish FMP and are not part of state compliance. Option 2. The states that account for more than 5% of total coastwide bluefish harvest (recreational and commercial combined) for the 1998 – 2008 period are required to collect a minimum of 100 bluefish ages (50 from January through June, 50 from July through December). These states are: Massachusetts, Rhode Island, Connecticut, New York, New Jersey, and North Carolina. Virginia must continue its current sampling regime for bluefish and provide that same minimum 100 samples as the other states. Every effort should be made to cover the full range of bluefish sizes with these samples. States are encouraged to process and age their own otolith samples, but may send their whole otolith to another state with ageing capacity. At the end of the first year of the sampling program, the TC will review the effectiveness of the sampling design and evaluate the optimal geographic range and sample size for bluefish age data. The TC may also recommend sampling in specific size bins to fully account for the length frequency observed in bluefish landings data. If changes are necessary to the sampling program, as recommended by the TC, then sampling protocols may be modified through Board action. 3.0 Compliance States must implement Addendum V to the following schedule:
Month day, 20XX: States must implement Addendum I. States may begin implementing management programs prior to this deadline if approved by the Bluefish Management Board.
References Atlantic States Marine Fisheries Commission (ASMFC). 2011. Bluefish Ageing Workshop Final Report. 20 pp. Northeast Fisheries Science Center. 2005. 41st Northeast Regional Stock Assessment Workshop (41st SAW): 41st SAW Assessment Report. Northeast Fisheries Science Center Reference Document 05-14.
