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

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106 CALIFORNIA COOPERATIVE OCEANIC FISHERIES INVESTIGATIONSMONTHLY LANDINGS OFANCHOVY DURINGS 1962-FIGUREwI~00,000'E F M A M J J A S O N DMONTHS1. Geographical distribution of population centers of guano birds and anchovy landings during 1962.y W ..!, .....'A-I
iod and after 8 AM during the rest of the year.The fishing activity lasts until sunset.The gannet dives from a certain air altitude toreach the depth required, probably not exceeding 15m of depth. The feeding hours begin at dawn andcontinue during daylight.The pelican dives from the air in a manner similarto that of the gannet, but rarely submerges thewhole body. The sea depth reached is therefore limitedto the length of its neck. This species feeds at differenthours of the day and also during the night.It has been stated that the operative range of thesebirds, with special reference to the cormorant, is between30 and 40 nautical miles and they clearly preferto seek their food near the coast rather than offshore.However, the gannets and the pelicans may be encounteredmore than 50 miles offshore.Frequently the three species are found fishing inthe same areas, competing with each other. On theother hand there also exists a kind of cooperation indetecting the fish schools. The flocks of cormorantare seen flying towards fishing areas first detected bygannets and pelicans, or vice versa.A study of the sizes of anchovies devoured by thebirds, based on examinations of the stomach contentsof the cormorant, showed that they capture all sizegroups between 2 and 14.5 cm SL or 3 and 16 cmTL (Figure 2). This size composition demonstratedREPORTS VOLUME XI, 1 JULY 1963 TO 30 JUNE 1966 107FIGURE 2..mm.<strong>11</strong>1 423 5.35 6.47 Z59 871 983 1095 12.071319 1431 <strong>11</strong>43 1655 LT. cm.Size distribution of anchovies in the stomach contents ofthe guanay. Material collected during 1954-1957.that the birds can prey upon somewhat smaller fishthan those generally caught in the purse seines of thefishermen. This shows that the birds are not selectiveas to size of the anchovy and are able to capture smallsizes, down to 2 cm in length, if theS are within theirreach.YearEstimated numberof birds(census data)1961 .....~.~~........~-- 12 x 1061962 _........~.-......-- 18 x 10'1963 ...~~-~.........---- 16 x 10'Anchovy consumedper dayin tons5,0008,0007,000FOOD CONSUMPTION AND GUANOPRODUCTIONIt is estimated that a cormorant, weighing 2 kilograms,consumes an average of 430 grams of food perday (Jordhn 1959) and the minimal daily requirementseems to be 200 grams (Barreda 1959).Different methods have been used to calculate therate of transformation of food to guano. Gamarra(1941) concluded, from experiments on birds in captivity,that 1 ton of guano was produced from 31tons of fish. However, more extensive observationsAn estimate, based on these values, leads us to theconclusion that annually the guano birds consumedbetween 1.8 and 2.8 million tons of anchovy duringthe period 1961-1963.The geographical and quantitative distribution ofthe birds in the summer of 1962 is shown in Figure1. This distribution has remained unchanged duringthe last years.If we group the bird numbers according to theareas of two latitudinal degrees (data from the 1962and 1963 censuses), it will be seen that the distri-
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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
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REPORTS TOT2T71\IF: SI, 1 JUJIT 196
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IiEPOHTS TOLUME XI, 1 JULY 1963 TO
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REVIEW OF THE PELAGIC WET FISHERIES
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KEI'OiiTH TOLUJIE SI, 1 JULY 1963 T
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PART IISYMPOSIUM ON ANCHOVIES, GENU
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OCEANIC ENVIRONMENTS OF THE GENUS E
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KEI'OKTS VOLIXI.: SI, 1 JULY 1963 T
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~~~REPORTS VOLUME XI, 1 JULY 1963 T
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REPORTS VOLUME SI, 1 JULY 1963 TO 3
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130'E 132' 134' 136' 138' 140' 142-
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REPORTS VOLUSIE SI, 1 JULY 1963 TO
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Page 57 and 58: KI3I’ORTH VOLUJIE XI, 1 JULY 1963
Page 59 and 60: REPORTS VOLUME XI, 1 JULY 1963 TO 3
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 and 70: INFLUENCE OF SOME ENVIRONMENTAL FAC
Page 71 and 72: REPORTS Y‘OLUJIE XI, 1 JULY 1963
Page 75 and 76: ~table shows the values calculated
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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: THE PREDATION OF GUANO BIRDS ON THE
Page 115 and 116: FISH E RYThe California anchovy fis
Page 117 and 118: ~~ ::REPORTS VOLUME XI, 1 JULY 1963
Page 119: CO-OCCURRENCES OF SARDINE AND ANCHO
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Page 124 and 125: CALIFORNIA COOPERATIVE OCEANlC FISH
Page 128 and 129: 126CALIFORNIB COOPERATIVE OCEANIC F
Page 132 and 133: ~~ ~130 CALIFORNIA COOPERATIVE OCEA
Page 134 and 135: 132 CALIF0RhTTIA COOPERATIVE OCEANI
Page 138 and 139: THE ACCUMULATION OF FISH DEBRIS IN
Page 143 and 144: PART IllSCIENTIFIC CONTRIBUTIONS
Page 151 and 152: REPORTS VOLU&IE XI, 1 JULY 1963 TO
Page 157 and 158: SUMMARY OF THERMAL CONDITIONS AND P
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SEASONAL VARIATION OF TEMPERATURE A
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REPORTS VOLUME SI, 1 JULY 1963 TO 3
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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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174 CALIFORNIA COOPERATIVE OCEANIC
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184CALIFORNIA COOPERATIVE OCEANIC F
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CONTENTSI. Review of Activities Pag
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