Fishery bulletin of the Fish and Wildlife Service - NOAA

More documents

Recommendations

Info

BIOLOGY OP THE ATLANTIC MACKEREL 169 took very few eggs that were not otherwise accounted for (by the contamination correction based on the average catch of the upper net and on the time taken to pass through the upper stratum). It is safe to conclude therefore, that the pycnocline forms a barrier to the downward extension of mackerel eggs. Further, the pycnocline is sufficiently well indicated by the thermocline in this region so that the latter may be used an an indicator of the lower limit of mackerel eggs. ^ И 10 ff u u * 20 1 w o NUMBER OF THOUSANDS OF MACKEREL EGGS PER HAUL TEMPERATURE, DECREES C. 0 5 10 ы я (S 5Q г*» . ,*-•""""* 25 Ä 30 „х- и ~" . 35 1Г1 0 в I 10 12 "\ x? / / xJr , BOTTOM ^ эгл aio эгл зао , 3ALINITY. РАЯТЗ PER THOUSAND Ю290 IJOBS5 1.0250 l
170 FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE his 3-day-old eggs 7 nor that of the sea water either at the beginning or end of his experiment. Since he was working before rigid control of temperature was customary, it is likely that the specific gravity of the water in his experiment may have been changed by warming. In the present example, at least, it is known that the temperature of the water was increasing at the time station 20498 was visited. At the temperature of the water in which the eggs were found on May 17, it takes about 5 days for incubation (p. 167), and it may be estimated that stage С eggs were spawned at least 3 days prior to stage A eggs, hence on May 14, when unfortunately this station was not visited. However, from interpolation (linear) both in space and tune between the temperature at station 20498 on May 17 and temperature at neighboring stations on May 12, it appears that the density of the water at the surface on May 14 could have been very nearly the density of the water at the 10-meter level on May 17. Hence it is preferable to ascribe the sinking of the late stages to the warming of the water with attendant decrease in density, rather than to an increase in the density of the eggs. THE LARVA » Yolk-sac stage.—The newly hatched larva ' is slightly less than 3 mm. in length, well covered with scattered black pigment spots which tend to be denser dorsally than ventrally. The eyes are colorless. The region of the gut is occupied by the yolk sac with its oil globule. Both sac and globule are about the same size as they were in the egg. The mackerel is readily distinguished from other similarly marked larvae with which it is found, by its larger size, stouter shape, coarser pigment spots, and its 30 myomeres. As development proceeds, the pigment becomes localized on top of the head and along dorsal and ventral edges of the body, the eye becomes black, the yolk sac absorbed, the mouth and gut formed. These changes are completed at a length of 4 mm. As seen in the laboratory and hatchery, the mackerel swim very feebly during the yolk-sac stage, with short, spasmodic, random movements. Their balancing faculty is undeveloped, their position being indifferently upside down, right side up, and at various angles. At sea they must be totally at the mercy of the water movements. Larval stage.—As used herein, this stage represents the period beginning after yolk-sac absorption and ending after fin formation, and it includes individuals between 4 and 8 mm. in length. In this stage, the mackerel is readily distinguished from other species by the row of black spots of irregular size and spacing along dorsal and ventral edges of the body, beginning about midway between snout and tail and extending almost to the end of the notochord (but not into the fin fold). Those in the dorsal row arc less numerous and more widely spaced than those in the ventral. Other species which were found with the mackerel, and which have also such dorsal and ventral rows of pigment, are the winter flounder (Pseudopleuronectes amerieanus), which differs from the mackerel by its greater number of myomeres (37-40) and its ' But be does give the specific gravity of newly spawned eggs as between 1.024 and 1.026, a figure very close to that of surface water at our station 20498. (See fig. 4.) • While the term larva may be applied to the entire plahktohlc existence, it is convenient to recognize three subdivisions: yolksac stage, larval stage, and post-larval stage. ï This description la based on formaldehyde preserved specimens because this is the form commonly available for study. In life, the newly-batched larva isjonger, measuring 3.1 or 3.2mm. (distortion and shrinkage decrease the length of preserved specimens), and in addition to the black pigmentation, have yellow and greenish pigment on each side of the head between the eye and otocyst, and on the surface of the oil globule (Ehrenbaum, 1005 p. 31).
Page 1 and 2:
UNITED STATES DEPARTMENT OF THE INT
Page 3 and 4:
UNITED STATES DEPARTMENT OP THE INT
Page 5 and 6:
ABSTRACT The results of an investig
Page 7 and 8:
2 FISHERY BULLETIN OF THE FISH AND
Page 9 and 10:
Page 11 and 12:
Page 13 and 14:
Page 15 and 16:
Page 17 and 18:
Page 19 and 20:
14 FISHEBY BULLETIN OF THE FISH AND
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
20 FISHERY BULLETIN OF THE FISH AKD
Page 27 and 28:
Fish and Wildlife Service, Fishery
Page 29 and 30:
Page 31 and 32:
Page 33 and 34:
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
32 FISHEKY BULLETIN OF THE FISH AND
Page 41 and 42:
FISHERY BULLETIN OF THE FISH AND WI
Page 43 and 44:
Page 45 and 46:
Page 47 and 48:
Page 49 and 50:
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
Page 59 and 60:
Page 61 and 62:
Page 63 and 64:
Page 65 and 66:
Page 67 and 68:
Page 69 and 70:
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
68 Centime tf гз 28 3l ,.-.-- 32
Page 77 and 78:
Page 79 and 80:
72 TABLE 18.- FISHERY BULLETIN OF T
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Blank page retained for pagination
Page 87 and 88:
ABSTRACT Plankton collections made
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
84 FISHERY BULLETIN OP THE FISH AND
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
92 FISHERY BTTLLETIN OF THE FISH AN
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
98 FIBHEBY BULLETIN OP THE FISH AND
Page 109 and 110:
100 FISHERY BULLETIN OF THE FISH AN
Page 111 and 112:
102 FISHERY BULLETIN OP THE FISH AN
Page 113 and 114:
ABSTRACT T7XCEPTIONAL DATA are avai
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
110 FISHEBY BULLETIN OF THE FISH AN
Page 123 and 124:
112 FISHEBY BULLETIN OF THE FISH AN
Page 125 and 126:
114 FISHERY. BULLETIN OF THE FISH A
Page 127 and 128:
116 FISHERY BULLETIN OP THE FISH AN
Page 129 and 130:
118 FISHEBY BULLETIN OP THE FISH AN
Page 131 and 132: 120 FISHEHY BULLETIN OF THE FISH AN
Page 133 and 134: 122 FISHERY BULLETIN OF THE FISH AN
Page 139 and 140: 128 FISHEEY BULLETIN OF THE FISH AN
Page 147 and 148: 136 FISHEKY BULLETIN OP THE FISH AN
Page 159 and 160: Blank page retained for pagination
Page 161 and 162: ABSTRACT This portion of a comprehe
Page 163 and 164: 150 FISHERY BULLETIN OP THE FISH AN
Page 165 and 166: 152 FISHERY BULLETIN JOF THE FISH A
Page 173 and 174: 160 FISHEBY BULLETIN OF THE FISH AN
Page 181: 168 FI8HEET BULLETIN OF THE FISH AN
Page 191 and 192: 178 FISHERY BULLETIN OP THE PISH AN
Page 201 and 202: 188 FISHERY BULLETIN OP THE PISH AN
Page 213 and 214: 200 FISHEBY BULLETIN OP THE FISH AN
Page 219 and 220: 206 FISHEET BULLETIN OP THE FISH AN
Page 223 and 224: 210 FISHERY BULLETIN OF THE PISH AN
Page 231 and 232: 218 FISHEKY BULLETIN OF THE FISH AN
Page 233 and 234:
Page 235 and 236:
Page 237 and 238:
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
Page 249 and 250:
Page 251 and 252:
Page 253 and 254:
FLUCTUATIONS IN ABUNDANCE OF RED SA
Page 255 and 256:
FISHERY BULLETIN OP THE CTBH AND WI
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
FISHEKY BULLETIN OP THE FISH AND WI
Page 265 and 266:
Page 267 and 268:
Page 269 and 270:
Page 271 and 272:
Page 273 and 274:
Page 275 and 276:
Page 277 and 278:
FISHEBY BULLETIN OF THE FISH AND WI
Page 279 and 280:
FISHEltY BULLETIN OF THE FISH AND W
Page 281 and 282:
Cold Creek« Spring Creek Moraine C
Page 283 and 284:
Page 285 and 286:
Page 287 and 288:
FISHERY BULLETIN OP THE FISH AND WI
Page 289 and 290:
Page 291 and 292:
Page 293 and 294:
Page 295 and 296:
Page 297 and 298:
Page 299 and 300:
Page 301 and 302:
1 2 3 4 . 1 2 3 4 Age of seaward mi
Page 303 and 304:
Page 305 and 306:
Page 307 and 308:
Page 309 and 310:
Page 311 and 312:
Page 313 and 314:
Page 315 and 316:
THE WHITEFISH FISHERY OF LAKES HURO
Page 317 and 318:
WHITEFISH FISHERY OF LAKES HURON AN
Page 319 and 320:
Page 321 and 322:
WHITEPISH FISHERY OF LAKES HURON AN
Page 323 and 324:
Page 325 and 326:
Page 327 and 328:
Page 329 and 330:
PART II FLUCTUATIONS IN THE PRODUCT
Page 331 and 332:
Page 333 and 334:
WHITEFISH FISHERY OF LAKES HUKON AN
Page 335 and 336:
Page 337 and 338:
Page 339 and 340:
Page 341 and 342:
Page 343 and 344:
Page 345 and 346:
Page 347 and 348:
Page 349 and 350:
Page 351 and 352:
Page 353 and 354:
Page 355 and 356:
Page 357 and 358:
Page 359 and 360:
Page 361 and 362:
. * - гоо WHITEFISH FISHERY OF L
Page 363 and 364:
Page 365 and 366:
Page 367 and 368:
Page 369 and 370:
WHITEFI8H>FISHEBY OF LAKES HURON AN
Page 371 and 372:
WHITEFISH FISHERY OF LAKES HUEON AN
Page 373 and 374:
Page 375 and 376:
Page 377 and 378:
Page 379 and 380:
Page 381 and 382:
Page 383 and 384:
PART IV OBSERVATIONS ON THE FISHING
Page 385 and 386:
WHITEÏ4SH FISHERY OF- LAKES HURON
Page 387 and 388:
Page 389 and 390:
Page 391 and 392:
Page 393 and 394:
Page 395 and 396:
Page 397 and 398:
Page 399 and 400:
WHITEFISH FISHERY OF LAKES HUBON AN
Page 401 and 402:
TVHITEFISH FISHERY OF LAKES HURON A
Page 403 and 404:
Page 405 and 406:
Page 407 and 408:
Page 409 and 410:
Page 411 and 412:
WHITEPISH FISHERY OF LAKES HURON AN
show all

Fishery bulletin of the Fish and Wildlife Service - NOAA

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?