Synopsis of the Third Annual Louisiana Oyster Stock Assessment Workshop
held12 August 2014
at theUniversity of New Orleans
Compiled by
Thomas M. SoniatOyster Research Laboratory
Department of Biological SciencesUniversity of New Orleans
8/29/2014
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Third Annual Louisiana Oyster Stock Assessment Workshop participants and support staff
Thomas SoniatDepartment of Biological SciencesUniversity of New Orleans
Patrick BanksLouisiana Department of Wildlife and Fisheries
Eric PowellGulf Coast Research LaboratoryUniversity of Southern Mississippi
Pete Vujnovich Louisiana Oyster Task Force
Chris SchiebleLouisiana Department of Wildlife and Fisheries
Nathan CooperDepartment of Computer SciencesUniversity of New Orleans
Susan ColleyDepartment of Biological SciencesUniversity of New Orleans
John FiniganDepartment of Computer SciencesUniversity of New Orleans
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Introduction
The Third Annual Stock Assessment Workshop was held on August 12, 2014 at the
University of New Orleans. The purpose of the Workshop was to evaluate the status of the oyster
stock in public oyster areas of Louisiana, estimate sustainable harvests for the upcoming oyster
season in those public areas, and review and propose management and scientific research
recommendations.
Background and Methods
A shell budget model is applied to estimate the sustainable catch of oysters on public
oyster grounds in Louisiana using no-net-shell-loss as a sustainability reference point. The model
simulates oyster growth and mortality, and natural shell loss. Shell mass is increased when
oysters die in place, and diminished when oysters are removed by fishing (Soniat et al. 2012).
Oyster density and oyster size from the 2014 Louisiana Department of Wildlife and Fisheries
(LDWF) Stock Assessment covering all the public oyster areas in all Coastal Study Areas
(CSAs) were input using an automated data entry form (Soniat et al. 2013;
www.oystersentinel.org). The model estimates the number of sacks of seed and sack oysters that
could be removed during the 2014/15 season with no net loss of shell. Primary model
components calculate growth, natural mortality, fishing mortality, cultch density, and sacks of
seed and sack (market) oysters fished (Figure 1). The shell budget model has practical
application such as identifying areas for closure, determining total allowable catch, managing
shell planting and reef restoration, and achieving product certification for sustainability.
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Figure 1. Schematic of major oyster model processes.
Oysters that are not lost to natural mortality or removed by fishing grow into new size
classes over time. Natural mortality provides new shell to the reef, whereas fishing removes it.
Natural shell loss occurs from taphonomic processes, mostly dissolution and biodegradation.
Change in cultch density is thus a function of initial cultch density, initial population numbers,
size-class distribution, shell growth, natural mortality, fishing mortality, and natural shell loss.
Fishing rates and times are adjusted to achieve sustainable harvest; that is, the reference point
defining sustainable harvest is a harvest that results in no net loss of cultch. (Model details are
provided by Soniat et al. 2012, 2013.)
The 2012 Stock Assessment (LDWF 2012) included, for the first time, precise
measurements on the quality and quantity of the cultch. Brown (surface) and black (muddy,
buried) substrate were collected from 1-m2 grids and weighed. These measurements were
repeated for the 2103 (LDWF 2013) and 2014 Stock Assessments. The substrate categories are:
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muddy oyster shell, brown oyster shell, muddy limestone, brown limestone, muddy clamshell,
brown clamshell, muddy concrete, brown concrete, muddy other substrate, and brown other
substrate. Although the quantity (g/m2) of the various substrate types were sampled in previous
Stock Assessments, only brown shell was used in earlier simulations. The 2014 simulations
include all brown substrate (cultch). By inference, the reference point determining sustainable
harvest focuses on exposed (brown) cultch because this is the substrate available for future
recruitment of spat.
Status of the Stock
The 2014 stock assessment sampling by LDWF indicates an approximate 30% increase in
statewide oyster stocks as compared to 2013. This increase was driven largely by increases in
oyster stocks located east of the Mississippi River in CSA 1N (47.8% increase), and CSA 5W
(25.2% increase). The 2014 Oyster Stock Assessment report provides comprehensive
information on the status of the stock.
Sustainable Harvests
Simulations were conducted to estimate sustainable harvests from reefs in all CSAs, the
locations of which are shown in Figure 2. Fishing rates were varied to identify a rate that resulted
in no net loss of cultch. Initial simulations were conducted for all stations (reefs and cultch
plants) without fishing (Table 1); those with a gain of cultch mass were deemed potentially
“fishable”. Reefs and cultch plants that were deemed “fishable” were simulated to determine a
sustainable Total Allowable Catch (hereafter simply referred to as TAC). Sustainability in
simulations is achieved by manipulating fishing effort to achieve no net loss of cultch. The
temporal distribution of fishing, fishing effort (approximate monthly effort as a percent of total
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effort) and fishing type (sack, seed) is informed by recent commercial fishing practices provided
by LDWF (Table 2).
Figure 2. Boundaries of LDWF Coastal Study Areas (CSA).
In CSA 1N, the stations which gained cultch in simulations without fishing included
Grand Banks, Grassy, Halfmoon, Millennium, Petit, Shell Point, West Karako and the 2011
Round Island cultch plant (Table 1). The simulated TAC for CSA 1N is 136,669 sacks of
market-sized oysters and 59,469 sacks of seed (Table 3).
The CSA 1S stations of the California Bay 2001 Cultch Plant, North California Bay,
North Lonesome, and Snake Island show a positive shell balance (Table 1): CSA 1S TAC is
estimated to be 7000 sacks of sack oysters and 200 sacks of seed (Table 3).
In CSA 3, the Lower, Middle, and Upper Hackberry Bay stations, the 2004 North and
South Hackberry Bay Shell Plants, and the 2008 and 2012 cultch plants in Hackberry Bay
showed a positive shell balance without fishing (Table 1). Using the open reefs of the 2004
Barataria Cultch Plant and the 2008 Cultch Plant in the simulation, the CSA 3 TAC is estimated
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to be 250 sacks of sack oysters. No fishing of seed was deemed sustainable in the combined
sack/seed fishing scenario (Table 2, Table 3).
The CSA 5E stations of Lake Chien 2004 Cultch Plant, Lake Chien 2008 Cultch Plant,
and Lake Felicity (Table 1), showed a cultch gain without fishing. A TAC for the CSA was not
calculated since the region is closed to fishing this coming season (Table 2).
Fishable stations from CSA 5W include the 2009 Sister Lake Cultch Plant, Buckskin
Bayou, Lake Mechant, Mid Bay Junop, the N 94 and 95 shell plants, the Sister Lake 2004 Cultch
Plant, and Walker’s Point (Table 1). Using the reefs open to fishing (Walker’s Point, North 95
Shell Plant, Buckskin Bayou, Lake Mechant), the TAC from CSA 5W is 2800 sacks of sack
oysters and 3700 sacks of seed (Table 3).
None of the stations in CSA 6 were considered fishable (Table1). No further simulations
were conducted. Low densities of oysters on these reefs resulted in cultch budgets controlled by
loss processes.
The Sabine Lake stations (CSA 7) showed a shell gain without fishing (Table 1);
however, they will not be open to fishing and thus are not included in the estimation of TAC. In
Lake Calcasieu, only West Rabbit and Northeast Rabbit showed a cultch gain (Table 1). A
simulation of these reefs in CSA 7 yields a TAC of 230,000 sacks of sack oysters. As a general
industry practice no fishing of seed oysters occurs in CSA 7 (Table 2).
In total, the TAC for the combined CSAs is 386,171 sacks of market oysters and 63, 461
sacks of seed oysters (Table 3). This is much greater than the 2013 statewide estimate of TAC as
76,763 sacks of market oysters and 19,642 sacks of seed.
Areas (reef groupings within a CSA) were designated for special consideration (Table 5)
by LDWF for management purposes. These were Grassy, Petit, Halfmoon Island, Round Island
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Cultch Plant, and Millennium Reef in CSA 1N, Lake Fortuna North and Lake Fortuna South in
CSA 1S, Bay Gardene and East Bay Gardene in CSA 1S, Indian Point, Big Charles, and
Lighthouse Point in CSA 6, Bayou Blanc, South Point, North Reef, and Middle Reef in CSA 6,
and SE Rabbit, West Rabbit, West Cove Transplant, NE Rabbit in CSA 7. Of the listed reefs
only reefs in CSA 1N and CSA 7 had a positive cultch balance without fishing; only those area
simulations were conducted. The CSA 1N area grouping simulation estimates a TAC of 96,000
sacks of market oysters and 98,000 sacks of seed oysters. An area simulation of CSA 1N without
seed fishing yields a TAC of 106,094. The CSA 7 area grouping estimates a TAC of 200,000
sacks of market oysters.
It should be noted that the present estimates of TAC are based on cultch stasis, not
enhancements to desired endpoints (Mann et al.2009). That is, since sustainable fishing
estimates are based on no net loss of cultch rather than a goal of increased cultch; a poor quality
reef, before fishing remains a poor quality reef after fishing if TAC model estimates are met.
Review 2013 SAW Recommendations
1. Conduct a second trial application of the model on the public oyster grounds in Hackberry
Bay. The 2013 SAW recommended that the 2013/2014 oyster season in Hackberry Bay be managed such
that the TAC was not exceeded. The TAC for the 2013/2014 trial was estimated to be 1085 sacks
of sack oysters and 1349 sacks of seed. Harvest was monitored during the season; however,
fishing exceeded the estimated TAC during the 2013/2014 oyster season. Estimated catch of market
oysters was 1,390 sacks, whereas estimated catch of seed oysters was 4,410 sacks. The model
predicted that there should be a decline in cultch density if TAC was exceeded, and the decline
was realized. The 2013 Stock Assessment brown shell density for CSA 3 was 1,327 g/m2. The
2014 Stock Assessment brown shell density for CSA 3 is 443 g/m2.
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2. Determine the loss rate of oyster shell from existing metrics. The rate of shell loss can be
calculated from oyster cultch density, numbers, size, and mortality. With the exception of
mortality, these metrics are provided by the Annual Stock Assessment. Mortality rates of large
oysters (> 2.5 inches) can be determined from existing sources (see recommendation 4 below for
discussion).
3. Assign loss rates to specific cultch types and include all cultch types in future simulations.
Recommended annual loss rates are: oyster shell 10%, Rangia shell 30%, mussel shell 80%,
limestone 1%, concrete 0.1%. This also required a determination of packing coefficient and
density (g/ml) for the various substrates, which was obtained (Table 4).
4. Determine growth and mortality along salinity gradients. Funding should be sought to
carry out a substantial program to obtain good growth and mortality data. When and where
available, data from existing LDWF Nestier tray studies should be used to determine growth and
mortality. The analysis of the change in numbers of oysters in identifiable cohorts of oysters
from various salinity regimes can be used to determine mortality. The effort has been directed
toward determining oyster age using existing resources. Staining of growth lines has been
successful (Figure 3). The difficulty is in determining the periodicity of the growth lines. We are
using oysters of a known age as a starting point. Assigning age will be based on a combination of
information from growth lines, growth rates, spawning events, and cohort analysis (Quick and
Mackin 1971).
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Figure 3. Growth lines along the chondrophore of an 11-month-old oyster stained with eosin and hematoxylin (oyster from John Supan).
5. Historical Stock Assessment data should be digitized by entry into the existing model
database. Due to lack of resources, an alternative approach was taken. Abundance of sack and
seed oysters for each CSA was determined using Stock Assessment reports from 1992 to 2013.
Oyster abundance was compared to the dominant Gulf of Mexico climate cycle (ENSO 3.4
Index) and river flow. Initial simple statistical tests (t-tests) showed no relationship between
ENSO, river flow and oyster yield (Figure 4).
SAW Recommendations for 2014
1. Request that LDWF develop a policy for the return of oyster shell from shucking houses to the
Public Oyster Grounds. Soniat and Banks should prepare a formal request to LDWF officials.
2. Devise an Area Management Plan. Banks should propose to Soniat and LDWF harvest areas
(groupings of reefs and shell plants) within each Coastal Study Area (CSA) to be managed as
a unit. These Area Management Units (AMUs) should be developed with enforcement
considerations in mind. Simulations of sustainable Total Allowable Catch (TAC) are to be
conducted for each AMU. Fishing closures should be considered on an AMU basis.
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3. Digitize all field data records from historical annual Stock Assessments. The cost and
difficulty of the task should not discourage this important effort. Soniat and Banks should
coordinate between UNO and LDWF Data Management personnel.
4. Expand model testing. Harvest from a CSA or AMU either exceeds or falls below the
estimated TAC. A comparison of harvest versus the TAC and its impact on cultch density is a
model test and could immediately be accomplished using 2013-2014 oyster season harvest
data (Table 6). In those CSAs or AMUs where harvest exceeds the TAC, a decrease in cultch
is predicted; likewise, in CSAs or AMUs where harvest is less than the TAC, an increase in
cultch is predicted. Soniat should lead this effort. Although Hackberry Bay was the only area
in which a model test was planned for 2014, comparisons of cultch from the 2013 and 2014
Stock Assessments are possible. Note that with the likely exception of Hackberry Bay, it is
uncertain if harvest came from only the reefs that were simulated. A variety of outcomes were
evident in these comparisons. In CSA 1N, total harvest was less than the TAC threshold, yet a
loss of brown oyster shell occurred from 2013 to 2014; however, the excess harvest was seed,
which is especially detrimental to the shell budget. In CSA 1S, seed harvest greatly exceeded
the TAC threshold, but market harvest was well below the threshold and there was a gain in
brown shell from 2013 to 2014. The results of the Hackberry Bay experiment were totally
consistent with predictions: seed, market and total harvest exceeded threshold and brown shell
decreased. Contrariwise, Sister Lake showed a shell increase, although seed, market and total
harvest exceeded the TAC threshold. Although no fishing of seed or sack oysters was deemed
sustainable in 2013 in CSA 6 (threshold = 0), substantial harvest occurred there, yet shell was
gained. In Lake Calcasieu (West Cove only), a 21% overharvesting of market oysters did not
prevent a gain of shell.
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19901991
19921993
19941995
19961997
19981999
20002001
20022003
20042005
20062007
20082009
20102011
20122013
-1.5-1
-0.50
0.51
1.5
ENSO 3.4 Index
19901991
19921993
19941995
19961997
19981999
20002001
20022003
20042005
20062007
20082009
20102011
20122013
0200400600800
1000
Riverflow (cfs x 1000)
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 20120
100200300400500600
Seed Oysters (barrels/acre)
CSA1 CSA2 CSA3 CSA4 CSA5 CSA6 CSA7
1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 20120
200400600800
10001200
Sack Oysters (sacks/acre)
CSA1 CSA2 CSA3 CSA4 CSA5 CSA6 CSA7
Figure 4. Time series of the ENSO 3.4 Index, Mississippi River flow at Talbert Landing, and stock estimates of seed and sack oysters by Coastal Study Area (traditional CSA designation).
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5. Determine the error of the estimate of oyster density and present this with annual oyster stock
assessment data. Sample selected areas with about 4 times the normal replication to establish
the number of samples needed. Banks should coordinate this activity.
6. Track the 2014-2015 harvest per vessel per day. A time series of the decrease in the number
of sacks harvested per day would be useful. Particularly critical is the time when harvesters
cannot achieve their 50 sack/day limit. Banks should direct this undertaking as part of normal
LDWF harvest monitoring activities during the upcoming oyster season.
7. Combine VMS tracks of individual boats on Public Grounds with trip tickets to estimate
CPUE as sacks/hour. Use VMS tracks to determine area swept by dredges. Soniat should lead
this effort.
8. Suggest a practical and desirable cultch density. Soniat should provide this estimate.
9. Continue age/growth/mortality studies using growth lines visible along the chondrophore.
Consider image analysis for the interpretation of growth line density. Soniat should lead this
study.
10. Estimate the proportion of private lease production that is dependent upon seed from the
Public Grounds. Banks should take the lead role here.
11. The Fourth Annual Louisiana Stock Assessment Workshop should be held between August
10th and August 28th, 2015.
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TABLE 1.
Simulations to determine “fishable” reefs, that is reefs that gain cultch without fishing. Shell refers to brown shell only, whereas cultch includes all brown cultch types.
CSA Station Name Initial Shell Final Shell Initial Cultch Final Cultch Cultch Decreased1N 3-Mile 853 839 1140 1040 Yes1N Cabbage Reef 4417 4047 4417 4047 Yes1N Drum Bay 1071 980 1072 980 Yes1N E. Karako 0 0 0 0 n/a1N Grand Banks 391 443 391 443 No1N Grand Pass 393 382 393 382 Yes1N Grassy 48 55 67 69 No1N Halfmoon 607 718 663 757 No1N Holmes 0 0 0 0 n/a1N Johnson Bayou 70 69 1875 1855 Yes1N Martin 0 0 0 0 n/a1N Millennium Reef 702 1217 3066 3387 No1N Morgan Harbor 928 858 928 858 Yes1N Petit 124 238 286 349 No1N Round Island 2011 Cultch Plant 782 5310 8752 13243 No1N Shell Point 209 667 4021 4421 No1N Turkey Bayou 815 740 1094 896 Yes1N W. Karako 0 369 0 369 No1S Battledore Reef 1946 1760 1956 1767 Yes1S Bay Crabe 99 89 99 89 Yes1S Bay Gardene 668 601 676 607 Yes1S Bay Long 880 825 880 825 Yes1S Bayou Lost 1700 1541 1704 1545 Yes1S Black Bay 504 477 506 479 Yes1S California Bay 235 211 254 224 Yes
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1S California Bay 2001 Cultch Plant 104 183 3448 3494 No1S Curfew 948 864 948 864 Yes1S E. Bay Crabe 842 795 872 811 Yes1S E. Bay Gardene 554 513 1008 831 Yes1S E. Pelican 252 227 342 310 Yes1S E. Stone 1726 1553 1726 1553 Yes1S Elephant Pass 977 900 977 900 Yes1S Horseshoe Reef 1773 1596 1793 1615 Yes1S Jessie 779 716 821 743 Yes1S Lonesome 272 267 518 440 Yes1S Mangrove Point 132 119 132 119 Yes1S N. Black Bay 590 531 590 531 Yes1S N. California Bay 1841 1857 1841 1857 No1S N. Lake Fortuna 752 714 752 714 Yes1S N. Lonesome 80 99 204 210 No1S S. Black Bay 566 509 594 529 Yes1S S. Lake Fortuna 626 597 632 599 Yes1S Snake 1364 1372 1364 1372 No1S Stone 1000 900 1028 920 Yes1S Sunrise Point 2 2 2 2 Yes1S Telegraph 532 490 556 496 Yes1S W. Bay Crabe 277 270 281 272 Yes1S W. Pelican 1228 1130 1272 1160 Yes1S Wreck 1088 979 1088 979 Yes3 2004 Barataria Bay Cultch Plant 252 229 2880 2838 Yes3 2004 N. Hackberry Shell Plant 1272 1762 5120 5552 No3 2004 S. Hackberry Shell Plant 190 320 874 997 No3 2008 Cultch Plant 444 677 3521 3707 No3 Lower Hackberry 40 217 100 260 No3 Middle Hackberry 794 1144 831 1156 No3 Upper Hackberry 100 382 2062 2174 No
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5E Lake Chien 2004 681 1150 2340 2792 No5E Lake Chien 2009 101 257 420 572 No5E Lake Felicity 13 31 197 213 No5W 09 SL Cultch Plant 852 1136 1282 1560 No5W Buckskin Bayou Junop 938 1741 959 1756 No5W Grand Pass 1289 1207 1485 1344 Yes5W Junop Bayou DeWest 702 632 702 632 Yes5W Lake Mechant 439 753 1805 2106 No5W Mid 94 Shell Plant 45 40 48 42 Yes5W Mid Bay Junop 456 680 456 680 No5W Mid Sister Lake 128 116 133 119 Yes5W N. 94 Shell Plant 0 0 0 0 n/a5W N. 95 Shell Plant 1005 1507 1168 1621 No5W Old Camp 594 541 594 541 Yes5W Rat Bayou 4200 4010 4200 4010 Yes5W S. 94 Shell Plant 103 93 103 93 Yes5W SL 2004 Cultch Plant 607 679 1078 1145 No5W Walkers Point 1456 1503 1555 1573 No6 Bayou Blanc 3829 3502 3829 3502 Yes6 Big Charles 1912 1742 1912 1742 Yes6 Dry Reef 697 640 697 640 Yes6 Indian Point 5827 5275 5827 5275 Yes6 Lighthouse Point 6776 6359 6776 6359 Yes6 Middle Reef 1000 907 1000 907 Yes6 N. Reef 206 186 206 186 Yes6 Rabbit 3554 3199 3554 3199 Yes6 Sally Shoals 1094 985 1094 985 Yes6 South Point 822 744 822 744 Yes7 09 Cultch Plant 0 0 0 0 n/a7 9 Mile 0 0 0 0 n/a7 Big Washout 266 239 266 239 Yes
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7 Little Washout 3224 2929 3224 2929 Yes7 Long Point 0 0 0 0 n/a7 Mid Lake 4132 3864 4132 3864 Yes7 N.E. Rabbit 460 497 1794 1431 Yes7 S.E. Rabbit 730 725 730 725 Yes7 Sabine Lake 1 4718 8376 4718 8376 No7 Sabine Lake 2 3604 6342 3604 6342 No7 Sabine Lake 3 5104 9104 5104 9104 No7 Sabine Lake 4 3834 8347 3834 8347 No7 Sabine Lake 5 2614 4534 2614 4534 No7 Sabine Lake 6 834 2978 834 2978 No7 W. Cove Trans 1040 983 1040 983 Yes7 W. Rabbit 1542 2638 1542 2638 No
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TABLE 2.Fishing effort by month for sack and seed oysters. Numbers are fractional effort expended per month as a portion of the overall effort.
Estimates are based on anticipated fishing effort.
CSA Fishing Type Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug1N Sack 0.00 0.20 0.35 0.25 0.10 0.05 0.05 0.00 0.00 0.00 0.00 0.00
Seed 0.00 0.70 0.10 0.00 0.00 0.10 0.10 0.00 0.00 0.00 0.00 0.00
1S Sack 0.00 0.20 0.30 0.20 0.10 0.05 0.05 0.10 0.00 0.00 0.00 0.00Seed 0.00 0.70 0.10 0.00 0.00 0.10 0.10 0.00 0.00 0.00 0.00 0.00
3 Sack 0.00 0.50 0.50 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Seed 0.00 0.70 0.30 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
5E Sack 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Seed 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
5W Sack 0.00 0.50 0.50 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Seed 0.00 0.70 0.30 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
6 Sack 0.00 0.10 0.20 0.20 0.20 0.10 0.10 0.10 0.00 0.00 0.00 0.00Seed 0.60 0.10 0.05 0.05 0.05 0.05 0.05 0.05 0.00 0.00 0.00 0.00
7 Sack 0.00 0.00 0.20 0.35 0.05 0.10 0.15 0.15 0.00 0.00 0.00 0.00Seed 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
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TABLE 3. Simulated sustainable catch (sacks) for CSAs. Not fished refers to a region closed to fishing. Not fishable indicates that none of the open reefs
in the region support a sustainable harvest. Refer to the text for the list of the reefs within each CSA included in these simulations.
CSA Fish.Type Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Total
1N Sack 0 0 23,804 48,706 34,070 13,812 7,397 8,880 0 0 0 0 136,669Seed 0 0 45,399 5,020 0 0 4,974 4,076 0 0 0 0 59,469
1S Sack 0 0 1,445 2,277 0 1,592 803 433 924 0 0 0 7,929Seed 0 0 205 29 0 0 28 0 0 0 0 0 262
3 Sack 0 0 234 255 0 0 0 0 0 0 0 0 489Seed 0 0 0 0 0 0 0 0 0 0 0 0 0
5E SackNot fishedSeed
5W Sack 0 0 1,484 1,377 0 0 0 0 0 0 0 0 2,861Seed 0 0 2,667 1,064 0 0 0 0 0 0 0 0 3,730
6 SackNot fishableSeed
7 Sack 0 0 0 74,428 95,787 7,006 16,377 24,204 20,362 0 0 0 238,223Seed 0 0 0 0 0 0 0 0 0 0 0 0 0
Sack Total 386,171Seed Total 63,461
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TABLE 4
Packing coefficients, density and annual percent loss of cultch types.
Cultch Type Packing Coefficient Density (g/mL) Annual Percent LossLimestone 57* 0.57 2.52 1
Limestone 4 0.52 2.53 1Clamshell 0.43 2.29 30
Mussel Shell 0.26 1.67 80Concrete 4 0.53 2.29 0.1Oyster Shell 0.59 2.20 10
* Size 57 values used in 2014 simulations.
TABLE 5.
Area Management simulations. Simulated reefs are Grassy, Petit, Halfmoon, Round Island Cultch Plant, and Millennium (CSA 1N), and S.E. Rabbit, W. Rabbit, W. Cove Transplant and N.E. Rabbit (CSA 7).
CSA Area(Acres)
Initial Cultch (g/m2)
Final Cultch(g/m2)
Percent Increase
Initial Oysters/m2
Final Oysters/m2
Market(Sacks)
Seed(Sacks)
1N 4,551 1,515 1,544 1.9 13.03 5.62 96,000* 98,000*7 3,388 1,472 1,554 5.6 9.49 2.68 200,000 0
*A simulation of CSA 1N without fishing for seed yields a TAC of 106,094 sacks of market oysters.
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TABLE 6.
A comparison of estimated 2013 harvest and 2013 TAC (model threshold) for seed and market oysters, and change in cultch (brown shell) from 2013 to 2014. The 2013 harvest is based upon boarding report estimates (on-the-water interviews of harvesters).
Seed (Barrels) Market (Sacks) Total (Barrels) Cultch (g/m2)Harvest
AreaEstimated
HarvestModel
Threshold Difference EstimatedHarvest
Model Threshold Difference Estimated
HarvestModel
Threshold Difference 2013 2014
CSA 1N 3,685 3,232 -453 4,016 9,936 5,920 5,693 8,200 2,507 281 47CSA 1S 2,170 708 -1,462 315 10,098 9,783 2,328 5,757 3,430 446 984
Hackberry Bay 2,205 675 -1,531 1,390 1,085 -305 2,900 1,217 -1,683 1,327 443
Sister Lake 7,315 5,207 -2,108 86,804 25,573 -61,231 50,717 17,994 -32,724 303 733
CSA 6 45,650 0 -45,650 3,031 0 -3,031 47,166 0 -47,166 906 2,700Calcasieu Lake (WC) 0 n/a 36,304 30,070 -6,234 18,152 15,035 -3,117 658 885
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Literature Cited
LDWF. 2012. Oyster Stock Assessment Report of the Public Oyster Areas in Louisiana. Oyster Data Report Series 18. Louisiana Department of Wildlife and Fisheries, Baton Rouge, LA.
LDWF. 2013. Oyster Stock Assessment Report of the Public Oyster Areas in Louisiana. Oyster Data Report Series 19. Louisiana Department of Wildlife and Fisheries, Baton Rouge, LA.
Mann, R., M. Southworth, J. M. Harding & J.A. Wesson. 2009. Population studies of the native eastern oyster, Crassostrea virginica, (Gmelin, 1791) in the James River, Virginia, USA. J. Shellfish Res. 28: 193-220.
Quick, J. A. & J. G. Mackin. 1971. Oyster parasitism by Labyrinthomyxa marina in Florida parasites in oysters. Professional Paper Series. Florida Department of Natural Resources. 55 pp.
Soniat, T.M., J.M. Klinck, E.N. Powell, N. Cooper, M. Abdelguerfi, E.E. Hofmann, J. Dahal, S. Tu, J. Finigan, B.S. Eberline, J.F. LaPeyre, M.K. LaPeyre & F. Qaddoura. 2012. A shell-neutral modeling approach yields sustainable oyster harvest estimates: a retrospective analysis of the Louisiana State Primary Seed Grounds. J.Shellfish Res. 4:1103-1112.
Soniat, T.M., S.B. Colley, N. Cooper, J. Dahal & J. Gallegos. 2013. Sustainable Oyster Shellstock Training Handbook. University of New Orleans. New Orleans, LA. 40p. http://www.oystersentinel.org/sites/all/manual/SosTrainingHandbook062013.pdf
Acknowledgments
The Workshop was funded by the Louisiana Department of Wildlife and Fisheries. We appreciate
the contributions of Drs. Eric Powell, John Klinck, Shengru Tu and Mahdi Abdelguerfi to initial model
development and implementation. The UNO Department of Computer Science provided facilities, staff
and computational resources for the Workshop.
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