No. l9

(Srnres A, Gnxnnel, No. 16)

THE FOOD OF THE PILCHARD, SARDINOPS CAERULE,4 (GIRARD),OFF THE COAST OF BRITISH COLUMBIA

BY

,JOHN LAWSON HART

Pacif.c B'iological Station andFisheries Departrnent of the Province of British Columbia

and

GEORGE I{ERBERT WAILES

(Recei.ved for publication May 26, 1931)

Con

trib

. Can

. Bio

l. Fi

sh. D

ownl

oade

d fr

om w

ww

.nrc

rese

arch

pres

s.co

m b

y C

ON

CO

RD

IA U

NIV

on

11/1

4/14

For

pers

onal

use

onl

y.

ABSTRACT

The contents of the digestive tracts of representative specimens from thecommercial catch for four seasons show fifty-three Diatomaceae ("green feed"),fifty-five Dinoflagellata, and twenty--six Crustacea ("red feed"), but chieflyDiatomaceae and Copepoda.

Con

trib

. Can

. Bio

l. Fi

sh. D

ownl

oade

d fr

om w

ww

.nrc

rese

arch

pres

s.co

m b

y C

ON

CO

RD

IA U

NIV

on

11/1

4/14

For

pers

onal

use

onl

y.

The Food of the Pilchard, Sarilinops caerulea (Girard), off the Coastof British Columbia

Bv JoHN LnwsoN HenrPacif,c Biolog'ical Station and

Fisheries Department of the Proaince of British Columbia

and

GBoncB HBnsenr Werr,Bs

INTRODUCTION

In 1929, the Biological Board of Canadd and the Fisheries Department ofthe Province of British Columbia undertook as a combined effort the investiga-tion of factors influencing the abundance of pilchards. Understanding the causesof fluctuation in abundance of any species involves the consideration of a numberof factors such as fecundity, m,ortality at different stages, food, the influence offisheries, etc. The present paper records the results of a preliminary investigationof the food of pilchards off British Columbia-an investigation the necessity ofwhich is attested by the complete absence of literature on the subject.

MATERIALS AND METHODS

Some two hundred and fifty food samples were obtained from pilchards ofthe commercial catch in the four summers 1927 to 1930. The collections of 1927and 1928 were mtade at various places off the coast of Vancouver island by Dr.H. Chas. \[/illhmson. In these two years the digestive tracts were removedfrom the fistiand preserved in formalin. The collections of 1929 and 1930 weremade at Nootka, B.C. In these years the contents of the median caeca andcardiac stomachs were pressed into labelled vials and there preserved in weakforrnalin. The volume of the food collected in this way was between three andfifteen cubic centimetres from each fish. More than fifteen cubic centimetresof food was rarely found in any one caecum and samples containing leSs thanabout three cubic centimetres were avoided wherever possible.

Microscopic analyses were made of the caecal contents obtained by eitherof these means. The various organisms were identified and the proportion eachformed of the total caecal contents estimated by eye. This part of the work wasdone entirely by G. H. Wailes.

The results of a qualitative and quantitative analysis of the food of anyspecies of fish made by the present method may be criticised for selectivity ofseveral sorts. The possibility of errors due to selectivity should be consideredin examining the results as, indeed, it was in compiling the data.

In the first place, consideration should be given to the fact that the fish

247

Con

trib

. Can

. Bio

l. Fi

sh. D

ownl

oade

d fr

om w

ww

.nrc

rese

arch

pres

s.co

m b

y C

ON

CO

RD

IA U

NIV

on

11/1

4/14

For

pers

onal

use

onl

y.

4

w.hose digestive tracts are examined are selected by the fishery on the basis ofthe depth at which they are swimming. That is to say, fish swimming at a depthof more than two or three metres are not seen by the fishermen and, accordingly,are not captured. For that reason the food analyses are likely to show a greaterpreponderance of surface forms than the real importance of such forms in thefood would warrant. In consequence, there is the probability that more diatomsand fewer copepods are recorded than would be the case if the samples had beenobtained from a true cross-section of the pilchard population.

Difierential digestive rates result in another kind of distortion of the recordeddata. Food organisms having heavy calcareous, silicious, or chitinous parts arenot digested beyond recognition as rapidly as more delicate species. Thus, it isto be expected that diatoms and those crustaceans having heavier carapaces willbe recorded more frequently in proportion to the actual number of occurrencesthan more fragile species and groups.

The chance selection of times for taking the samples may lead to some slightdistortion of the results.

. RESULTS

The results of the analyses are summari zed in the accompanying table. Inthe first column of the table is a list of all the organisms found in any of the fourseasons. For each of the seasons is given the number of stomachs sampled, thenumber of stomachs in which each organism occurred and its average percentagein all the stomachs for that year. The absence of an organism in any season isindicated by a dash; percentages under 0.1 by x. Each of the importanr groupsof food organisms has the average percentage for the group calculated and shownfor each season. In marshalling related organisms no attempt is made to keepthe groups of equal taxonomic significance. Convenience is the chief con-sideration.

It is usual to find that pilchards captured in the same haul have caecalcontents of very similar cornposition. Accordingly, to avoid unduly weightingthe results in cases where a number of samples are available from fish of the sameschool, the average percentage of each food organism for all the fish of that dayis calculated and the new values are regarded as representing the caecal analysisof one fish in computing the food percentages for the year.

248

Con

trib

. Can

. Bio

l. Fi

sh. D

ownl

oade

d fr

om w

ww

.nrc

rese

arch

pres

s.co

m b

y C

ON

CO

RD

IA U

NIV

on

11/1

4/14

For

pers

onal

use

onl

y.

rrt0

6,

1928sEA.sotr

XI'UBER, OF SIOIIACES E[.AI[INEX)

Fooa olEBnlBDs

DIATOUACE.AE

latleptlils tBlAl'ltbrgaste'1on611e J.eltodp.EAstcromhalud hsptEotls

PILCEAND TOOD

L9tl

5t

20,?

3 . 3 - . - E - " - E tis H s H s H$E 8 E 8 1 6 H r, 5 u e 3 2 e ggE g E g E 5 E, r l r 4 72 - I x2 a . l z ? t1 r ' l t ? rZ x I x6 = I r l rl t L 9 . 4 2 9 L . ,2 x l l4 . 2 1 r 1 1 . ? I r

l o . 5 r . 2 r -2L r .O? . 8 ? . r 8 . ? 7 . 22 z ? . ? 9 . 2 ? r

1 1 4 r ? a1 . 1 5 . 2 6 ri . 6 2 a . 5 * .s , l 6 . 2 a l \ . t

iz l .o 1 .7 4, . , " ,

?.51 8 2 ai . r 2 . L 2 xL 2 . 7 7 r . 4 6 . ? L r . 4f . i i r 1 1 . 4 6 . r

15 1.0 5 L.L Lat 5.4 ?7 .+2 x 2 . 6 . L r , r 2 t

26 1.0 5 L.t t l . , 27 -1

18 1.0 Lrl 8.0 , , .81 : r 5 ' ' l t

l l . l 1 x 4 . l Z r . ?8 . r , 4 .o ,o l .o+ x, Z+ r . l t 2 r I l7 t I T l r

Li .8 r ,.2 79 .6 52 'I.E2 : r 2 . ,, . e r . 9 2 9 , 4 r 8 . 2- - 1 . 1 2 z 2 a4 ' t ? . 1 r ' L l / t ' ri . 1 4 . 6 8 9 2 . 1 2 7 . 4

r . l ? t27 ?.o I L.6 1r8 '1.0 ?o . 'Li - 6 L.9 Lll 1r.o 2'l- 1.0

i . ; i . i ; ; '9 '12 - l . I4 . r r 2 . r 1 0 ' 1t . > 4 L . 1 ' . ) 2 z4 L . 2 1 t 4 . 1

,o I: i , .4 97 ,.o 2! 1.52e r.i 7 2.9 14 .L r? 2.0la -., ! n.Z 9 .l ,ri ,:2

d,a].icetlsElnaserlata

nsotell stnro tg.LfACtslllgBlaoulphla arotloaRtd.dulphla llg;!.!B I oilulphla 19!a:!gn1E!!es.Ecierusc b-grs9!f

apEloxllatuseggp&.El€llEo-eElixlcorr,l€Arbr 11saledlplcnsC$,v!slcl.gslslosr!

lgnbsurall8pp.

anrstlegslleue var. laqltloagcEeb;Ec

ei!.LteElsEe!tsel

.].oEterLu-E Ye!. Ie-o-!g

29$, ? . 9 68.,

nbl.zoaol.sala alataRhlsoaol'enle babeteteRhlzo golcal e egglglf pB

BhfzeElleafr sioftgrfqt&lBhlzoaolcnlB atv].lforel8Sk€].etonsna A!.Silhl4Stophanoplrla palnorlanaTha].aasloEr-!a a.stLYaJ-ieThal,asEl o61ria c!44gEataridtecel€lrc (!ce1Plgn6tXe,LcEelgglre uolacasklos]-d'{Thele6sloslra psclfloa

Ehite€-s:tcE;lre relailgEb&Lceeilceua 8p!.Thalasslothrh pitzaohlolal6sIhala€6iothliir lon4€eji4CLcptooyl,tr0llcus qgsilccs

Porq€ltagr of Dletonaceae

249

Con

trib

. Can

. Bio

l. Fi

sh. D

ownl

oade

d fr

om w

ww

.nrc

rese

arch

pres

s.co

m b

y C

ON

CO

RD

IA U

NIV

on

11/1

4/14

For

pers

onal

use

onl

y.

L928

I2 a5 z

1: : - t ; i I

L929 19ro

:

SEASON

other ArcAE

I lalosDhaera vlrldlErTlrnr-6;;Tous afEae-

F0nflrrnIFElla

a$tlUEc 'nlverEa

AIDIOI.ABII.

Df o IEEDEISIC hlstltoo 9u'6I.jli&o@Il:ltgg sctose

DITOEL.0CET,IIAIA

?lorooeatlq! rraollaGvEno0latup Ep.{O!_!.LlUgS qclntluuaphelaonona re.brllllalsDlpophyBla aouxheteDtEopblrEls aouteDl!.opLvsls €IfnCgllggDllophygl8 ECalCleDlaophnslr lg4lfgg]&teD_L49!!I9!C prverlcuD:ltrolbfglg eph.arrloeSrl.esegfglus &sf.qo

notloaDlmra

- : ? zZ z

6 2 5 r .L r z 5 aI II a S rt z2 a , 4 t2 a L z a

, t 6 rI t r 4 r

1 a, t l r7 s . + a, z z a '

6 I a -9 - r a

1 8 t 1 al x z tS r L z r

5 ? r 6 r, ,

6 1 8 ! t :6 r r 1 2 lL 7 r . 7 a

4 r , ] . a1 8 T I

5 1 2 ) B a$ r l 5 r1 4 t 2 r7 x .5 t 5 a5 a 2 t

L ? x 4 I5 x 4 a

1 9 t L 5 lL , x , , I I

? 88 z : . 9 :

I II0 'l

S r r t4 t L r r

I 2 8 t V ? tt o r I E rz 4 z ) rl x , 2 4 r1 r . 2 4 7, ' x . 5 t2 i r l

2 Z

2.2 L.7

: : :I -x l rr l rr I x

: : :! -

I -

t -I -

29

1L22',16

LZ

24Ia

5

1.

;6

b

6l1

a

6L'

2,I

,oL2

?o

21

252

1 I

1 -

: :1 r

2:2 7, 7L -

I t

; ;Z r .

: .

?:t a

: :? z

i ;1 r

i ;

: :1 .0

I

I

I

I

I

I

aaZII

xxI

:I

I

xz

:

ergeEtrlotr!oonlooLalass.es&sBl€elJlEDeDtsrotrunEubillorlaetrochofoen8ggploe€ceobloEEu.Ea].aualloespu-aotulatunsubpurotulatusraaiareur_noresgtpeaqlTg!994eQ-u]Es

2 ? :

2 z4 r4 rl :

r 7 x8 r4 x

I x

: :2 . 7

Lerldlnlun ceFasugPebidlntuo n1clapluEBglgljl4jlgg . rlono o aathuPerlaUniun a:E!-g!u.@?eriallnluo palllduo?erto,tntuE Delluo ialuDFI-;EEEE [oro-Io=Tonooavtoxns qlplg@ var. !:+g.!gglgleQtrgLilu4 fussggIgEUS turoeCaxBilJrq ure8.hlgSgrgLlun EL!99 va!. allslrl,laeCo:ratlun EggfcCelqeCcratlun EzorlounC6ratluE Denteeonuq_glatiup dlvuloatun

PeloaD.tag€ of Dlnoflsgellata

250

Con

trib

. Can

. Bio

l. Fi

sh. D

ownl

oade

d fr

om w

ww

.nrc

rese

arch

pres

s.co

m b

y C

ON

CO

RD

IA U

NIV

on

11/1

4/14

For

pers

onal

use

onl

y.

Lgzg L?29 19r0sEAtt0lf

Sr!ICO AII.CET,LAIT

Dlctvooba fllgbDlatophanrg apooulu|!Dlstepbapus speoulu va!. SS-ISSCXISSIDl,stgphanrs sB.Ebtla tX!!&rEl!q

TINIINUOINEA

'rlrn!:!s!s!cfc ElEc.lSt€aogomcl].e !lva].lsSt.no same].].a TgStflC-CSeU.c].loostoE€Ila aubulataFave]-].a flanoLsoanaPalafsvolle rleeltoa?arafavella perumalontatePtYohoovus urnulq

Pcroeutago of llntlnnolnea

POIjTCHAEIPA

NOIIFERA

- 5 . x ? xx ? O r 6 r- 4 7 2 a- 2 r -- ] . t Z r

? xl r Z zI r 2 - i6 r 7 r l

t , 2 . , L 9 r2 t . r ? t

1 r

L r I2 - tZ z .5 x .1: '2

"-2 x 1

; ; : : i i L ; ;l r 1 r/ t r I r I r4 r

- 1 ? r 5 0 r- ] . 1 r 1 5 r- L 2 r 1 5 r- 1 z r r

- 4 . 0 . ,

, . 0

I

I

x

.4

, r .I 0 t 1

4 a

t z4 r7 - l

- 2 r B a- r r . L , rz 1 1 9 a

8 r4 I

, Z2 x ,

4 . 5

gyttoharta baltloell lCboogia nart na

OVA HISTIDA

!.roohlaola Dlaohlolatuear,oohlsola elgIgll.Iggbfeo$ nocbluEl?!ooh18ola EuItlBplnBIloebllsilg spp.

OVA (unlitcatlf le0)

500-500 r dlaneter.100-J00 r illataeterUaCc! l00A allsnster

CI,IDOCERA

3c.eos sp.Poalon polvph6oold.agSraalae ioranannlEYaaIae E@!!g_a

Peroentagb of Cladooera

251

Con

trib

. Can

. Bio

l. Fi

sh. D

ownl

oade

d fr

om w

ww

.nrc

rese

arch

pres

s.co

m b

y C

ON

CO

RD

IA U

NIV

on

11/1

4/14

For

pers

onal

use

onl

y.

8

L221

19 '.4

5 . 1

L?28

I -

x , 2 r- l x

/ 2 1

I -

I 4 Iz 9 !x B r

,L.' L'.,

L9??

t2 0.8

4 . 8

I

1 . 0

x

I

2.8

ttr0sEts0x

COPEPODA

JuveDl].Bs Bpp.UEloetrttf table renalas

Pcioenta4e of Copepoila

CIRXIPEDIA

naDplll BItp.brlg sp.

PeloeDtase of Clrrlpeola

TESIDACEA ANE EUPEAUSIDACEA

EuDhausla DaolfloaIltysanoossa 9p1nlf 6ra'l4yslE g! var.uEl0cntif lablo remalng

?ercentage of Llyslataoea & DrphauElalaoea

DEC.APODA

Crab zoeaCrab BegalopaShrhp laryao

Porcsntege of Docapoda

PEI,ECY?ODA

Iervae

SPPENDICUIJ4RII DA8

olkoBleura gpp.

PISCES

Apoo(LYtes polsonatu6 ?

Digesteal nateria].

l f al O t 6 r1 , z r 4 a

I t Z a1 a

L 4 r , 1 0 xl l

r t x r . a? t I r] . x1 = I r

9 0 - Z L l, 8 r l 4 r

r " T r r r t14.6 '6. '

,I

!IO

a,?2?14

I 8I a

I

2 td al t9 -

?o.2

6 z

? r .I I

4 . '

: ,.2, . o

4

i?,

x

:? . o

I

I

?1 .',I 45.1

x

I

L .5

x

I

I

5 . O

252

Con

trib

. Can

. Bio

l. Fi

sh. D

ownl

oade

d fr

om w

ww

.nrc

rese

arch

pres

s.co

m b

y C

ON

CO

RD

IA U

NIV

on

11/1

4/14

For

pers

onal

use

onl

y.

DISCUSSION

Among the Diatomaceae the differentiation of species in some groups dependson the characters and disposition of the chromatophores; in a semi-digestedstate these distinctions are apt to be lost; hence, for example, some species of thegenus Chaetoceros may pass unrecognized or be recorded less frequently than theyshould in the list of food organisms. In other cases the breaking up of chains ofindividuals into single units increases the difficulties of identification; in thegenus Thalass'ios,ira single cells may require special preparation and high powersof the microscope for their recognition. These Have tleen grouped together inthe list as Thalass,ios,ira spp. This difficulty also has been experienced in thegenus Chaetoceros.

Since the character of the appendages is largely relied upon as a means ofidentification in the Crustacea it is always difficult and often impossible to deter-mine the relative numbers of such species as may be recognisable in the com-minuted state in which they usually occur in a pilchard caecum; smaller andmore fragile species are especially liable to escape observation.

Mysis rayi var. represents a form of this genus as yet undescribed.The proportion of unidentified material is high in the two years Lg27 and

7928. This may be due to the method used in preserving the material in thesetwo years, and would indicate the use of the other method in subsequent foodstudies.

There are two dominant types of food. These are Diatomaceae and Crus-tacea, respectively referred to, as "green feed" and "red feed" by the fishermen.

The number of years for which there are data and the degree of representa-tiveness of the sampling make definite conclusions inadvisable. It is suggestive,however, that the year 1929 is notable both for the low oil production per ton ofpilchards and, according to the present study, for the relatively high proportionsof Diatomaceae in the food. There is the possibility at least that the nature ofthe food taken by pilchards may be of economic importance and that the "redfeed" which makes the process of reduction to oil and meal difficult, in the endleads to a higher production of oil.

253

Con

trib

. Can

. Bio

l. Fi

sh. D

ownl

oade

d fr

om w

ww

.nrc

rese

arch

pres

s.co

m b

y C

ON

CO

RD

IA U

NIV

on

11/1

4/14

For

pers

onal

use

onl

y.

t0

AUTHORITIES FOLLOWED

Caurentl, MrronBo H. Some free-swimming copepods of the Vancouver islandregion. Trans. Roy. Soc. Can., ser.3, 23 (5) 303-33f . 1929.

GnnN, H. H. eNo E. C. ANcst. Plankton diatoms of Puget sound. Pub. Pugetsd.. Mar. Biol. sto.7,4l7-519. 1931.

Kororl, Cnenr-Bs A. enl Anrnun S. CeMpenrr,. A conspectus of the marine andfresh water Ciliata belonging to the suborder Tintinnoinea, with descrip-tions of new species principally from the Agassiz expedition to the easterntropical Pacific, 1904-1905. Univ. Calif. Pub. Zool.34, l-403. 1929-

LBwrs, R. C. The food habits of the California sardine in relation to the sea-sonal distribution of microplankton. Bull. Scripps Inst. Ocean. Tech. Ser.2, 155-180. 1929.

Warlns, G. H. Dinoflagellates from British Columbia with descriptions of newspecies, Part I. Vanc. Mus. Art Notes 3 (1) 20-31. 1928.

Dinoflagellates from British Columbia with descriptions of newspecies, Part II. Vanc. Mus. Art Notes 3 (2) 27-35. 1928"

254

Con

trib

. Can

. Bio

l. Fi

sh. D

ownl

oade

d fr

om w

ww

.nrc

rese

arch

pres

s.co

m b

y C

ON

CO

RD

IA U

NIV

on

11/1

4/14

For

pers

onal

use

onl

y.