Synopsis of the Fifth Annual Louisiana Oyster Stock Assessment Workshop

Synopsis of the Fifth Annual Louisiana Oyster Stock Assessment Workshop

held

30 August 2016

at the

University of New Orleans

Compiled by

Thomas M. Soniat

Department of Biological Sciences

and

Canizaro Livingston Gulf States Center for Environmental Informatics

University of New Orleans

11/30/2016

Fifth Annual Louisiana Oyster Stock Assessment Workshop

Working Group Members and Support Staff

Members

Steve Beck

Louisiana Department of Wildlife and Fisheries

Eric Powell

Gulf Coast Research Laboratory

University of Southern Mississippi

Thomas Soniat

Department of Biological Sciences

Canizaro Livingston Gulf States Center for Environmental Informatics

University of New Orleans

Pete Vujnovich

Louisiana Oyster Task Force

Support Staff

Nathan Cooper

Department of Computer Sciences

Canizaro Livingston Gulf States Center for Environmental Informatics

University of New Orleans

Introduction

The Fifth Annual Stock Assessment Workshop was held on August 30, 2016 at the University of New Orleans. The purpose of the Workshop is 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 propose and review management and 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-cultch-loss as a sustainability reference point. The model simulates oyster growth and mortality, and natural cultch 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 2016 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). The model estimates the number of sacks of seed and sack oysters that could be removed during the 2016/17 season without a loss of cultch. In addition to the standard of no-net-cultch loss, simulations were constrained by the (presumed) monthly effort for sack and seed (Table 1) and the proportion of sack to seed previously harvested in each CSA (Table 2).

Primary model components calculate growth, natural mortality, fishing mortality, cultch density (g/m2), and sacks of seed and sack (market) oysters fished (Figure 1).

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 cultch 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 cultch 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, 2015.)

The cultch budget model has practical application such as identifying areas for closure, determining total allowable catch, managing cultch planting and reef restoration, and achieving product certification for sustainability.

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 2013(LDWF 2013), 2014 (LDWF 2014), 2015 LDWF (2015) and 2016 Stock Assessments. The substrate categories are: 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. All brown cultch types were used as the cultch reference point.

Status of the Stock

The 2016 stock assessment sampling by LDWF indicates a statewide 12.2% reduction in seed, and a 28.8% reduction in sack oyster abundance, as compared to 2015. Abundance of seed and sack oysters (combined) are 81% below the long term average (1982-2016). Coastal Study Areas are large management units (watersheds) – from CSA1 in the east to CSA 7 in the west (Figure 2).CSA 1N, CSA 5E and CSA 5W showed a decrease in seed oyster abundance as compared to 2015, whereas other CSAs showed an increase as compared to last year. Sack oyster abundance increased as compared to last year in only CSA 6 and CSA 7 (Sabine Lake excluded). The 2016 Oyster Stock Assessment report provides comprehensive information on the status of the stock.

Figure 2. Boundaries of LDWF Coastal Study Areas (CSA).

Sustainable Harvests

Simulations were conducted to estimate sustainable harvests from reefs in all CSAs.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; 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 effort) and fishing type (sack, seed) is informed by recent commercial fishing practices provided by LDWF. The simulations were constrained by conserving the percent monthly effort for sack and seed (Table 1) and the proportionality between them (Table 2). By thus constraining fishing, some reefs showed a net cultch gain –even under the no-net cultch loss standard.A list of fishable reefs is given in Table 3.

In CSA 1N, the stations which gained cultch in simulations without fishing included Millenium Reef, Grand Banks, Halfmoon, Three Mile 2013 Cultch Plant, Johnson Bayou, Shell Point, East Karako, Three Mile, Drum Bay and the Drum Bay 2013 Cultch Plant (Table 3). No reefs in CSA 1S were deemed fishable. In CSA 3, Middle Hackberry and the 2008 and 2014 Cultch Plants in Hackberry Bay show a positive cultch balance without fishing. The CSA 5E stations of the Lake Chien 2004 Cultch Plant, the Lake Chien 2009 Cultch Plant, and Lake Felicity are fishable, as are the CSA 5W stations of Mid Bay Junop, Grand Pass, Walkers Point, Mid Sister Lake and the Sister Lake 2004, 2009 and 2012 Cultch Plants. In CSA 6, only Nickle Reef is fishable. Sabine Lake stations 1-4 (CSA 7) showed a shell gain without fishing; however, Sabine Lake (AMU 1) will not be open to fishing. In AMU 2 (West Lake Calcasieu), West Cove Central, NW Rabbit Island and West Rabbit Island showed a cultch gain without fishing, whereas in AMU 3 (East Lake Calcasieu) only Lamberts Reef was fishable. Note that “fishability” is determined by an interaction of cultch density and oyster density (Table 3). Some reefs with low oyster densities are “fishable’ because cultch density is low. With less cultch available to be lost, fewer oysters are needed to achieve a no-net-cultch-loss reference standard. Such reefs, however, provide little sustainable catch.

Table 1. Sack and seed fishing pressures for each CSA, based on recent fishing pressures. Values are percent effort per month per CSA. Sack fishing pressure for a month is shown as the top number, whereas seed fishing pressure is shown below it.

CSA / Sept / Oct / Nov / Dec / Jan / Feb / Mar / Apr
1N / 24 / 73 / 3
89 / 6 / 5
1S / 20 / 30 / 20 / 10 / 5 / 5 / 10
70 / 10 / 10 / 10
3 / 90 / 10
100
5E / 30 / 70
5W / 63 / 37
100
6 / 10 / 20 / 20 / 20 / 10 / 10 / 10
60 / 10 / 5 / 5 / 5 / 5 / 5 / 5
7 / 15 / 20 / 20 / 15 / 15 / 15

Table 2. The proportion (percent) of seed fishing to sack fishing per season in each CSA, based on recent fishing practices.

CSA / Seed / Sack
1N / 65 / 35
1S / 76 / 24
3 / 25 / 75
5E / 0 / 100
5W / 10 / 90
6 / 10 / 90
7 / 0 / 100

1

Table 3. Stations in each Coastal Study Area (CSA) and Area Management Unit (AMU). Stations are on natural reefs, shell plants (SP) and cultch plants (CP). Size assigned to stations is given in acres. Fishable reefs are indicated by the integer “1”; unfishable reefs are indicated by the integer “0”. Oyster numbers (O) include all size classes. Initial densities for number of oysters per m2 (O/m2 A) and cultch in grams per m2 (Clh/m2 A) are given. Corresponding post-simulation numbers are listed as O/m2 B and Clh/m2 B. Sack refers to the sustainable harvest of market-sized oysters, whereas Seed is the sustainable harvest of seed-sized oysters (and incident shell), both in units of a Louisiana sack.

CSA / Station / Acres / AMU / Fish? / O/m2 A / O/m2 B / Sh/m2 A / Sh/m2 B / Clh/m2 A / Clh/m2 B / Sack (sacks) / Seed (sacks)
CSA1N / Cabbage Reef / 1804 / 3 / 0 / 13.4 / 6 / 2458 / 2250 / 2458 / 2250 / 0 / 0
CSA1N / Turkey Bayou / 1804 / 3 / 0 / 0 / 0 / 494 / 445 / 651 / 555 / 0 / 0
CSA1N / Millenium Reef / 1066 / 2 / 1 / 18.2 / 8.8 / 797 / 868 / 961 / 962 / 2557 / 21757
CSA1N / Grassy / 1066 / 2 / 0 / 0 / 0 / 7 / 6 / 8 / 7 / 0 / 0
CSA1N / Grand Banks / 1066 / 2 / 1 / 10.4 / 5.8 / 710 / 710 / 710 / 710 / 0 / 2541
CSA1N / Round Island 2011 CP / 291 / 2 / 0 / 7 / 4.2 / 2038 / 2118 / 4560 / 4554 / 0 / 0
CSA1N / Halfmoon / 1066 / 2 / 1 / 9.2 / 4.6 / 711 / 960 / 1270 / 1271 / 13163 / 23275
CSA1N / Petit / 1066 / 2 / 0 / 0.4 / 0.2 / 276 / 263 / 336 / 305 / 0 / 0
CSA1N / 3-Mile Pass 2013 CP / 158 / 2 / 1 / 20 / 10.3 / 562 / 952 / 2868 / 2869 / 1273 / 5246
CSA1N / Johnson Bayou / 200 / 3 / 1 / 0.8 / 0.3 / 25 / 25 / 25 / 25 / 0 / 137
CSA1N / Shell Point / 47 / 4 / 1 / 9.8 / 5.5 / 203 / 306 / 1478 / 1478 / 0 / 298
CSA1N / E. Karako / 1020 / 4 / 1 / 2 / 1.1 / 402 / 402 / 402 / 402 / 853 / 2893
CSA1N / W. Karako / 1020 / 4 / 0 / 0.4 / 0.2 / 145 / 136 / 209 / 181 / 0 / 0
CSA1N / 3-Mile / 1020 / 4 / 1 / 2.8 / 1.6 / 397 / 402 / 412 / 412 / 246 / 1758
CSA1N / Grand Pass / 1804 / 3 / 0 / 0.4 / 0.2 / 427 / 408 / 427 / 408 / 0 / 0
CSA1N / Drum Bay / 1596 / 5 / 1 / 4 / 2.1 / 714 / 714 / 714 / 714 / 3217 / 9899
CSA1N / Drum Bay 2013 CP / 200 / 5 / 1 / 4.2 / 2.4 / 314 / 401 / 1812 / 1813 / 122 / 1038
CSA1N / Morgan Harbor / 2954 / 6 / 0 / 0 / 0 / 1028 / 925 / 1028 / 925 / 0 / 0
CSA1N / Holmes / 1592 / 7 / 0 / 0 / 0 / 2 / 2 / 3 / 3 / 0 / 0
CSA1N / Martin / 1592 / 7 / 0 / 0 / 0 / 31 / 28 / 31 / 28 / 0 / 0
CSA1S / Lake Fortuna 2012 CP / 300 / 1 / 0 / 1 / 0.6 / 65 / 75 / 3859 / 3788 / 0 / 0
CSA1S / S. Lake Fortuna / 1727 / 1 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA1S / 2009 Lonesome CP / 243 / 2 / 0 / 0 / 0 / 92 / 83 / 95 / 83 / 0 / 0
CSA1S / Snake / 716 / 2 / 0 / 0 / 0 / 40 / 36 / 73 / 43 / 0 / 0
CSA1S / Jessie / 275 / 2 / 0 / 0 / 0 / 15 / 13 / 17 / 15 / 0 / 0
CSA1S / Horseshoe Reef / 829 / 2 / 0 / 0 / 0 / 260 / 234 / 263 / 237 / 0 / 0
CSA1S / E. Stone / 829 / 2 / 0 / 0 / 0 / 287 / 258 / 341 / 269 / 0 / 0
CSA1S / N. Lake Fortuna / 1727 / 2 / 0 / 1 / 0.6 / 1091 / 1001 / 1093 / 1001 / 0 / 0
CSA1S / N. Black Bay / 829 / 2 / 0 / 0 / 0 / 444 / 400 / 495 / 410 / 0 / 0
CSA1S / Bayou Lost / 275 / 2 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA1S / Lonesome / 715 / 2 / 0 / 0 / 0 / 98 / 88 / 192 / 124 / 0 / 0
CSA1S / Black Bay / 716 / 2 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA1S / E. Bay Gardene / 632 / 3 / 0 / 0 / 0 / 23 / 21 / 29 / 25 / 0 / 0
CSA1S / Bay Gardene / 632 / 3 / 0 / 0 / 0 / 1435 / 1291 / 1705 / 1456 / 0 / 0
CSA1S / S. Black Bay / 715 / 4 / 0 / 0 / 0 / 1245 / 1121 / 1401 / 1154 / 0 / 0
CSA1S / Elephant Pass / 202 / 4 / 0 / 0 / 0 / 442 / 398 / 442 / 398 / 0 / 0
CSA1S / Curfew / 715 / 4 / 0 / 0 / 0 / 512 / 461 / 551 / 471 / 0 / 0
CSA1S / N. California Bay / 715 / 4 / 0 / 0 / 0 / 418 / 376 / 418 / 376 / 0 / 0
CSA1S / Bay Crabe / 511 / 4 / 0 / 0 / 0 / 0 / 0 / 4 / 2 / 0 / 0
CSA1S / E. Bay Crabe / 511 / 4 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA1S / W. Bay Crabe / 511 / 4 / 0 / 0 / 0 / 12 / 11 / 12 / 11 / 0 / 0
CSA1S / Stone / 715 / 4 / 0 / 0 / 0 / 531 / 478 / 677 / 520 / 0 / 0
CSA1S / California Bay / 923 / 5 / 0 / 0 / 0 / 662 / 596 / 1982 / 888 / 0 / 0
CSA1S / Telegraph / 715 / 5 / 0 / 0 / 0 / 0 / 0 / 4 / 1 / 0 / 0
CSA1S / Sunrise Point / 923 / 5 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA1S / Bay Long / 923 / 5 / 0 / 0 / 0 / 269 / 242 / 326 / 254 / 0 / 0
CSA1S / E. Pelican / 1445 / 5 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA1S / Mangrove Point / 1445 / 5 / 0 / 0 / 0 / 1103 / 993 / 1143 / 1001 / 0 / 0
CSA1S / W. Pelican / 923 / 5 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA1S / Battledore Reef / 271 / 6 / 0 / 0 / 0 / 223 / 201 / 223 / 201 / 0 / 0
CSA1S / Wreck / 4486 / 6 / 0 / 1.2 / 0.7 / 721 / 671 / 729 / 673 / 0 / 0
CSA3 / Lower Hackberry / 5 / 2 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA3 / 2012 Cultch Plant / 200 / 2 / 0 / 3 / 1.8 / 1004 / 972 / 6756 / 6543 / 0 / 0
CSA3 / Middle Hackberry / 5 / 2 / 1 / 1 / 0.5 / 458 / 468 / 474 / 474 / 6 / 4
CSA3 / Upper Hackberry / 5 / 2 / 0 / 3 / 1.7 / 836 / 816 / 1398 / 1260 / 0 / 0
CSA3 / 2004 N. Hackberry SP / 10 / 2 / 0 / 11.8 / 6.2 / 162 / 211 / 1418 / 1180 / 0 / 0
CSA3 / 2004 S. Hackberry SP / 25 / 2 / 0 / 0 / 0 / 286 / 257 / 362 / 330 / 0 / 0
CSA3 / 2008 Cultch Plant / 50 / 2 / 1 / 8.8 / 4.7 / 288 / 345 / 1134 / 1135 / 37 / 158
CSA3 / Hackberry 2014 CP / 30 / 2 / 1 / 40.2 / 21.9 / 154 / 538 / 8092 / 8096 / 75 / 513
CSA3 / 2004 Barataria Bay CP / 40 / 3 / 0 / 0 / 0 / 60 / 54 / 4752 / 4697 / 0 / 0
CSA5E / Lake Chien 2004 / 16 / 2 / 1 / 30.8 / 15.1 / 679 / 783 / 2955 / 3036 / 85 / 0
CSA5E / Lake Chien 2009 / 22 / 2 / 1 / 4.2 / 2.2 / 392 / 405 / 1627 / 1627 / 1 / 0
CSA5E / Lake Felicity / 40 / 3 / 1 / 13.8 / 6.7 / 179 / 221 / 1879 / 1904 / 0 / 0
CSA5W / Lake Mechant / 30 / 1 / 1 / 29.4 / 15.7 / 454 / 602 / 2789 / 2790 / 0 / 284
CSA5W / Buckskin Bayou Junop / 17 / 2 / 0 / 4.4 / 2.5 / 666 / 658 / 673 / 663 / 0 / 0
CSA5W / Rat Bayou / 34 / 2 / 0 / 13.6 / 6.7 / 1576 / 1509 / 1577 / 1511 / 0 / 0
CSA5W / Mid Bay Junop / 73 / 2 / 1 / 13.4 / 5.8 / 286 / 286 / 286 / 286 / 0 / 112
CSA5W / Junop Bayou DeWest / 34 / 2 / 0 / 16.6 / 7.9 / 701 / 694 / 703 / 695 / 0 / 0
CSA5W / Grand Pass / 107 / 3 / 1 / 33.2 / 15 / 1310 / 1366 / 1481 / 1481 / 938 / 439
CSA5W / Walkers Point / 107 / 3 / 1 / 23 / 9.9 / 516 / 527 / 525 / 532 / 476 / 531
CSA5W / Old Camp / 140 / 3 / 0 / 2.8 / 1.4 / 505 / 466 / 507 / 468 / 0 / 0
CSA5W / Mid Sister Lake / 56 / 3 / 1 / 1.2 / 0.6 / 228 / 228 / 232 / 232 / 56 / 18
CSA5W / N. 94 Shell Plant / 191 / 3 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA5W / Mid 94 Shell Plant / 552 / 3 / 0 / 0.2 / 0.1 / 39 / 38 / 39 / 38 / 0 / 0
CSA5W / S. 94 Shell Plant / 513 / 3 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA5W / N. 95 Shell Plant / 107 / 3 / 0 / 10.4 / 5.2 / 518 / 542 / 614 / 610 / 0 / 0
CSA5W / SL 2004 Cultch Plant / 82 / 3 / 1 / 8.8 / 4.3 / 385 / 395 / 686 / 686 / 55 / 75
CSA5W / 09 SL Cultch Plant / 156 / 3 / 1 / 18.4 / 8.3 / 337 / 353 / 477 / 477 / 0 / 573
CSA5W / Sister Lake 2012 CP / 365 / 3 / 1 / 26 / 11.2 / 332 / 427 / 1466 / 1466 / 4947 / 2405
CSA6 / Big Charles / 15 / 1 / 0 / 3.3 / 1.8 / 5728 / 5180 / 5870 / 5268 / 0 / 0
CSA6 / Lighthouse Point / 30 / 1 / 0 / 1 / 0.6 / 4460 / 4046 / 5431 / 4722 / 0 / 0
CSA6 / Indian Point / 100 / 1 / 0 / 1.3 / 0.7 / 4830 / 4356 / 4844 / 4358 / 0 / 0
CSA6 / Sally Shoals / 5 / 2 / 0 / 0 / 0 / 662 / 596 / 1651 / 1287 / 0 / 0
CSA6 / Dry Reef / 10 / 2 / 0 / 0 / 0 / 1096 / 986 / 1215 / 1068 / 0 / 0
CSA6 / South Point / 250 / 3 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA6 / Rabbit / 15 / 3 / 0 / 0 / 0 / 1686 / 1517 / 2055 / 1775 / 0 / 0
CSA6 / N. Reef / 10 / 3 / 0 / 0.3 / 0.2 / 2374 / 2139 / 2656 / 2332 / 0 / 0
CSA6 / Highspot / 250 / 3 / 0 / 0.7 / 0.4 / 3025 / 2726 / 3040 / 2732 / 0 / 0
CSA6 / Bayou Blanc / 15 / 3 / 0 / 0 / 0 / 4377 / 3939 / 4721 / 4170 / 0 / 0
CSA6 / Middle Reef / 20 / 4 / 0 / 0.3 / 0.2 / 1193 / 1079 / 1194 / 1079 / 0 / 0
CSA6 / Nickle Reef / 100 / 4 / 1 / 19.7 / 9.7 / 2252 / 2256 / 2256 / 2257 / 2950 / 792
CSA7 / Sabine Lake 1 / 260 / 1 / 1 / 60.4 / 20.8 / 1466 / 2557 / 1466 / 2557 / 70730 / 0
CSA7 / Sabine Lake 2 / 260 / 1 / 1 / 27.8 / 8.6 / 3886 / 4191 / 3886 / 4191 / 43982 / 0
CSA7 / Sabine Lake 3 / 260 / 1 / 1 / 56 / 15.3 / 4220 / 5259 / 4220 / 5259 / 99262 / 0
CSA7 / Sabine Lake 4 / 260 / 1 / 1 / 22.8 / 7.3 / 2556 / 2851 / 2556 / 2851 / 33644 / 0
CSA7 / Sabine Lake 5 / 219 / 1 / 0 / 0 / 0 / 2566 / 2309 / 2840 / 2501 / 0 / 0
CSA7 / Sabine Lake 6 / 219 / 1 / 0 / 0 / 0 / 2110 / 1899 / 3074 / 2574 / 0 / 0
CSA7 / West Cove Central / 755 / 2 / 1 / 1.2 / 0.1 / 376 / 376 / 376 / 376 / 7714 / 0
CSA7 / NW Rabbit Is. / 366 / 2 / 1 / 2 / 0.5 / 546 / 564 / 546 / 564 / 6736 / 0
CSA7 / W. Rabbit / 755 / 2 / 1 / 2.2 / 0.8 / 758 / 759 / 758 / 759 / 8055 / 0
CSA7 / S.E. Rabbit / 366 / 2 / 0 / 1.2 / 0.7 / 932 / 856 / 932 / 856 / 0 / 0
CSA7 / N.E. Rabbit / 755 / 2 / 0 / 2 / 1.2 / 258 / 301 / 484 / 459 / 0 / 0
CSA7 / W. Cove Trans / 366 / 2 / 0 / 1.6 / 0.9 / 1456 / 1326 / 1460 / 1329 / 0 / 0
CSA7 / Lamberts Reef / 240 / 3 / 1 / 7 / 1.3 / 440 / 632 / 444 / 635 / 15662 / 0
CSA7 / Chenier Reef / 35 / 3 / 1 / 105.4 / 27.7 / 1384 / 3219 / 7172 / 8937 / 16435 / 0
CSA7 / Big Washout / 467 / 3 / 0 / 0.6 / 0.3 / 2020 / 1826 / 2020 / 1826 / 0 / 0
CSA7 / Long Point / 264 / 3 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA7 / 9 Mile / 264 / 3 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA7 / 09 Cultch Plant / 14 / 3 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0 / 0
CSA7 / Little Washout / 467 / 3 / 0 / 1.2 / 0.7 / 1792 / 1624 / 1792 / 1624 / 0 / 0
CSA7 / Mid Lake / 467 / 3 / 0 / 0 / 0 / 430 / 387 / 430 / 387 / 0 / 0

1

The TAC for individual fishable reefs (stations) is shown in Table 3. The TAC for a CSA or AMU is the sum of TAC for each fishable reef therein. TAC for CSA 1N AMU 2 is estimated as 16,993 sacks of market-sized oysters and 52,819 sacks of seed (Table 4). Most of the sustainable harvest is available on Millenium and Halfmoon reefs. CSA 1N AMU 3 has a TAC of 137 sacks of seed oysters. CSA 1N AMU 4 has an estimated TAC of 1,099 sacks of sack oysters and 4,949 sacks of seed; most of the production is from East Karako and Three Mile. An estimated TAC of 3,339 sacks of market oysters and 10,937 sacks of seed is estimated from CSA 1N AMU 5 – from Drum Bay Reef and the Drum Bay 2013 Cultch Plant. CSA 1S has no level of harvest deemed sustainable for 2016 (Table 4). In CSA 3, only 118 sacks of sack oysters and 675 sacks of seed were deemed harvestable (Table 4); this minor resource is available in AMU 2 -- largely from the 2008 and 2014 cultch plants. A small sustainable harvest (118 sacks of Sack oysters) was estimated from CSA 5E AMU 2, almost all of which is available from the Lake Chien 2004 Cultch Plant. Note that no fishing for seed occurs in CSA 5E (Table 2). The CSA 5W AMU 1 station of Lake Mechant supports a small seed-oyster TAC (284 sacks). Mid Bay Junop (CSA 5W AMU 2) supports a TAC of 112 sacks of seed oysters (Table 4). Most of the available harvest in CSA 5W (6,475 sacks of sack oyster, 4,041 sacks of seed) is from AMU 3 (Table 4) – principally Grand Pass, Walkers Point and the Sister Lake 2009 and 2012 Cultch Plants. In CSA 6, only AMU 4 had reefs considered fishable (Table 3). A TAC of 2,950 sacks of sack oysters and 792 sacks of seed is estimated there, all of which is provided by Nickle Reef. Sabine Lake (CSA 7 AMU 1) has a considerable sack resource (TAC = 247,618 sacks, Table 4); however, Sabine Lake will not be open to fishing. In CSA7 AMU 2 (West Lake Calcasieu), West Cove Central, Northwest Rabbit and West Rabbit (Table 3) has a sustainable catch of 22, 505 sacks of market oysters (Table 4). CSA 7 AMU 3 (East Lake Calcasieu) yields a TAC of 32,097 sacks of market oysters (Table 4). No fishing for seed oysters is allowed in CSA 7 (Table 2).

The TAC for the Louisiana Public Oyster Grounds for the 2016-2017 season, based on a no-net-cultch-loss standard, is estimated to be 85,659 sacks of market oyster and 74,746 sacks of seed (Table 4). This estimate does not include the resource in Sabine Lake which is not open to fishing.

Table 4. Sustainable harvests of sack and seed oysters by CSA and AMU.

CSA / AMU / Sack (sacks) / Seed (sacks)
CSA1N / 2 / 16,993 / 52,819
CSA1N / 3 / 0 / 137
CSA1N / 4 / 1,099 / 4,949
CSA1N / 5 / 3,339 / 10,937
CSA1N / 6 / 0 / 0
CSA1N / 7 / 0 / 0
CSA1S / 1 / 0 / 0
CSA1S / 2 / 0 / 0
CSA1S / 3 / 0 / 0
CSA1S / 4 / 0 / 0
CSA1S / 5 / 0 / 0
CSA1S / 6 / 0 / 0
CSA3 / 2 / 118 / 675
CSA3 / 3 / 0 / 0
CSA5E / 2 / 86 / 0
CSA5E / 3 / 0 / 0
CSA5W / 1 / 0 / 284
CSA5W / 2 / 0 / 112
CSA5W / 3 / 6472 / 4041
CSA6 / 1 / 0 / 0
CSA6 / 2 / 0 / 0
CSA6 / 3 / 0 / 0
CSA6 / 4 / 2950 / 792
CSA7 / 1 / 247618 / 0
CSA7 / 2 / 22505 / 0
CSA7 / 3 / 32097 / 0
Total / 333277 / 74746
Total (w/o Sabine) / 85659 / 74746

A set of simulations were conducted on fishable reefs with less than 1000 g/m2 of cultch with the goal of achieving a 10% increase in cultch mass (Table 5). The number of stations meeting this criterion were few, and yielded a TAC of only 18,993 sacks of market oysters and 15,539 sack of seed. Reefs with poor cultch quality do not support dense oyster populations and yield little TAC.

Table 5. Sack and seed TAC estimates (in sacks) for stations with an initial density of cultch (Clh g/m2 A) < 1000 g/m2, and with the requirement that final cultch density (Clh g/m2 B) show a 10% increase. Initial number of oysters per square meter (O/m2 A) is given. CP = Cultch Plant.

CSA / Station / AMU / O/m2 A / Clh/m2 A / Clh/m2 B / Sack (sacks) / Seed (sacks)
CSA1N / Millenium Reef / 2 / 18 / 961 / 1,058 / 1502 / 12,559
CSA1N / Johnson Bayou / 3 / 0.8 / 25 / 28 / 0 / 102
CSA1N / E. Karako / 4 / 2 / 402 / 442 / 70 / 235
CSA1N / Drum Bay / 5 / 4 / 714 / 786 / 768 / 2,340
CSA5W / 09 Sister Lake CP / 3 / 18 / 476 / 525 / 0 / 83
CSA5W / Walkers Point / 3 / 23 / 525 / 578 / 256 / 220
CSA7 / NW Rabbit Is. / 2 / 2 / 546 / 601 / 735 / 0
CSA7 / Lamberts Reef / 3 / 7 / 444 / 635 / 15,662 / 0
Total / 18,993 / 15,539

A simulation was conducted of TAC for stations with an initial density of oysters ≥ 25 oysters/m2 and an initial abundance of cultch ≥ 1000 g/m2, with a no-net loss of cultch standard. The TAC estimate is 22,480 sacks of market oysters and 3,641 sacks of seed (Table 6). This represents a 75% reduction in market oysters and a 51% reduction in seed oysters as compared to the no-net-loss standard scenario without initial oyster and cultch density minima (Table 4). If the requirement for initial cultch is ≥ 3,000 grams m-2of cultch, only Sabine Lake 2, Sabine Lake 3 and Chenier Reef would qualify (Table 6). Sabine Lake is closed to fishing. Thus, under a standard of an initial density of oysters ≥ 25 oysters/m2, an initial density of cultch ≥ 3000 g/m2, no-net-loss of cultch, and the requirement that the area be open to fishing, these stringent standards yield a TAC of only 16,435 sacks of market oysters and no seed.

Table 6. Sack and seed TAC estimates (in sacks) for stations with an initial density of oysters (O/m2 A) ≥ 25 oysters/m2 and an initial density of cultch (Clh g/m2 A ) ≥ 1000 g/m2. A no-net-loss of cultch standard is applied. CP = Cultch Plant

CSA / Station / AMU / O/m2 A / Clh g/m2 A / Sack (sacks) / Seed (sacks)
CSA3 / Hackberry 2014 CP / 2 / 40.2 / 8,092 / 75 / 513
CSA5E / Lake Chien 2004 / 2 / 30.8 / 2,954.6 / 85 / 0
CSA5W / Lake Mechant / 1 / 29.4 / 2,788.8 / 0 / 284
CSA5W / Grand Pass / 3 / 33.2 / 1,480.8 / 938 / 439
CSA5W / Sister Lake 2012 CP / 3 / 26 / 1,465.6 / 4,947 / 2,405
CSA7 / Sabine Lake 1 / 1 / 60.4 / 1,466 / 70,730 / 0
CSA7 / Sabine Lake 2 / 1 / 27.8 / 3,886 / 43,982 / 0
CSA7 / Sabine Lake 3 / 1 / 56 / 4,220 / 99,262 / 0
CSA7 / Chenier Reef / 3 / 105.4 / 7,172 / 16,435 / 0
Total / 236,454 / 3,641
Total (w/o Sabine) / 22,480 / 3,641

A series of simulations were conducted to allow fishing down to a 1000 g/m2 cultch standard (Table 7). Such a fishing scenario usually produces an increase in harvest, but to the detriment of the reef itself. Comparisons of the fishing down to no-net-loss standard illustrate notable classes of responses. In some cases, fishing down the reef has little impact on reef quality or TAC. Examples are the 2004 Hackberry Cultch Plant and the Hackberry 2008 Cultch Plant. These reefs have initial cultch densities near 1000 g/m2 and moderate densities of oysters. A second type of response is found among reefs with relatively high oyster and cultch densities, and fishing profiles that are “sustainable under conditions” – meaning that fishing conditions (Tables 1&2) are fulfilled before the reef is depleted to the 1000 g/m2 cultch threshold. Examples of such reefs are the Hackberry Bay 2104 CP, the Sister Lake 2012 CP, and Nickle Reef. Reefs of this type yield increased TAC without wholesale reef destruction. A third class of reefs are those with adequate cultch and low oyster populations. Examples are the Lake Fortuna 2012 CP and the Hackberry Bay 2012 CP. Fishing down reefs with high cultch densities and low oyster populations is essentially “fishing for cultch”, and extremely detrimental to reef quality. This is apparent by a comparison (Table 7) between the ratios of seed fished (excluding incident shell) and seed fished (including incident shell) these reefs. For example, fishing down the Lake Fortuna 2012 CP yields a seed TAC of 54,972 sacks (including shell), of which only 549 sacks is the estimated volume of the live seed (without shell).

1

Table 7. A comparison of simulation results between a no-net loss standard (top) and simulations that allow fishing down the cultch to about 1000 g/m2 (bottom). Stations in each Coastal Study Area (CSA) and Area Management Unit (AMU). Stations are on natural reefs, shell plants (SP) and cultch plants (CP). Size assigned to stations is given in acres. Fishable reefs by the no-net loss standard are indicated by the integer “1”; unfishable reefs are indicated by the integer “0”. Oyster numbers (O) include all size classes. Initial densities for number of oysters per m2 (O/m2 A) and cultch in grams per m2 (Clh/m2 A) are given. Corresponding post-simulation numbers are listed as O/m2 B and Clh/m2 B. Sack refers to the sustainable harvest of market-sized oysters, Sp Sd refers to volume of seed fished (excluding incident shell), whereas Seed is the sustainable harvest of seed-sized oysters (and incident shell) -- all in units of a Louisiana sack.

CSA / Station / Acres / AMU / Fish? / O/m2 A / O/m2 B / Sh/m2 A / Sh/m2 B / Clh/m2 A / Clh/m2 B / Sack O Sks Fsh / Sp Sd Sks Fsh / Seed Sks Fsh
CSA1N / Round Island 2011 CP / 291 / 2 / 0 / 7 / 4.2 / 2038 / 2118 / 4560 / 4554 / 0 / 0 / 0
CSA1N / Round Island 2011 CP / 291 / 2 / 7 / 1.5 / 2038 / 496 / 4560 / 1015 / 6610 / 6610 / 67293
CSA1N / 3-Mile Pass 2013 CP / 158 / 3 / 1 / 20 / 10.3 / 562 / 952 / 2868 / 2869 / 1273 / 957 / 5246
CSA1N / 3-Mile Pass 2013 CP / 158 / 3 / 20 / 4.7 / 562 / 378 / 2868 / 1015 / 5145 / 4412 / 23686
CSA1N / Drum Bay 2013 CP / 200 / 6 / 1 / 4.2 / 2.4 / 314 / 401 / 1812 / 1813 / 122 / 67 / 1038
CSA1N / Drum Bay 2013 CP / 200 / 6 / 4.2 / 1.5 / 314 / 233 / 1812 / 1023 / 1113 / 658 / 10102
CSA1S / Lake Fortuna 2012 CP / 300 / 1 / 0 / 1 / 0.6 / 65 / 75 / 3859 / 3788 / 0 / 0 / 0
CSA1S / Lake Fortuna 2012 CP / 300 / 1 / 1 / 0.2 / 65 / 20 / 3859 / 1021 / 0 / 549 / 54972
CSA3 / Hackberry 2012 CP / 200 / 2 / 0 / 3 / 1.8 / 1004 / 972 / 6756 / 6543 / 0 / 0 / 0
CSA3 / Hackberry 2012 CP / 200 / 2 / 3 / 0.8 / 1004 / 630 / 6756 / 4344 / 1680 / 197 / 25067
CSA3 / 2004 N. Hackberry SP / 10 / 2 / 0 / 11.8 / 6.2 / 162 / 211 / 1418 / 1180 / 0 / 0 / 0
CSA3 / 2004 N. Hackberry SP / 10 / 2 / 11.8 / 5.3 / 162 / 180 / 1418 / 1008 / 0 / 9 / 147
CSA3 / Hackberry 2008 CP / 50 / 2 / 1 / 8.8 / 4.7 / 288 / 345 / 1134 / 1135 / 37 / 20 / 158
CSA3 / Hackberry 2008 CP / 50 / 2 / 8.8 / 4.1 / 288 / 304 / 1134 / 1009 / 122 / 70 / 539
CSA3 / Hackberry 2014 CP / 30 / 2 / 1 / 40.2 / 21.9 / 154 / 538 / 8092 / 8096 / 75 / 39 / 513
CSA3 / Hackberry 2014 CP / 30 / 2 / 40.2 / 14.5 / 154 / 333 / 8092 / 5558 / 631 / 365 / 4475
CSA5W / Sister Lake 2012 CP / 365 / 3 / 1 / 26 / 11.2 / 332 / 427 / 1466 / 1466 / 4947 / 242 / 2405
CSA5W / Sister Lake 2012 CP / 365 / 3 / 26 / 10.5 / 332 / 396 / 1466 / 1390 / 6372 / 377 / 3752
CSA6 / Big Charles / 15 / 1 / 0 / 3.3 / 1.8 / 5728 / 5180 / 5870 / 5268 / 0 / 0 / 0
CSA6 / Big Charles / 15 / 1 / 3.3 / 1.5 / 5728 / 4724 / 5870 / 4346 / 0 / 7 / 899
CSA6 / Nickle Reef / 100 / 4 / 1 / 19.7 / 9.7 / 2252 / 2256 / 2256 / 2257 / 2950 / 135 / 792
CSA6 / Nickle Reef / 100 / 4 / 19.7 / 8.1 / 2252 / 1923 / 2256 / 1925 / 3857 / 487 / 2888

Table 8. A comparison of simulated (sustainable) harvest and harvest estimate (in sacks), and the expected impact on cultch mass (g/m2) of Coastal Study Areas (CSA). Harvest data are reported by “Area”, as listed. Simulations are based on reefs fished within the designated Area. Where Harvest Estimate exceeds Simulated Harvest for Total sack and seed oysters, the expectation is that cultch mass will decrease. Likewise, where Simulated Harvest exceeds Harvest Estimate the expectation is that cultch mass will increase.