Depth Distribution of Oceanic Shrimps
(Decapoda; Natantia) off Oregon'
B WILLIAM G. PEARCY
Department of Oceanography
Oregon Stale University, Gorvallis, Oregon
AND CARL A. FORSS
Biology Department
Walla Walla. College, College Place, Washington
ABSTRACT
Sixteen species of oceanic shrimps, seven Penaeidea and nine Caridea, appeared in 244
collections made within the upper 1500 m at one station in the northeast PaciFic off Oregon.
Most of the species were primarily mesopelagic in distributiott
The most abundant species, Sergestes similis, was the only shrimp common in epipelagie
waters at night and the only species clearly demonstrating did vertical migrations. Night catches
exceeded day catches in near-surface waters, while day catches exceeded night catches at middepths. Sergcsles similis migrated into the upper 50 m at night and on one occasion was collected
at the surface.
INTRODUCTION
NEKT0YIc SHRIMPS often comprise a signi6cant portion of the biornass of
rnidwater collections from the open ocean and the deep sea. Sergestids, for
example, may be s abundant that they are suspected to cause sonic scattering
layers in the ocean (Barharn, MS, 1957, 1963). There is a commercial 6shery
for Sergestes in Japan (Yaldwyn, 1937).
Important studies of verlical distribution of oceanic and deep-sea shimps
include Waterman et al. (1939), Welsh et al. (1937), Sund (1920), Stephensen
(1923), and Murray and Hjort (1912). None of these studies was made in
the Pacihc Ocean.
The cruises of the Albatross have provided material for several reports
on penaeid and carid shrimps from the northeastern PaciFic (Faxon, 393;
Rathbun, 1910; Schmitt, 1921). Since most of these collections were made
with bottom trawls on the continental shelf, little about the vertical distiib
ution of oceanic species can be concluded.
In this paper we present data on the vertical distribution of oceanic
shrimps found oil the coast of Oregon. Specimens were collected from the
'Received for publication February 4, 1966.
J. Fsrr. P.s. Bi. CaN.oA,
Printed in Canada.
1133
23(8), 1966.
VVALLA WALLA COLLEGE
CONTRIBUTiONS IN BIOLoGY
NTJMBER
JURNAL FISHERIES RESE.RCH ilfl,RI) OF (',NAl).. Vol.. i.;, N''.
1136
S.
l"(,(
upper 1500 in of water mainly at one station over a period of 3 years. F'orss
(MS, 1965, and unpublished data) discusses the systematic relationships of
these species. The distribution of other small nektonic animals (fishes and
squids) has been reported by Pearcy (1964, 1965) and Pearcy and Laurs
(1966).
METHODS
Shrimps were collected mainly from a single station located about 50
miles off the central Oregon coast (44°39'N, 125°15'W) from the R/V Acona.
This location is just beyond the continental slope where the water depth is
about 2000 in. Collections were made in daylight and darkness during all
seasons of the year from june 1961 through September 1964.
Eighty-two collections were made with a 6-ft Isaacs-Ki(ld midwater trawl.
These collections were taken to depths of approximately 200, 500, and 1000 iii
using the methods described by Pearcy (1964). The front half of this net
consisted of a 76-mm stretch mesh, the alter half was lined with 13-mm stretch
mesh, and the codend was a -m plankton net (0.571-mm mesh aperture).
Forty-live tows were made with an Isaacs-Kidd iniciwater trawl modified
to capture animals within three depth strata during one oblique tow. The
conventional 6-ft trawl was adapted with a multiple plankton sampler (Be,
1962) as an opening and closing codend unit (Pearcy and Hubbard, 1964).
This unit was calibrated to sample from 0 to 150, 150 to 500, and 500 to 1000 ni
(Pearcy and Laurs, 1966). A depth-distance recorder provided estimates of
the volume of water filtered within each depth stratum. This net was lined
throughout with a 10-mm stretch mesh.
Plankton nets, 1 in in diameter (mesh aperture 0.571 mm), were used
to collect 99 samples. Pressure-actuated wire cutters (Yentsch et al., 1962),
calibrated by lowering vertically at sea, were used to open and close the nets.
Nets were fished in tandem providing samples from depths of 0 to 150, 150
to 500, 500 to 1000, and 1000 to 1500 in.
In addition to these collections we made 18 horizontal midwater trawl
tows at night at various depths within the upper 200 in. Five of these tows
were made at another station 25 miles west of the mouth of the Columbia
River.
All samples were preserved at sea with 10% buffered formalin. Shrimps
were counted and identified in the laboratory ashore.
RESULTS AND DiSCUSSION
VERTICAL DIsTRIBuTIoN
No species of shrimp was captured exclusively within the upper 200 in
with any type of net (Table I). Eight species were captured within the upper
200 in as well as within deeper layers: Scr'es1es sirniUs, Pasiphaca pacijica,
P. chacei, Pelalidiurn suspiriosum, Hyrnenodora frontaUs, H. gracilis, Systellaspis braueri, and Bentheogennema sp. Of these, only Sergestes similis, by far
l'),\I&UV AND I)iSS; U;i-\NIC 5IIIi!\lP5
the must. alniinlant. Species, was capt.iiied iii large niiiulcrs within the epipelagic or surface waters; this was on1y during the night. I'asiphaea Pa;iJ(ra
and P. cltacci were rarc in the collections at this station, althoiighi they have
been captured frequently in 0-200-rn tows elsewhere oil Oregon (Forss and
Pearcy, unpublished data).
Sonic of the above species, although present, were uncommon in collec-
tions from epi pelagic waters. Judged from the distribution of catchcs, especially
in the nonclosing net, Petalidium suspiriosum, Ilymciiodora fronlaiis, H. gracilis,
Sysicliaspis braucri, and Bentiteogennema sp. were most abundant belOW 200
in (Table IA). A few of the individuals found in the Ui per net of t he open iii gclosing codend of the inidwater trawl (Table I B) may he contamination Irom
previous tows in deeper water.
Eight species were never captured in tows conlnecl to e)ipelagic waters.
Bent hcogcnnc,na borealis, Notostonius japonicus, Gen nodes pro pin qu us, and
Acanihephyra curtirostris were found only in tows that fished below 150-20() in.
Parpasiphaë .culcatifrons, P. cristala, Sergia Icunirentis, and çcnnadas incerizis,
*
-
though few in numbers, were captured only in nonclosing tows to depths of
1000 in or opening-closing tows at 500-1000 in.
Thus, from our collections we can construct a generalized table of vertical
distribution as follows:
EPIPELAGIC (0-200 in) only
None
EPIPELAGIC (0-200 in) and MESOPELAGIC (200-1000 m)
Scrges!es similis
Pasiphaca pacific
Pas-iphaca chacci
MESOPELAGIC (200-boo m)
200-1000 in mainly
J'etaiidiunisu.s/iriosum
Ilymcnodora frontalis
.Tiymcnodora graciiis
Systeilaspis braueri
13e,nthcogcnnema sp.
200-1000 in only
Notostoznus japonicus
I3cntheogcnnenia borealis
Gen.nadas Propinquus
A canthephyra curtirostris
500-1000 in only
Parapasiphae sulcatifrons
Parapasiphaë cristata
Sergia tenuiremis
Gennadas incerius
1138
J
ilsil Ei(I ES RESEARCh iAt(i) (IF CANADA, VOL. 23, NO. 8,
1915,
This arrangement is tentative, especially for the lower niesopelagic shrimps
that were rarely captured. Moreover, the distribution of mesopelagic species
may obviously extcn(1 into bathypelagic depths below 1000 m.
Some morphological and distributional evidence can also be cited to
support the conclusion that the penacid Sergestes similis and the caricls Pasipliaca pacifica and P. chacci are shallow in distribution compared to the other
species. They are nearly transparent when alive. Only the "organ of Pesta"
in the cephalothorax of S. similis is densely pigmented. The deeper shrimps,
on the other hand, are all more extensively pigmented. Our Hynenodora spp.
are orange, and the other niesopelagic species are a deep red or scarlet, typical
colorations for mesopelagic and bathypelagic shrimps (Faxon, 1895; Murray
and lljort, 1912; and Marshall, 1954).. Also, S. similis and P. pacifica are
common in midwatcr collections over the continental shelf or inner slope off
Oregon (Forss and Pearcy, unpublished data) indicating that these species
occur in fairly shallow waters. Moreover these two species have been collected
in tije northeastern Pacific where the depth of the bottom was less than 300 m,
while A. curtirosiris and II. fronlalis were captured only where the water depth
was 589 ni or more (Schmitt, 1921).
Two species of shrimps collected off Oregon were also included in Tchindonova's (1959) account of the depth distribution of macroplankton from the
northwestern Pacific. She reported Sergestes sirnilis within the upper 1000 rn
with a center of abundance between 100 and 500 m. ilymenodora frontalis
had a wide depth distribution between about 200 and 3000 ni with a center
of abundance between 500 and 1000 m. Thus our results agree with hers for
these species.
VERTICAL MIGRATIONS
Vertical migrations of Sergesles have been reported by Welsh et al. (1937),
Sund (1920), Yaldwyn (1957), and Waterman Ct al. (1939). Differences between
our catches made at night and those made during the clay with the openingclosing nets demonstrate that S. similis also undertakes did vertical migrations.
In the upper 150 m more S. similis were always caught in the midwater trawl
at night than during the day (Fig. 1 and Table I). Between 150 and 500 m
catches were usually higher during the clay than the night. These opposite
trends at surface and mid-depths indicate did vertical movement. Although
S. similis frequently occurred in the 500-1000-rn stratum, their density in
deep water was lower than in overlying waters. An exception was the capture
of 174 animals in a 500-1000-in day tow (for XI in Fig. 1). Consistent day
night differences, however, were not apparent in deep water. Similarly, the
catches of S. similis in the meter net showed distinct diel variations above
500 m and were low below 500 in (Table IC).
Daynight differences are evident from the '0 to 200-rn nonclosing midwater trawl collections (Table IA); here the catch per hour during the night
was also many times higher than that made during the day. Trends are not
1139
PEARCY AND FORSS: OCEANIC SIIItIMPS
NIGHT
DtIY
U
.k.
I
I
tO
0
I
tO
40
AVERAGE NUMOER PER 1000m3
1. Vertical distribution of Seres(i',c j,,,iI,s during day and night periods
at three depths. Each horizotital bar rCI)rcSCIitS au average i1Ii)iiIhlV catili
nuade with the unidwater Irawl and opening and rinsing rodeuuil device at t lie
SI a I toil 5(1 ni lies west of N wja rt, ( )rcgon R nina ii ittu ocra Is dcci g ' ta I e !uOui I Ii S.
Nove iii icr I )(,2 In j ii y I
11G.
evident in the 0 500-tn tows, however, probably liccatI$c I lie trawl sampled
conti ii uousl y and iccaiise tile lv)jmfllati011 Si lii III V iuinvcd till and (town Wi tli ii
this zone.
Our study provides no similar evidence for vertical migrations of other
species, but conclusions cannot be iiiade because the catches were small.
UPPER DEPTh DISTIUBuTION OF SERGFSTFS SIMILIS
Three series of stratified, nonclosing niidwatcr collections made at various
depths in the upper 200 in provided information on the upper depth range of
S. similis at night (Table II). In August 1961, S. siutilis was collected in all
1140
JOURNAL FISHERIES RESEARCH BOARD OF CANADA, VOL. 23. NO. 8, 1966
TA8LE I.
Catches of oceanic shrimps in collections to various depths within the upper 1500 in at a station off Newport
Pasiphaes
Sergestes
strnii:s
Day
A. Nonclosing midwater
trawl
0-200 in (32 collections)
Total No.
No.perhour
26
Night
Day
3829
3.7
0-500ns (24 collectioss)
Total No.
1128
No.perhour
chacei
pacifica
Night
Day
4
273.5
Night
2
52.8
Petal idiu m
Day
.05
nema sp.
Day
Night
Syst cit ssis
braucri
Day
Night
1
.07
10
2
.1
Bemmtleogen-
frontalis
Night Day Night
.07
1
Ifynzesodora
suspirissmcmn
1
.29
1109
53.7
Pasiplisea
.
.1
53
55
1
2.6
.05
.48
3
2.5
18
.14
5
.86
.24
0-1000 in
(26 collections)
Total No.
No.perhour
573
9.4
384
4
1
14.8
.02
120
2
.07
91
2.0
.08
388
3.5
53
273
6.4
.87
10.5
9
24
21
.81
.39
.35
B. Opening.closing
midwater trawl
0-150 in (45 collections)
Total No.
232
No. /10S/m3
1.82
545
12
6.05
.01
.09
t
19
17
1
.01
.21
.13
.01
150-500 in
(45 collections)
Total No.
No. /103/mS
500-1000 m
(45 collections)
Total No.
614
187
2.35
302
No. /103/m3
2
.89
46
.80
.15
.004
.01
1
.002
3
2
1
.003
17
.07
.01
11
0-150 in (37 collections)
150-500 in
(32 collections)
Total No.
3
50
48
13
.3
2
2
500-1000 in
(22 collections)
TotalNo.
3
7
2
I
I
1000-1500 m
(8 cllctlons)
Total No.
.
1
3
11
.03
.29
C. Openingclosing
meter nets
Total No.
.01
.003
.OS
.39
2
1
85
147
2
.02
.005
18
1
.04
.0.1
1141
PEARCY AND FORSS: OCEANIC SHRIMPS
Osegnn. t9l-6-1. The species are listed in rdr of vertical distributin on the basis of data froru the nonclosing niidsvater trawl.
NotusDmus
jcponicuS
y
Gennrdcs
propingircs
Night Day
.3
.05
Day
.08
Besfhsgen. Py.rapuspha3 Parapasipha
crit itS
sulcc.t i/cons
nema borealis
Night
Day
15
5
Night Day Night
Day
Acarthtphyra
gurlirstrgs
Night Day
Night
Gesnsdes
Scrgia
incerlus
£enuirCmis
Day
Night
Day
Night
.05
92
2
.05
gr.ahs
1
1
.03
Night
Ilynuscs!ori
1.5
3
.08
.58
2
4
2
.08
.07
.08
2
1
1
.02
.04
2
.03
2
1
.02
.08
.02
.08
1
1
.02
.01
I
1
1
.003
.004
2
1
.005
2
1
.003
.002
.003
.01
2
1
1
.003
.002
1
.01
.002
.003
1142
JoURNAL FISHERIES RESEARCH BOARD OF CANADA, 'VOL. 23. NO. 8, 19(tó
TABLE II.
Catches of Scrgcslcs si,nilis in horizontal tows at various depths within the upper
200 ni during the night at two stations, assuming a 4:1 cable to depth ratio.
Maximum
depth (in)
No.
Total No.
Surface
per hour
95
2327
470
217
225
15
25
50
100
200
211 . 1
5411.6
626.6
380.7
357.1
158.6
146
Surface
0.0
0
10
25
50
100
150
200
Surface
10
20
50
200
140
136
381
129
106
52
421.0
0
0
0.0
0.0
0.0
3.10.0
952.5
258.0
Location, time,
and conditions
50 miles off Newport
0156-03301'sT
August 9, 1961
overcast - rain
50 miles off Newport
2214-0154 PST
February 26, 1962
no moon
185.9
91.2
0
270
642.8
204.8
127
25 miles off Columbia River
0007-0427 I'ST
September 19, 1962
moon visible
tows from the surface to 200 m. Highest catches were at 15 rn. In February
1962, no S. snrUs was taken at the surface, and peak concentrations were
taken at i0-5() in. In September 1962, S. sirnils was not captured within the
upper 20 iTt but only occurred in the 50- and 200-rn tows. The clear night and
moonlight probably affected the ascent of animals during this latter series of
tows. These limited data show that the upper depth distribution of S. sirnilis
is variable. They ascend into the upper 50 rn at night, well above the base
of the halocline (100-200 in), and sometimes into the summer thermocline
(10-50 m) as well.
ACKNOWLE DGM ENTS
This research was supported by Atomic Energy Commission Contracts
No. AT(45-1)1726 and AT(45-1)17.50. We wish to thank C. N. Mooers and
R. M. Laurs for translating the Russian paper.
BARITAM, E. G.
California.
1963.
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