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

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ESPINO AND WOSNITZA-MENDO: PERUVIAN HAKE FISHERIES, 1971-82CalCOFl Rep., Vol. XXVII, 1986TABLE 3Number of Two-Year-Old RecruitsN (11)(Millions)1971 406.51972 442.31973 379.31974 368.71975 412.8I976 1,076.71977 521.4I978 483.31979 337.81980 209.71981 170.41982 198.00.12-Y/RIkgl0.11 -0.10-0.09-B/RIk 1.1.3.1.1.0.90.08-F I1.0-1 19811.00.07-.0.7-0.50.04-0.03-~0.31.0-1.0-0.02-1.0191 1 r , I 1 1 1 1 10 0.2 0.45 0.6 0.8 1.2 1.4 1.6 X1.0 {0.01 -A-19781.04 A . 19771 . 0 ~ g 7 61.oj /-* 19731972s 1971I I I I I I11 111 IV v VI VII AGEFigure 5. Variation of fishing mortality rate (F) for females, 1971-82.O:l4 0:31 Os1 Ob4 0:68 0:82 0.95 1:OS FIII-VIIf182)Figure 6. Yield per recruit for females (-).(-----)..0.1Biomass per recruit for femalesthe last year (1982) for each age-group as 100%. M is aconstant of 0.3. The calculations were made with a unitof 1,000 recruits, leading to yield per recruit for differentvalues of F (Figures 6 and 7). In both sexes, weobserve that the actual (1982) F value is much higherthan the value needed to obtain the maximum yield.The actual F value for males is 0.80 (age-groups111-V), whereas the optimal F should be 0.48, whichwould mean a 40% decrease in fishing effort. For females,the actual F is 0.68 (age-groups 111-VII) andshould be 0;31 (55% lower).Because fishing mortality is directly correlated withfishing effort, this would indicate a considerabledecrease in fishing effort. But a direct reduction of effortwould cause serious socioeconomic consequences;we therefore recommend that the minimum mesh size118
ESPINO AND WOSNITZA-MENDO: PERUVIAN HAKE FISHERIES. 1971-82CalCOFI Rep., Vol. XXVII. 1986Y/ R[kglo.09j \\\\ FhaxlB/R[kgl10.60.16C"E" C 0.36- 0.5- 0.40.3 -I"E"- 0.3i0.20.1II I I I I I I I I0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 X::il0.0 1Figure 7. Yield per recruit for males (-).(-----),Biomass per recruit for malesbe increased to at least 1 10 mm. A similar measure wastaken in the South African hake fishery in 1974(Wysokinski 1976). Environmental conditions like ElNifio may also act to preserve the stock. In 1982-83 thestock was apparently unavailable to the fishery, becauselandings did not exceed 33,000 MT.Exploitation RateBecause we find very different distribution andconcentration of fish stocks off Peru during so-callednormal and abnormal years of El Niiio, existing productionmodels are not so useful for estimating theequilibrium yield. Therefore, we have taken thecatches of "normal" years (1973-76 and 1979) fromTable 1 to calculate an average equilibrium yield of103,300 MT and a biomass of 454,000 MT. This givesus an equilibrium exploitation rate of "E" calculated asC/B of about 0.25 with 95% confidence limits between0.16
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REPORTSVOLUMECICTCIBERXXVll1986
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EDITOR Julie OlfeSPANISH EDITOR Pat
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COMMITTEE REPORTCalCOFI Rep., Vol.
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FISHERIES REVIEW: 1985CalCOFl Rep.,
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FISHERIES REVIEW: 1985CalCOFI Rep.,
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BINDMAN: 1985 NORTHERN ANCHOVY SPAW
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~~ ~BINDMAN: 1985 NORTHERN ANCHOVY
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WOLF AND SMITH: MAGNITUDE OF SARDIN
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PUBLICATIONSCalCOFI Rep., Vol. XXVI
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Part I1SYMPOSIUM OF THE CALCOFI CON
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PETERSEN ET AL.: NEARSHORE HYDROGRA
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LAVENBERG ET AL.: SOUTHERN CALIFORN
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STEPHENS ET AL.: LARVAL FISH RECRUI
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Page 87 and 88: LOVE ET AL.: INSHORE SOFT SUBSTRATA
Page 109: Part 111SCIENTIFIC CONTRIBUTIONS
Page 112 and 113: BAILEY ET AL.: FORECASTING HAKE REC
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Page 116 and 117: ESPINO AND WOSNITZA-MENDO: PERUVIAN
Page 124 and 125: MacGREGOR: SEBASTES ABUNDANCECalCOF
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MOSER ET AL.: EARLY STAGES OF OCEAN
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ARCOS AND FLEMINGER: CALANOID COPEP
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TRUJILLO-ORTIZ: ACARTlA CALIFORNIEN
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TRUJILLO-ORTIZ: ACARTIA CALIFORNIEN
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TRUJILLO-ORTIZ: ACARTIA CALlFORNlEN
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TRUJILLO-ORTLZ: ACARTIA CALIFORNIEN
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CHEN: VERTICAL DISTRIBUTION OF PELA
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CHEN: VERTlCAL DISTRIBUTlON OF PELA
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JOOCHEN: VERTICAL DISTRIBUTION OF P
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BRINTON ET AL.: GULF OF CALIFORNIA
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METHOT: FRAME TRAWLCalCOFI Rep., Vo
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-130' 125. 120' 11.5. 110.I I I I I
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