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

More documents

Recommendations

Info

104 CALIFORNIA COOPERATIVE OCEANIC FISHERIES INVESTIGATIONSv)nzav)2 25It-Z -20a-UI-f: /5aIcnc- /olL0U 5Wm23z0LARVAE AREAS B-E-a 250-I-v)W> -4 200-v)0aUW-a 150-Wa>Ua--I -00-LL00z- 50-E M M J S N E M M J S N E M M J S N E M M J S N E M M J1961 1962 1963 1964 -1965FIGURE 9.iz125 0I-aI-cn100 Eawa75 2a-IlL050Kwmr325 2with larval drift into the area from a spawningcenter lying to the south, the coastal current displacingthe larval stock northwards from the spawningcenter. This could be verified as regards area Dduring 1962-63, but observational data are not sufYicientfrom area F to establish this conclusion.A COMPARISON BETWEEN LARVALABUNDANCE AND RECRUITMENTWe can presume that a closer relationship existsbetween larval abundance and recruitment strengththan between spawning intensity and recruitmentstrength. However, our conclusions are limited bythe fact that we have only been able to examine theabundance of the earliest stages in the growth ofIn Figure 9 the number of larvae and recruit abundanceare compared for the region as a whole. Thehighest numbers of larvae were found during the1961-62 spawning cycle, but the resulting recruitgroup was not outstanding. The big recruit groupappearing in 1964 seems not to have been derivedfrom a rich larval stock in the region as a whole.The evidence suggests that during the three spawningcycles larval abundance was highest during 1961-62, there was a big decline during 1962-63 and then asubstantial increase during 1963-64, but not up to the1961-62 level. Roughly this sequence reflects whathas happened in recruitment, but the series of observationis too short to afford firm conclusions.REFERENCESAhlstrom, Elbert H. 1959. Distribution and abundance of eggsof the Pacific sardine, 1952-56. U.S. Fish & Wild. Serv.,Fish. Bull. 60(165) :185-213.Einarsson, H., and B. Rojas de Mendiola. 1963. Descripcion dehuevos y larvas de anchoveta peruana (Engraulis ringens J.)Inst. Invest. Recurs. Mar., Bol. l(1) :1-23.Einarsson, H., B. Rojas de Mendiola and H. Santander. In press.El desove en aguas peruanas durante 1961-1964. Primer SeminarioLatinoamericano sohe el Oce'ano Pacific0 Oriental,Actus.
THE PREDATION OF GUANO BIRDS ON THE PERUVIAN ANCHOVY(ENGRAULIS RllNGZNS JENYNS)ROMULO JORDANlnstituto del Mar del Per6lima, Per6INTRODUCTIONThe Perurian anchovy is regularly preyed uponby a variety of animals belonging to different ordersof the animal kingdom. Among those that thrive onits abundance are invertebrates, such as medusaeand squids, and a multitude of carnivorous fishes,birds and mammals. Two great industries owe theirexistence to the stock of anchovy: the guano industry,based on the collection of the bird droppings,which have served as a fertilizer of the soilfrom ancient times and the fishmeal industry, man’sexploitation of the anchovy resource, a recent innovation.Although the majority of the birds that inhabitthe Peruvian islands and coasts prey upon the anchovyto some extent, the list of the principal predatorsis not extensive. The main species are thefollowing :Family : SpheniscidaeXpheniscus hziinboldti Meyer-“Peruvianpenguin ”Family : ProcellariidaePufinus griseus ( Gmelin) -‘ ‘ Sooty shear-water”Family : PelecanidaePelecanus occidentalis thagus Molina-“Peruvian pelican’ ’Family : SulidaeXicla variegata (Tschudi)-“ Gannet”Xula nebouxi Milne-Edwards “Bluefootedbooby”Family : PhalacrocoracidaePhalacrocorax bougainvillii Lesson-“ Cormorant”Phalacrocorax gainaardi (Lesson)--“Red-footed shag”Phalacrocorax brasilianus (Humboldt)-“Bigua cormorant”Family : LaridaeLarus pipixcan Wagler (migratoria)-‘ ‘ Franklin’s gull ’ ’Family : SternidaeLarosterna inca (Lesson)-‘ ‘ Inca tern”Three of these species, the “guan;ty” (cormorant),the ipiquero 7 (gannet), and the 6 alcatraz 7 7 (pelican),are the main consumers, because of their greatnumbers. These are the species that transform theanchovy into the valuable fertilizer, which is de-posited in more than 40 islands and headlands alongthe Peruvian coast.Because of their overwhelming importance, thepresent discussion on the predation of birds on thestock of anchovy is limited to these three species.SPECIES COMPOSITION AND GEOGRAPHICALDISTRIBUTION OF THE MAIN POPULATIONCENTERSIn the order of importance the main guano producersare cormorants, gannets, and pelicans. Theepicenter of their distribution lies between lat. 6’S. and lat. 12” S. The birds occupy this zone duringspring and summer, when they form their densestconcentrations ; subsequently, during autumn andwinter, the birds are more dispersed and their areaof distribution is greatly enlarged, extending fromlat. 1” N. to lat. 38” S. The quantities and locationsof the main bird colonies along the Peruviancoast are shown in Figure 1.The number of adult birds, based on graphical censusesmade in December, 1962 and February, 1963,was estimated as being about 18 millions (JordAnand Fuentes, 1964), with the following frequenciesof species:Millions PercentCormorant ................................ 14.89 82.4Gannet __________________________________ 2.76 15.3Pelican _____ _ ____________________________ 0.42 2.3During the last 20 years this relative frequency doesnot seem to have changed substantially.FOOD AND FEEDINGThe anchovy constitutes 96% of the food of thecormorant (JordSn 1959) and at least 8Q% of the foodof the gannet and the pelican. During periods of lowavailability of the anchovy, due to changes in theoceanic climate of the Peru current or other causes,the birds suffer from malnutrition which eventuallyleads to cachexia and death. This is the reason why thebirds are completely dependent on the availabilityof the anchovy.The feeding habits of the three species differ, bothas regards fishing methods and time of food collecting.The cormorant dives and swims underwater in thepursuit of its prey to depths that exceed 12 m. Thesearch begins at 6 AM during the reproductive pe-105 1
Page 1 and 2:
STATE OF CALIFORNIAMARINE RESEARCH
Page 3 and 4:
STATE OF CALIFORNIADEPARTMENT OF FI
Page 5 and 6:
RONALD REAGAXGovcriwr of the Slate
Page 7 and 8:
PART 1REVIEW OF ACTIVITIESJuly 1,19
Page 9 and 10:
REPORTS YOLUAIE SI, 1 JULY 1963 TO
Page 11 and 12:
REPORTS VOLUNE XI, 1 JULY 1963 TO 3
Page 13 and 14:
REPORTS YOLUME SI, 1 JULY 1963 TO 3
Page 15 and 16:
REPORTS VOLUME XI, 1 JULY 1963 TO 3
Page 17 and 18:
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:
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 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
~~~REPORTS VOLUME XI, 1 JULY 1963 T
Page 43 and 44:
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 51 and 52:
Page 53 and 54:
Page 55 and 56: REPORTS VOLUME XI, 1 JULY 1963 TO 3
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 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
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 105: REPORTS VOLUME XI, 1 JULY 1963 TO 3
Page 109 and 110: iod and after 8 AM during the rest
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
Page 122 and 123: 120 CALIFORNIA COOPERATIVE OCEANIC
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
Page 159 and 160:
SEASONAL VARIATION OF TEMPERATURE A
Page 161 and 162:
REPORTS VOLUME SI, 1 JULY 1963 TO 3
Page 163 and 164:
including the semiannual harmonic?
Page 165 and 166:
Page 167 and 168:
REPORTS VOiLUME XI, 1 JULY 1983 TO
Page 169:
Page 172 and 173:
170 CALIFORNIA COOPERATIVE OCWIC FI
Page 174 and 175:
172 CALIFORNIA COOPERATIVE OCBANIC
Page 176 and 177:
174 CALIFORNIA COOPERATIVE OCEANIC
Page 178 and 179:
Page 180 and 181:
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
184CALIFORNIA COOPERATIVE OCEANIC F
Page 188 and 189:
Page 190:
CONTENTSI. Review of Activities Pag
show all

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

Create successful ePaper yourself

Delete template?

Save as template?