Length-weight relationships for 15 species of reef fish caught in the lagoonal seine-net fishery at

31 Pages·2011·1.04 MB·English

by  Alasdair Edwards

Length-weight relationships for 15 species of reef fish caught in the lagoonal
seine-net fishery at Rodrigues Island, Indian Ocean

A. J. Edwards1, E. R. Hardman, F. E. I. Blais, M. S. Desiré, J. S. J. Raffin, S. Perrine, R. Raffaut,
T. L. Hooper, T. E. J. Hooper

Shoals Rodrigues, Pointe Monier, Rodrigues

1 School of Biology, Newcastle University,
Newcastle upon Tyne NE1 7RU, United Kingdom
August 2011

Citation:
Edwards AJ, Hardman ER, Blais FEI, Desiré MS, Raffin JSJ, Perrine S, Raffaut R, Hooper, TL and Hooper
TEJ (2011) Length-weight relationships for 15 species of reef fish caught in the lagoonal seine-net
fishery at Rodrigues Island, Indian Ocean. Shoals Rodrigues: Pointe Monier, Rodrigues. 29 pp.
Introduction
From 2002 to 2006 samples of fish commonly caught in the Rodrigues lagoonal seine-net fishery were
both weighed and measured to establish length-weight relationships. Fish were weighed to the
nearest 0.1 g where possible and total length (horizontal distance from tip of snout to rearmost fin
rays of the spread caudal fin) was measured on a measuring board to the nearest 0.1 cm. For 15
species that had more than 15 individuals measured in this way, weight-length relationships were
calculated according to:
W  aLb
where W is weight (g) and L is length (cm).
Sample sizes ranged from 17 to 519. For one species, the Bluespot mullet (Moolgarda seheli), the
relationship had a relatively poor fit and should be treated with caution. The data utilised to construct
the weight-length relationships are summarised in Table 1.

Table 1. Summary of weight-length relationships calculated for 15 reef fish species relatively
commonly caught in the Rodrigues Island lagoonal seine-net fishery. The number of fishes measured,
the range of lengths obtained, calculated intercept and slope for the power relationship, and
coefficient of determination (R²) for the weight-length regression are shown for each species.
Sample size Range of TL (cm) Regression
Species n Min Max a b R²
Siganus sutor 519 14.1 48.0 0.0127 3.0308 0.9762
Gerres longirostris 226 20.5 41.0 0.0075 3.1338 0.9401
Lethrinus nebulosus 189 14.5 59.0 0.0193 2.8897 0.9779
Caranx melampygus 167 18.0 57.7 0.0096 3.0598 0.9867
Mulloidichthys flavolineatus 70 24.5 36.7 0.0056 3.1758 0.9492
Mulloidichthys vanicolensis 66 15.5 35.0 0.0062 3.1590 0.9388
Epinephelus merra 50 11.5 24.0 0.0334 2.7333 0.9636
Siganus argenteus 40 17.7 35.5 0.0120 3.0208 0.9863
Acanthurus triostegus 33 12.5 23.0 0.0223 3.1054 0.9386
Naso unicornis 28 22.5 56.0 0.0321 2.8220 0.9144
Chlorurus sordidus 22 18.0 34.0 0.0165 3.0635 0.8913
Lethrinus harak 22 25.1 42.0 0.0163 2.9673 0.9555
Gnathanodon speciosus 21 17.5 34.1 0.0072 3.1805 0.9824
Rhinecanthus aculeatus 17 14.0 27.0 0.1559 2.4059 0.9559
Moolgarda seheli 53 32.3 59.0 0.8158 1.8494 0.4290

1
Siganus sutor (Valenciennes, 1835)
Cordonnier; Shoemaker spinefoot
Family: Siganidae (Rabbitfishes)

Siganus sutor
1400
y = 0.0127x3.0308
1200
1000
)g 800
( t
h
g
ie 600
W
400
200 n = 519
0
0 10 20 30 40 50
Length (cm TL)

2
Siganus sutor (n=519) Total length (cm) Weight (g)
Fish # Length Weight Fish # Length Weight Fish # Length Weight
1 17.9 81.1 51 24.0 186.5 101 27.5 272.0
2 18.8 104.1 52 24.0 193.0 102 27.7 279.4
3 19.1 91.2 53 24.0 182.0 103 27.7 279.4
4 19.5 107.9 54 24.2 186.8 104 28.0 320.0
5 20.0 110.9 55 24.4 201.1 105 28.0 288.0
6 20.1 119.2 56 24.4 190.7 106 28.0 331.6
7 20.5 118.2 57 24.5 193.0 107 28.0 337.2
8 20.5 120.4 58 24.5 193.8 108 28.0 323.5
9 20.7 125.9 59 24.5 193.0 109 28.0 322.2
10 20.7 115.8 60 24.6 212.5 110 28.0 320.0
11 20.8 114.4 61 24.6 196.2 111 28.0 288.0
12 20.8 131.4 62 24.9 233.6 112 28.0 331.6
13 21.0 130.0 63 25.0 222.0 113 28.0 337.2
14 21.0 111.1 64 25.0 215.0 114 28.0 323.5
15 21.0 125.3 65 25.0 219.0 115 28.2 321.5
16 21.0 130.0 66 25.0 235.0 116 28.2 321.5
17 21.3 136.2 67 25.0 246.8 117 28.3 290.0
18 21.5 138.3 68 25.0 247.6 118 28.4 278.1
19 21.6 150.5 69 25.0 222.0 119 28.4 303.0
20 21.6 134.1 70 25.0 215.0 120 28.5 350.3
21 21.7 145.7 71 25.0 219.0 121 28.7 300.5
22 21.7 133.6 72 25.0 235.0 122 28.9 273.9
23 21.8 130.3 73 25.4 234.6 123 28.9 374.6
24 22.1 153.4 74 25.5 235.0 124 28.9 273.9
25 22.1 142.1 75 25.5 236.5 125 29.0 294.0
26 22.4 172.2 76 25.5 235.0 126 29.0 342.0
27 22.5 140.5 77 25.5 236.5 127 29.0 346.8
28 22.5 170.7 78 25.6 243.0 128 29.0 359.3
29 22.6 159.8 79 25.6 244.1 129 29.0 310.9
30 22.6 159.7 80 25.6 226.1 130 29.0 481.1
31 22.6 159.8 81 26.0 225.0 131 29.0 442.4
32 22.7 180.3 82 26.0 259.0 132 29.0 377.5
33 22.7 144.2 83 26.0 251.0 133 29.0 351.4
34 22.9 169.8 84 26.0 225.0 134 29.0 294.0
35 22.9 171.2 85 26.0 259.0 135 29.0 342.0
36 22.9 150.4 86 26.0 251.0 136 29.0 346.8
37 23.2 157.3 87 26.3 253.7 137 29.1 343.3
38 23.5 167.0 88 26.4 293.3 138 29.5 393.2
39 23.5 171.0 89 26.5 271.0 139 29.5 394.9
40 23.5 178.6 90 26.5 264.6 140 29.5 339.8
41 23.5 167.0 91 26.6 265.4 141 29.5 393.2
42 23.5 171.0 92 26.6 219.1 142 29.5 394.9
43 23.7 165.8 93 26.6 260.5 143 29.7 336.3
44 23.8 189.9 94 26.6 286.0 144 30.0 368.0
45 23.9 191.0 95 26.7 262.4 145 30.0 419.0
46 23.9 191.0 96 27.1 283.3 146 30.0 333.8
47 24.0 193.0 97 27.4 261.0 147 30.0 372.8
48 24.0 182.0 98 27.4 261.0 148 30.0 382.8
49 24.0 212.8 99 27.5 272.0 149 30.0 332.7
50 24.0 168.1 100 27.5 302.5 150 30.0 379.4

3
Fish # Length Weight Fish # Length Weight Fish # Length Weight
151 30.0 368.0 201 32.4 452.2 251 39.0 862.4
152 30.0 419.0 202 32.4 489.7 252 39.0 783.0
153 30.0 333.8 203 32.4 496.1 253 39.3 803.5
154 30.3 381.7 204 32.5 508.3 254 39.7 818.5
155 30.3 372.7 205 32.5 440.0 255 40.2 936.5
156 30.3 381.7 206 32.5 490.6 256 41.6 936.0
157 30.4 417.5 207 32.5 471.7 257 25.5 238.4
158 30.5 372.5 208 32.7 512.5 258 27.1 282.5
159 30.5 389.5 209 32.8 481.6 259 24.3 195.8
160 30.5 372.5 210 32.8 481.5 260 40.8 881.1
161 30.6 379.6 211 32.8 484.3 261 23.5 202.2
162 30.8 392.4 212 32.9 448.1 262 27.9 313.0
163 30.8 392.4 213 33.0 440.9 263 29.5 296.3
164 30.9 442.9 214 33.0 476.7 264 23.8 199.7
165 30.9 427.6 215 33.0 440.9 265 26.1 244.9
166 31.0 379.0 216 33.1 519.0 266 22.2 131.8
167 31.0 426.6 217 33.1 570.3 267 29.6 336.6
168 31.0 432.0 218 33.2 517.4 268 26.5 268.0
169 31.0 353.0 219 33.3 504.0 269 28.4 334.1
170 31.0 354.3 220 33.4 524.0 270 26.0 245.8
171 31.0 397.4 221 33.5 507.0 271 23.9 192.9
172 31.0 418.5 222 33.5 507.0 272 28.7 217.3
173 31.0 456.1 223 33.6 553.0 273 20.5 131.6
174 31.0 417.8 224 33.7 562.5 274 28.1 218.0
175 31.0 379.0 225 33.9 630.6 275 34.6 524.4
176 31.0 426.6 226 34.0 496.8 276 25.1 192.5
177 31.0 432.0 227 34.0 491.0 277 26.3 234.6
178 31.0 353.0 228 34.0 545.6 278 26.5 264.4
179 31.0 354.3 229 34.0 521.0 279 25.0 207.0
180 31.1 465.4 230 34.1 495.8 280 26.5 253.5
181 31.2 397.1 231 34.2 630.0 281 25.6 241.2
182 31.3 472.0 232 34.2 523.8 282 36.4 715.5
183 31.4 428.6 233 34.3 540.5 283 23.0 157.6
184 31.4 447.1 234 34.5 575.3 284 24.0 204.0
185 31.5 448.3 235 34.6 605.0 285 35.5 551.4
186 31.5 425.8 236 34.6 562.5 286 27.1 289.5
187 31.5 482.5 237 34.8 602.8 287 31.8 477.6
188 31.5 461.4 238 34.8 543.0 288 22.7 146.4
189 31.6 450.0 239 35.0 583.6 289 22.7 143.8
190 31.9 424.2 240 35.0 567.0 290 23.7 166.7
191 32.0 404.0 241 35.1 627.4 291 21.9 134.2
192 32.0 462.0 242 35.4 592.5 292 26.3 273.9
193 32.0 424.2 243 35.8 643.3 293 42.5 906.4
194 32.0 517.0 244 36.0 618.0 294 41.9 945.2
195 32.0 469.3 245 36.1 638.9 295 27.5 296.5
196 32.0 404.0 246 36.1 638.9 296 23.0 198.3
197 32.1 450.5 247 36.5 692.1 297 28.5 325.9
198 32.1 505.5 248 36.5 727.3 298 34.0 539.1
199 32.3 489.0 249 37.1 691.0 299 38.0 744.5
200 32.3 480.0 250 38.5 802.3 300 36.4 671.5

4
Fish # Length Weight Fish # Length Weight Fish # Length Weight
301 26.4 220.7 351 41.9 1203.3 401 34.7 698.3
302 23.9 158.6 352 34.0 583.8 402 31.5 520.4
303 23.5 170.3 353 32.5 489.2 403 20.6 126.1
304 27.0 283.3 354 28.5 323.3 404 21.9 145.0
305 22.0 160.8 355 30.5 451.2 405 21.7 152.4
306 28.0 314.0 356 30.0 398.0 406 19.8 121.6
307 28.2 351.0 357 34.5 603.5 407 21.7 142.5
308 26.6 274.9 358 37.0 774.7 408 23.9 192.7
309 26.3 347.4 359 38.0 863.7 409 23.2 174.6
310 40.3 912.8 360 34.5 586.4 410 22.6 169.9
311 36.5 522.8 361 32.0 491.4 411 19.3 96.3
312 38.8 829.5 362 31.5 480.2 412 20.4 134.7
313 30.2 386.8 363 30.0 371.0 413 21.7 143.1
314 27.6 333.7 364 30.5 405.6 414 24.2 211.2
315 28.3 313.1 365 28.7 449.2 415 19.9 115.6
316 27.8 303.0 366 27.0 279.2 416 23.6 189.8
317 26.4 254.8 367 31.4 469.2 417 22.8 179.2
318 26.4 280.0 368 30.4 443.2 418 17.1 73.6
319 26.2 278.8 369 25.4 241.2 419 19.5 107.2
320 35.0 650.7 370 39.5 860.0 420 19.6 101.5
321 33.0 533.4 371 39.1 862.2 421 18.4 92.0
322 32.5 460.4 372 42.0 1218.4 422 20.9 122.9
323 30.3 376.4 373 38.1 828.1 423 20.9 130.8
324 31.6 452.7 374 38.3 867.5 424 18.4 88.9
325 29.7 378.2 375 40.4 890.0 425 17.2 72.5
326 31.0 444.2 376 39.3 901.8 426 33.5 526.9
327 31.5 431.9 377 34.5 598.6 427 32.2 482.3
328 28.5 357.9 378 38.3 880.0 428 31.7 476.1
329 27.5 303.8 379 36.5 601.9 429 32.0 549.4
330 28.8 312.4 380 35.0 720.0 430 33.0 520.1
331 28.3 330.9 381 40.3 980.0 431 36.7 729.0
332 27.2 309.8 382 31.7 442.6 432 31.8 468.9
333 23.3 191.5 383 31.5 446.1 433 35.6 672.1
334 27.9 307.8 384 30.0 403.9 434 35.6 682.8
335 26.6 262.9 385 29.6 413.9 435 32.0 516.7
336 26.4 254.9 386 29.0 359.8 436 32.3 441.3
337 25.4 228.9 387 30.9 470.3 437 34.2 506.8
338 24.3 199.8 388 33.8 517.0 438 32.0 411.0
339 24.0 181.2 389 29.0 395.6 439 18.5 94.5
340 35.0 594.2 390 21.0 133.2 440 25.0 214.5
341 35.0 622.5 391 36.5 715.2 441 26.8 282.5
342 25.5 272.1 392 34.0 602.1 442 32.5 509.5
343 31.0 449.2 393 38.2 911.2 443 39.5 1136.5
344 48.0 1298.6 394 36.1 700.8 444 39.8 888.0
345 33.3 550.0 395 37.7 824.2 445 31.8 459.0
346 37.1 709.7 396 31.1 616.0 446 30.6 378.8
347 29.8 419.7 397 30.9 475.0 447 35.7 621.3
348 41.1 1036.1 398 38.9 903.0 448 27.9 313.0
349 39.9 1012.9 399 33.7 754.5 449 32.9 442.9
350 31.0 448.3 400 35.0 793.2 450 29.1 361.6

5
Fish # Length Weight Fish # Length Weight
451 26.3 259.4 501 42.7 1283.4
452 18.4 94.9 502 34.5 624.5
453 35.4 601.6 503 29.6 343.0
454 39.4 909.9 504 21.5 138.8
455 22.5 158.4 505 33.6 534.7
456 36.1 632.0 506 37.9 781.1
457 27.6 301.5 507 40.0 1014.0
458 27.4 288.0 508 28.4 372.3
459 23.2 171.5 509 29.7 362.7
460 19.1 117.8 510 31.6 515.3
461 33.9 750.0 511 26.5 290.0
462 35.4 725.0 512 20.6 136.8
463 32.4 490.0 513 17.4 67.0
464 27.9 350.0 514 14.1 38.7
465 28.0 325.0 515 35.9 810.5
466 26.4 180.0 516 31.2 491.6
467 42.5 1149.6 517 27.0 283.0
468 34.4 629.4 518 24.4 214.0
469 28.2 307.9 519 20.9 130.8
470 23.5 189.4
471 19.1 100.8
472 14.5 47.4
473 41.5 930.0
474 33.0 501.4
475 27.6 263.8
476 23.7 179.4
477 18.8 87.7
478 30.0 361.0
479 29.5 310.8
480 33.0 422.7
481 31.0 362.3
482 31.5 401.9
483 27.7 297.6
484 27.6 309.4
485 33.5 445.7
486 39.0 801.0
487 32.0 492.7
488 35.0 553.0
489 26.4 247.8
490 28.0 288.4
491 25.3 209.7
492 29.9 366.6
493 35.1 670.4
494 42.1 1120.2
495 33.0 535.9
496 29.0 409.5
497 35.6 684.5
498 23.6 228.5
499 26.8 262.8
500 38.3 925.5

6
Gerres longirostris (Lacepède, 1801)
Breton; Longtail silverbiddy
Family: Gerreidae (Mojarras)

Gerres longirostris
1200
y = 0.0075x3.1338
1000
800
)
g
( th 600
g
ie
W
400
200
n = 226
0
0 10 20 30 40 50
Length (cm TL)

7
Gerres longirostris (n=226) Total length (cm) Weight (g)
Fish # Length Weight Fish # Length Weight Fish # Length Weight
1 20.5 114.0 51 28.6 206.1 101 31.5 366.5
2 20.5 90.9 52 29.0 279.2 102 31.5 352.5
3 21.0 95.4 53 29.0 254.6 103 31.6 406.4
4 21.0 97.2 54 29.0 262.9 104 31.6 420.8
5 21.0 111.1 55 29.0 278.7 105 31.7 364.9
6 21.5 102.8 56 29.0 270.2 106 31.8 478.2
7 22.5 123.8 57 29.0 255.0 107 31.9 369.8
8 23.0 135.4 58 29.1 307.0 108 31.9 365.1
9 23.0 149.4 59 29.2 290.7 109 31.9 387.7
10 23.0 138.8 60 29.4 309.0 110 32.0 371.8
11 23.5 160.0 61 29.4 297.9 111 32.0 401.2
12 23.5 160.0 62 29.5 321.0 112 32.0 368.5
13 23.5 143.1 63 29.5 294.7 113 32.3 402.4
14 24.0 168.6 64 29.5 287.9 114 32.3 376.5
15 24.6 175.0 65 29.5 329.3 115 32.4 423.4
16 24.6 179.2 66 29.7 323.7 116 32.4 438.8
17 25.0 194.5 67 29.7 338.2 117 32.5 370.8
18 25.2 211.2 68 29.8 321.2 118 32.5 370.8
19 25.2 180.7 69 29.9 315.9 119 32.7 376.0
20 25.8 211.3 70 29.9 293.8 120 33.0 429.2
21 26.0 192.0 71 29.9 234.8 121 33.0 403.4
22 26.0 192.0 72 30.0 301.5 122 33.0 418.4
23 26.0 208.4 73 30.0 291.9 123 33.2 455.5
24 26.2 206.4 74 30.2 353.4 124 33.3 477.0
25 26.3 183.8 75 30.5 373.7 125 33.4 439.1
26 26.5 200.9 76 30.5 373.7 126 33.5 439.7
27 26.7 228.9 77 30.5 320.8 127 33.7 473.0
28 26.8 252.7 78 30.5 333.0 128 34.0 467.2
29 27.0 222.9 79 30.5 355.5 129 34.2 482.6
30 27.3 249.4 80 30.5 308.9 130 34.7 455.8
31 27.5 256.4 81 30.5 498.6 131 34.9 486.3
32 27.5 256.4 82 30.6 326.5 132 35.0 485.5
33 27.5 248.4 83 30.7 373.1 133 35.5 490.3
34 27.8 283.0 84 30.7 344.0 134 36.0 449.7
35 28.0 248.0 85 30.7 376.6 135 36.7 1005.7
36 28.0 248.0 86 30.8 343.2 136 36.7 678.9
37 28.0 237.5 87 30.8 344.8 137 37.1 1070.0
38 28.0 276.3 88 31.0 361.1 138 37.8 1083.0
39 28.0 270.0 89 31.0 353.9 139 37.8 648.8
40 28.2 254.3 90 31.0 393.3 140 39.0 1089.4
41 28.2 239.4 91 31.0 359.6 141 33.9 400.9
42 28.3 274.1 92 31.1 348.9 142 35.0 449.5
43 28.4 280.0 93 31.1 421.2 143 31.4 324.2
44 28.5 258.0 94 31.1 415.5 144 30.5 293.4
45 28.5 258.0 95 31.2 347.5 145 34.2 488.6
46 28.5 255.7 96 31.2 392.1 146 27.8 254.3
47 28.5 270.5 97 31.2 350.0 147 29.5 294.2
48 28.5 262.6 98 31.2 334.3 148 33.7 502.9
49 28.5 264.8 99 31.4 390.6 149 31.1 390.6
50 28.6 312.2 100 31.5 321.1 150 30.0 322.0

8