CalCOFI Reports, Vol. 11, 1967 - California Cooperative Oceanic ...

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68 CAIjIE'ORSId COOPERATIVE OCEANIC FISHERIES IKVESTIGATIONSweights which produced the rupture of the membrane,or which produced signs of destruction in the embryos,were considered to be critical weights. This method issimilar to the one used by Galkina (1957) , in her workon the herring of the Okhotsk Sea. In order to submitthe eggs to shocks, they were taken in approximatelyequal amounts by means of a pipette, and weredropped upon a nylon tulle tautly extended on theconcave side of a petri dish. The eggs were droppedfrom heights of 23 and 50 em. The embryos used werein the following stages of development : the beginningof blastula, early gastrulation, the stage at which theblastoporic ring exceeds the equator of the eggs, andembryos in the stage of tail growth. The eggs submittedto shock were placed in aquaria and the followingday the mortality rate was determined. A similarmethod was employed by Rollefseii (1932) for determiningthe susceptibility of cod embryos.The eggs used for the light, salinity, pressure andshock experiments were kept at a temperature rangingbetween 14" and 15" C. The embryos used in all theexperiments developed from eggs of anchovies whichapproached the shore for reproduction in October.This last observation is necessary, especially in regardto experiments on the influence of temperature,since it is known that embryos from anchovies spawningin summer (for instance) at much higher temperaturesof the water, can show different physiologicalcharacteristics with respect to the temperature factor.INFLUENCE OF TEMPERATUREAs is well known, the rate of the embryonic developmentof 8 given species is directly related to the temperature.The higher the temperature, the more rapidthe developmental processes take place (Leiner, 1923 ;VucetiG, 1957, etc.). In this respect the anchovy followsthe general rule. At the temperature of 14"-15"C., hatching occurs 69 to 72 hours after fertilization ;at 19"-20" C., 50 to 53 hours after fertilization. Therate of development within the aforementioned tcmperaturesis shown in Table 1.Besides the differences in developmental rate, otherphenomena related to temperature became apparent.TABLE 1THE EMBRYONIC DEVELOPMENT OF THE ANCHOVY AT DIFFERENTTEMPERATURES1 Hours of developmentStage of development 14-15' C. 19-20° C.__First cell formation .__________..__..__Oh35m Oh35mTwo-blastomere stage. - ----.- ----- - 1h10m lhOOmFour-Blastomere stage. ___---.- --.- - 1h40m 1h20mEarly blastula.. _.___.__.._.________.2h25m 2h00mBlastula __.__ .- -.- -- -.- --..---..- 5h00m 4h20mEarly gastrula. .._.__.__...._.....___16 h 45 m 15 h 30 mClosing of the blastopore .___.____...._33 h 30 m 29 h 00 mBlastopore closed. Stage of Kupffervesicle.-----------..--------.-----The embryo occupying 3/6 of perimeter..39 h 00 m56 h 30 m32 h 30 m44 h 30 mThe embryo occupying % of perimeter-. 66 h 00 m 50h00mhatching_.-_____--_^..^--^..^-^^.--- 69 - 72 h 51 - 53 hIWithin 14" to 15" C., 90 to 95% of hatching isobtained with very few anomalous cases, whilst within19" to 20" C., 80 to 90% of the eggs hatch, andanomalies appear with greater frequency. Theseanomalies consist mainly in axial deviations, especiallyin the region of the tail. Differences in thelength of the larvae born at these different temperatureshave not been observed. The influence of thetemperature was manifested also in the heart beat.The heart beat of an embryo immediately prior tohatching, at temperatures within 14" to 15" C., wason the average 65 to 70 beats per minute, whilst attemperatures between 19"-20" C., it was about 100beats per minute.A temperature of 4" C. was lethal for the embryosof anchovy. Eggs placed at 4' C. in the earlyblastula stage showed a complete halt in their development.After 5 to 6 days, and always in the same stage,they died and became opaque. When eggs which hadbeen kept for 1 to 2 days at 4" C. were transferredto aquaria at a normal temperature (14" C.), theirdeath occurred more quickly. Thus the lower temperatureseems to cause irreversible changes.From the aforementioned results, there seem to begrounds for making certain assumptions with regardto the optimal temperatures for the embryonic developmentof the anchories reproducing in spring.As has been mentioned in a previous publication(Dz. de Ciechomski) the anchovy begins to spawn ina rather intensive way at 10" to <strong>11</strong>" C. The greaterspawning intensity is achieved within <strong>11</strong>.5" to 13.8'C. Thus a temperature of 10" C. may be consideredas the lower limit of the optimal temperature rangefor development. It has been noted that developmentat a temperature within 19"-20" C. does not takeplace in a completely normal manner, and thus thereseems to be an upper temperature limit to the optimalrange. The assumption which can be made from thesedata is that the anchovy which spawns in the springhas its optimal developmental range within 10" C.and 16"-17" C. These values might be somewhatdifferent for individuals of the same species that reproducein summer at higher water temperatures.INFLUENCE OF SALINITYA large number of species of the clupeid group showgreat tolerance in respect to the salinity factor. Forthe embryonic development of Clupea harengus,Ford (1928) gives salinity limits from 4.8%0 to 37.@h0.Holliday and Blaxter (1960) give the values 5.9%/,,to 52.5%0 (for the same species). Demir (1963) observedthat Engraulis encrasicolus in European waters candevelop normally within salinities from 9%0 to 37.5c/00.For the species of the family Engraulidae which livein waters close to the American Continent, no sufficientdata are available at present on this problem.In the case of the Argentine anchovy (Engraulisanchoita) it has been possible to establish that it doesnot possess as great a tolerance in respect to salinitythresholds for its embryonic development.Anchovy eggs which are transferred at any stageto water of a lower than normal salinity sink and
REPORTS Y‘OLUJIE XI, 1 JULY 1963 TO 30 JUNE 1966 69continue their development whilst lying on the bottomof the aquarium. Upon transferring the eggs at theblastula stage to water with a salinity of 3.4740, mostof the embryos die within a short time. Many eggsincrease in size and take the shape of a very widebarrel. This phenomenon is probably caused by perturbationsin osmoregulation. Some of the embryosreach the Iiupffer visicle stage, all of them showinganomalies in the axial part. The axis of the embryotakes the form of an “S” or a sinuous shape, as isshown in Figure 1. At this stage all of the eggs die.When the transfer has been made while the embryosare still in the stage at which the tail has alreadybeen separated from the vitellus, the embryos continuetheir development only for a short time. Then theycome to show axial alterations as in the precedingcase, and they die. The embryos transferred in theappear to be normal. From the remaining 40% a smallportion does not reach the hatching stage and mostof the larvae show small abnormalities. Eggs in anystage of development, when kept in high salinitywater, remain buoyant close to the surface. The value33.5%0 corresponds to the normal salinity at whichthe anchovy spawns in the sea.Observing the embryonic development of the anchovyin salinities higher than normal, several resultsare obtained. In water with 50%0 salinity, developmentcontinues in a more or less normal fashion.The hatching rate is high (90-95%) and few abnormalitiesare observed. The developmental rateappears to be to a certain degree higher than that ofthe controls. In water of 6Oo/oO salinity, about 70%of the embryos reach the hatching stage. Most of theembryos that hatch are abnormal, and in most cases,show anomalies in the region of the tail (Figure 2).Some monsters are born almost without a tail. These2FIGURE 1.Embryos of the anchovy maintained at salinity 3.4% showinganomalies in the axial part.blastula stage to water with a salinity of 8.4g0 coiitinuetheir development up to the stage in which theembryo occupies about 3 of the perimeter of the egg.From this moment on the eggs all die. An increase inthe size of the eggs is not observed as at 3.4%0 salinity,but most of the embryos show the same axial alterations.The embryonic development seems to lag a little ascompared to the controls. In water with a salinityof 16.8%0, the embryos develop at a somewhat slowerrate than the controls and most of them (60 to 70%)are able to hatch. Among the resulting larvae a fewappear to be normal but die soon after hatching.Most of the larvae hatch in an earlier stage of developmentthan the controls and many of them showabnormalities, especially in the region of the tail.These latter results offer grounds for assuming thatlow salinity has a greater effect on the development ofthe embryo than upon the action of the hatchingenzymes. With water of 23.8%0 salinity, normal hatchingof approximately 6076 of the eggs is obtained.These larrae do not differ from the controls andFIGURE 2. Monsters of the anchovy born in water of 60%0.larvae reach a length of only 1.25-1.35 mm, whilstthe length of the controls is about 3 mm. Malformationin the embryonic fin are observed in some larvaejust after hatching, and an anomaly is also observedin the existence of a very large cavity in the anteriorpart of the vitellum. Similar abnormalities have beenfound by Nakai (1962) in the case of eggs of Xardinamelanostica kept in salinities much higher thannormal.It can be assumed from these data that the Argentineanchovy does not show as high a tolerancein respect to salinity thresholds as do some relatedspecies, such as Engradis encrasicolus. The limitingsalinities, within which the embryonic developmentof Engraulis anchoita can take place more or lessnormally, would be fixed at 25.8:ho and SO%,. Thisphenomenon might be due to the fact that the Argentineanchovy IiTTes in il habitat undergoing slightchanges in salinity, and that. therefore, it has not
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STATE OF CALIFORNIAMARINE RESEARCH
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STATE OF CALIFORNIADEPARTMENT OF FI
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RONALD REAGAXGovcriwr of the Slate
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PART 1REVIEW OF ACTIVITIESJuly 1,19
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REPORTS YOLUAIE SI, 1 JULY 1963 TO
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REPORTS VOLUNE XI, 1 JULY 1963 TO 3
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REPORTS YOLUME SI, 1 JULY 1963 TO 3
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REPORTS VOLUME XI, 1 JULY 1963 TO 3
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REPORTS vor,uiwIi; SI, 1 JULY 1063
Page 19 and 20: REPORTS TOT2T71\IF: SI, 1 JUJIT 196
Page 21 and 22: IiEPOHTS TOLUME XI, 1 JULY 1963 TO
Page 23 and 24: REVIEW OF THE PELAGIC WET FISHERIES
Page 25 and 26: KEI'OiiTH TOLUJIE SI, 1 JULY 1963 T
Page 27 and 28: REPORTS VOLUME XI, 1 JULY 1963 TO 3
Page 29 and 30: PART IISYMPOSIUM ON ANCHOVIES, GENU
Page 31 and 32: OCEANIC ENVIRONMENTS OF THE GENUS E
Page 33 and 34: KEI'OKTS VOLIXI.: SI, 1 JULY 1963 T
Page 41 and 42: ~~~REPORTS VOLUME XI, 1 JULY 1963 T
Page 45 and 46: REPORTS VOLUME SI, 1 JULY 1963 TO 3
Page 47 and 48: 130'E 132' 134' 136' 138' 140' 142-
Page 49 and 50: REPORTS VOLUSIE SI, 1 JULY 1963 TO
Page 57 and 58: KI3I’ORTH VOLUJIE XI, 1 JULY 1963
Page 61 and 62: REPORTS VOLUME SI, 1 JULY 1963 TO 3
Page 65 and 66: REPORTS VOLUIIE SI. 1 JULY 1963 TO
Page 67 and 68: REPORTS T’OLUME XI, 1 JULY 1963 T
Page 69: INFLUENCE OF SOME ENVIRONMENTAL FAC
Page 75 and 76: ~table shows the values calculated
Page 77 and 78: ateREPORTS T-OLTJIT", SI, 1 JULl 19
Page 79 and 80: REPORTS POLGNE SI, 1 JU LY 1963 TO
Page 81 and 82: REPORTS VOLUXE XI, 1 JULY 1963 TO 3
Page 85 and 86: _________--_____REPORTS VOLUJIE SI,
Page 87 and 88: REPORTS TOLTIJIE SI, 1 JULY 1963 TO
Page 89 and 90: -20/5-0 10-f 5-w 25-0 20-= 15-: 10-
Page 91 and 92: REPORTS VOLUNE SI. 1 JULY 19G3 TO 3
Page 97 and 98: REPORTS VOLURlE SI, 1 JULY 1963 TO
Page 107 and 108: THE PREDATION OF GUANO BIRDS ON THE
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Page 115 and 116: FISH E RYThe California anchovy fis
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Page 119: CO-OCCURRENCES OF SARDINE AND ANCHO
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120 CALIFORNIA COOPERATIVE OCEANIC
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CALIFORNIA COOPERATIVE OCEANlC FISH
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126CALIFORNIB COOPERATIVE OCEANIC F
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~~ ~130 CALIFORNIA COOPERATIVE OCEA
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132 CALIF0RhTTIA COOPERATIVE OCEANI
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THE ACCUMULATION OF FISH DEBRIS IN
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PART IllSCIENTIFIC CONTRIBUTIONS
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REPORTS VOLUME SI, 1 JULY 1963 TO 3
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REPORTS VOLU&IE XI, 1 JULY 1963 TO
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SUMMARY OF THERMAL CONDITIONS AND P
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SEASONAL VARIATION OF TEMPERATURE A
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including the semiannual harmonic?
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REPORTS VOiLUME XI, 1 JULY 1983 TO
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170 CALIFORNIA COOPERATIVE OCWIC FI
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172 CALIFORNIA COOPERATIVE OCBANIC
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184CALIFORNIA COOPERATIVE OCEANIC F
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CONTENTSI. Review of Activities Pag
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