kinds and abundance of fish larvae in the eastern tropical pacific, based on collections made on ...

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KINDS AND ABUNDANCE OF FISH LARVAE IN THE EASTERN
TROPICAL PACIFIC, BASED ON COLLECTIONS MADE ON EASTROPAC I
ELBERTH . AHLSTROM'
ABSTRACT
This paper deals with kinds and counts of fish larvae obtained in 482 oblique plankton hauls taken
over an extensive area of the eastern tropical Pacific on EASTROPAC I, a four-vessel cooperative
survey made during February-March 1967. On the basis of abundance of larvae, the dominant fish
group in oceanic waters are the myctophid lanternfishes (47 %), gonostornatid lightfishes (23 %),
hatchetfishes, Sternoptychidae (6 YO),b athylagid smelts (5 %). Scombrid larvae ranked fifth, and ex-
ceeded 2 % of the count.
Two kinds of larvae were outstandingly abundant : larvae of the lanternfish Diogenichthys laternatus
made up over 25 % of the total, while larvae of the gonostornatid genus Vinciguerriu made up almost
20 %. More fish larvae were obtained per haul, on the average, in the eastern tropical Pacific than
were obtained per haul in the intensively surveyed waters of the California Current region off Cal-
ifornia and Baja California.
EASTROPAC I was the first and most wide- bution and abundance of sardine spawning, and
ranging of a series of cooperative cruises made the factors underlying fluctuations in survival
in the eastern tropical Pacific between February of the early life-history stages of sardines. The
1967 and April 1968. A vast expanse of the plankton collections not only contained eggs and
eastern tropical Pacific was surveyed on EAS- larvae of sardine but those of most other pelagic
TROPAC I, extending from lat 20" N to 20" S, fishes in the California Current region. A de-
and from the American coasts offshore to long cision was made to attempt to identify and enu-
126" W (Fig. 1). Four research vessels par- merate all fish larvae in the collections in order
ticipated in EASTROPAC I: Alaminos oper- to obtain more precise information about the eco-
ated by Texas A & M, occupied the inner pat- logical associates of the sardine. At that time
tern, while Rockaway operated by the U.S. few fish larvae, other than those of the sardine
Coast Guard, David Starr Jordan operated by and anchovy, could be identified.
the Bureau of Commercial Fisheries (now the Within a few years most kinds of fish larvae
National Marine Fisheries Service), and Argo were identified to genus or species. Once the
operated by the Scripps Institution of Ocean- larvae were identified and enumerated, it be-
ography, occupied patterns successively seaward. came obvious that this was an exceptionally use-
The oceanographic, biological, and meteorolog- ful tool for evaluating fish resources. Most
ical data collected on EASTROPAC cruises will oceanic fishes have pelagic eggs and/or larvae
be graphically presented in a series of EAS- that are distributed in or just below the photic
TROPAC atlases, including generalized charts zone, i.e. within the upper 150 to 200 m of depth.
dealing with fish eggs and larvae. At no other time in their life histories are so
The present paper is the result of a chain of many kinds of fishes associated together-deep-
events that began 2 decades ago, at the initiation sea fishes (mesopelagic and bathypelagic) as
of CalCOFI (California Cooperative Oceanic well as epipelagic species-where they can be
Fisheries Investigations) in which a large-scale collected quantitatively with a single type of
sea program was set up to investigate the distri- gear, a plankton net.
Once the larvae of the pelagic fish fauna of
a region, such as those in the California Cur-
National Marine Fisheries Service Fishery-Ocean-
ography Center, La Jolla, Calif. 92037. rent region, are known, there is a large trans-
Manuscript received September 1970.
FISHERY BULLETIN: VOL. 69, NO. I, 1971. 3
FISHERY BULLETIN: VOL. 69, NO. I
t-_ _
t
t :
A044
E :A iA
A
A
c
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f
A
A : a
A* e a80 97
22225544 A 102 221 i
AA i
AA f
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AA221155
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AA LA a
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2200.... ll aa dd
113300.. 1122
FIGURE1. -Location of plankton stations occupied by four research vessels participating in EASTROPAC I.
Symbols for vessels indicated in legend above. Samples collected from Argo are numbered as 11.000 series
(as 11.022, 11.173), samples from David Starr Jordan as 12.000 series, Rockaujay samples as 13.000 series and
Alaminos samples as 14.000 series.
ference of the accumulated knowledge and skills
METHODS OF MAKING
for work in other areas, such as, in this in- ZOOPLANKTON COLLECTIONS
stance, the eastern tropical Pacific. My study
Three nets, differing in size and in coarseness
was undertaken to demonstrate the value of
of mesh, were employed to collect zooplankton
identifying all elements of the fish fauna of
and micronekton on EASTROPAC cruises. In
tropical regions, rather than restricting interest this paper I am concerned primarily with
to scombrid larvae. Much information can be oblique hauls made with the net of intermediate
gained for little extra expense (a few percent size and mesh-a net, 1-m mouth diameter, con-
of the cost of collecting the material at sea). structed of 505 p nylon (Nitex) cloth, with ap-
Of equal consequence, identification of all kinds proximately a 5 to 1 ratio of effective straining
of fish larvae can be made more critically in- surface (pore area) to mouth area. This net
cluding scombrid larvae. was paired in an assembly frame with a finer-
4
AIILSTROM: FISH LARVAE IN EASTERN TROPICAL PACIFIC
meshed net when hauled obliquely, but was used TABLE1 .-Depth of paired oblique plankton hauls taken
alone for taking surface hauls. The finer- by the four research vessels on EASTROPAC I. (Net
lowered by paying out 300 m of towing cable)
meshed net was 0.5 m in diameter at the mouth,
constructed of 333 p Nitex cloth, with approx- Average depth Number of hauls taken to eachI depth inteI rval from
imately an 8 to 1 ratio of effective straining ockawny Alominoi vessels
surface to mouth area. The third net, used for M
collecting micronekton, had a 5-ft square mouth 70.1- 80.0 I I
80.1- 90.0 1 I
opening and was constructed of mesh measuring 90.1 - 100.0 __ __
approximately 5.5 x 2.5 mm; this net could 100.1-110.0 1 __1
110.1- 120.0 _-
not be operated from the research vessel Rock- 120.1-130.0 3 5
away on EASTROPAC I but was employed from 130.1-140 0 __1 2
140.1-15 0.0 I
the other three vessels. 150.1-16 0.0 2 3
Usually four zooplankton collections were 160.1-17 0.0 2 6
170.1-180.0 I 7
made at each "biological" station: an oblique 180.1. I 90.0 5 29
collection and a surface collection with the 1-m 190.1-200.0 IO 52
200 1-210.0 30 188
net, an oblique collection with the 0.5-m net, and 210.1 -220.0 41 168
an oblique collection with the micronekton net. 220.1-230.0 _5_ 17
230.1-240.0 1
In taking oblique plankton hauls, the 1-m net
Total I I9 121 139 1 03 482
was paired in an assembly frame with the 0.5
m net. The assembly of nets was fastened to
the towing cable by a bridle about 5 m above were all taken before midnight (2201-2400)
a 100-lb weight. The assembly was lowered to on Rockaway, for example, while on Argo
depth by paying out 300 m of towing cable at most hauls, were made after midnight (be-
the controlled rate of 50 m of wire per minute. tween 0001 and 0400 hr). The time of day
The assembly remained at depth for 0.5 min and of occupancy of stations (based on the midtime
then was retrieved at a uniform rate of 20 m of each haul) is summarized by hourly intervals
per min. Total towing time was about 21.5 min. in Table 2. At least some hauls were taken
Towing speed was ca. 2 knots. The depth during every hour of the day, although fewer
reached by the net was estimated from the angle than 10 (2-8) were obtained during six of the
of stray (departure from the vertical) of the hourly intervals. Fewest hauls were obtained
towing cable. We sought to maintain an angle between 0901 and 1000 hr (2 hauls) and be-
of stray of 45", which lowered the assembly tween 2101 and 2200 hr (4 hauls), whereas
to a depth of approximately 210 m. Our con- the largest number of hauls were taken between
cern was to sample the upper 200-m stratum. 2201 and 2300 hr (59 hauls) and between 1001
The average depths of hauls taken by the four and 1100 hr (53 hauls). Hauls were made
research vessels are summarized in Table 1. with equal frequency during the four periods
Over 80 'j% of the hauls made on EASTROPAC I of the day on Argo, Jordan, and Rockaway;
were lowered to depths of 200 m or more, and most plankton hauls were taken near midnight
nearly 95 76 reached depths of 180 m or greater. or noon from Alaminos.
However, two hauls were exceptionally shallow The numbering system for observations em-
(71-90 m) , and nine additional hauls were taken ployed on EASTROPAC cruises made use of five
to depths of less than 150 m. digits divided into two groups, as 11.022, 12.002,
Usually four paired net-assembly hauls were etc. The outer digit preceding the period is the
taken per day, spaced at about 6-hr intervals. cruise number common to all vessels participat-
Although the four hauls were planned to be taken ing in a given EASTROPAC cruise; for EAS-
at about midnight, dawn, noon, and sunset, the TROPAC I, this number is 1. The other digit
timing of hauls was not coordinated between preceding the period is the identifying number
research vessels. The middle-of-the-night hauls given to each research vessel, with the lowest
5
FISHERY BULLETIN: VOL. 69, NO. I
TABLE 2.-Hour of day that paired oblique plankton were aliquoted - four collections were split into
hauls were taken from the four research vessels par- 50 5: aliquots, two collections into 25 ‘/. aliquots.
ticipating in EASTROPAC I. (Midtime of haul used.)
The author made all identifications and counts
1 Number of hauls taken during each hour of the day from of larvae from EASTROPAC I collections. Ac-
tual counts of larvae rather than standardized
values (see below) are used in tabulation
0001-0100 7 IO 0 3 20 throughout this paper, except one (Table 7).
01 01 -0200 8 7 0 2 17
0201-0300 5 2 0 0 7 There are several reasons why I chose to do this.
0301 -0400 9 0 7 0 16 As indicated previously, all hauls were made in
040I -0500 1 I 1IO7 I 20
0501 -0600 2 9 3 24 a roughly comparable fashion. In many studies
060 I -0700 7 IO I 1 19 the investigator is interested in the presence or
0701- 0800 13 10 0 0 23
0801 -0900 7 0 0 0 7 absence of the larvae of a given species or as-
0901-1000 0 0 0 2 2 semblage of species as such relate to water
1001-1100 I 0 26 26 53
1101-1200 I 5 5 10 21 masses, community composition, time of day, etc.
1201 -1 300 7 22 3 I 33 Such information is most readily obtained from
1301 -1 400 12 3 1 4 20
1401 -1 500 8 0 0 0 8 records of actual counts. Some statistical tests
1501-1600 I 1 12 I 15 require the use of original counts rather than
I 601 -1 7M) 0 0 IO 3 13
1701-1800 8 6 12 6 32 standardized data. For persons interested in
1801-1900 7 19 1 0 27 deriving standardized counts comparable with
1901-2000 10 1 0 0 11
2M)1-2100 3 3 0 0 6 those employed for CalCOFI data (Ahlstrom,
21 01 -2200 0 1 0 3 4 1953), standard haul factors for the 482 oblique
220 1-2300 2 2 23 32 59
2301 -2400 0 9 I1 5 25 hauls taken with the 1-m net on EASTROPAC I
are given in Appendix Table 7.
Total I19 121 139 103 482
Two major considerations in the quantitative
number given to the offshore vessel. The three sampling of fish larvae for resources evaluation
digits following the period are numbers given are (1) how well has their depth range been
to observations made from each vessel during a covered and (2) how effectively have the larvae
cruise, numbered sequentially. Not all “stations” been sampled within this layer?
included oblique plankton hauls; hence there are We do not have direct answers to either of
gaps in numbers applied to plankton collections. these questions from EASTROPAC cruises.
The locations of plankton stations occupied by No studies were made on depth distributions of
the four research vessels participating in fish eggs and larvae in the EASTROPAC area.
EASTROPAC I are shown in Figure 1. Sam- As will appear, fewer fish larvae were obtained
ples collected from the Argo are designated as during daylight hours than in night hauls; how-
the 11.000 series, samples from the David Starr ever, we lack information on how completely
Jordan as 12.000 series, Rockaway samples as larvae were sampled in night hauls.
13.000 series and Ahminos samples as 14.000
series. In tables to follow, the series of samples
taken by each vessel is designated by the above DEPTH DISTRIBUTION OF FISH
identifying series numbers. The aggregate of LARVAE
stations occupied by each vessel is referred to in Although collecting methods used on EAS-
text discussions as its pattern. TROPAC did not permit a study of depth distri-
bution of fish larvae, such information for the
California Current region off California and
PROCESSING SAMPLES ASHORE
Baja California and in a less detailed way for
As noted above, only samples from 1-m the NORPAC Expedition of 1955 are available
oblique net hauls were sorted routinely for fish (Ahlstrom, 1959).
eggs and larvae. As a rule the entire sample was In the California Current region, most fish
sorted; in fact only six collections out of 482 eggs and larvae were distributed within the up-
6
AHLSTROM: FISH LARVAE IN EASTERN TROPICAL PACIFIC
per mixed layer or in the upper portion of the importance of the thermocline in the depth distri-
thermocline, between the surface and approxi- bution of larvae, the pattern of thermocline depth
mately 125 m. Of the 15 most common kinds was analyzed for EASTROPAC I (Table 3).
of fish larvae taken in vertical distribution ser- Thermocline depth was invariably shallow in
ies, 12 were so distributed (ibid., p. 134). Two the inner pattern occupied by Alaminos (data
of the kinds that occurred most commonly below not included in Table 3); the greatest depth
the thermocline were bathylagid smelts, closely recorded was only 40 m, and the majority of
related to the two common bathylagid smelts observations were at depths shallower than 20
taken on EASTROPAC I. m. Along the six station lines covered in Table
On the NORPAC Expedition of August 1955, 3, thermocline depths were shallowest near the
two depth strata were sampled at most stations ; equator, and usually were deepest at the north-
a closing net, fastened to the towing cable 200 m ern (20-15' N) and southern (15-20' S) ends
below a standard open plankton net, sampled of the lines. The thermocline also deepened off-
the level between 262 and 131 m on the average, shore; approximately three-fourths of the rec-
while the upper net sampled from the surface ords of thermocline depths of 50 m or greater
to approximately 131 m deep. Only about one- were from the two outer lines, occupied by Argo.
ninth as many larvae were taken in the closing Most oblique plankton hauls taken on EAS-
net hauls as in the upper net hauls; fully half TROPAC I sampled to depths of 200 m or more
of these were larvae of hatchetfish, family Ster- (Table 2) , hence sampled considerably deeper
noptychidae, largely absent from upper net than the thermocline in all parts of the EAS-
hauls. The two most abundant kinds of fish TROPAC area.
larvae taken on EASTROPAC I were those of
the myctophid lanternfish, Diogenichthys latern-
EFFECTIVENESS OF SAMPLING FISH
atus, and of the gonostomatid lightfish, Vinci-
LARVAE IN DAYLIGHT HAULS
guerriu spp. In NORPAC collections, only 3 %
AS COMPARED WITH NIGHT HAULS
of the larvae of D. laternatus were taken in the
closing net hauls and only 2 '/o of the Vinciguer- Fewer fish larvae were obtained in hauls made
~ i laarv ae. Among the kinds of larvae common during daylight hours than at night (Table 4).
to both the NORPAC and EASTROPAC sur- Original (unstandardized) counts of larvae av-
veys that occurred in significant numbers in the eraged 2.76 times as many in night hauls as in
deeper NORPAC collections were those of Chaul- day hauls, 285 larvae per occupancy as compared
iodus (79 (: taken in closing net hauls), Proto- with 103 larvae. Hauls made within 1 hr of
myctophum (48 9) and Zdiucanthus (32 %). sunrise or sunset contained intermediate num-
Inasmuch as the vertical distribution studies in bers of larvae, averaging 217 larvae per oc-
the California Current region had pointed up the cupancy.
Stotion line 1 I RaI nge in depth 1 of thermocline (m) ot latitudes All
along longitude 20.150 N 15-_10' _N 10.50 N 50 N.O~ 0.5' s 5-10' S 10-15' S 15-20' S latitudes
7
FISHERY BULLETIN: VOL. 69, NO. I
I
ARLSTROLM: FISH LARVAE IN EASTERN TROPICAL PAClFIC
Larvae of some families of fishes were sampled were taken in 45 '/o of night hauls, but in only
almost as well in day hauls as in night hauls 31 9;' of day hauls. In the discussions that fol-
-including Sternoptychidae, Bathylagidae, and low I make use of all collection data, irrespective
Melamphaidae. In contrast, less than one- of time of collection.
fourth as many gonostomatid larvae and one-
third as many myctophid larvae were taken in NUMBERS OF FISH LARVAE
day hauls, on the average, as in night hauls.
OBTAINED ON EASTROPAC I
Catches of scombrid larvae were more variable
Fish larvae were obtained in 478 of 482
with regard to time of sampling-the night-day
oblique plankton tows made with the 1-m plank-
ratio in the outer half of the EASTROPAC area
ton net on EASTROPAC I. The number of
was only about 1.5 to 1, whereas the ratio
larvae per collection ranged from 0 to 2,197,
jumped to about 7.5 to 1 in the inner pattern
averaging 197 larvae (actual counts).
occupied by Alaminos. Larvae collected about
Differences in abundance of larvae with lat-
in- equal amounts in day and night hauls were
itude are summarized for the four series in Table
those known to occur principally below the
6. Fish larvae were obtained in largest num-
thermocline.
bers, on the average, in an equatorial band ex-
Despite the lower abundance of larvae in day
hauls as compared with night hauls, the per- tending from about lat 10" N to 5" S. The least
productive waters for fish larvae were in the
centage of hauls containing larvae of most fam-
ilies was only slightly lower (Table 5). The central water mass of the South Pacific, espe-
cially between lat 15" and 20" S.
most marked day/night difference in frequency
Abundance of fish larvae also decreased off-
of occurrence was for scombrid larvae, these
shore; averaging only 130 larvae per haul in
the outer pattern, occupied by A~goa, s com-
TABLE5 .-Percentage of hauls containing larvae of
the more abundant fish families on EASTROPAC I, pared with 246 larvae per haul in the inner
grouped by day, night and dawn or sunset. pattern, occupied by Alaminos.
Tropical waters and oceanic waters are usu-
ally considered to be relatively unproductive,
compared with temperate coastal regions such
% % % %
Myctophidae 97.4 97.8 99.0 97.9 as the California Current region (Ryther, 1969).
Gonostornatidae 92.7 97.3 95.2 95.0 Hence, it is surprising to find that the average
Sternoptychidae -70.5 76.1 67.6 69.9
Bathylagidoe 61.1 65.2 61.9 62.9 number of fish larvae obtained per haul on
Melamphaidae 60.6 65.2 58.1 61.8 EASTROPAC I was larger than either on the
Scornbridae 31.1 45.1 40.0 38.4
All others 94.8 99.5 97.1 97.1 CalCOFI cruises from the California Current
Total 97.9 100.0 100.0 99.2 region (Ahlstrom, 1969) or on NORPAC (un-
I I
Argo Dnoid Starr lordon Rochamay Alominor Totol
11.000 Series 12.000 Series 13.000 Series 14.000 Series EASTROPAC I
Loiitude hNauol. s laNrvoa. e hNauol.s laNrvoo. e hNauol.s laNrvoa. e hNaoul.s loNrov.ae hNauol.s laNrvoa. e AIvoervrhaoageu elp neor .
20" N-15" N I16 1,070 1 20 I 4.128 I 5 I 462 __ I .__. I 41 5,660 138.0
15' N-IO" N 14 1,372 23 3,130 26 5,508 _- 63 10.010 158.0
IO" N- 5" N 14 2,516 14 3,344 29 10.104 15 5,167 72 21,131 293.5
5' N- 0" 14 4,797 15 4,403 14 4,331 27 11,329 70 24,860 355.1
0' . 50 s 14 2,089 18 5,454 14 4,350 17 5,042 63 16,935 268.8
5" s-I00 s 13 1,370 15 1,051 14 2,360 16 2.1 13 58 6.894 118.9
Ii..O_5"* S$- --_m1_5a ' ss- z-1n4_ 1,759132 88 856133 2125 21,,393287 2_8 . 1,67_3 . 5650 36,.233845 6948..72
Total I19 15.519 121 22,886 139 31,380 103 25,324 482 95,109 197.3
FISHERY BULLETIN: VOL. 69, NO. I
published data). Standard haul totals of larvae The majority of EASTROPAC larvae were
are used in this comparison (Table 7) not ori- those of fishes which never attain a large size as
ginal counts. CalCOFI cruises repeatedly sur- adults-myctophids, gonostomatids, sternopty-
veyed a coastal area extending 200 to 300 miles chids, etc.-hence numbers of larvae, per se,
offshore between San Francisco, California, and cannot be considered reliable indices of biomass.
Magdalena Bay, Baja California. NORPAC The familial composition of larvae was not dis-
was the first comprehensive survey of the North similar on KORPAC and EASTROPAC, how-
Pacific, made in August-September 1955; the ever; hence this comparison of relative abun-
area surveyed by four CalCOFI vessels partici- dance of larvae is more relevant, as regards
pating in NORPAC was between lat 20" and 45" biomass, than the comparison with CalCOFI
N and offshore to long 150" W. fauna.
TABLE7 .-Comparison of the average number of fish
larvae obtained per haul (standard haul values) EAS- KINDS OF FISH LARVAE OBTAINED
TROPAC I,1 NORIP NAC{, a~nd~ Ca~lClOIF I cruisesI. ON EASTROPAC I
Average Total Average
Cruises Year depth number of number The kinds of larvae obtained on EASTRO-
of hovls fish larvae' larvae/houl
PAC I are summarized by family and vessel
EASTROPAC I 1967 482 co, 200 m 274,131 569
NORPAC 1955 196 ca. 260 m 27,000 '138 pattern in Table 8, the principal summary table
ColCOFl cruises 1956 1,407 ca, 140 m 408,140 290
in this paper. Larvae of more than 50 families
1957 1,493 ca. 140 m 493,550 331
1958 1,852 ca. 140 m 456,020 246 are listed, but larvae of 10 families contributed
1959 2,182 ca. 140 m 470,450 216
19M) 1,826 ca. 140 m 504,980 277 90 qi> of the total. The myctophids were the
dominant group with 47.2 % of the larvae oc-
Stondord haul totals.
a Data from two net houlr combined: an average of 124 lorvoe per curring in nearly 98 % of the collections. Gono-
haul were taken in upper net hovls (0 to 130 m) and on average of 14
lorvae per houl in closing net haulr,,sornpling between co. 260 and 130 m. stomatid larvae were about half as numerous,
EASTROPAC hauls sampled a somewhat contributing 23.2 $6 of the larvae while oc-
deeper stratum than hauls made on CalCOFI curring in 95 % of the collections. Hatchetfish
cruises, ca. 200 m as compared to ca. 140 m. As larvae (Sternoptychidae) ranked third in
indicated previously, information is available for abundance with 6 c/o of the larvae taken in 70 "/o
the majority of NORPAC stations on the rel- of the hauls. Bathylagid larvae also exceeded
ative abundance of fish larvae in the level be- 5 76 of the total and occurred in 63 $% of the
tween ca. 130 and 260 m (closing net hauls) as collections. Scombrid larvae ranked fifth and
compared with the level above, 0 to 130 m. Only exceeded 2 56 of the count, followed by Breg-
about one-ninth as many larvae were taken in the macerotidae, 1.9 76, Paralepididae, 1.7 %, Idia-
deeper hauls. canthidae, 1.0 P, Nomeidae, 1.0 %, and Mel-
The difference between catches of larvae on amphaidae, 0.9 $6. About one-third of the re-
EASTROPAC I and NORPAC are particularly maining larvae were too poorly preserved (dis-
marked-four times as many larvae were taken integrated) to identity.
per haul, on the average, on EASTROPAC I as On the basis of larval abundance, the domi-
on NORPAC (both nets combined). For com- nant orders of fishes in oceanic waters are the
parison with shallower CalCOFI hauls, I am as- Myctophiformes and Salmoniformes, making up
suming that 10 '/o of the EASTROPAC larvae between 85 and 88 $6 ; the latter value assumes
were obtained in the level between ca. 140 and a proportionate representation of larvae of these
200 m. The adjusted value for EASTROPAC groups in the "disintegrated" category, i.e.,
larvae, 512 larvae per haul, on the average, is larvae too damaged or disintegrated to identify
1.55 times as large as the highest CalCOFI val- with certainty. Despite the dominance of fishes
ue listed (331 larvae per haul in 1957) and 2.35 of the above two orders, a number of other
times as large as the lowest value (216 larvae groups of fishes are represented in the oceanic
per haul in 1959). pelagic fish fauna. The berycoid fishes are rep-
10
AfiLSTROM: FISH LARVAE IN EASTERN TROPICAL PACIFIC
FISHERY BULLETIN: VOL. 69, NO. 1
resented by Melamphaidae, a family of fishes that Appendix Table S.-Counts of selected ca-
is almost as ubiquitous as the myctophids or tegories of fish larvae by station. Table con-
gonostomatids. Fishes of the gadoid family, tains 23 categories including 10 species, 10
genera, 2 families, and 1 suborder; 9 of these
Bregmacerotidae, also are widely distributed in
were included in the category “other identi-
the warmer waters of all oceans. Among the
fied larvae” in Appendix Table 1.
ubiquitous epipelagics are the flyingfishes, Ex-
ocoetidae. Appendix Table 4.-Summary of occur-
Only a moderate number of perciform fishes rences and numbers of larvae of eight families
are widely distributed in offshore, oceanic wa- limited in distribution to a broad coastal band
ters. Among the more important are fishes of or around offshore islands. Only positive
the families Scombridae, Gempylidae, Trichiur- stations are included. These eight families
idae, Istiophoridae, Coryphaenidae, Bramidae, also were included in the category other
“
Nomeidae, Apogonidae, Chiasmodontidae, and identified larvae” in Appendix Table 1.
Tetragonuridae.
Appendix Table 5.-Numbers and kinds of
Larvae of some demersal fishes have a much
larvae of Gempylidae-Trichiuridae obtained
wider offshore distribution than one would asso-
in EASTROPAC I collections. Only positive
ciate with the known distribution of adults. In-
stations are included. A summary of this ap-
cluded in this group are larvae of bothid and
pendix table is given in Table 19.
cynoglossid flatfishes, and larvae of Scorpaeni-
dae, Gobiidae, and Labridae. Appendix Table 6.-Numbers and kinds of
Another widely distributed group in oceanic flatfish (Pleuronectiformes) larvae obtained
waters are the bizarre ceratioid fishes. The in EASTROPAC I collections. Only positive
rotund larvae of these fishes were taken in about hauls are included. A summary of this ap-
30 ?h of the EASTROPAC collections, always in pendix table is given in Table 22.
small numbers.
Appendix Table “.-Standardized haul
The basic data on the kinds and numbers of factors for the 482 oblique 1-m net hauls taken
fish larvae obtained in the 482 EASTROPAC I on EASTROPAC I. These factors adjust ori-
collections are contained in six appendix tables, ginal counts of larvae to the comparable stan-
whose contents are summarized below, and keyed dard of numbers of larvae in 10 m3 of water
to Table 8 and to other tables in this report. strained per meter of depth fished.
Appendix Table 1.-Counts of fish larvae, I will not attempt to comment on all 58 cate-
tabulated by family, for all stations occupied gories (family or larger grouping) summarized
on EASTROPAC I. This table contains 22 in Table 8, but will limit my discussion to 31
categories, mostly families, but for complete-
of these. In order to tie the text discussion
ness, a category is included for “other identi- closely to this table, I retain the numbers for
fied larvae,” one for “unidentified larvae” and
categories as given in Table 8; those discussed
one for “disintegrated larvae” (Le., larvae too in the text are preceded by an asterisk in this
damaged or disintegrated to identify with any
table.
certainty).
Appendix Table 2.-Myctophid larvae, tab- COMMENTS ON LARVAE OF THE
ulated by genus or species, for all stations oc- MAJOR FISH FAMILIES COLLECTED
cupied on EASTROPAC I. Myctophid larvae ON EASTROPAC I
are tabulated by species for 12 kinds, and by
genus for 8 kinds. Also included are cate- 1. CLUPEIDAE
gories for unidentified myctophids, and total ( 10 occurrences, 81 larvae)
myctophids. A summary of this appendix Three species of clupeid larvae were taken
table is contained in Table 15. in EASTROPAC I collections-Opisthonema sp.
12