CalCOFI Reports, Vol. 27, 1986 - California Cooperative Oceanic ...

More documents

Recommendations

Info

BINDMAN: 1985 NORTHERN ANCHOVY SPAWNING BIOMASSCalCOFI Rep., Vol. XXVII, 1986The egg production method estimate of spawningbiomass (Parker 1980; Stauffer and Picquelle 1980) is:where B =P =w =R =F =s =A =k =B = PAkWRFSspawning biomass in metric tons,daily egg production rate in number ofeggs per day per 0.05 m2,average weight of mature females ingrams (g),female fraction of the population byweight,batch fecundity in number of eggs,fraction of mature females spawning perday ,area of survey in units of 0.05 m2, andconversion factor from grams to metrictons ( lop6 MT/g).An estimate of an approximate variance for thebiomass estimate, der&ed using the delta method(Seber 1982), is:var(B)Z= B2{var(P)/P2 + var(W)/W2 + var(R)/R2 +var(F)/F2 + var(S)/S2 + 2[cov(PW)/PW -COV(PR)/PR - COV(PF)/PF - COV(PS)/PS -COV(WR)/WR - COV(WF)/WF - COV(WS)/WS+ cov(RF)/RF + cov(RS)/RS + cov(FS)/FSI 1.DAILY PRODUCTION OF EGGSThe daily production of eggs in the sea, P, is thenumber of eggs spawned per night per unit area (0.05m2, the area of the ichthyoplankton net) averaged overthe range and duration of the survey. The density ofeggs was determined from an ichthyoplankton survey,and the embryonic developmental stage of each eggwas determined by microscopic inspection. The agesof the eggs in hours from spawning were computedfrom the embryonic developmental stage by aFORTRAN program (Hewitt et al. 1984; Lo 1985)which assumes that the daily spawning of anchovyeggs occurs at 2200 hours. An exponential mortalitycurve for the eggs was fit to the egg age data. I estimatedthe daily production of eggs as the value of thepredicted curve at the time of spawning.In order to reduce the variance of the estimate of P, Iused a two-step sampling scheme with postsurveystratification. The first step was the systematicichthyoplankton sample of the survey area. Each samplewas assigned a weighting factor proportional to the36.3330- -''21 I 1 I l l I I I I I I120 123 120 117 114Figure 4. Subdivision of 1985 survey into strata (stratum 1 is the spawningarea; stratum 0 is devoid of eggs).area the station represented. The second step was todivide the survey area into two strata: stratum 1 was definedas the area where eggs were found or were likelyto be found based on incidence in surroundinglocations, and stratum 0 was the area devoid of eggs(Figure 4).The egg mortality modelwas fit to the data by a weighted nonlinear leastsquaresregression, with station-weighting factors usedas the weights,where P,, = the number of eggs of age t from thejthstation in the ith stratum,t = the age in days measured as the elapsedtime from the time of spawning to thetime of sampling at thejth station (becausespawning occurs once a day andbecause the incubation period was 3days or less, as many as 3 cohorts ofeggs could be found at each station),Z = the instantaneous rate of mortality on adaily basis,PO = the daily egg production rate instratum 0; it is zero by definition, and18
BINDMAN: 1985 NORTHERN ANCHOVY SPAWNING BIOMASSCalCOFl Rep., Vol. XXVII, 1986PI = the daily egg production rate instratum 1.Mean half-day frequencies for the age data along withthe fitted curve and a 95% confidence region for theregression line are described in Figure 5. By definition,the number of eggs produced in stratum 0 is zero. Thedaily egg production rate for the total survey area andits variance (Jessen 1978) is:whereP = (Al/A) PI (4)var(P) = (1 + l/n)[(AI/A) var(P1)] (5)n = the total number of stations,AI = the area of stratum 1, andA = the total survey area.The estimates used to compute P, and their variancesare given in Table 1. P was found to be 6.41 withinstratum 1. For the entire 51,720 n.mi.2 survey area, theestimate of P is 4.78 eggs per day per 0.05 m2 with anapproximate variance of 0.33. This gives a coefficientof variation of 12.0%ADULT PARAMETERS W, F, S, AND RThe parameters W, F, S, and R were estimated from asample of adult anchovies collected by midwater trawl.For each parameter (here denoted y), a weighted mean,F, and a weighted variance were estimated (Cochran1963):wherevar6) = $i [(mi/m)2~j-y’>2]/[n(n-~~] (7)Imi = the number of fish subsampled fromthe ith trawl,fi = the average number of fish subsampledper trawl,n = the number of positive trawls,k ’z3a 6 .Wnv)00w 4U0aWm= 23z00.0 0.5 1 .0 1.5 2.0 2.5AGE (days)Figure 5. Egg mortality curve. The data are summarized as the meanabundance by half-day intervals, although the regression was fit to the individualdata points. A 95% confidence region for the regression (brokenlines) is indicated.-y, = the average value for the ith trawl = C.yjj/mj, andjyv = the observed value for thejth fish in theith trawl.Average Female WeightThe average weight of an adult female, W, and itsvariance were estimated using equations 6 and 7, whereyi was the average female weight in the ith trawl. I computedaverage female weight by selecting 25 maturefemales from each trawl; however, this was not alwayspossible because some trawl samples were too small orwere dominated by immature fish.Just prior to spawning, the eggs in a mature female’sovaries become bloated with fluid (hydrated). Icorrected for the extra weight of the hydrated eggs byregressing the weight of mature females without hydratedeggs against their ovary-free weight and then estimatingthe weight of the hydrated females as if theyTABLE 1Parameters for Computing Daily Egg ProductionStratum 0 Stratum I Total surveyP (eggs/day-0.05m2) 0 6.41 4.77var(P) 0 0.44 0.33Z (day- ’)var(Z)000.290.0070.290.007A (0.05m2) 0.904 X IO” 2.644 X IO’* 3.548 X 10l219
Page 1: REPORTSVOLUMECICTCIBERXXVll1986
Page 4 and 5: EDITOR Julie OlfeSPANISH EDITOR Pat
Page 7: COMMITTEE REPORTCalCOFI Rep., Vol.
Page 10 and 11: FISHERIES REVIEW: 1985CalCOFl Rep.,
Page 12 and 13: FISHERIES REVIEW: 1985CalCOFI Rep.,
Page 18 and 19: BINDMAN: 1985 NORTHERN ANCHOVY SPAW
Page 22 and 23: ~~ ~BINDMAN: 1985 NORTHERN ANCHOVY
Page 28 and 29: WOLF AND SMITH: MAGNITUDE OF SARDIN
Page 34 and 35: PUBLICATIONSCalCOFI Rep., Vol. XXVI
Page 37 and 38: Part I1SYMPOSIUM OF THE CALCOFI CON
Page 39 and 40: PETERSEN ET AL.: NEARSHORE HYDROGRA
Page 55 and 56: LAVENBERG ET AL.: SOUTHERN CALIFORN
Page 67 and 68: STEPHENS ET AL.: LARVAL FISH RECRUI
Page 69 and 70: STEPHENS ET AL.: LARVAL FISH RECRUI
Page 71 and 72:
STEPHENS ET AL.: LARVAL FISH RECRUI
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
LOVE ET AL.: INSHORE SOFT SUBSTRATA
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109:
Part 111SCIENTIFIC CONTRIBUTIONS
Page 112 and 113:
BAILEY ET AL.: FORECASTING HAKE REC
Page 114 and 115:
BAILEY ET AL.: FORECASTING HAKE REC
Page 116 and 117:
ESPINO AND WOSNITZA-MENDO: PERUVIAN
Page 118 and 119:
Page 120 and 121:
Page 122 and 123:
Page 124 and 125:
MacGREGOR: SEBASTES ABUNDANCECalCOF
Page 126 and 127:
MacGREGOR: SEEASTES ABUNDANCECalCOF
Page 128 and 129:
Page 130 and 131:
Page 132 and 133:
-~ ~MacCREGOR: SEBASTES ABUNDANCECa
Page 134 and 135:
Page 136 and 137:
Page 138 and 139:
LLUCH-BELDA ET AL.: GULF OF CALIFOR
Page 140 and 141:
Page 142 and 143:
Page 144 and 145:
DuracionQUINONEZ-VELAZQUEZ Y GOMEZ-
Page 146 and 147:
FIEDLER: OFFSHORE ENTRAINMENT OF AN
Page 148 and 149:
Page 150 and 151:
Page 152 and 153:
Page 154 and 155:
Page 156 and 157:
SCHMITT: SELECTIVITY AND FEEDING OF
Page 158 and 159:
Page 160 and 161:
Page 162 and 163:
SCHMIlT: SELECTIVITY AND FEEDING OF
Page 164 and 165:
MOSER ET AL.: EARLY STAGES OF OCEAN
Page 166 and 167:
~MOSER ET AL.: EARLY STAGES OF OCEA
Page 168 and 169:
Page 170 and 171:
Page 172 and 173:
ARCOS AND FLEMINGER: CALANOID COPEP
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
Page 188 and 189:
Page 190 and 191:
TRUJILLO-ORTIZ: ACARTlA CALIFORNIEN
Page 192 and 193:
TRUJILLO-ORTIZ: ACARTIA CALIFORNIEN
Page 194 and 195:
TRUJILLO-ORTIZ: ACARTIA CALlFORNlEN
Page 196 and 197:
Page 198 and 199:
Page 200 and 201:
TRUJILLO-ORTLZ: ACARTIA CALIFORNIEN
Page 202 and 203:
Page 204 and 205:
Page 206 and 207:
Page 208 and 209:
CHEN: VERTICAL DISTRIBUTION OF PELA
Page 210 and 211:
CHEN: VERTlCAL DISTRIBUTlON OF PELA
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
JOOCHEN: VERTICAL DISTRIBUTION OF P
Page 218 and 219:
Page 220 and 221:
Page 222 and 223:
Page 224 and 225:
Page 226 and 227:
Page 228 and 229:
Page 230 and 231:
BRINTON ET AL.: GULF OF CALIFORNIA
Page 232 and 233:
Page 234 and 235:
Page 236 and 237:
Page 238 and 239:
Page 240 and 241:
Page 242 and 243:
Page 244 and 245:
Page 246 and 247:
Page 248 and 249:
Page 250 and 251:
Page 252 and 253:
Page 254 and 255:
Page 256 and 257:
Page 258 and 259:
Page 260 and 261:
Page 262 and 263:
Page 264 and 265:
Page 266 and 267:
Page 268 and 269:
Page 270 and 271:
METHOT: FRAME TRAWLCalCOFI Rep., Vo
Page 272 and 273:
Page 274 and 275:
Page 276 and 277:
Page 278 and 279:
Page 280 and 281:
Page 283 and 284:
-130' 125. 120' 11.5. 110.I I I I I
show all

CalCOFI Reports, Vol. 27, 1986 - California Cooperative Oceanic ...

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

Delete template?

Save as template?