NOAA Technical Report NMFS 89 ,

,

April 1990

Early-Life-History Profiles,

Seasonal Abundance, and

Distribution of Four Species

of Carangid Larvae off Louisiana,

1982 and 1983

Richard F. Shaw

David L. Drullinger

U.S. Department of Commerce
NOAA TECHNICAL REPORT NMFS _

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5285 Port Royal Road, Springfield, VA 22161. Although the contents have not been copyrighted and may be reprinted entirely, reference to source is appreciated.

48. Widow rockfish: Proceedings of a workshop, Tiburon, California, December

11-12,1980, by William H. Lenarz and Donald R. Gunderson (editors). January 1987,

57 p.

49. Reproduction, movements, and population dynamics of the southern kingfish,

Menticirrhus americanus, in the northwestern Gulf of Mexico, by Stephen M. Harding

and Mark E. Chittenden, Jr. March 1987,21 p.

50. Preparation of acetate peels of valves from the ocean quahog, Arctica islandica,

for age determinations, by John W. Ropes. March 1987,5 p.

51. Status, biology, and ecology of fur seals: Proceedings of an international

workshop, Cambridge, England, 23-27 April 1984, by John P. Croxall and Roger

L. Gentry (editors). June 1987,212 p.

52. Limited access alternatives for the Pacific ground fish fishery, by Daniel D.

Huppert (editor). M'ay 1987, 45 p.

53. Ecology of east Florida sea turtles: Proceedings of the Cape Canaveral. Florida,

sea turtle workshop. Miami, Florida, February 26-27, 1985, by Wayne N. Witzell

(convener and editor). May 1987,80 p.

54. Proximate and fatty acid composition of 40 southeastern U.S. finfish species,

by Janet A. Gooch, Malcolm B. Hale, Thomas Brown, Jr., James C. Bonnet, Cheryl

G. Brand, and Lloyd W. Reiger. June 1987, 23 p.

55. Proximate composition, energy, fatty acid, sodium, and cholesterol content of

finfish, shellfish, and their products. by Judith Krzynowek and Jenny Murphy. July

1987, 53 p.

56. Some aspects of the ecology of the leatherback turtle Dermochelys coriacea at

Laguna Jolova. Costa Rica, by Harold F. Hirth and Larry H. Ogren. July 1987, 14 p.

57. Food habits and dietary variability of pelagic nekton off Oregon and WaShington.

1979-1984, by Richard D. Brodeur, Harriet V. Lorz, and William G. Pearcy. July

1987, 32 p.

58. Stock assessment of the Gulf menhaden, Brevoortia patronlls, fishery, by Douglas

S. Vaughan. September 1987, 18 p.

59. Atlantic menhaden, Brevoortia tyronnllS, purse seine fishery, 1972-84, with a

brief discussion of age and size composition of the landings, by Joseph W. Smith,

William R. Nicholson, Douglas S. Vaughan. Donnie L. Dudley, and Ethel A. Hall.

September 1987, 23 p.

60. Gulf menhaden, Brevoortia patronlls, purse seine fishery, 1974-85, with a brief

discussion of age and size composition of the landings, by Joseph W. Smith. Eldon

J. Levi, Douglas S. Vaughan, and Ethen A. Hall. December 1987, 8 p.

61. Manual for starch gel electrophoresis: A method for the detection of genetic variation. by Paul B. Aebersold, Gary A. Winans, David J. Teel, George B. Milner, and

Fred M. Utter. December \987, 19 p.

62. Fishery publication index, 1980-85; Technical memoradum index, 1972-85, by

Cynthia S. Martin. Shelley E. Arenas, Jacki A. Guffey, and Joni M. Packard.

December 1987. 149 p.

63. Stock assessment of the Atlantic menhaden, Brevoortia tyrannus, fishery, by

Douglas S. Vaughan and Joseph W. Smith. January 1988, 18 p.

64. Illustrated key to penaeoid shrimps of commerce in the Americas, by Isabel Perez

Farfante. April 1988, 32 p.

65. History of whaling in and near North Carolina, by Randall R. Reeves and Edward

Mitchell. March 1988, 28 p.

66. Atlas and zoogeography of common fishes in the Bering Sea and northeastern

Pacific, by M. James Allen and Gary B. Smith. April 1988, 151 p.

67. Index numbers and productivity measurement in multispecies fisheries: An

application to the Pacific coast trawl fleet, by Dale Squires. July 1988. 34 p.

68. Annotated bibliography II of the hard clam Mercenaria mercellaria, by 1.L.

McHugh and Marjorie W. Sumner. September 1988, 59 p.

69. Environmental quality and aquaculture systems: Proceedings of the thirteenth

U.S.-Japan meeting on aquaculture, Mie, Japan, October 24-25, 1984, edited by Carl

J. Sindermann. October 1988, 50 p.

70. New and innovative advances in biology/engineering with potential for use in

aquaculture: Proceedings of the fourteenth U.S.-Japan meeting on aquaculture, Woods

Hole, Massachusetts, October 16-/7, 1985, edited by Albert K. Sparks. November

1988, 69 p.

71. Greenland turbot Reillhardtius hippoglossoides of the eastern Bering Sea and

Aleutian Islands region, by Miles S. Alton, Richard G. Bakkala, Gary E. Walters,

and Peter T. Munro. December 1988, 31 p.

72. Age determination methods for northwest Atlantic species, edited by Judy Penttila

and Louise M. Dery. December 1988, 135 p.

73. Marine flora and fauna of the Eastern United States. Mollusca: Cephalopoda,

by Michael Vecchione, Clyde F.E. Roper, and Michael 1. Sweeney. February 1989,

23 p.

74. Proximate composition and fatty acid and cholesterol content of 22 species of

northwest Atlantic finfish, by Judith Krzynowek, Jenny Murphy, Richard S. Maney,

and Laurie 1. Panunzio. May 1989, 35 p.

75. Codend selection of winter flounder Pseudopleurollectes americallllS, by David

G. Simpson. March 1989, 10 p.

76. Analysis of fish diversion efficiency and survivorship in the fish return system

at San Onofre Nuclear Generating Station, by Milton S. Love, Meenu Sandhu,

Jeffrey Stein, Kevin T. Herbinson, Robert H. Moore, Michael Mullin, and John S.

Stephens. Jr. April 1989, 16 p.

77. Illustrated key to the genera of free-living marine nematodes of the order

Enoplida. by Edwin J. Keppner and Armen C. Tarjan. July 1989, 26 p.

78. Survey of fishes and water properties of south San Francisco Bay, California,

1973-82, by Donald E. Pearson. August 1989,21 p.

79. Species composition, distribution, and relative abundance of fishes in the coastal

habitat off the southeastern United States, by Charles A. Wenner and George R.

Sedberry. July 1989,49 p.

80. Laboratory guide to early tife history stages of northeast Pacific fishes, by Ann

C. Matarese, Arthur W. Kendall, Jr., Deborah M. Blood, and Beverly M. Vinter.

October 1989, 65 I p.
NOAA Technical Report NMFS 89

Early-Life-History Profiles,

Seasonal Abundance, and

Distribution of Four Species

of Carangid Larvae off Louisiana,

1982 and 1983

Richard F. Shaw

David L. Drullinger

April 1990

,to""" OF co U.S. DEPARTMENT OF COMMERCE

4-'1; '2 ~+ Robert Mosbacher, Secretary .: ' ." Q~, ... National Oceanic and Atmospheric Administration

: ~- ; John A. Knauss, Under Secretary for Oceans and Atmosphere ;"

~~ 8 . ~..,q. National Marine Fisheries Service

"<4Trs Of t' William W. Fox, Jr., Assistant Administrator for Fisheries
The National Marine Fisheries Service (NMFS) does not approve, recommend

or endorse any proprietary product or proprietary material mentioned in this

publication. No reference shall be made to NMFS, or to this publication furnished

by NMFS, in any advertising or sales promotion which would indicate or imply

that NMFS approves, recommends or endorses any proprietary product or proprietary material mentioned herein, or which has as its purpose an intent to cause

directly or indirectly the advertised product to be used or purchased because of

this NMFS publication.

11
CONTENTS

Acknowledgments iv

Introduction 1

Methods and Materials

Ichthyoplankton samples 2

Bioprofiles 3

Results

Caranx crysos 3

Chloroscombrus chrysurus 9

Decapterus punctatus 12

Trachurus lathami 17

Discussion 18

Citations 21

Appendix: Bioprofiles

Caranx crysos 26

Chloroscombrus chrysurus 29

Decapterus punctatus 32

Trachurus lathami 35

1Il
Acknowledgments _

Data collection and preliminary analyses were funded by the Louisiana Board

of Regents Research and Development Program (contracts 84-LBR/054-B34

and 85-LBR/OI3-805), and final analysis was supported by the Marine

Fisheries Initiative (MARFIN) Program (contract NA86-WC-H-06117). We

would like to thank those who helped us acquire data and samples collected

during the first 2 years of the SEAMAP Ichthyoplankton Program: Louisiana Department of Wildlife and Fisheries; Thomas Potthoff, William J.

Richards, and Kenneth Savastano of the National Marine Fisheries Service;

Nikki Bane and members of the SEAMAP Subcommittee; and John V. Gartner, Jr., of the Florida Department of Natural Resources. We also thank

James H. Cowan, Jr., James G. Ditty, Mark M. Leiby, David Ruple, and

Joanne Lyczkowski-Shultz, who provided valuable expertise toward the

identification of many poorly described species. To Scott G. Leibowitz,

special thanks for his work on the mapping graphics package. The comments and criticisms of two anonymous reviewers are also appreciated.

iv
Early-Life-History Profiles,

Seasonal Abundance,

and Distribution of Four

Species of Carangid

Larvae off Louisiana,

1982 and 1983

RICHARD F. SHAW

DAVID L. DRULLINGER*

Coastal Fisheries Institute

Center for Wetland Resources

Louisiana State University

Baton Rouge, Louisiana 70803-7503

ABSTRACT

We present data on ichthyoplankton distribution, abundance,

and seasonality and supporting environmental information for

four species of coastal pelagics from the family Carangidae: blue

runner Caranx crysos, Atlantic bumper Chloroscombrus chrysurus, round scad Decapterus punctatus, and rough scad Trachurus lathami. Data are from 1982 and 1983 cruises off Louisiana sponsored by the Southeastern Area Monitoring and

Assessment Program (SEAMAP). Bioprofiles on reproductive

biology, early life history, meristics, adult distribution, and

fisheries characteristics are also presented for these species.

Maximum abundances of larval blue runner, Atlantic

bumper, and round scad were found in July inside the 4O-m

isobath, although during the rest ofthe cruises these species were

rarely found together. Larval Atlantic bumper were captured

in June and July only; blue runner in May, June, and July; and

round scad in all seasons. Atlantic bumper larvae, concentrated

mostly off western Louisiana, were by far the most abundant

carangid in 1982 and 1983. Larval blue runner were the second

most abundant summer-spawned carangid in 1982 and 1983,

but their abundance and depth distribution varied considerably

between years. Relative abundance oflarval round scad off Louisiana was low, and they were captured only west of the Mississippi River delta, although they are reported to dominate

carangid populations in the eastern Gulf of Mexico. Rough scad

were primarily winter/spring and outer-shelf (40-182 m)

spawners. They ranked third in overall abundance, but were

the most abundant target carangid on the outer shelf. Ecological

parameters such as surface salinity, temperature, and station

depth are presented from capture sites for recently hatched

larvae «2.5 mm notochord length, except round scad) as well

as for all sizes of fish below 14 mm standard length.

*Present address: Surface Water Quality Division, Michigan Department

of·Natural Resources, P.O. Box 30028, Lansing, MI48909.

Introduction _

Exploratory fishing surveys in the Gulf of Mexico have identified the carangids as being abundant (JuhlI966, Bullis and

Carpenter 1968, Bullis and Thompson 1970, Klima 1971)

and have found evidence that commercial quantities of round

scad Decapterus punctatus, rough scad Trachurus lathami,

and blue runner Caranx crysos may exist (Klima 1971). In

the United States these species may have commercial potential for export marketing and as baitfish. Also, in conjunction with the small and abundant Atlantic bumper Chloroscombrus chrysurus, these species constitute an important,

if not primary, food source for many predatory game and

commercial fishes and may therefore directly affect the

biomass ofthese predators. Other available forage fish may

not be as abundant throughout their geographical range, reach

high enough schooling densities, nor have the same palatability as these species (Reintjes 1979a).

Despite the potential importance of such coastal pelagics

as the carangids, we do not presently know enough about

them to accurately assess the extent to which they can be

feasibly exploited (Nakamura 1980, Vaughan et al. 1986).

This inadequacy is especially apparent in our understanding

of the early-life-history stages. Very little is known about

larval abundance, seasonality, and distribution of these

species off Louisiana, or about the oceanographic factors that

may be important for their survival. Knowledge of spawning location and season, for example, could have immediate

applications because some of the carangid fisheries exploit

only spawning concentrations (Elwertowski and Boely 1971).

Information on spawning aggregations could affect efficiency

and development of the fisheries (Leak 1977).

This research was undertaken to augment information on

the early life history ofthe four previously mentioned species

of carangids. This is especially important in light of (1) the

increasing awareness that some of our fisheries may be

approaching, or may have already reached, their maximum

sustainable yields; (2) tOOay's political and economic climate

with its justifiable emphasis on creating new job opportunities, utilizing untapped renewable resources, and balancing the international trade deficit; and (3) the appreciation

of each Gulf state's need to develop, maximize, effectively

manage, and partition fishery resources while minimizing

conflicts between commercial and recreational users. Information provided in this report should help solidify the data

foundation necessary for sound management of the Gulfs

"fisheries of the future."

Our research approach for this 2-year project was to (1)

thoroughly survey the pertinent literature and compile, consolidate, and synthesize appropriate data for incorporation

into bioprofiles of the early life histories of the selected

species; and (2) sort, identify, and analyze larval fish samples

requested from the Southeast Area Monitoring and Assessment Program (SEAMAP), focusing on collections in Louisiana territorial and offshore waters during 1982 and 1983

cruises.
Table 1

Summary of 1982 SEAMAP ichthyoplankton sampling in Louisiana proximal waters.

Vessel or state Cruise Dates Station no. Sample no. Gear Location

Oregon II 125 02/24-03/17 36005-36580 869-963 Bongo Mississippi delta area

Oregon II 126 04/20-05/24 36689-36777 91-360 Bongo/Neuston Louisiana offshelf

Oregon II 127 06/02-06/27 36788-36937 497-634 Bongo/Neutson Louisiana shelf

Louisiana 0 06/01-07/30 01-43 454-496 Ring Louisiana coastline

Jeff and Tina 0003 06/16-07/06 B2oo-B220 415-447 Bongo/Neuston East Texas/West Louisiana, shelf

Oregon II 130 10/I7-11/23 37389-38268 2052-2127 Bongo/Neuston East Louisiana/Mississippi, shelf

Table 2

Summary of 1983 SEAMAP ichthyoplankton sampling in Louisiana proximal waters.

Vessel or state Cruise Dates Station no. Sample no. Gear Location

2133-2162

Oregon II 133 03/13-03/29 38604-38775 3339-3341 Bongo/Neuston East of Mississippi River delta

Oregon II 134 04/25-05/23 39073-39198 1163-1471 Bongo/Neuston Louisiana offshelf

Oregon II 135 06/08-07/05 39242-39390 1908-1994 Bongo/Neuston Louisiana shelf

Tommy Munro 135 06/07-06/14 AI-BI82 1639-1673 Bongo/Neuston Mississippi shelf

Louisiana 02 06/ 13-06/16 01001-07005 1703-1735 Ring Louisiana coastline

Louisiana 03 06/21-06/23 01001-07005 1736-1765 Ring Louisiana coastline

Suncoaster 01 07/01-07/04 B179-B183 1685-1696 Bongo/Neuston Mississippi shelf

Oregon II 138 10/12-10/31 39580-39849 3352-3452 Bongo/Neuston East of Mississippi River delta

Tommy Munro RD83 10/18-10/19 1-3 1884-1889 Bongo Mississippi shelf

Oregon II 140 12/14-12/21 40197-40231 1814-1838 Bongo/Neuston Louisiana offshelf

Methods and Materials _

Ichthyoplankton samples

Samples of larval and early juvenile carangids from the

SEAMAP ichthyoplankton collections were examined for the

presence of our target species: Caranx crysos, Chloroscombrus chrysurus, Decapturus punctatus, and Trachurus lathami. Samples analyzed in 1982 were from cruises conducted

24 February-17 March and 20 April-30 July (Richards et al.

1984), and an additional cruise 17 October-23 November.

In 1983, samples were analyzed from cruises conducted 13

March-5 July, and during 12-31 October and 14-21 December (Kelley et al. 1985). For both years our targeted species

were analyzed from station locations off Louisiana between

long. 88°30'W and 94°30W and from the Louisiana coast

to lat. 26°OO'N, approximately 322 kIn offshore. Offshore

stations were generally arranged in a systematic grid at

minimum intervals of 55 kIn (30 nautical miles) or one-half

degree, but coastal stations were usually irregularly spaced

or clumped. SEAMAP vessels were provided by the National

Marine Fisheries Service and by state agencies (Tables 1 and

2). Sampling consisted of oblique plankton tows taken with

60-cm bongo nets (0.333-mm mesh) within 5 m of the bottom (at station depths of <205 m) or from a depth of 200

m and lO-min neuston tows with the 1X2-m net (0.947-mm

m~sh) half submerged (Thompson and Bane 1986). In addition, 0.5-m ring nets with 0.333-mm mesh were used aboard

Louisiana and Alabama vessels to take lO-min surface hauls

2

on north-south transects within the 5-m depth contour. Towing speed for all collections was 0.8m/s. A more detailed

treatment of the sampling grid and procedures is presented

elsewhere (Stuntz et al. 1982, Thompson and Bane 1986).

Carangid larvae were identified to the lowest taxonomic

level possible and verified against available ichthyoplankton

reference collections. Many carangids found in the SEAMAP

samples were either nontarget species or unidentifiable. Larvae and juveniles of the Caranx hippos/latus complex were

by far the most common nontarget carangids. Other carangids

found were undescribed Caranx spp., Elagatis bipinnulata,

Oligoplites saurus, Selar crumenophthalmus, Selene spp.,

Seriola spp., and Trachinotus spp. .

Target species were enumerated and measured. Standard

lengths (SL) were taken to the nearest tenth millimeter and

are presented in l-mm increments (i.e., 1.0-1.9 mm, 2.0-2.9

mm) in the length-frequency histograms. Standard length was

considered synonymous with notochord length in preflexion larvae. Any fishes larger than 13.9 mm SL were considered juveniles and not included in this analysis. In each

sample, all fish of a target species were measured unless there

were more than 52 individuals. For collections of over 52

specimens, we measured the longest and shortest individuals

and used a random-numbers table to select 50 others from

a dish with a grid system. We adjusted the length-frequency

histograms from net collections with greater than 52 larvae

of a given species, using a multiplier to give equal weight

to the length data subsampled from the larger collections.
Table 3

Number of SEAMAP stations sampled for carangids off Louisiana, 1982 and 1983. No samples taken in January, August, or September.

NS = no samples taken.

Gear and

Year depth Feb Mar Apr May June July Oct Nov Dec

Bongo

1982 <40 m 5 27 17 3 II

40-182 m 36 8 14 I 12

>182 m 23 26 8 2 5

Total 5 63 23 34 39 4 2 28 NS

1983 <40 m 2 13 I 6

40-182 m I 4 I 11 4 2 3

>182 m 2 10 18 4 6

Total NS 5 14 19 24 5 12 NS 9

Neuston or Ring

1982 <40 m 37 23

40-182 m 8 14 I

>182 m 23 29 8 3 2

Total NS NS 23 37 S9 23 3 3 NS

1983 <40 m 54 I

40-182 m 4 I II 4 3

>182 m 3 10 17 4 S

Total NS 3 14 18 6S S 4 NS 8

Spawning season and location (depth or distance from

shore), larval distribution and abundance, and larval ecology

(i.e., temperature and salinity at time of capture) were determined for all target species. Yearly abundance of each larval species was determined at three depth zones: inner shelf

(depths <40 m), outer shelf (40-182 m), and offshore (>182

m). Station abundances and length-frequency data for each

species were plotted by gear type and month. Monthly groupings were considered optimal because they allowed variations in the sampling effort (cruise tracks) and spawning

intensity or site location to be viewed over time without considerable loss ofsample size or geographic coverage. Abundances of larvae caught in unmetered neuston or 0.5-m ring

nets are listed as catch-per-unit-effort (CPUE), where a unit

of effort is defined as one complete tow ("" 10 min). Only

bongo nets were metered, allowing calculations ofthe volume

of water filtered. Abundances of fish captured in bongo nets

are presented as the number of larvae under 10 m2 of sea

surface, written in the text as no. fishllO m2 . Yearly mean

abundances were calculated over those months when capture of a species was deemed likely, referred to as the larval

season. Both positive and zero-catch stations were included

in mean abundance estimates. The number of total stations

sampled each month is given in Table 3.

Bioprofiles

We found most of the literature reviewed in the bioprofiles

(see Appendix) through computer-assisted literature searches

utilizing on-line databases such as Aquatic Science Abstracts

(1978-83), BIOSIS (1969-83), Comprehensive Dissertation

3

Abstracts (1861-1983), Oceanic Abstracts (1964-83), and

Zoological Record (1978-80).

The total number of literature citations on these species

is somewhat deceptive; review of the literature reveals relatively few early-life-history studies from the Gulf of Mexico targeting these species. The available summary information often pieced together data from throughout the world's

oceans or on similar species of the same genus. For these

reasons, we have purposely avoided using summations of

all the available information to make all-inclusive statements

on spawning seasonalities, egg and larval distributions,

meristics, etc., in our early-life-history bioprofiles. We have

instead reported specific facts from specific authors and

locales so that readers can locate information relevant to their

particular problems or decide how much weight to give to

each finding based on its timeliness or proximity to a given

geographical area. In the absence of data from the Gulf or

on the appropriate species, we have provided information

from other areas, oceans, or species, and have so indicated

in each instance.

Results _

Caranx crysos

In general, young of C. crysos (1.5-13.0 mm SL), our second most abundance target species, were distributed across

Louisiana's continental shelf waters, except east of the

Mississippi River delta (Figs. 1-4). During May 1982 offshore sampling (depths>182 m), larvae were captured only

along the edge of the continental shelf, suggesting that there
CARANX CRYSOS

100

80

60

MAY + N = 3 40

20

0

> 60 () JUNE z

w N = 30 40 :J

0

w 20 a:

LL

n 0 0

STANDARD LENGTH (mm)

w r-I u a. Z L-J >0 -10

C(

c

z E] >10 - 100

:J

m

C( 1m >100 - 1000

60

40

20

o

JULY

N = 137

1234567891111

0123

Figure 1

Size-frequency distribution and abundance (N/I0 m2 ) of

Caranx crysos larvae

for positive-catch

months during 1982

SEAMAP bongo net

collections off Louisiana. Stations sampled (+); N = total

number caught.

4
CARANX CRYSOS

100

80

.1 60

MAY

40 N = 2

20

0

> 60 . . + . <;) t + 0 JUNE

z

w N = 275 40

=>

0

w 20 r:r:

LL I' 0 0

STANDARD LENGTH (mm)

Figure 2

Size-frequency distribution and catchper-unit-effort (Nt

tow) of Caranx crysos

larvae for positivecatch months during

1982 SEAMAP neuston and half-meter

ring net coUections

off Louisiana. Stations sampled: +

neuston, * ring nets.

N = total number

caught; no larvae

taken in ring nets.

N = 4

JULY

1234567891111

0123

0 ............--

20

60

I' 40

18 r-I

w L-J >0 -10

;:)

l:l. [ill ..... >10 - 100

(.)

em >100 - 1000

5
CARANX CRYSOS

100

80

60 III MAY

+ , 40 N =

+ ,

0 . 20

2.

0

>- 0

Z

W

:J

0

W

a:

LL

0

60

JUNE 21 + +

40 N = 8

20

w

() 0 0 II z >0 ·10 1234567891 1 1 1 4(

c [ill >10·100 0123

z ...

III

:::)

4( m>100·1000 STANDARD LENGTH (mm)

Figure 3

Size-frequency distribution and abundance (N/IO m2 ) of Caranx crysos larvae for positive-catch months during 1983

SEAMAP bongo net collections off Louisiana. Stations sampled (+); N = total number caught.

6
CARANX CRYSOS

+ •

• + v v

1234567891111

0123

STANDARD LENGTH (mm)

a

100

> 80

0

Z

w 60

::::» JUNE

0 N = 16 w 40 a:

u.

0 20

>0 ·10

>10·100

>100 ·1000

Figure 4

Size-frequency distribution and catch-per-unit-effort (N/tow) of Carom: crysos larvae for June (the only positive,atch month)

during 1983 SEAMAP neuston and half-meter ring net collections off Louisiana. Stations sampled: + neuston, *ring nets.

N = total number caught; no larvae taken in ring nets.

may have been high abundance on the shelf where no stations were sampled. This supposition was not supported by

the June 1982 bongo net surveys, however, which indicated

that the highest abundance was indeed at the shelf break,

although the neuston net collections indicated the presence

oflarvae across the shelf. In July 1982, larvae were present

in high abundance on the inner shelf (depth <40 m), but

because coverage of the stations at all depths was poor, the

across-shelf distribution of larvae could not be resolved.

During 1983, the association of high larval abundance with

the shelfbreak was not evident. The only larva taken in May

(21 May, 2.8 mm SL) was collected in the central Gulf. In

June, larvae were found much nearer shore than during the

same period in 1982. Many of those larvae were small (2-3

mm SL), indicating inshore spawning as opposed to inshore

transport from offshore spawning sites. Abundance decreased

slightly in the offshore direction (Table 4), primarily because

the few positive stations on the inner shelf had relatively large

numbers of larvae.

Most of the 478 C. crysos larvae collected were taken in

June, when coverage of onshelfstations was good. Maximum

abundance in 1982, however, occurred during July when larvae were captured at all bongo stations sampled (Table 5).

Larvae in the 1-3 mm SL size range were caught in May,

June, and July (Figs. 1-4) indicating spawning each of those

months. Larvae longer than 6.0 mm SL were rarely captured.

The earliest spawning was indicated by a 4.5-mm SL larva

captured on 5 May, which points to a late-April hatch.

Table 4

Abundance (N/I0 m2 ) and depth distribution of target carangid

larvae by species and year. Numbers in parentheses are positivecatch stations per total stations sampled. Abundances and total

stations are for months during larval season only.

Taxa <40 m 40-182 m >182 m

Coram crysos

1982 4.8 (3/58) 2.8 (7171) 1.6 (4/64)

1983 0.4 (3122) 0.3 (1123) 0.2 (1/34)

Chloroscombrus chrysurus

1982 150.7 (11/20) 1.7 (4/23) 0.0 (0/59)

1983 81.3 (8/20) 2.2 (2/22) 0.0 (0/32)

Decapterus punctatus

1982 0.6 (4/58) 0.4 (4171) 0.0 (0/64)

1983 0.1 (1/22) 0.1 (1/26) 0.3 (2/40)

Trachurus lathami

1982 0.1 (1/43) 4.7 (13/56) 0.0 (0/54)

1983 0.0 (0/2) 11.2 (5/9) 0.5 (2/56)

At locations where recently hatched larvae «2.5 mm SL)

were captured, surface temperature was 28.8°-30.1 °C and

salinity 25.0-36.2 ppt (Table 6). At locations where all sizes

of larvae were captured, surface salinity was 24.8-37.7 ppt,

with most larvae captured at salinities below 33 ppt, despite

the predominance of collections near the shelfbreak. Surface

temperature at locations where all sizes of larvae were captured was 23.3°-32.0°C.

7
Table 5

Caranx crysos mean larval abundance (NII0 m2 ) as determined from metered bongo

tows, and mean catch-per-unit-effort (number captured/tow) as determined from neuston

and unmetered O.5-m ring net tows, for positive-eatch stations only. Spawning season

considered to be March-November (Ditty et al. 1988). For total SEAMAP yearly sampling effort by month, gear type, and depth, see Table 3.

Mean variable May June July

Bongo catch

1982 0.5 '(2/34) 3.0 (8139) 97.4 (4/4)

1983 0.3 (1119) 1.0 (4/24) 0.0 (0/5)

Neuston or ring catch

1982 2.0 (1/37) 25.1 (II/59) 4.0 (1/23)

1983 0.0 (0118) 5.3 (3/65) 0.0 (0/5)

Surface salinity (ppt)

1982 37.0 2(36-38) 31.6 (25-36) 30.2 (28-32)

1983 36.7 30.9 (25-35)

Surface temperature (0C)

1982 23.5 (23-24) 29.8 (28-32) 29.4 (29-30)

1983 26.9 27.2 (27-28)

Station depth (m)'

1982 106 (71-150) 259 (19-954) 30 (20-52)

1983 2926 21 (11-42) ._._--_.

'Frequency of occurrence: number of positive-catch stations per number ofstations sampled.

2Range of values.

'Sampling methodology for bongo nets limits tows to upper 200 m of water (see Methods

section).

Table 6

Mean surface salinities, temperatures, and water depths at sites where larvae <2.5 mm

SL were captured.

Salinity Temperature Station depth

(ppt) (0C) (m)

x min-max x min-max x min-max

Caranx crysos

1982 31.1 25.0-36.2 29.6 28.8-30.1 269 23-954

1983 *

Chloroscombrus chrysurus

1982 27.0 16.5-33.7 30.1 27.0-32.1 18 2-49

1983 26.4 19.8-36.1 27.6 26.7-28.7 17 6-51

Decapterus punctatus

1982 *

1983 *

Trachurus lathami

1982 ** 20.2 18.0-21.0 59 37-91

1983 36.0 35.8-36.3 22.3 21.8-23.0 III 102-121

*Larvae <2.5 nun SL were either not present or were too difficult to identify to species level.

**Salinity data not available.

8
CHLOROSCOMBRUSCHRYSURUS

JUNE

N = 1756

JULY

N = 396

100

80

60

40

20

a

>()

z

w

:;)

0

w

a:

u.

0

60

40

20

t .. + + t + t t t

II

w II 0 0 a >0 -10

C(

z 1234567891111

c EJ >10 - 100 0123 z .... ::) rill >100 - 1000 STANDARD LENGTH (mm) II)

C(

I'

Figure 5

Size-frequency distribution and abundance (N/l0 m2 ) of Chloroscombrus chrysurus larvae for positive-eatch months during 1982 SEAMAP bongo net collections off Louisiana. Stations sampled (+); N = total number caught.

Chloroscombrus chrysurus

Larval Atlantic bumper, our most abundant target species,

were captured along the entire Louisiana coastline, both east

and west of the Mississippi River delta, though highest concentrations were west of long. 91.5°W (Figs. 5-8). The

largest single-station catches taken by neuston net (679 fish,

6.4-13.0 mm SL) and by bongo net (953 fish or 2118 fish/

10 m2, 1.2-3.8 mm SL) were from south of central Louisiana in 18-20 m of water during 1982 and 1983, respectively. Most larvae were taken inshore of the 27-m isobath.

Only 40 of the 4675 larvae and early juveniles captured were

9

taken between 27 and 60 m, and beyond that only a single

4.9-mm SL larva was taken at 100 m.

Inner-shelf abundance was one to two orders of magnitude

above that of the other carangid larvae examined (Table 4).

Chloroscombrus chrysurus were also captured at 48 % of the

inner-shelf stations sampled, the highest among the target

carangids.

Atlantic bumper are primarily summertime spawners and

their larvae were captured during June and July only (Table

7). Spawning by Mayor perhaps earlier was indicated by

specimens as large as 13 mm SL taken as early as 17 June.

No larvae were found in pre-June SEAMAP collections, but
CHLOROSCOMBRUS CHRYSURUS

0 ....----...•

JUNE

N = 681

JULY

N = 779

1234567891111

0123

STANDARD LENGTH (mm)

100

80

60

40

20

0

>()

Z

W

"

w

a:

u..

-;!!.. 0

60

40

20

0

1

w >0 -10

IT] >10 - 100

u m

m >100 - 1000

II

21

21

Figure 6

Size-frequency distribution and catch-per-unit-effort (Nltow) of Chloroscombrus chrysurus larvae for positive-catch months

during 1982 SEAMAP neuston and half-meter ring net collections off Louisiana. Stations sampled: + neuston, *ring nets.

Catch: <> neuston, f:,. ring. N = total number caught.

10
CHLOROSCOMBRUSCHRYSURUS

100

> 80 0

z

w 60 :) JUNE + + a

w N = 1003 40 a:

u. w i-I 20 (.) >0 ·10 0

z LJ

c(

21 z

c [ill •• w •• >10·100 a

::J 1m 1234567891111

CD

c( >100 ·1000 0123

• >1000 STANDARD LENGTH (mm)

Figure 7

Size-frequency distribution and abundance (NII0 m2 ) of Chloroscombrus chrysurus larvae for June (the only positive-catch

month) during 1983 SEAMAP bongo net collections off Louisiana. Stations sampled (+); N = total number caught.

station coverage during those months was restricted to offshore waters where there is apparently no spawning. No larvae were captured in October SEAMAP samples (no cruises

in August or September), but adults are known to spawn off

Louisiana in August and September (D. Leffler, R. Shaw,

and D. Drullinger, unpubl. data). Length-frequency data indicated that larvae were generally longer in July than in June

(Figs. 5-8).

Recently hatched Ch. chrysurus larvae «2.5 mm SL) were

captured where surface salinity was 16.5-36.1 ppt (Table

6). Larger larvae were captured at salinities as low as 10.4

ppt. Mean salinity at spawning sites was well below 30 ppt,

which is typical for nearshore waters off Louisiana. Surface

temperature where recently hatched larvae were captured was

26.7°-32.1 °e, and larger larvae were found generally within

the same temperature range.

11

Table 7

Chloroscombrus chrysurus mean larval abundance (NII0 m2 ) as

determined from metered bongo tows, and mean catch-per-uniteffort (number captured/tow) as determined from neuston and

unmetered O.5-m ring net tows, for positive-catch stations only.

Spawning season considered to be April-November (Ditty et aI. 1988;

this work). For total SEAMAP yearly sampling effort by month,

gear type, and depth, see Table 3.

Mean variable June July

Bongo catch

1982 176.3 '(11139) 282.4 (4/4)

1983 22.5 (10/24) 0.0 (0/5)

Neuston or ring catch

1982 49.1 (14/59) 97.8 (8/23)

1983 5.3 (7/65) 1.0 (1/5)

Surface salinity (ppt)

1982 26.7 2(10-34) 27.2 (18-32)

1983 25.8 (12-36)

Surface temperature (0C)

1982 29.7 (27-32) 30.1 (29-32)

1983 27.3 (25-29) 30.0

Station depth (m)3

1982 23 (9-100) 19 (2-52)

1983 18 (6-51) 90

1Frequency of occurrence: number of positive-catch stations per number

of stations sampled.

2Range of values.

lSampling methodology for bongo nets limits tows to upper 200 m of

water (see Methods section).
CHLOROSCOMBRUS CHRYSURUS

100

-80

60

JUNE

40 N = 37

20

>

0 0

Z

W

0

w

a:

LL

0 100

80

60

JULY

40 N = 1

20

0

1234567891111

0123

STANDARD LENGTH (mm)

a.

w 0 >0 -10

;:)

c. [].. >10 - 100

u

II >100 - 1000

21 + t ..

a.

o

00

Figure 8

Size-frequency distribution and catch-per-unit-effort (Nltow) of Chloroscombrus chrysurus larvae for positive-eatc~ months

during 1983 SEAMAP neuston and half-meter ring net collections off Louisiana. Stations sampled: + neuston, *rmg nets.

Catch: <> neuston, /:;. ring. N = total number caught.

Decapterus punctatus

Larval round scad were captured most commonly off western

Louisiana, with no larvae collected east of the Mississippi

River delta (Figs. 9-12). Preflexion larvae were collected

between 13 and 115 m (usually <40 m) during June and July,

indicating inner- to rnidshelfspawning during those months.

The few larvae captured in March, May, October, and

December were widely scattered, primarily beyond the 48-m

isobath. Highest abundances were on the continental shelf

during 1982 but beyond the shelf during 1983 (Table 4).

A total of81 larvae and early juveniles (2.6-13.9 mm SL)

were captured off Louisiana during 1982 and 1983. Ofthose,

70 were taken in 1982. Only 5 of 11 larvae captured in 1983

were taken in bongo nets, so abundance calculations are based

on very small catches. Overall, D. punctatus were the least

abundant of the four species examined.

Larvae were most abundant in June and July (Table 8);

specifically in July of 1982, when they were captured in 3

of 4 bongo tows and 2 of 2 neuston tows off west Louisiana.

Unfortunately, the low number ofsamples taken at that time

prevented a determination of how widespread the larvae

12
30 100

80

60

2. MARCH

N = 1 40

20

28 a

DECAPTERUS PUNCTATUS

> 60

u JUNE

z 40 N = 14 + . + w

::>

0

w 20

a:

LL

a 28 0

28

Will u' Z L-.J

C( EJ···· c····.. Z :::::

~11

>0 ·10

>10 - 100

>100 - 1000

60

40

20

a

JULY

N = 5

1234567891111

0123

STANDARD LENGTH (mm)

Figure 9

Size-frequency distribution and abundance (NII0 m1 ) of

Decapteruspunctatus

larvae for positivecatch months during

1982 SEAMAP bongo

net collections off

Louisiana. Stations

sampled (+); N =

total number caught.

13
DECAPTERUS PUNCTATUS

JUNE

= 6

JULY

N = 41

1234567891111

0123

STANDARD LENGTH (mm)

0-'-----

100

80

60

40

20

0

>()

z

w

0

w

a:

LL

0

60

40

20

, , ,

>0 -10

>10 - 100

>100 - 1000

, , ,

w LJ

::>a Q.L;1 Ulfl

30

.1

30

.1'

.1

Figure 10

Size-frequency distribution and catch-per-unit-effort (Nltow) of Decapterus punctatus larvae for months with positive neuston

catches during 1982 SEAMAP neuston and half-meter ring net collections off Louisiana. Stations sampled: + neuston, * ring nets. N = total number caught; no larvae taken in ring nets.

14
MAY

N =

20

40

60

80

O-l--------

100

, t

, + <>

a.

DECAPTERUS PUNCTATUS

o

20

3

JUNE

N = 40

>- 60 ()

z

w

::::>

o

w

a:::

LL

cf.

Figure 11

Size-frequency distribution and abundance (N/I0 m2 ) of

Decapterus punctatus

larvae for positivecatch months during

1983 SEAMAP bongo

net collections off

Louisiana. Stations

sampled (+); N =

total number caught.

1234567891111

0123

STANDARD LENGTH (mm)

O...L---- >0 ·10 0

>10·100

>100· 1000

) L-_" .. f) 100 30 ) ---1

'~-~~£ 80

~-~ 60 DECEMBER .... + + + N = 1 40

20

15
DECAPTERUS PUNCTATUS

II

4

JUNE

N =

OCTOBER

N = 2

1234567891111

0123

STANDARD LENGTH (mm)

0-'----

100

80

60

40

20

0

>()

Z

W

::J

"

W

a:

u.

0

60

40

20

>0 -10

>10 - 100

>100 - 1000

[] W

:::J~

c.~ ullm

I'

Figure 12

Size-frequency distribution and catch-per-unit-effort (Nltow) of Decapterus punctatus larvae for months with positive neuston

catches during 1983 SEAMAP neuston and half-meter ring net collections off Louisiana. Stations sampled: + neuston,

* ring nets. N = total number caught; no larvae taken in ring nets.

actually were. Surface-towed 0.5-m ring nets were used

extensively in nearshore waters during June and July, but

no larval D. punctatus were taken, possibly because the ring

nets were used to depths of only 9 m. No specimens were

captured inshore of 13 m, even in bongo or neuston nets

towed in waters as shallow as 5 m.

June and July were the only months when larvae less than

6.0 mrn SL were captured. In addition, year-round spawning was indicated by the presence of a 8.2-mm SL larva captured on II March, a 12.6-mrn individual ca~tured on 3 May,

a 6.4-mrn larva captured on 14 December; and two individuals, 6.8 and 7.8 mrn, captured on 12 October (Figs. 9-12).

Surface temperatures and salinities at spawning sites could

not be clearly determined because of the lack ofrecently hatched specimens «2.5 mm SL). Not only were small fish

lacking in our samples, but the problem may have been compounded by the difficulty in identifying early post-yolksac

D. punctatus. Surface-temperature and salinity means

(ranges) at locations where all sizes of larvae were captured

were 28.5°C (l9.00-30.0°C) and 29.8 ppt (27.6-33.2 ppt),

respectively, in 1982; and 26.2°C (23.1 °-27.40c) and 34.3

ppt (33.3-36.4 ppt), respectively, in 1983.

16
Table 8

Decapterus punctatus ~ean larval abundance (N/I0 m2) as determined from metered bongo tows, and mean catch-per-unit-effort (number captured/tow) as determmed from neuston and unmetered O.S-m ring net tows, for positive-catch stations only. Spawning season considered to

be year-round (Ditty et al. 1988; this work). For total SEAMAP yearly sampling effort by month, gear type, and depth, see Table 3.

NS = no samples taken; NA = data not available.

May June July

0.0 (0/34) 1.4 (4/39) 3.5 (3/4)

0.3 (1/19) 0.4 (2/24) 0.0 (0/5)

0.0 (0/37) 3.0 (2/59) 22.0 (2/23)

0.0 (0/18) 2.0 (2/65) 0.0 (0/5)

29.6 2(28-33) 29.6 (28-32)

34.2 34.0 (33-36)

29.1 (27-30) 29.5 (29-30)

23.1 27.2 (27-28)

38 (13-88) 24 (20-27)

1181 47 (24-115)

October November December

0.0 (0/2) 0.0 (0/28) NS

0.0 (0/12) NS 0.7 (1/9)

0.0 (0/3) 0.0 (0/3) NS

2.0 (1/4) NS 0.0 (0/8)

33.4 36.4

26.3 25.0

494 3111

NS

NS

NS

NS

September

April

0.0 (0/23)

0.0 (0/14)

0.0 (0123)

0.0 (0/14)

NS

NS

NA

August

NS

NS

NS

0.0 (0/3)

0.1 '(1/63)

0.0 (0/5)

48.0

19.0

Mean variable

Neuston or ring catch

1982

1983

Surface salinity (ppt)

1982

1983

Surface temperature (OC)

1982

1983

Station depth (m)3

1982

1983

Bongo catch

1982

1983

Neuston or ring catch

1982

1983

Surface salinity (ppt)

1982

1983

Surface temperature (0C)

1982

1983

Station depth (m)3

1982

1983

Bongo catch

1982

1983

March ------------_.

'Frequency of occurrence: number of positive-catch stations per number of stations sampled.

2Range of values.

3Sampling methodology for bongo nets limits tows to upper ZOO m of water (see Methods section).

Trachurus lathami

Sampling during December, April, and May (Figs. 13-15)

in waters greater than 100 m deep revealed larval rough scad

scattered between 102 and 3111 m (Table 9); however, they

were generally found at the edge of the shelfbreak, possibly

indicating concentrations on the sparsely sampled outer shelf.

During March (1982 only), good onshelf station coverage

in the Mississippi River delta area revealed that larvae were

in fact relatively common on the outer shelf, but that they

were virtually absent on the inner shelf.

A total of 102 larvae (1.8-7.7 mm SL) were captured off

Louisiana during 1982 and 1983. Larvae were caught at 26

stations, but the numbers caught at each station were always

low. Mean abundance on the outer shelf was clearly higher

17

than that of the other three target carangids, but abundances

on the inner shelf and offshore were very low (Table 4). In

overall abundance they ranked third.

Relatively small larvae (1.8-7.7 mm SL) were present during all months of capture, December, March, April, and May

(Figs. 13-15), indicating spawning throughout winter and

spring. Length-frequency data were insufficient to provide

information about spawning peaks or periods.

Recently hatched larvae «2.5 mm SL) were found at surface temperatures of 18.00 - 23.0 0 C and salinities of 35.8-

36.3 ppt (Table 6). Many small larvae were captured near

the mouth of the Mississippi River on a cruise in March 1982

a time when there was considerable freshwater input. Thei;

proximity to that freshwater discharge would indicate that

they are quite tolerant of low salinities. Unfortunately, no
TRACHURUS LATHAMI

w 21 ()

z 0 >0 ·10

OIl( EJ Q

z .... >10·100

IX)

OIl( m>100 - 1000

100

> 80

()

z

w 60

:::;) MARCH 0

w N = 57 40

a:

LL

20 0

0

1234567891111

0123

STANDARD LENGTH (mm)

Figure 13

Size-frequency distribution and abundance (N/I0 m') of Trachurus lothami larvae for March (the only positivc-<atch month)

during 1982 SEAMAP bongo net collections off Louisiana. Stations sampled (+); N = total number caught.

salinities were recorded on that particular cruise, so our

reported minimum salinities at capture sites are probably

high. At locations where all sizes of larvae were captured,

surface temperatures were 18.0o

-25.0°C, and salinities were

32.0-36.4 ppt.

Discussion

Three ofthe species examined, Caranx crysos, Chloroscombrus chrysurus, and Decapterus punctatus, have summertime spawning periods, though D. punctatus was captured

during all seasons. Maximum abundances for all three ofthe

summer-spawning species occurred during July 1982. During that month only four stations were sampled (off western

Louisiana near midshelf), but three of those stations yielded

larvae of all three species, and only D. punctatus was absent from the fourth. Larvae of the summer-spawning species

were otherwise rarely captured together (especially C. crysos

and Ch. chrysurus). At those July stations, four other larval

or early-juvenile carangid species were also captured: Caranx

hippos or latus, Oligoplites saurus, Selar crumenophth2lmus,

and Selene setapinnis (Shaw and Drullinger, unpubl. data).

In a study off western Florida, C. crysos shorter than 5.5

mm SL were found only beyond the 67-m isobath, and were

thought to have a completely separate depth distribution from

the nearshore-dwelling Ch. chrysurus (Leak 1981). Montolio

(1976), however, found C. crysos larvae primarily in depths

of 10-20 m in Gulf waters off the UniteC: States and Mexico. Data presented herein are intermediate between those

of Leak and Montolio. In 1982, larvae were usually con18

centrated beyond 40 m, but in 1983 they were frequently

captured inside the 40-m isobath and as shallow as 11 m.

There appears to be yearly or geographical variability in the

depth distribution of C. crysos larvae.

In comparison with the other carangids examined, C.

crysos had the highest offshore abundance. On the inner

shelf, C. crysos abundance ranked a distant second to that

of Ch. chrysurus, and on the outer shelf (40-182 m) it was

below only that of T. lathami. Based on an ongoing survey

around the Mississippi River delta in which C. crysos larvae dominated summertime collections (Shaw and Drullinger, unpubl. data), this species may be much more abundant than the SEAMAP coverage would indicate. SEAMAP

summertime larval C. crysos abundance may have been

underestimated if abundances were, in fact, highest on the

shelf prior to or after June and July. In further support of

this, spawning peaks for C. crysos in the north-central Gulf

have been found to occur in April-May and in AugustSeptember (Montolio 1976), mostly on the shelf. This species

requires further study of its geographical and yearly variability in spawning depth and season to elucidate actual larval

distribution and abundance.

Similarly, little is known about Ch. chrysurus larvae from

off Louisiana. In general, this and previous studies characterize Ch. chrysurus as a nearshore spawner and the most

abundant carangid in the north-central Gulf. We found Ch.

chrysurus larvae to be concentrated mostly off central and

western Louisiana. Salinities reported from capture sites off

Louisiana were often lower (as low as 10.0 ppt) than those

reported from Florida (Leak 1977, 1981).
30 100

80

60

APRIL

40 N = 13

1.0

21'

0

Ie

100

_.~

> 80 (J

Z

II W 60 , , 0 MAY

w 40 N = <> + , a::

u.

0 20 .. 0

.. OW

z

01 >0 -10

[ill >10 - 100

Ii] >100 - 1000

60

40

20

o

DECEMBER

N = 14

1234567891111

0123

STANDARD LENGTH (mm)

Figure 14

Size-frequency distribution and abundance (N/I0 m2 ) of

Trachurus lathami

larvae for positivecatch months during

1983 SEAMAP bongo

net collections off

Louisiana. Stations

sampled (+); N =

total number caught.

19
TRACHURUS LATHAMI

+ +

100

80

60

APRIL

40 N = 15

20

a

>

()

Z

w

:::>

"

w

a:

Ll.

0

60

MAY

40 N = 2

20

a

1234567891111

0123

STANDARD LENGTH (mm)

<>

21 W 0 >0 ·10

;:)

Q. EJ..... >10·100

U

iii >100·1000

93

o

21

A,+

v

30

Figure 15

Size-frequency distribution and catch-per-unit-effort (N/tow) of Trachurus lathami larvae for positive-catch months during

1983 SEAMAP neuston net collections off Louisiana. Stations sampled (+); N = total number caught.

Decapterus punctatus are considered common east of the

Mississippi River (Hoese and Moore 1977), but their larvae

were absent adjacent to the delta and offthe Mississippi coast.

They were the least-common target carangid off LouIsiana,

except on the inner shelf where they were more abundant

than T. lathami. Depth distribution for larval D. punctatus

on the Louisiana shelf and off Florida's west coast were

similar (Leak 1977, 1981). Their adults may migrate offshore for the winter and back onshore during spring (Leak

1977, 1981). Discovery of a 6-mm SL larva far offshore in

the central Gulf during December may indicate spawning in

that winter offshore population.

The principal winter-spawning species, T. lathami, has

been found to school as adults with a winter-spawning clupeid

Etrumeus teres (Reintjes 1979a, Leak 1981). We found the

distribution of larvae of these two species to closely overlap

on the outer shelf during March (Shaw and Drollinger 1990).

Larvae were in close proximity to the mouth of the Mississippi River at a time ofrelatively high discharge. Trachurus

lathami spawning is known to be associated with "high

amplitude events" or gradients (Leak 1977, 1981), so it was

not surprising to find their larvae associated with zones

ofturbulent mixing between the Mississippi River plume and

the high-salinity oceanic waters of the open Gulf.

20
Table 9

Trachurus latham; mean larval abundance (N/I0 m2 ) as determined from metered bongo tows, and mean catch-per-unit-effort (number captured/tow) as determined from neuston and unmetered O.5-m ring net tows, for positive-eatch stations only. Spawning season considered to

be November-May (Ditty et al. 1988). Note gap between December and March; for total SEAMAP yearly sampling effort by month, gear type,

and depth, see Table 3. NS = no samples taken; NA = data not available.

Mean variable December March April May

Bongo catch

1982 NS 4.7 (14/63) 0.0 (0/23) 0.0 (0/34)

1983 9.2 '(3/9) 0.0 (0/5) 4.9 (3/14) 0.3 (1/19)

Neuston ring catch

1982 NS NS 0.0 (0/23) 0.0 (0/37)

1983 0.0 (0/8) 0.0 (0/3) 5.0 (3/14) 1.0 (2/18)

Surface salinity (ppt)

1982 NA

1983 36.0 35.5 2(32-36) 36.2 (36-36)

Surface temperature (0C)

1982 20.3 (18-22)

1983 23.3 (22-25) 21.8 (20-23) 22.9 (22-23)

Station depth (m»)

1982 63 (37-91)

1983 1111 (102-3111) 658 (102-2926) 1427 (459-2268)

'Frequency of occurrence: number of positive-catch stations per number of stations sampled.

2Range of values.

3Sampling methodology for bongo nets limits tows to upper 200 m of water (see Methods section).

The vast majority of T. lathami larvae were captured

between 40 and 182 m, which agrees with previous findings

off Florida (Houde et al. 1984) and Louisiana (Ditty and

Truesdale 1984). Reported adult distributions are similar

(Mansueti 1960, Fischer 1978b).

Larvae of T. lathami superficially resemble those of D.

punctatus, but behaviorally they may be quite different. Most

D. punctatus captured were large; about half were near or

above the maximum cutoff size for fish included in this

analysis (13.9 mm), and only 10 were below 5.0 mm SL.

Conversely, only small T. lathami were captured; none were

above 7.7 mm SL, and only 10 were above 5.0 mm SL. It

appears that T. lathami larvae longer than approximately 8.0

mm SL either dwell nearbottom, below maximum bongo

sampling depth, or are much more capable of avoiding capture than are D. punctatus of equal size. Since adult and

juvenile T. lathami reside near the bottom (Stuck and Perry

1982), the hypothesis that larvae avoid capture through a

demersal lifestyle has some credence. Juveniles of D. punctatus are nearsurface pelagics (Fischer 1978a) especially during the daytime (Fahay 1975), which could account for our

capture oflarger fish in surface and oblique gear. The reason

for low numbers of small D. punctatus remains a mystery,

except that a few were possibly misidentified and therefore

not included in this analysis.

21

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25
Caranx crysos (Mitchill) blue runner

Other scientific names recently used: C. fusus (Reintjes

1979a).

Adult Distribution

Geographic

Western North Atlantic Found from Halifax Harbor,

Nova Scotia, throughout the Gulf of Mexico, Caribbean, Bermuda, and West Indies to Cananeia and Sao Paulo, Brazil

(Fischer 1978a). Has 28 species of Carangidae (Aprieto

1974); other Caranx spp. in the Gulf of Mexico are C. bartholomaei, C. hippos, C. latus, C. lugubris, C. ruber (Hoese

and Moore 1977; Laroche et aI., in prep.); C. sexfasciatus

(circumtropical) and C. vinctus, whose juveniles resemble

C. crysos (Nichols 1939, 1944); C. dentex (Berry 1959); and

C. guara (Erdman 1956, Puerto Rico).

Vertical (depth) or distance from shore

A pelagic schooling fish (Reintjes 1979a) almost always taken

in upper 100 m (McKenney et al. 1958), apparently present

over the continental shelf as juveniles and adults, but uncommon, if at all, in Gulf estuaries (Leak 1977).

Stock Abundance

Presently unknown for the Gulf-clearly an area of needed

research.

Fisheries

Gulf of Mexico

Northern Gulf Traditionally used for bait, but recently sold

as fresh and frozen food fish; potential for export marketing

(Reintjes 1979a).

Florida Over 278,379 kg sold ($26,880) as food fish from

both coasts of Florida in 1956; highly prized live bait for

amberjack Seriola spp., and sailfish Istiophorus platypterus

(McKenney et al. 1958). Catch fluctuated between 270 and

99 metric tons (t) in the last decade; taken primarily by beach

seine in northwestern Florida April-September and sold as

bait for snapper (family Lutjanidae) or to Puerto Rico and

the Virgin Islands as food (Leak 1977).

Louisiana/Mississippi Off the barrier islands, large incidental catches often taken by commercial red drum

(Sciaenops oceliatus) purse-seiners, who often set on the

surface-schooling C. crysos, which stack over red drum

schools (Overstreet 1983).

26

Other

Gulf and Caribbean Important food item in West Indies

and Gulf, eaten in Puerto Rico and Trinidad (McKenney

et al. 1958).

Gulf According to 1975 FAO statistics, catch in the Gulf

(Area 31) of 6579 t-only 635 t landed in the U.S.-marketed

fresh or salted (Fischer 1978a).

Small fisheries for Caranx spp. worldwide; fish imported

from the United States sold as food in Puerto Rico and the

Virgin Islands (Leak 1977).

Problems

Recognized as a respectable game fish (Berry 1959) and baitfish (McKenny et al. 1958, Reintjes 1979a).

Reproduction

Sexual maturity

Northwest Florida Age-at-maturity size ~267 mm fork

length (FL), based on 185 fish taken May-August (Goodwin and Finucane 1985).

South Pass, Louisiana Four females (247-267 mm SL)

with enlarged ovaries (but not running ripe) and one male

(225 mm SL) with enlarged testes taken in July (Berry 1959).

Pensacola Beach, Florida Gonads ofsix specimens (three

males and three females) taken in July were enlarged but not

as well developed as those of the South Pass, Louisiana,

specimens (Berry 1959).

Sex ratio

Northwest and south Florida Male-to-female ratio significantly different from 1:1 (1.0M:1.66F and 1M:1.91F,

respectively) whereas 1M: 1.15F off the Mississippi River

delta (Goodwin and Finucane 1985).

Fecundity

Off south and northwest Florida and Mississippi River

delta Based on 25 fish, fecundity ranged from 41 ,000 (243

mm FL, 288 g) to 1,546,000 ova (385 mm FL, 1076 g)

(Goodwin and Finucane 1985).

Spawning season

Spawning takes place at night for Caranx sp. from Madras,

India (Subrahmanyam 1964).
Off south aud northwest Florida and Mississippi River

delta June-August spawning season, based on data collected using a gonadosomatic index (GSI), but a second and

significant GSI peak observed off northwest Florida in October 1980 and 1981 with small females (200-250 mm FL)

suggests the possibility of two spawning peaks in the Gulf,

which might explain the presence of larvae year-round

(Goodwin and Finucane 1985).

Gulf Larvae found throughout but greatest densities in the

central region; most abundant April-May and AugustSeptember in 10-20 m depths (Montolio 1976).

Eastern Gulf Twelve larvae identified as C. crysos, 72 as

Caranx spp.; virtually all taken beyond the 50-m contour

during spring-summer (Houde et al. 1979).

Florida and Caribbean Spawning possibly year-round, but

primarily January-August with a peak in summer (AprilAugust), when 75% of the postlarvae were collected; larvae and juveniles taken over deep water in upper 100 m in

temperatures of20o-30.8°C and salinities of33.2-36.2 ppt

(McKenney et al. 1958).

West Florida Caranx spp. larvae beyond the 50-m isobath

and>140 km offshore; C. crysos move offshore to spawn;

larvae taken in August-no larvae <5.5 mm taken at stations

shallower than 67 m (Leak 1977, 1981).

Puerto Rico Based on ripe or near-ripe gonads, spawns

in May (Erdman 1956).

Southeastern U.S. coast Spawns offshore near or beyond

183-m contour early April-early September (based on a

12.4-mm SL individual taken in May and a 13.2-mm SL

specimen taken in October); concentrations of larvae and

juveniles found in the Gulf Stream May-November (peak

June to mid-August), larvae taken in temperatures of

20.4°-29.4°C and salinities of 35 .2-36.0 ppt (Berry 1959).

U.S. South Atlantic Bight Total of 59 larvae taken yearround, but most taken January-August with a peak in summer (Fahay 1975).

North and South Atlantic Larval specimens taken from

Nova Scotia to Brazil in all months except September and

November; most taken January-August, particularly after

April (Leak 1977).

Eggs

General description

No information for C. crysos.

Hawaii Caranx mate eggs are pelagic, clear, and spherical,

with a yolk diameter ofO.66±0.02 mm (Miller and Sumida

1974).

27

General characters for Carangidae eggs (Fahay 1983:240):

"Pelagic, shell smooth, yolk homogeneous or segmented,

I oil globule anterior in late eggs and hatchling (eggs described in only a few species)."

Egg diameter

No information for C. crysos.

Caranx mate egg diameter (live) 0.72±0.02 mm (Miller and

Sumida 1974).

Perivitelline space

No information for C. crysos.

Caranx mate perivitelline space 0.026±0.004 mm (Miller

and Sumida 1974).

Oil globule

No information for C. crysos.

Caranx mate has one oil globule 0.19-0.20 mm (Miller and

Sumida 1974).

Incubation time

No information for C. crysos.

Caranx mate incubation time of26 h at 24.5°C (Miller and

Sumida 1974).

Larvae

Hatching length

No information for C. crysos.

Caranx mate larvae hatch at a mean length of 1.46 mm SL

(range 1.32-1.70 mm SL; N=47), preserved mean length

of 0.98 mm SL (0.87-1.03 mm SL; N= 10) (Miller and

Sumida 1974).

Early-life-history information

Gulf During four research cruises in 1973-74, the greatest

concentrations of fry taken in depths of 10-20 m; no significant ratio between day and night catch (Montolio 1976).

Florida and Caribbean No evidence of any diurnal migration in larvae collected (McKenney et al. 1958).

Charleston, South Carolina Significantly more larvae

caught (total number 191; 7-37 mm TL) with a Boothbay

neuston net during the day than at night in July (Eldridge

et al. 1977).
Southeastern U.S. coast Larvae and juveniles have an

affinity for the Gulf Stream and offshore waters; some move

inshore after attaining lengths of 80-100 mm (Berry 1959).

Laroche et al. (in prep.) cite Chacko (1950) and Padoa (1956)

as providing early-life-history information from the Indian

Ocean and Gulf of Napoli, respectively.

Meristics

Dorsal VIII + 1,22-25, well formed at 5.4 mm SL (Berry

1959, southeast U.S. coast); VIII+I, 23 (Boschung 1957,

Mobile Bay, Alabama).

Anal II + I (full complement by 5.4 mm SL), 19-21

(developed by 7.5-8.5 mm SL, Berry 1959); 11+1, 20

(Boschung 1957).

Pectorals I, 19-23 (by 8.5 mm SL, Berry 1959).

Myomeres 25 (Fahay 1983, northwestern Atlantic).

Larval description

Gulf Illustrations of wild-caught larvae (Monto1io 1976).

Caranx sp. (Laroche et aI., in prep.).

Florida and, Caribbean Illustrations and comparative information fpr wild-caught larvae (McKenney et aI. 1958).

West Florida Comparative descriptions and early-lifehistory information for wild-caught larvae (Leak 1977).

Southeastern U.S. coast Illustrations and comparative

information for wild-caught larvae; also illustrations of C.

bartholomaei and C. hippos/latus larvae (Berry 1959).

U.S. Mid-Atlantic Bight Atlas of larval stages compiled

from the works of other authors listed above (Johnson 1978).

West Africa Illustrations and comparative information for

wild-caught larvae; also illustrations of C. rhonchus and C.

senegallus larvae (Aboussouan 1975). C. rhonchus (Conand

and Franqueville 1973).

Java Sea Caranx sp., C. armatus, C. crumenophthalmus,

C. kurra, C. macrosoma (Delsman 1926).

India C. kalla (Bapat and Prasad 1952).

Juvenile

Undergoes metamorphosis at "-'8.5 mm SL; virtually all adult

characteristics present at 59.3 mm (Johnson 1978).

Juveniles associated with floating objects such as Sargassum

(Dooley 1972, Bortone et aI. 1977, Fischer 1978a).

West Florida One juvenile taken in May, and 19 taken in

June-july over depths of 70-225 m (Leak 1977).

Dauphin Island, Alabama One juvenile (146 mm) taken

in June (Swingle 1971).

28

Mississippi Juveniles (21-30.0 mm SL) taken off barrier

islands in August surface tows (Stuck and Perry 1982).

Central Gulf Juveniles and larvae most abundant during

April-May and August-September (Montolio 1976).

Louisiana One juvenile (45 mm) taken in June in waters

29.3°C and 21.8 ppt (Perret et aI. 1971).

Gulf Stream off southeastern U.S. coast Juveniles collected April-May to October (Berry 1959, Dooley 1972) and

year-round, with a peak in summer (Fahay 1975).
Chloroscombrus chrysurus (Linnaeus) Atlantic bumper

Adult Distribution

Geographic

Western Atlantic and Gulf Found from Cape Cod, Massachusetts, to Uruguay and throughout the Gulf of Mexico

(Briggs 1958); offBermuda and possibly throughout the West

Indies (Fischer 1978a); uncommon north of South Carolina

(Hildebrand and Schroeder 1928).

Vertical (depth) or distance from shore

Eastern Gulf Adults and juveniles present nearshore along

beaches and within estuaries spring-fall, but absent in winter

(Leak 1977).

Adults school around pilings and range offshore to the

l800-m isobath, but are generally taken within l8-m contour (Klima 1971, Johnson 1978).

Stock Abundance

Gulf of Mexico

Gulf Common in shallow Gulf and high-salinity bays

(Hoese and Moore 1977). Commonly taken by both seining and trawling in open waters (Ginsburg 1952).

West Florida Abundant nearshore and accessible to coastal

fisheries (Leak 1981).

Mississippi Sound Sixteenth-most abundant species taken

(Christmas and Waller 1973).

Louisiana Most abundant carangid collected (Perret et al.

1971).

OffCaminada Pass, Louisiana Fifth-most abundant taxa

of larvae collected, representing 94 % of all carangid larvae

taken and 5% of the total number of larvae collected (Ditty

1986).

Texas Fourth-most abundant species taken in nearshore

trawling during 1965 (Compton 1965).

Other

No data found.

Fisheries

Gulf of Mexico

Little potential as a food fish, but possible potential for a

reduction or pet-food fishery because of nearshore abundance; presently no directed fishery, probably would develop

only as a bycatch-in 1979, 700 t were landed in the north29

eastern Gulf as bycatch of a baitfish and shrimp-trawl fishery

(Leak 1977,1981).

Other

Venezuela No specific fishery but abundant locally and

marketed fresh, salted, and frozen (Fischer 1978a).

West Africa Landings of 1000-1200 t/yr (Conand and

Franqueville 1973; Leak 1977, 1981).

Problems

Very bony (Leak 1977).

Reproduction

Sexual maturity

Texas Males mature by 137 mm and females by 155 mm

(Gunter 1945).

Both males and females mature by 135 mm (Reintjes 1979a)

Sex ratio

No species-specific data found.

Fecundity

No species-specific data found.

Spawning season

Eastern Gulf All 774 larvae taken in spring and summer

within the 50-m depth contour with 95 % of occurrences in

depths <35 m (Houde et al. 1979).

West Florida Spawns May-November (peak in AugustSeptember); taken in surface temperatures of 24°-31°C

(peak 29°-3rC) and salinities of 27-37 ppt (peak 36-37

ppt) within the 50-m isobath (primarily within the 30-m contour and within 80 kID of shore); larvae <3.5 mm look like

Caranx crysos, but spawning areas separate enough to allow

"cautious identification" (c. crysos spawns at depths >50

m and >140 kID offshore) (Leak 1977, 1981).

Everglades, southwest Florida In coastal waters, 3751

specimens taken (depths 0.8-12 m) in temperatures of

20.8°-30.0°C and salinities of31.9-38.4 ppt during quarterly sampling; most abundant in May (1.5-9.5 mm SL larvae

collected) and August (1.2-5.3 mm SL); taken year-round

in coastal waters, one specimen (14 mm SL) taken in estuarine waters in August (Collins and Finucane 1984).
Lower Mobile Bay, Alabama Total of261 larvae (x length

2.5 mm) taken July-October, peak in August; fifth-most

abundant larval species (2.8% of total catch) (Williams

1983).

Back and Biloxi Bays, Mississippi Total of 22 larvae taken

in July and August (Shultz and Richardson 1985).

Mississippi Sound Specimens 5-21 mm TL taken in plankton tows June-July and specimens 35 mm TL or less JuneOctober; spawning seems to peak in summer (Christmas and

Waller 1973).

Mississippi Offthe barrier islands, larvae (2.0-7.0 mm SL)

taken June-October, with peak in August; 92 % taken in

waters 23°-31°C (Stuck and Perry 1982).

Barataria and Timbalier Bays, Louisiana Spawns in

depths <20 m, <15 krn offshore in July and August; 1061

larvae (2.0-18.6 mm) taken (Walker 1978).

Caminada Bay, Louisiana Total of 147 specimens (l0-51

mm SL) collected June-August with a peak in July (Sabins

1973).

OtT Caminada Pass, Louisiana During an ichthyoplankton

survey November 1981-0ctober 1982, larvae taken JuneOctober with a peak abundance in July; 94% of larvae taken

when surface water temperatures averaged 30°C, most (60%)

near mid-depth, 31 % near surface, and 9% near bottom

(Ditty 1986).

Central Gulf Larvae collected between the Mississippi and

Atchafalaya river deltas and the 10-100 m isobaths during

July 1976; 95 % taken inside 25-m contour (Ditty and

Truesdale 1984).

Aransas-Corpus Christi Bay Complex, Texas Total of

129 larvae taken June-November, peak June-July (Allshouse

1983).

Aransas Pass, Texas Larvae (6-28 mm) collected JuneSeptember (Hoese 1965).

Texas Ripe males and females taken June and August

(Gunter 1945).

Southeastern U.S. Probably spawns spring-summer

(Fischer 1978a).

U.S. South Atlantic Bight Eight larvae taken MayOctober (Fahay 1975).

Southern Brazil Larvae taken over continental shelf

August-November in waters 18°-22°C (Leak 1977).

Eggs

General description

No species-specific data found.

30

General characters for Carangidae eggs (Fahay 1983:240):

"Pelagic, shell smooth, yolk homogeneous or segmented,

1 oil globule anterior in late eggs and hatchling (eggs described in only a few species)."

Egg diameter

No species-specific data found.

Perivitelline space

No species-specific data found.

Oil globule

No species-specific data found.

Incubation time

No species-specific data found.

Larvae

Hatching length

No species-specific data found.

Early-life-history information

Caminada Pass, Louisiana Caught mostly during daytime

ebb tides (Sabins 1973).

Meristics

Dorsal VIII + I, 26-28 (modally 27) (Johnson 1978, MidAtlantic Bight); VIII + I, 25-28 for juveniles (Laroche

et aI., in prep., Gulf); VIII +1, 27-28 (Boschung 1957,

Mobile Bay, Alabama); VII-VIII + 1,24-28 (Fahay 1983,

northwest Atlantic).

Anal 11+1, 25-27 (Johnson 1978); 26-28, usually 27

(Boschung 1957); II + I, 25-28 (Laroche et a!., in prep.).

Pectorals 18-20, predominantly 19 (Johnson 1978); 19-20

(Boschung 1957); 20-21 formed by 9.5 mm SL (Laroche

et a!., in prep.).

Vertebrae 10+ 14 (Miller and Jorgenson 1973, Western

Atlantic; Laroche et a!., in prep.).

Larval description

West Florida Comparative descriptions and early-lifehistory information for wild-caught larvae (Leak 1977).

Northern Gulf Illustrations and comparative information

for wild-caught larvae (Laroche et a!. 1984, In prep.).
West Africa lllustrations and comparative information for

wild-caught larvae (Aboussouan 1975). C. cosmopolita

(Aboussouan 1968).

Juvenile

Young fish may occur far offshore (Fischer 1978a); frequently associated with jellyfish (Reid 1954, Franks 1970, Fischer

1978a).

Buttonwood Canal, Everglades, Florida Total of 24

specimens taken September-November in water temperatures

of 23.3°-34.0°C and salinities of 15.5-41.1 ppt (Roessler

1970).

Alligator Harbor, Florida Young taken in early September

(Joseph and Yerger 1956).

West Florida Juveniles taken along beaches and within

estuaries spring-fall, but absent during winter (Leak 1977).

Six specimens (42-46 mm) taken from marshes in October

(25°C, 30.2 ppt) (Kilby 1955).

Cedar Key, Florida Total of 17 juveniles (30-47 mm)

taken in October (23°-24°C, 21.8-22.0 ppt) (Reid 1954).

Tampa Bay, Florida Two specimens (23.2 and 39 mm)

taken in July (Springer and Woodburn 1960).

Alabama Total of 113 specimens taken in estuaries July

(one 2l-mm fish) to December (one 39-mm fish), but almost

all taken August-September; minimum sizes taken in August

and September, 35 mm and 20 mm, respectively (Swingle

1971).

Mobile Bay, Alabama Large numbers of small fish «38

mm) taken in October (Boschung 1957).

Mississippi Sound Specimens 19-114 mm TL collected;

fish <35 mm taken June-October (peak in August) in waters

15°-35°C with salinities mostly over 25 ppt (Christmas and

Waller 1973).

Mississippi Off the barrier islands, juveniles (8.0-74.0 mm

SL) taken in plankton tows June-October, with a peak in

September (Stuck and Perry 1982).

Chandeleur Islands, Louisiana Seven specimens (25-32

mm SL) collected in July and four (16-24 mm SL) taken

in September (Laska 1973).

Louisiana Most abundant carangid; 699 collected (29-114

mm) in April and June-November with peak abundances

June-September (Perret et al. 1971).

Vermilion Bay, Louisiana In July, 33 specimens collected

(15°-35°C, 6-36 ppt) (Norden 1966).

Marsh Island, Louisiana Total of 139 juveniles collected

late June-early October, with peak abundances in June and

July; water temperatures at capture 26.2°-32°C (Tarbox

1974).

31

Texas Total of 144 fish including some adults (66-205 mm)

taken June-October; in August fish 68-178 mm (25.4°-

30.0°C, 16.5-37.2 ppt) (Gunter 1945).

Galveston Island, Texas Fish (50-110 mm) taken JulyOctober (Arnold et al. 1960).

Mustang Island, Texas Juveniles taken March-August

(McFarland 1963).

Aransas Pass, Texas Juveniles collected in a tidal trap

October-February (Copeland 1965).
Decapterus punctatus (Agassiz) round scad

Adult Distribution

Geographic

Found throughout the Gulf of Mexico, Caribbean, West

Indies, and Bermuda (Fischer 1978a).

Western North Atlantic Present from Nova Scotia to Rio

de Janeiro, Brazil (Jordan and Evermann 1896, Berry 1968);

28 species of Carangidae (Aprieto 1974); three species of

Decapterus distinguished by scale and scute counts: D.

macarellus, D. punctatus, and D. tabl (Berry 1968).

Vertical (depth) or distance from shore

Gulf Occurs uncommonly, if ever, in estuaries (Christmas

and Waller 1973, Leak 1977). Evidently common over the

continental shelf of the eastern Gulf, but less abundant

westward (Montolio 1976, Reintjes 1979a); taken in the

eastern Gulf to 366 m, peak abundance 57-92 m; greatest

numbers in spring in depths 18 m, in summer in depths

18-37 m, in fall uniformly distributed over the shelf and in

waters 37-93 m deep (Klima 1971); gulfwide, concentrated

in 10-20 m depths, but also occurs past 50-m depths (Montolio 1976). Widespread and not uncommon on the outer

shelf and inshore east of the Mississippi (Hoese and Moore

1977).

A schooling species, primarily in midwater or nearbottom

in shallow water to about 90 m, but is also a nearsurface

pelagic, especially as a juvenile (Fischer I978a).

Eastern Gulf May migrate onshore (depths <18 m) in

spring, and offshore and/or southward during winter; found

80-160 kID from shore in depths 30-100 m most of the year

(Leak 1977, 1981).

Southeastern U.S. continental shelf Adults taken in bottom trawls between 10 and 110 m; summer though winter,

greatest catches in depths of 18-55 m; in spring, greatest

catches 10-18 m; contributed greatest biomass of the pelagic

species (Barans and Burrell 1976).

Juveniles up to 80 mm SL caught as far offshore as 473 kID;

larger fish caught nearer shore at mid-depth or the surface

(Berry 1968).

Found schooling with chub mackerel, Scomber japonicus

(Reintjes 1979b).

32

Stock Abundance

Gulf of Mexico

Gulf Subject of experimental electrified bottom-trawling

by Russians (Maksimov 1977).

Eastern Gulf Has potential to provide large catches (Houde

et al. 1984); most abundant carangid larvae-adult stock

estimated at 100,000-200,000 t and annual potential yield

at 70,000-80,000 t (LeakI977).

Western Florida Between Cape St. George and San BIas,

18-20 schools (7-9 t each) sighted at the surface during one

survey (Juhl 1966).

Other

Venezuela Abundant (Fischer 1978a).

Fisheries

Gulf of Mexico

Along with Opisthonema oglinum and Sardinella aurita

(family Clupeidae), potential aggregate catches of 1 million-2

million t for use as bait and cat food (Houde 1975; Reintjes

1979a, 1980).

Eastern Gulf Potential for exploitation of D. punctatus to

significantly increase world catch of round scads; 0.5 million

t of Decapterus species landed in 1978 (179 t landed in the

northeastern Gulf by beach seining and nearshore purse seining spring-early fall, when fish were nearshore); potential

uses include human consumption, bait, reduction, and cat

food (Leak 1977, 1981).

Western Florida Commercially exploited; 316 t

($104,512) landed in 1975 (Snell 1977).

Florida Small beach-seine fishery April-November for bait

(Klima 1971); bait fishery takes fish 100-170 mm between

0+ and 2 years old (Reintjes 1979a).

Other

Presently large fisheries on Decapterus species in the East

China Sea, Sea of Japan, Philippine Archipelago, and off

west Africa (Leak 1981).

Problems

Beach-seine and nearshore purse-seine fisheries exploit only

a fraction of the stock; full utilization of the resource would

require greater fishing effort offshore, where the stock is

abundant year-round (Leak 1977, 1981).
Reproduction

Sexual maturity

West Florida Young-of-the-year, mature D. punctatus

females as small as 107 mm SL may spawn around September; these fish may be as young as 4-7 months if they grow

as fast as D. pinnulatus and Selar crumenophthalmus off

Hawaii, or Trachurus trachurus in the North Sea (Leak 1977,

1981).

Northwest Florida All males mature at 145-149 mm; all

females mature at 130-134 mm (Naughton et al. 1986).

Eastern Gulf Fish of <135 mm FL «1 yr old) rarely

observed to have mature ovaries, but age 0+ fish may contribute substantially to spawning (Houde et al. 1984).

Sex ratio

IM:IF (Reintjes 1979a).

1.12M: IF in 1981, 1. 11M: IF in 1982 survey (Houde et al.

1984).

Fecundity

Asynchronous oocyte development (Reintjes 1979a).

Northwest Florida Apparently a serial spawner-batch

fecundity of 20 fish (146-188 mm) was 21,000-146,000 ova

(Naughton et al. 1986).

Spawning season

Dense plankton concentrations possibly stimulate spawning

and enhance larval survival; plankton volumes weakly but

significantly correlated with abundance of larvae; spawning

possibly associated with upwellings or frontal zones (Leak

1977).

Gulf Larvae taken throughout the Gulf, but appear most

abundant on west Florida shelf (Aprieto 1974, Montolio

1976); larvae found mostly in 10-20 m depths, but also past

50 m; two major spawning periods, April-May and October-November (Montolio 1976).

Eastern Gulf Most frequently occurring carangid larvae

and among the 20 most frequently observed species; 4431

larvae collected year-round (throughout the eastern Gulf,

spring-fall; winter larval distribution restricted to south

Florida), most larvae (68 % of occurrences) taken at depths

<50 m (Houde et al. 1984).

West Florida Most abundant carangid larvae in eastern

Gulf; spawns year-round in surface temperatures of 20°-

30°C (significantly greater catches in waters 23 °-30°C) and

salinities of 27-37 ppt (peak catches in waters 36-37 ppt)

over entire west Florida shelf, but larvae most abundant in

spring and summer (primarily spawning in depths of 2-100

m), decreasing steadily in fall and winter (spawning in

33

depths of 30-100 m, 80-160 km offshore); small larvae taken

from a total depth range of 2-225 m, 55 % of larval catch

taken in depths of 30-100 m, 37 % in depths <30 m, and

9% in depths >100 m; some evidence of bimodal spawning

off both west Florida and south Texas (Leak 1977, 1981).

Florida and Yucatan Straits Larvae taken year-round at

surface temperatures of21 °-31 °C, lowest larval abundances

in late fall-winter (Lyons 1978).

Mississippi Off barrier islands, larvae (3.0-15.0 mm SL)

taken in bottom tows June-August with a peak in July (Stuck

and Perry 1982).

Off Caminada Pass, Louisiana An ichthyoplankton survey

November 1981-0ctober 1982 took larvae in May (Ditty

1986).

Texas Based on larval abundance, spawns April-September

in depths of 42-182 m, 45-95 km offshore (Finucane et al.

1979).

South Texas, west Florida, and eastern Atlantic Spawns

in water temperatures >20°C (Aboussouan 1975).

Beaufort, North Carolina Spawns May-November (peak

in July-September) inshore and offshore (Hildebrand and

Cable 1930).

U.S. South Atlantic Bight 826 specimens taken yearround, peak larval abundance in spring (Fahay 1975).

West Africa Begins spawning in water temperatures

>20°C (Conand and Franqueville 1973).

Eggs

General description

No specific information on D. punctatus.

General characteristics for Carangidae eggs (Fahay 1983:

240): "Pelagic, shell smooth, yolk homogeneous or segmented, 1 oil globule anterior in late eggs and hatcWing (eggs

described in only a few species)."

Egg diameter

No species-specific information found.

Perivitelline space

No species-specific information found.

Oil globule

No species-specific information found.

Incubation time

No species-specific information found.
Larvae

Hatching length

No species-specific information found.

Early-life-history information

Larvae may be associated with dense plankton concentrations, upwellings, or frontal zones (Leak 1977, Lyons 1978).

Gulf No apparent day/night catch differences (Montolio

1976, Leak 1981).

Charleston, South Carolina During mid-July, 118 juveniles (24-27 mm TL) taken using a Boothbay neuston net;

statistically more fish captured during the day (Eldridge et al.

1977).

Meristics

Dorsal VIII + I, 29-37 (dorsal fins continuous to "-'30-50

mm SL [Berry 1968, western Atlantic)); VIII + I, 27-34

(completion of fin rays by 10 mm [Fahay 1983, northwest

Atlantic)); VIII + 1,30-33 attained by 11 mm SL (Laroche

et al., in prep., Gulf).

Anal II + 1,24-31 (anal fins continuous to "-'30-40 mm SL,

Berry 1968); II +I, 24-30 attained by 9-11 mm, (Fahay

1983); II + 1,26-28 attained by 11 mm SL (Laroche et al.,

in prep.).

Pectorals 18-20 (Berry 1968); 19-21 attained by 11 mm

SL (Laroche et al., in prep.).

Myomeres/Vertebrae 25 myomeres, 10+ 15 vertebrae

(Berry 1968, Fahay 1983).

Larval description

Gulf Illustrations and comparative information for wi1dcaught larvae (Aprieto 1974). Illustrations of wild-caught

larvae (Montolio 1976, Laroche et al. 1984).

North Carolina Illustrations of wild-caught larvae (Hildebrand and Cable 1930).

U.S. Mid-Atlantic Bight Atlas of larval stages compiled

from works of other authors listed above (Johnson 1978).

West Africa Illustrations and comparative information for

wild-caught larvae (Aboussouan 1975).

Mediterranean Schnakenbeck (1931).

Black Sea D. russelli (~Caran.x kurra) (Delsman 1926).

Arabian Sea D. kilione (Tsokur 1977).

Madras Coast, India D. russelli (Vijayaraghavan 1958).

D. maruadsi (Shojima 1962).

34

Juvenile

Gulf Transforms to juvenile stage at "-' 10 mm (Aprieto

1973). Transforms to juvenile stage at 10.9-19.0 mm SL

(Laroche et al., in prep.).

Florida 282 specimens (35-78 mm) taken from the Sargassum complex ofthe Florida Current, all but four juveniles

(53-60 mm) collected November-June (Dooley 1972).

Mississippi Off barrier islands, juveniles (16-22.0 mm SL)

taken in plankton tows between July and September (Stuck

and Perry 1982).

U.S. South Atlantic Bight Juveniles apparently rise to the

surface during predawn period, occupy the surface during

the day, and descend at night (Fahay 1975).
Trachurus lathami Nichols rough scad

Adult Distribution

Geographic

Western North Atlantic Found from Nova Scotia to northern Argentina, including the Gulf of Mexico (Berry and

Cohen 1972, Reintjes 1979a); apparently rare in the West

Indies (Fischer 1978b).

Western Atlantic Usually recognized as the only species

of Trachurus in the western Atlantic (Nichols 1940, Ginsburg

1952, Berry and Cohen 1972), although T. picturatus

binghami has been reported from the Caribbean south to

Panama (Nichols 1940); genus has a total of 13 species (Berry

and Cohen 1972).

Vertical (depth) or distance from shore

A pelagic species usually not taken in shore-seining but apparently found near bottom (Ginsburg 1952) in depths of

50-90 m (Mansueti 1960; Fischer 1978b).

Gulf Present from Florida to Texas; adults form large

schools over the outer continental shelf in depths>183 m

January-March; found schooling with chub mackerel

(Reintjes 1979a,b). Fairly common in the northern Gulf,

east of the Mississippi River, generally found slightly farther offshore than other coastal pelagics (Klima 1971,

Christmas and Waller 1973, Haese and Moore 1977); occurs

uncommonly if at all in Gulf estuaries; larvae and probably

adults as well are much more common offsouth Texas than

over the west Florida shelf, based on larval collections (Leak

1977, Finucane et al. 1979).

Tampa Bay, Florida More abundant offshore and over

rocky reefs (Springer and Woodburn 1960).

Stock Abundance

Gulf of Mexico

Eastern Gulf Stock estimated at 20,000-50,000 t and annual potential yield at 12,000-14,000 t for a seasonal midwater trawl fishery near the edge of the continental shelf

winter-early spring; Trachurus is characterized by large

abundances in high-amplitude cycles such as upwellings,

countercurrents, and rips (Leak 1977).

Cameron, Louisiana Massive school of Etrumeus teres

(family Clupeidae) and rough scad, 56 krn long (18 krn of

which was without interruption) sighted during a January

1969 Oregon II cruise (Reintjes 1979a).

Texas Second-most abundant carangid after Selene setapinnis in trawls on the brown shrimp grounds; one of the most

abundant fish on the Labos Island ground in 1954 (Hildebrand

1954).

35

Other

West Indies Apparently rare (Fischer 1978b).

Fisheries

Gulf of Mexico

Eastern Gulf Commercial catches small, but possibility of

a significant catch from the Gulf as a whole if western stocks

are larger, especially if the rough scad bycatch from an

Etrumeus teres fishery is developed, since massive combined

schools have been reported (Leak 1981).

Other

Major fisheries for Trachurus species in the northeast Atlantic, off Chile and Peru, in the East China Sea, and off west

and southwest Africa, which landed 2.7 million t in 1978,

a major contribution to the world fish catch; Atlantic fisheries

are primarily for reduction (meal and oil) while Pacific

fisheries are primarily for food (Leak 1977, 1981).

Small developing fisheries off Venezuela and California, on

the Mediterranean and Black Seas, and off New Zealand that

use midwater trawls, purse seines, lampara, and lift nets

(Leak 1977, 1981).

Problems

Most efficient means of exploitation involves midwater trawling targeted at spawning concentrations, as is presently

employed in west Africa (Leak 1977).

Reproduction

Sexual maturity

Age at maturity probably <2 years; off Argentina, size at

this age 130-150 mm TL (Reintjes 1979a).

Sex ratio

Argentina 1M: IF (Reintjes 1979a).

Fecundity

No specific information on T. lathami (Reintjes 1979a).

California T. symmetricus, mean number of eggs/g from

30 fish was 109 (based on 15 fish, 217-258 mm FL, 66

eggs/g, and 15 fish, 438-554 mm FL, 152 eggs/g)

(MacGregor 1976).
North Sea and English Channel T. trachurus, fecundity

range of 168,000-860,000 oocytes for fish 250-380 mm TL

(Macer 1974).

Spawning season

West Florida Spawns primarily offshore November-May

(peak January-February in 50-200 m depths) beyond the

30-m isobath (total depth range 20-219 m); proportion of

larvae collected from depths of 30-50 m smaller than that

from depths >50 m (140 km offshore); larvae collected from

waters with surface temperatures of 18°-26°C and salinities

of 35-36 ppt. Spawning associated with upwellings, countercurrents, rips, high zooplankton production, and temperatures of 10°-25°C (Leak 1977, 1981).

Eastern Gulf Total of 185 larvae taken fall-spring (apparently does not spawn in summer), generally over depths

>50 m (70% of occurrences in 50-200 m), widely distributed

(Houde et a1. 1984).

Lower Mobile Bay, Alabama Larvae taken in June and

August (Williams 1983).

OffCaminada Pass, Louisiana An ichthyoplankton survey

November 1981-0ctober 1982 took larvae in February (Ditty

1986).

Louisiana Larvae collected January-February 1976 between the Mississippi and Atchafalaya deltas in 10-100 m;

99% of the rough scad larvae taken outside of the 30-m contour (Ditty and Truesdale 1984).

South Texas Larvae collected January-May, surface temperatures 13°-21°C; larvae most abundant at depths >45 m

and >50 km offshore (Finucane et a1. 1979).

Gulf and Caribbean Probably spawns offshore from April

to June; epipelagic when very young (Fischer 1978b).

Charleston, South Carolina Young collected with a

Boothbay neuston net during mid-July (Eldridge et al. 1977).

Indian River, Delaware Three larvae (3-5 mm) taken in

June (de Sylva et a1. 1962).

California T. symmetricus (jack mackerel) appears to

prefer spawning around midnight (Farris 1963).

Eggs

General description

No specific information on T. lathami.

General characteristics for Carangidae eggs (Fahay 1983:

240): "Pelagic, shell smooth, yolk homogeneous or segmented, 1 oil globule anterior in late eggs and hatcWing (eggs

described in only a few species)."

California T. symmetricus, yolk diameter of 0.68-0. 88 mm

(Ahlstrom and Ball 1954).

36

Africa T. trachurus, egg spherical, with a thin transparent

membrane and a segmented yolk (Kiliachenkova 1970, Haigh

1972).

Egg diameter

No specific information on T. lathami.

California T. symmetricus, egg diameter of 0.90-1.08 mm

(Ahlstrom and Ball 1954).

Africa T. trachurus, egg diameter of 0.9-1.1 mm (Kiliachenkova 1970) or 0.7-1.09 mm (Haigh 1972).

Perivitelline space

No specific information on T. lathami.

California T. symmetricus, perivitelline space 0.09 mm

(Ahlstrom and Ball 1954).

Oil globule

No specific information on T. lathami.

Africa Diameter of T. trachurus oil globule 0.19-0.28 mm,

yellowish-brownish pigment around anterior part (Haigh

1972); single oil droplet 0.15-0.20 mm wide (Kiliachenkova

1970).

Incubation time

No specific information on T. lathami.

Larvae

Hatching length

No specific information on T. lathami.

Northwest Africa T. trachurus hatches at 1.8-1.9 mm with

no functional mouth and unpigmented eyes (Kiliachenkova

1970).

Early-life-history information

No major early life history studies found.

Meristics

Dorsal VIII+I, 28-33 (Boschung 1957, Mobile Bay, Alabama); (x 30.3 rays [Nichols 1940, Gulf]); vm+ I, 30-33

attained by 10 mm SL (Laroche et al., in prep., Gulf);

28-34 rays, x30.8 (Berry and Cohen 1972, western Atlantic and Gulf).

Anal 11+1,26-30 (Boschung 1957); 11+1,27-30 attained

by 10 mm SL (Laroche et aI., in prep.); 24-30 rays,

x 27.6 (Berry and Cohen 1972).
Pectorals 21-22 (Boschung 1957).

Vertebrae 10+ 14 (Boschung 1957, Berry and Cohen

1972); 24 (Fahay 1983, northwest Atlantic; Laroche et aI.,

in prep.).

Scutes 67-75, x 70.1 (Nichols 1940).

Larval descriptions

Larval development of T. lathami most closely resembles

that of T. mediterraneus and is sometimes confused with that

of Decapterus punctatus; T. lathami larvae <4.0 mm more

densely pigmented, especially along ventral and dorsal surfaces, than D. punctatus of the same length, but larger larvae of both species may be similarly pigmented (Leak 1977);

also see (Laroche et al.. in prep.).

Gulf Illustrations and comparative information for wildcaught larvae (Laroche et al. 1984).

U.S. Mid-Atlantic Bight Excellent atlas of larval stages

(Johnson 1978).

California T. symmetricus (Ahlstrom and Ball 1954).

British waters T. trachurus (Russell 1976).

West Africa T. picturatus, T. trecae (Aboussouan 1975).

South Africa T. trachurus (Haigh 1972).

Northwest Africa T. trachurus (Kiliachenkova 1970).

USSR seas T. mediterraneus (Aleev 1957).

Mediterranean Sea T. mediterraneus (Dechnik and Seniokova 1964).

Sea of MarmaralBlack Sea T. mediterraneus, T. trachurus

(Demir 1961).

Peru T. symmetricus murphyi (Santander and de Castillo

1971).

Gulf of Guinea T. trachurus (Zhudova 1969).

Japan T. japonicus (Uchida et al. 1958).

Argentina T. picturatus australis (Ciechomski and Weiss

1973).

Arabian Sea T. mediterraneus (Tsokur 1977).

Juvenile

Florida Current, Miami Description ofjuveniles (Schekter 1972).

Tampa Bay, Florida Juveniles collected (Springer and

Woodburn 1960).

Mississippi Off barrier islands, juveniles (32 nun SL) taken

in bottom tows during July and October (Stuck and Perry

1982).

37

Texas In July, 29 specimens (99-120 nun) collected in

waters of 28.3°C and 35.8 ppt (Gunter 1945). Juveniles

collected by trawling in depths >37 m (Hildebrand 1954).

Chesapeake Bay One specimen (102 nun SL) collected in

July at a depth of 18 m and salinity of 14 ppt in a shrimp

trawl (Mansueti 1960).

New Jersey Juveniles taken in temperatures of 14°-18.5°C

and salinities of 29-30.5 ppt (Milstein and Thomas 1976).

Newburyport, Massachusetts One specimen (103 nun)

taken on rod and reel; juveniles reach /'\)75-80 nun, l-yearolds reach 80-140 nun (one annulus) (Merriman 1943).