NOAA Technical Report NMFS 49 March 1987

Reproduction, Movements,

and Population Dynamics

of the Southern Kingfish,

Menticirrhus americanus,

in the Northwestern Gulf of Mexico

Stephen M. Harding

Mark E. Chittenden, Jr.

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service
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.

13. Guidelines for reducing porpoise mortality in tuna purse seining, by James M.

Coe, David B. Holts, and Richard W. Butler. September 1984, 16 p.

14. Synopsis of biological data on shortnose sturgeon. Acipenser brevirostrum

LeSueur 1818, by Michael J. DadswelJ, Bruce D. Taubert, Thomas S. Squiers, Donald

Marchette, and Jack Buckley. October 1984,45 p.

15. Chaetognatha of the Caribbean sea and adjacent areas, by Harding B. Michel.

October 1984, 33 p.

16. Proceedings of the Ninth and Tenth U.S.-Japan Meetings on Aquaculture, by

Carl J. Sindermann (editor). November 1984, 92 p.

17. Identification and estimation of size from the beaks of 18 species of cephalopods

from the Pacific Ocean, by Gary A. Wolff. November 1984. 50 p.

18. A temporal and spatial study of invertebrate communities associated with hardbottom habitats in the South Atlantic Bight, by E. L. Wenner, P. Hinde, D. M. Knott,

and R. F. Van Dolah. November 1984, 104 p.

19. Synopsis of biological data on spottail pinfish, Diplodus holbrooki (Pisces:

Sparidae), by George H. Darcy. January 1985, II p.

20. Ichthyoplankton of the Continental Shelf near Kodiak Island, Alaska, by Arthur

W. Kendall, Jr., and Jean R. Dunn. January 1985,89 p.

21. Annotated bibliography on hypoxia and its effects on marine life, with emphasis

on the Gulf of Mexico, by Maurice L. Renaud. February 1985, 9 p.

22. Congrid eels of the eastern Pacific and key to their Leptocephali, by Solomon

N. Raju. February 1985, 19 p.

23. Synopsis of biological data on the pinfish. Lagodon rhomboides (pisces:Sparidae),

by George H. Darcy. February 1985. 32 p.

24. Temperature conditions in the cold pool 1977-81: A comparison between southern

New England and New York transects, by Steven K. Cook. February 1985.22 p.

25. Parasitology and pathology of marine organisms of the world ocean, by William

J. Hargis, Jr. (editor). March 1985, 135 p.

26. Synopsis of biological data on the sand perch, Diplectrum !ormosllm (Pisces:

Serranidae), by George H. Darcy. March 1985,21 p.

27. Proceedings of the Eleventh U.S.-Japan Meeting on Aquaculture, Salmon

Enhancement, Tokyo, Japan, October 19-20, 1982, by Carl J. Sindermann (editor).

March 1985, 102 p.

28. Review of geographical stocks oftropical dolphins (Stenel/a spp. and Delphinus

delphis) in the eastern Pacific, by William F. Perrin, Michael D. Scott, G. Jay Walker,

and Virginia L. Casso March 1985, 28 p.

29. Prevalence, intensity, longevity, and persistence of Anisakis sp. larvae and Laeistorhynchus tenuis metacestodes in San Francisco striped bass, by Mike Moser, Judy

A. Sakanari, Carol A. Reilly, and Jeannette Whipple. April 1985,4 p.

30. Synopsis of biological data on the pink shrimp, Pandalus borealis Kroyer, 1838,

by Sandra E. Shumway, Herbert C. Perkins, Daniel F. Schick, and Alden P. Stickney.

May 1985, 57 p.

31. Shark catches from selected fisheries off the U.S. east coast, by Emory D. Anderson, John G. Casey, John J. Hoey, and W. N. Witzell. July 1985, 22 p.

32. Nutrient Distributions for Georges Bank and adjacent waters in 1979, by A. F.

J. Draxler, A. Matte, R. Waldhauer, and J. E. O'Reilly. July 1985, 34 p.

33. Marine flora and fauna of the Northeastern United States. Echinodermata:

Echinoidea, by D. Keith Serafy and F. Julian Fell. September 1985, 27 p.

34. Additions to a revision of the shark genus Carchorhinus: Synonymy of Aprionodon and Hypoprion, and description of a new species of Carcharhinus (Carcharhinidae),

by J. A. F. Garrick. November 1985, 26 p.

35. Synoptic review of the literature on the Southern oyster drill Thais haemastoma

floridana, by Philip A. Butler. November 1985, 9 p.

36. An egg production method for estimating spawning biomass of pelagic fish:

Application to the northern anchovy, Engraulis mordax, by Reuben Lasker (editor).

December 1985, 99 p.

37. A histopathologic evaluation of gross lesions excised from commercially important North Atlantic marine fishes, by Robert A. Murchelano. Linda Despres-Patanjo,

and John Ziskowski. March 1986, 14 p.

38. Fishery atlas of the northwestern Hawaiian Islands, by Richard N. Uchida and

James H. Uchiyama (editors). September 1986, 142 p.

39. Survey of fish protective facilities at water withdrawal sites on the Snake and

Columbia Rivers, by George A. Swan, Tommy G. Withrow. and Donn L. Park. April

1986, 34 p.

40. Potential impact of ocean thermal energy conversion (OTEC) on fisheries, by

Edward P. Myers, Donald E. Hoss, Walter M. Matsumoto, David S. Peters, Michael

P. Seki, Richard N. Uchida, John D. Ditmars, and Robert A. Paddock. June 1986,

33 p.

41. A stationary visual census technique for quantitatively assessing community structure of coral reef fishes, by James A. Bohnsack and Scott P. Bannerot. July 1986, 15 p.

42. Effects of temperature on the biology of the northern shrimp, Pandalus borealis,

in the Gulf of Maine, by Spencer Apollonio, David K. Stevenson, and Earl E. Dunton.

Jr. September 1986,22 p.

43. Environment and resources of seamounts in the North Pacific, by Richard N.

Uchida, Sigeiti Hayasi, and George W. Boehlert (editors). September 1986, 105 p.

44. Synopsis of biological data on the porgies, Calamus arctifrons and C. proridens

(Pisces: Sparidae), by George H. Darcy. September 1986, 19 p.

45. Meristic variation in Sebastes (Scorpaenidae), with an analysis of character association and bilateral pattern and their significance in species separation, by Lo-<:hai Chen.

September 1986, 17 p.

46. Distribution and relative abundance of pelagic nonsalmonid nekton off Oregon

and Washington 1979-84, by Richard D. Brodeur and William G. Pearcy. December

1986, 85 p.
NOAA Technical Report NMFS 49

Reproduction, Movements,

and Population Dynamics

of the Southern Kingfish,

Menticirrhus americanus,

in the Northwestern Gulf of Mexico

Stephen M. Harding

Mark E. Chittenden, Jr.

March 1987

U.S. DEPARTMENT OF COMMERCE

Malcolm Baldrige, Secretary

National Oceanic and Atmospheric Administration

Anthony J. Calio, Administrator

National Marine Fisheries Service

William E. Evans, 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.

ii
CONTENTS

Introduction 1

Methods 1

Results

Maturation 2

Spawning periodicity 2

Spring 3

Fall 3

Bathymetric distribution and recruitment 3

Age determination and growth 4

Maximum size, life span, and sex ratio 4

Weight, girth, and length relationships 4

Discussion

Maturation 4

Spawning periodicity 4

Bathymetric distribution and recruitment 5

Age determination and growth 5

Sex ratio and maximum size 6

General discussion 6

Acknowledgments 6

Citations 6

Figures 8

Tables 16

iii

Reproduction, Movements,

and Population Dynamics

of the Southern Kingfish,

Menticirrhus americanus,

in the Northwestern

Gulf of Mexico

STEPHEN M. HARDINGl

MARK E. CHITTENDEN, JR.2

Department of Wildlife and Fisheries Sciences

Texas A&M University

College Station, Texas 77843

ABSTRACT

Menlicirrhus americanus in the northwestern Gulf of Mexico mature at 150-220

mm TL and 12-14 months of age, with males maturing when 10-40 mm smaller

than females. Spawning occurs within a broad period from February through

November with two discrete peaks which coincide with the periodicity of downcoast alongshore currents (towards Mexico) in spring and fall. This species occurs

at depths of less than 5 to 27 m, being most abundant at 5 m or shallower. Youngof-the-year recruit primarily at 5-9 m or shallower and gradually expand their

bathymetric range. Age determination by length frequency is feasible in M.

americanus but not as simple as in species that spawn in one major period of the

year. Only one or two spawned groups normally predominated at anyone time

and no more than three co-occurred with few possible exceptions. Observed mean

sizes were 138 mm TL at 6 months, and 192 and 272 mm at ages I and II, respectively. Typical maximum size was 296-308 mm and typical maximum age is

probably 2-3 years. The largest fISh captured were 392 and 455 mm. Observed

sex ratio was 1.2 females to 1 male. Weight, girth, and length-length regressions

are presented.

'Present address: 43 Nonotuck Street, Nonhampton, MA 01060.

'Present address: Virginia Institute of Marine Science, Gloucester Point, VA 23062.

INTRODUCTION _

The southern kingfish, Menticirrhus americanus, is an inshore

bottomfish ranging from Long Island, New York to Florida, through

the Gulf of Mexico (Gulf), and south to Buenos Aires, Argentina

(Schaefer 1965; Johnson 1978). In U.S. waters, this species is most

common south of Chesapeake Bay (Welsh and Breder 1923). It is

a popular sport and food fish along the southeast coast of the U.S.

and in the Gulf where it is taken incidentally in commercial fisheries (Dunham 1972; Knowlton 1972; Mcilwain 1976). Although

its distribution in estuaries is not well documented, M. americanus

is considered estuarine-dependent (Gunter 1945) and uses all estuarine areas primarily as a nursery (McHugh 1967).

The life history of M. americanus is poorly known. Detailed

studies have been made only along the southeast coast of the U.S.

(Bearden 1963; Smith and Wenner 1985). Knowledge ofthis species

in the Gulf is general and based chiefly on faunal studies, including

Gunter (1945), Hildebrand (1954), Moore et al. (1970), Franks et

al. (1972), and Christmas and Waller (1973); however, they are

sometimes conflicting, e.g., widely different spawning seasons have

been suggested (Welsh and Breder 1923; Hoese 1965; Miller 1965;

Jaanke 1971).

This report describes maturation, spawning periodicity, bathymetric distribution, seasonal abundance, recruitment, size at age,

maximum size, sex ratios, length-weight, length-girth, and lengthlength relationships of Menticirrhus americanus in the northwestern

Gulf of Mexico.

METHODS _

Menticirrhus americanus were collected along a transect off Freeport, Texas (Fig. 1) on 71 monthly or twice-monthly cruises from

October 1977 to August 1981 aboard a chartered shrimp boat using

10.4 m (34 ft) trawls with 4.4 cm stretched mesh cod end and tickler

chain. Stations were initially located at 9, 13, 16, 18,22,27,36,

and 47 m depths. This was expanded to include 5 and 24 m after

November 1978 and 55,64,73,82,86, and 100 m after May 1979.

Day collections were made through September 1978 with usually

alternating day and night cruises in each month thereafter. Two

10-minute tows (bottom time) were made at each depth, except that

only one tow was made at each depth prior to October 1978, usually

8 tows were made at 16 m, and 24 tows at 22 m.

All M. americanus were measured to the nearest millimeter in

total length, fixed in 10% Formalin, and later preserved in 70%

ethanol. After preservation the following data were taken on all

fish captured from September 1979 to August 1981: total length

(TL). standard length (SL), girth between first and second dorsal

spine (G), total weight (TW), gonad weight (GW), sex, and ovary

maturity stage. All sizes reported in this paper are mm TL. Size

at maturity and/or spawning periodicity were determined from

I) maturity stagt:s (Table I) using a modification of Kesteven's

system (Bagenal and Braum 1978);

2) length frequencies by maturity stage (Fig. 2) or cruise (Fig. 3);

3) gonadosomatic indices (GSI) calculated as GSI = 100

GW/TW; and

4) regressions of ovary weight on total length.

Age was determined from length frequencies using the Petersen

Method (Lagler 1956). Spawned groups were specified by season

and year hatched, e.g., Fall 1980 (Table 2, Fig. 3). Descriptions

ofspawning periodicity using length frequencies assume the following size-at-age combinations predicted from regressions ofsize on
age for Fall 1980 and Spring 1981 groups: 20-30 mm at 1 month,

50-60 mm at 3 months, and 100-130 mm at 6 months. These regressions were chosen because (1) the Spring 1981 group was the only

clear spring-spawned cohort and (2) the Fall 1980 group clearly

showed growth, was easily followed, and, unlike other Fall cohorts,

all regression equations gave reasonably similar hatching dates and

sizes at age.

Hatching dates used to set time scales for calculating growth were

determined by a one-step iteration process following Standard and

Chittenden (1984). Initial hatching dates of I February and 10ctober were assigned to respective spring and fall groups to start the

process. Data used in these regressions were based on early life

periods when cohorts were most clearly identifiable, beginning when

the groups appeared fully recruited, as evidenced by increasing size

(growth), in successive collections (generally February-March and

May for fall- and spring-spawned fish, respectively), and continuing until the group identity and/or boundaries became less certain

(usually at 4-8 months after recruitment). Calculated hatching dates

and spawning period duration are sensitive to the time intervals

chosen because the slope of the line varied. Hatching dates, for

example, were 1-2 years early when data included the period

November-January when only the oldest, largest fish of a cohort

had recruited. Linear equations were used for prediction if the

quadratic term was not significant at a = 0.07 or produced a curve

unsuitable for growth analysis, i.e., upwardly concave with no

x-intercept (Table 3, Fig. 4C).

Duration of the spawning period was approximated following

Geoghegan and Chittenden (1982) as:

Time-specific mean size range early in Iif,:

Mean growth/day early in life

Calculations were based on May-August data for spring groups and

February-May data for fall groups, months when they first appeared

fully recruited. Time-specific size range was calculated for each

group as the mean of the ~9% confidence intervals for observations in these specific time periods (Table 4). Growth increments

were estimated as the difference between mean lengths at the initial and final collections in these time periods predicted from regressions used to calculate hatching dates (Table 4). Mean growth/day

was estimated as the growth increment divided by the time interval

between initial and final collections.

Typical maximum length was approximated as a length (lL)

exceeded by only 0.5-1.0% of a catch (Standard and Chittenden

1984). Percent values were derived from a cumulative percent

length-frequency curve for all fish captured from October 1977 to

August 1981. Regression relationships were calculated following

standard procedures in Snedecor and Cochran (1980). All length

frequencies herein were smoothed by moving averages of three size

intervals.

2

RESULTS _

Maturation

Menticirrhus americanus in the northwestern Gulf mature at 150-220

mm, and males mature at a smaller size than females. Mean sizes

of males were 10-40 mm less than females in each named stage

after maturing virgin (Fig. 2, Table 5). No fish remained in the

maturing virgin stage when greater than 250 mm, and few were

greater than 220 mm in this stage. Gonad maturation was distinct

at 130-150 mm as a few females and many males entered the early

developing stage. Extrapolated x-intercepts and inflection points of

regressions of gonad weight on total length for females were 180-230

mm (Fig. 5, Table 6). Most fish in the late developing through

resting stages, particularly females, were greater than 200 mm (Fig.

2). Age compositions and sizes presented later indicate M. americanus mature to first spawn at 12-14 months.

Little or no somatic growth occurs after M. americanus enter later

stages of maturation. Mean sizes for females were 258 mm in the

late developing stage, 262 mm when gravid, 265 mm when ripe,

258 mm when spawing/spent, and 247 mm when resting (Fig. 2,

Table 5). Mean sizes for males were 225 mm for the late developing stage, 222 mm for ripening/spawning, and 238 mm when resting. Maximum and minimum sizes and 99% confidence limits of

observations also generally remained similar from the late developing through the resting stage for both sexes (Table 5). The broad

99% confidence interval for ripening/spawning males resulted from

the small number of fish (n = 2) collected in this stage. Seemingly

decreased size of females in the resting stage may reflect incomplete separation of resting and maturing virgin stages.

Spawning periodicit)'

Menticirrhus americanus spawn within a broad period from February or March through November. Females in the ripe, gravid, or

spawning/spent stages, and/or with high GSI values, occurred in

most calendar months throughout this period except September and

October (Figs. 6, 7); fish in the late developing stage were collected in every calendar month except September. At least a few

fish 40-60 mm and 2-3 months of age were collected in every calendar month except September and November (Fig. 3, see especially

1981); a few fish 60-80 mm and 3-4 mO:lths of age were collected

in September and/or November of 1979 and 1980.

Little spawning of M. umericanus apparently occurs In the period

June-September. Few fish 40-80 mm and 2-4 months old were captured July-November, although fish this size, clearly part of an abundant group of recent recruits, were conunon or abundant in December-March most years and in late May through June 1981 (Fig. 3)

High GSI values after April or May are based on only a few males

or females, and mean values distinctly declined after that time (Fig.

7). That some spawning may occur III summer, however, is suggested by the presence of a few fish 40-80 mm during July to

November, some labeled as Sm 79 (Fig 3), and by the presence

of a few females in the gravid and ripe stages or with high GSI

values in the summer (Figs. 6, 7).

Although M. americanus spawn over a broad time period, spawning primarily occurs during two discrete periods: spring (JanuaryApril) and fall (August-November).
Spring-Modal groups of spring-spawned fish are readily followed

in length frequencies (Fig. 3) from 19 May 1981, when fish 40-80

mm and 2-4 months of age recruited, through 6 August 1981 when

they were 80-150 mm. Minor groups of fish 60-120 mm also appeared in June and early July of 1979 and 1980; they were apparently

spring spawned because fish this size made up the clear Spring 81

cohort in June and July. Calculated hatching dates for the Spring

81 cohort, the only spring group that could be followed for any

length of time, were 2 January, 8 March, or 20 April 1981, depending on the data included and whether linear or quadratic regression

is used (Fig. 4; Table 3, Eq. I, 2, 3). The first date may be too

early because it includes one 40-mm fish collected on 2 March and

may be biased towards an early date by the incomplete recruitment

suggested by that one large, early hatched fish. Moreover, the linear

equation it is based on explains much less variation in total length

(lOOr 2 = 86.2%) than the linear (l00r 2 = 92.7%) or quadratic

(lOOr 2 = 98.4%) equations with the 2 March collection deleted

(Table 3). Hatching dates are 8 March-20 April, regardless of the

data set manipulated ifthe collection of2 March is deleted. Gonadal

data also indicate a spring spawning period: I) mean GSI values

of males and females rise to a peak in March and April 1980 and

1981 and decline thereafter (Fig. 7), and 2) slopes of the regressions of gonad weight on total length for females were at a maximum in the period February-April (Fig. 5, Table 6).

Fall-Fall-spawned cohorts initially recruit in abundance each year

in the period December-February at 50-150 mm (Fig. 3), although

their upper size boundaries may not be clear from then through

February or March. Following this initial period, well defined modal

groups of fall-spawned fish are readily followed in the period early

April-July in 1979, mid February-late July or later in 1980, and

mid March-early August in 1981; cohort mean sizes and observed

size ranges were similar at comparable times each year (Table 2;

Harding 1984, Appendix I). Calculated hatching dates (Table 3)

varied depending on the collections used, but generally occurred

in the fall for the seemingly best data sets. Dates for the Fall 80

cohort, the clearest fall cohort with the best fitting regressions

(lOOr 2 = 89-94%), were II August, 20 September, 3 October,

and 5 November 1980 (Fig. 4, Table 3). Dates for the Fall 79 cohort

were 3 June and 15 March 1978, and 17 June, 9 November, and

20 November of 1979; the former two equations explain only half

the variation (IOOr 2 = 42-45%) of the latter three (IOOr 2 =

79-92 %) and seem unrealistic because their hatching dates appear

to be a year too early. The 17 June date, moreover, is based on

linear regression and has a lower lOOr 2 value than the two remaining quadratic equations. Dates for the Fall 78 groups were 25

November 1977, 4 September 1976, and 5 August or 31 December 1978; the former two equations explain much less variation

(IOOr 2 = 30-63%) than do the latter two (IOOr 2 = 73-87%),

which may reflect incomplete recruitment in February, and seem

unrealistic because their hatching dates appear to be 1-2 years too

early.

Little or no spawning seemingly occurs in late fall or early winter

during an interval of about 2-3 months duration between spring and

fall spawning. This is suggested by the distinct gap between modes

for Spring 81 and Fall 80 cohorts in late May and June of 1981

(Fig. 2). Differences between mean sizes of these cohorts were 98,

86, and 84 mm on 19 May, 7 June, and 16 June, respectively (Table

2), which suggests an interval of about 4-5 months between mean

hatching dates.

Length-frequency and gonad data conflict on whether spring or

fall spawning predominates; the former data suggests predominant

3

fall spawning and the latter data indicates predominant spring spawning. As noted, mean and maximum GSI values for males and females

rose to a peak in March and April and declined thereafter (Fig.

7), and slopes of the regressions of gonad weight on total length

for female Menticirrhus americanus were at their greatest in the

period February-April (Fig. 5, Table 6). However, mean and maximum GSI values were generally low in the fall (Fig. 7), and no

ripe or gravid fish were captured in September and October (Fig.

6). In contrast, length frequencies show a clear and abundant springspawned group only in 1981 (Fig. 3); few spring-spawned fish were

captured in 1979 and 1980. Fall-spawned fish recruited in abundance from December through February each year, and their modes

are dominant and readily followed.

Spawning intensity is greatest over a 2-4 month period in spring

and seemingly longer in fall. Calculated spawning period durations

based on mean 99 % confidence limits of observations and predicted

growth/day for the Spring 81 group, the only usuable spring cohort,

were 120,68, and 75 days (Table 4). Spawning durations for fall

groups varied depending on the data used and were more prolonged

than for spring groups. Durations were 155-217 days for the Fall

80 group, 183-275 days for the Fall 79 group based on the three

seemingly most realistic regressions (see above paragraph, also

Table 3), and 139-174 days for the Fall 78 group (Table 4). Estimates of growth/day used to calculate spawning period durations

are sensitive to data intervals used and considerations noted in the

previous paragraph about most realistic regressions apply here also.

Bathymetric distribution and recruitment

Menticirrhus americanus occur at depths of less than 5 to 27 m

in the northwest Gulf off Freeport. Catch per tow was greatest at

5 m, the shallowest depth occupied (Fig. 8). It decreased sharply

between 5 and 13 m and then gradually to 27 m. Only 30 fish were

captured in 124 tows at 24 m and 12 fish in 126 tows at 27 m. No

fish were captured in 789 tows at 36 to 100 m.

Young-of-the-year recruit primarily at depths of 5-9 m if not

shallower. Recent fall-spawned recruits 40-160 mm were abundant

at 5-9 m in the December-March period (Fig. 9A, B); few of these

fish less than 150 mm recruited at 13-16 m or deeper. Greatest

recruitment was at 5 m, the shallowest depth occupied. Similarly,

new spring-spawned recruits 30-110 mm were most abundant at

5-9 m in the period June-August and during May (Fig. 9C, D);

few of these fish less than 100 mm were captured at 13-16 m or

deeper.

Fall-spawned young-of-the-year gradually expand their bathymetric range. Although few fall-spawned recruits, and only larger

ones, occurred deeper than 9 m in the period December-March,

they were common at 13-16 m in the period April-May when they

were 100-200 mm (Fig. 9C) and reached 18-27 m by the period

July-August (Fig. 9D). Despite this offshore dispersal, fall-spawned

fish remained most abundant at 5-9 m throughout their first year.

Larger, presumably older, fall-spawned young-of-the-year apparently lead the offshore dispersal. No fall-spawned recruits less

than 100 mm were captured deeper than 9 m in the period December-May, with the exception of one 71-mm fish at 16 m in the period

February-March and two fish 96 and 100 mm at 13 m in the period

December-January (Fig. 9A, B, C). In contrast, presumably younger

fish 50-100 mm were abundant at 5-9 m, a contrast that suggests

offshore dispersal of larger, older fish after an inshore recruitment.

This interpretaion is supported by the clear size gradient of fallspawned recruits in the period February-March during which the

smallest fish occurred at 5 m (Fig. 9B).
Age I and II fall-spawned fish are distributed throughout their

bathymetric range without clear patterns of seasonal movement.

Newly Age I fish were most abundant at 5-9 m depths during the

period September-January and April-May (Fig. 9A, C, E); these

fish were common to 16 m. Their abundance at 5 m was much lower

in February-March and June-August compared to other depths at

other periods. Large Age II fish appeared uniformly disHbuted

throughout their depth range.

Age determination and growth

Few spawned groups of M. americanus exist at anyone time in

the northwest Gulf and only one or two normally predominate. No

more than three spawned groups occurred in one month with the

possible exception of groups on 10 June and 24 September 1979,

11 July 1980, and 19 May, 16 June, 22 July, and 6 August 1981,

when spring- or summer-spawned individuals occurred along with

the generally predominant fall cohorts (Fig. 3). Three fall-spawned

groups often occurred in one month, these being young-of-the-year

and Ages I and II, although age designations often may not b~ exact

for the larger individuals, for example, on 4 and 19 May, 16 June,

22 July, and 6 and 18 August 1981 when only one or two fall groups

generally predominated. Fall groups were generally most clear just

after they began to recruit during December-February through the

following September-October, when their boundaries became uncertain at modal lengths of about 170-190 mm and 10-14 months of

age. Spring fish were clearly identifiable only in 1981, but even

this cohort was readily followed only from 19 May through 6 August

1981 when they were 80-145 mm and 4-8 months old (Fig. 3).

Spring-spawned fish evident in June, July, and August of 1979 and

1980 were negligible in abundance and did not persist.

Observed mean sizes of fall-spawned M. americanus were consistent between years. Mean sizes, based on averaging mean sizes

at age over collections in the period September-November, were

138 mm at 6 months, and 193 and 272 mm at Ages I and II (Table

7). Mean lengths at Age I were 181 mm for Fall 77, 207 mm for

Fall 78, 184 mm for Fall 79, and 200 mm for Fall 80 groups. Meap.

sizes at Age II were 270 mm for Fall 76, 285 mm for Fall 77, 262

mm for Fall 78, and 278 mm for Fall 79 (Table 7).

Maximum size, life span, and sex ratio

The typical maximum size attained by M. americanus in the northwest Gulf is 300-310 mm, although individuals may reach 450 mm.

The largest fish we captured were 392 and 455 mm, although a

preserved specimen did not exist to confirm the latter value. The

largest male and female sexed were 303 and 345 mm, respectively. During October 1977 to August 1981,99% of the 9,447 fish

captured were less than 296 mm, and 99.5% were less than 308

mm (Fig. 10). Fish of 296-308 mm would seem to be typically only

2-3 years old at most, because mean size at Age II was 272 mm,

with the mean upper 99 % confidence limit about observations being

352 mm (Table 7).

Female M. americanus were more numerous than males. The

observed sex ratio was 1.2 females to I male among 3,076 mature

fish examined. This ratio differed significantly from I: I <x 2 =

23.7, df = 1, a = 0.05).

4

Weight, girth, and length relationships

Regressions of total weight-total length, girth-total length, and standard length-lotal length are presented with supporting statistics in

Table 8. Length-weight regressions were not significantly different

in slope between sexes (F = 0.57; df = 1,3141; a = 0.05), but

they differed in elevation (F = 25.8; df = 1,3142; a = 0.05).

Regression slopes for males and females differed significantly from

irnmatures (F = 68.8; df = 1,5762; a = 0.05). However, pooled

regressions are presented for males and females and for males,

females, and immatures, because they may be more useful in stock

assessment than individual regressions. For simplicity, pooled

regressions are presented for length-length and length-girth relationships.

Length-weight regression slopes for mature and immature fish

significantly exceeded a hypothesized (3 = 3.0 (matures: t = 69.9,

df = 3143, a = 0.05; immatures: t = 18.12, df = 2554, a

0.05) indicating allometric growth for both groups.

DISCUSSION _

Maturation

Little information is available on maturation of M. americanus. Our

finding that males and females in the northwest Gulf mature at

150-220 mm at Age I agrees with sizes of 135 and 192 mm in the

South Atlantic Bight at age I (Smith and Wenner 1985; Hildebrand

and Cable 1934). Bearden (1963) believed males matured at 240

mm TL (195 mm SL) at Age II and females at 280-300 mm TL

(230-250 mm SL) at Age II-III, but Smith and Wenner felt Bearden

collected primarily at estuarine stations which lacked smaller,

mature, Age I fish. The smallest "ripe" fish (Irwin 1970) obtained

off Louisiana were a 260 mm TL (215 mm SL) male and a 265

mm TL (218 mm SL) female, but he did not define "ripe."

Spawning periodicity

The broad spawning period of February or March through November that we found for M. americanus agrees with many other studies

in the Gulf and Atlantic. However, the literature on spawning

periodicity conflicts and has been interpreted in a variety of ways,

including (1) a broad spawning period in the Gulf of fall and/or

winter through spring (Welsh and Breder 1923; Miller 1965; Jaanke

1971) or (2) a broad spawning period of spring through late summer or fall in the Gulf (Gunter 1945; Hoese 1965; Moe and Martin 1965; Christmas and Waller 1973) and along the Atlantic coast

north and south of Cape Hatteras (Pearson 1941; Bearden 1963;

Smith and Wenner 1985). Peak spawning, moreover, has been interpreted to occur in a variety of ways, including (I) a peak in spring

or early summer in the Gulf (Reid 1954; Springer and Woodburn

1960) and along the Atlantic coast north and south of Cape Hatteras (Hildebrand and Schroeder 1928; Hildebrand and Cable 1934;

Bearden 1963) and (2) a peak in the fall along the Atlantic coast

north of Cape Hatteras (Welsh and Breder 1923). In reality, it appears that M. americanus in the gyre ofthe northwestern Gulf (Kelly

e, al. 1984) at least, has a complex spawning periodicity and life

history, described below, which has not been recognized because

few studies have been made in detail on this species and/or few

have had the frequent sampling over such a long duration of time

as ours.

Our finding that spawning occurs in two primary discrete periods,

spring and fall, has generally not been recognized. However, Welsh
and BredeI' (1923) suggested peak spawning in spring and fall along

the southeast Atlantic coast off Fernandina, Florida, although Hildebrand and Cable (1934) and Smith and Wenner (1985) suggested

this might reflect insufficient collecting in the intervening summer

months. That criticism, however, can not be applied to our study.

Our finding of peak spawning in discrete spring and faJ! periods,

moreover. is similar to recent findings that several other fishes also

spawn with this periodicity in the northwestern Gulf, including

Peprilus burti (Murphy 1981; Murphy and Chittenden unpub!.),

Cynoscion arenarius (Shlossman and Chittenden 1981), C. nothus

(DeVries and Chittenden 1982), Fundulus grandis (Waas and Strawn

1983), and Larimusfasciatus (Standard and Chittenden 1984). This

occurs in a variety of families and may represent a broad phenomenon in the Gulf (Murphy and Chittenden unpub!.).

Standard and Chittenden (1984). based on Murphy and Chittenden

(unpub!.), suggested a hydrographic basis for spring and fall spawning peaks in P. burti, C. nothus, and L. fasciatus which probably

applies also to C. arenarius and M. americanus, both of which have

pelagic eggs and larvae (Johnson 1978): spawning is timed to coincide with the periodicity of downcoast alongshore currents (toward

Mexico). These currents probably transport pelagic eggs and larvae "downstream" to nurseries in the northwest Gulf from spawning grounds located "upstream" in or toward the north central Gulf.

Reversed current transport mechanisms in the summer (Temple and

Martin 1979) would carry pelagic eggs and larvae offshore, which

presumably would be unfavorable to M. americanus, or toward the

north central Gulf. The latter possibility could explain the apparent

absence of summer spawning in length frequencies in M. americanus and other species. However, M. americanus is abundant in

summer off Texas at Port Aransas (Gunter 1945; Miller 1965), in

the Padre Island surf (Chittenden pel's. observ.), and off the jetties

of Brownsville (Standard pel's. observ.) based on angling. Presumably, summer-spawned individuals from these locations would be

transported upcoast to Freeport where our study was made unless

(1) transport occurs over even greater distances towards the north

central Gulf or (2) summer spawning is truly negligible.

We have interpreted spawning of Menticirrhus americanus as

occurring in two main periods. However, spot (Leiostomlls xanlhurus) spawn in one discrete period but recruit to the Gulf in two widely speparate periods (Hata 1985). It is possible that this pattern could

apply to Menticirrhus americanus. because our collections were

made towards the deeper part of its bathymetric range. Timefrequent collections in estuaries, the surf zone, and/or shallow Gulf

inshore of our collections would resolve whether Menticirrhus

americanus has two discrete spawning periods as we have suggested

or possibly one spawning period (presumably late winter and early

spring based on gonad data) with two periods of recruitment.

Bathymetric distribution and recruitment

Menticirrhus americanus is essentially an inshore species of the

white shrimp community described by Hildebrand (1954) and Chittenden and McEachran (1976). We found that it occupies a primary depth range of 5-27 m off Texas, which agrees with other

studies done in the Gulf (Miller 1965; Moe and Martin 1965; Chittenden and McEachran 1976) and the Atlantic (Hildebrand and Cable

1934; Bearden 1963; Smith and Wenner 1985). Although we captured no M. americanus deeper than 27 m, they have been reported

as deep as 36-45 m off Mississippi and Texas (Irwin 1970; Hildebrand 1954) and to 54 m off South Carolina (Bearden 1963).

We found that the gradual dispersal offshore after inshore recruitment and size gradient with depth (fish <160 mm shallower than

5

9 m; fish >200 mm at 13-27 m) agrees with Hildebrand (1954)

who found only fish greater than 200 mm TL at 22-32 m offTexas,

and with Irwin (1970) who found fish less than 185 mm TL (150

mm SL) in depths shallower than 16 m but larger fish to 23 m depths

off Mississippi.

Our finding that young M. americanus recruit primarily in inshore areas in the Gulf (5-9 m when 40-160 mm TL) agrees with

Miller (1965) who captured them at 5-8 m off Port Aransas, Texas.

This species also recmits to the Gulf in the same general periods

(May-June and December-February) as several other Gulf fishes

that spawn in two periods a year, such as P. burti, C. arenarius,

and L. fasciatus (Murphy 1981; Shlossman and Chittenden 1981;

Standard and Chittenden 1984).

Age determination and growth

Age determination of M. americanus is feasible using length frequencies. However, as in our study, collections must be made

frequently in time and over a long duration, because boundaries

of age groups and age designations are not clear every month,

especially for larger individuals. Despite that problem, age designation and group boundaries are quite clear in certain months (for

examples, the Spring 81 and Fall 80 groups in May and June 1981,

the Fall 79 group in April 1979). From the clear groups, one may

work chronologically backward or forward in time and gradually

assign age designation and boundaries with reasonable certainty.

Age determination by length frequencies in M. americanus is similar

in these respects to P. burti (Murphy 1981), C. arenarius (Shlossman and Chittenden 1981), and C. nothus (DeVries and Chittenden 1982), all of which appear to spawn over a broad period of

time but in two discrete major spring and late summer or fall periods.

In contrast, age determination by length frequency is simple and

very clear in other species of Gulf shrimp communities such as

Micropogonias undulatus (White and Chittenden 1977; Chittenden

unpub!. data), Stenotomus caprinus (Geoghegan and Chittenden

1982), L. fasciatus (Standard and Chittenden 1984), and Polydactylus octonemus (Dentzau 1985), all of which spawn in one discrete

period each year (Micropogonias and Stenotomus) or spawn in one

major and one very minor spring and/or fall period, such as Larimus

and Polydactylus. Therefore, it appears the simplicity of age determination via length frequencies may suggest life history patterns:

those shrimp community fishes for which this procedure is difficult

may have a complex life history and multiple major spawning

periods; those for which it is simple may have one discrete major

spawning period, with or without a second minor period.

The limited literature on growth of M. americanus is mostly for

the Atlantic coast. Mean sizes of fish we captured at 6 months and

Age I (138 and 193 mm, respectively) agree with mean sizes

reported throughout this species range [125 mm TL = 100 mm

SL at 6 months, and 185-200 mm TL = 150-160 mm SL at Age

I off South Carolina (Bearden 1963); 145 mm TL = 117 mm SL

at 5-6 months off Tampa Bay, Florida (Springer and Woodburn

1960); 160 mm TL at Age I off New Jersey (Welsh and BredeI'

1923); 170 mm TL at Age I at Fernandina, Florida (Welsh and

BredeI' 1923); 170-180 mm TL at Age I in the South Atlantic Bight

(Smith and Wenner 1985); 180-220 mm TL at Age I off North

Carolina (Hildebrand and Cable 1934)]. The mean size offish we

captured at Age IT (272 mm TL) agrees with sizes of 270-280 mm

TL (220-230 mm SL) reported by Bearden (1963) but is a little

larger than those reported by Welsh and BredeI' (1923) off New

Jersey (250 mm TL) and Smith and Wenner (1985) (220-240 mm

TL). The latter authors reported mean sizes of 260 mm TL at Age
III and felt Bearden's size-at-age estimates, which agree with ours,

were too large.

Sex ratio and maximum size

Sex ratios of M. americanus have not been reported. Smith and

Wenner's (1985) data give a ratio of 1.48 females to each male

in the South Atlantic Bight, while we found a 1.2: 1 ratio.

The 392 and 455 mm maximum sizes we found for M. americanus off Texas are much greater than those in other Gulf studies,

where maxima were 330 mm (Franks et al. 1972),320 mm (Hildebrand 1954), and 318 mm (Gunter 1945). However, maximum

lengths reported by these authors are similar to the typical maximum sizes of 300-310 mm we found. Typical maximum sizes in

the Gulf appear similar to those in the South Atlantic Bight where

Smith and Wenner (1985) found 99% were less than 300 mm and

90% less than 230 mm (we found 90% less than 233 mm). The

largest fish reported in the Gulf and South Atlantic Bight have been

405 mm (Hammond and Cupka 1977),404 mm (Smith and Wenner 1985), and 392 and 455 mm (this study), although no specimen was found to confirm the 455 mm fish and it may be an error.

If this indeed represents an error, a 419 mm specimen from the

Chesapeake region (Hildebrand and Schroeder 1928) is the largest

record and may reflect the zoogeographic variation in population

dynamics near Cape Hatteras, North Carolina, suggested by White

and Chittenden (1977), Murphy (1981), Shlossman and Chittenden (1981), and Geoghegan and Chittenden (1982).

General discussion

Our studies suggest M. americanus is a species of small size, early

age at maturity, short life span (tL = 2-3 year), and high total annual mortality rates (theoretically 80-90% for a 2-3 year life span

from the procedure of Royce 1972: 238). These attributes are similar

to those of other members of the white shrimp community, such

as Micropogonias undulatus (White and Chittenden 1977), Peprilus

burti (Murphy 1981), Cynoscion arenarius (Shlossman and Chit·

tenden 1981), C. nothus (DeVries and Chittenden 1982), and

Larimusfasciatus (Standard and Chittenden 1984). This lends further support to the suggestion (Chittenden and McEachrar.. 1976;

Chittenden 1977) that members of this community have a common

pattern of population dynamics.

ACKNOWLEDGMENTS ,

We wish to express our thanks to former students and members

of the Bryan Mound nekton project: R. Baker, M. Burton, T.

Crawford, V. Fay, T. Fehrman, P. Geoghegan, R. Grobe, D. Hata,

M. Murphy, J. Pavela, M. Rockett, J. Ross, P. ShJossrnan, B.

Slingerland, G. Standard, and H. Yette. Special thanks [0 R Case,

M. Cuenco, and J. Cummings for their computer programming

assistance, and Captains H. Forrester, M. Forrester, R. Forrester,

D. Peavy, P. Smirch, and A. Smircic for their skills in seamanship. J. McEachran and L. Ringer reviewed drafts.

This report is based on a thesis submitted by the senior author

in partial fulfillment of the requirements for the Master of Science

degree at Texas A&M University. Financial support was provided,

in part, by the Texas Agricultural Experiment<tJ Station; the Strategic

Petroleum Reserve Program, Department ot' Energy; and by the

Texas A&M Sea Grant College Program, supported by the NOAA

Office of Sea Grant, U.S. Department of Commerce.

6

CITATIONS _

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Publ., Oxford.

BEARDEN, C. W.

1963. A contribution to the biology of the king whiting, genus Menricirrhus of

South Carolina. Contrib. Bears Bluff Lab. 38: 1-27.

CHITTENDEN, M. E., Jr.

1977. Simulations of the effects of fishing on the Atlantic croaker, Micropogon

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CHITTENDEN, M. 1'., Jr., and J. D. McEACHRAN.

1976. Composition, ecology, and dynamics of dermersal fish communities on

the nvrthwestern Gulf of Mexico continental shelf. with a similar synopsis for

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CHRISTMAS, J. Y., and R. S. WALLER.

J973. Estuarine vertebrates, Mississippi. In J. Y. Christmas (editor), Cooperative

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DENTZAU, M.

1985. Aspects of the life history of the Atlantic threadfin, Polydactylus OCIOnemus. M.S. Thesis, Texas A&M Univ., 68 p.

DeVRIES, D. A., and M. E. CHITTENDEN, Jr.

1982. Spawning, age determination, longevity, and mortality of the silver seatrout, Cynoscion nothus in thc Gulf of Mexico. Fish. Bull., U.S. 80:487-500.

DUNHAM, F.

1972. A study of commercially important estuarine-dependent industrial fishes.

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1972. A study of nektonic and benthic limnas of the shallow Gulf of Mexico

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GEOGHEGAN, P., and M. E. CHITTENDEN. Jr.

1982. Reproduction, movements, and population dynamics of the longspine

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GUNTER, G.

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HAMMOND, D. L., and D. M. CUPKA.

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HATA,D. N

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7

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1983. Seasonal and lunar cycles in gonadosomatic indices and spawning readiness of Fundulus grandis. Contrib. Mar. Sci. 26: 127-141.

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1923. Contributions to life histories of Sciaenidae of the eastern United States

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96'00'

28"30'

95'30' 94'30'

/ ,-18

C-------'

.27

28"30'

2fJ'OO'

183~----­

366 ~./ _../--\

,--

27"':$1 ~732~7'30'

96'00' 95'30' 95'00 94'30'

Figure I-Location of sampling area. Station depths and bathymetric contours are in meters.

8
MALE FEMALE

80

60

40

20

IMMATURE

n " 2556

i:=111.7

80

60

40

20

IMMATURE

n " 2556

i .. 111.7

EARLY DEVELOPING

n" 341

i::: 233.6

GRAVID

n" 28

r

C

/ 261.6

MATURING VIRGIN

n" 1011

i" 161.8

LATE DEVELOPING

n" 96

I~ i:258.1

,_""'0

20

30

10

10

MATURING VIRGIN

n " 763 i" 160.6

EARLY DEVELOPING

n" 540

i" 194.7

15

20

10

10

>(,)

z

w

::::)

a

w

a::

II.

RIPE

n" 27

• I~' "" 264.6 i i

LATE DEVELOPING

n" 116

~. j:225.t

RIPENING/SPAWNING

n:2

i" 221.5

SPAWNING/SPENT

n" ,.

Hi" 258."

i

100 ,"''''' 200

RESTING

n " 27

i" 237.9 J i

300 400 500

10

100

RESTING

n:: 180

• ~"2<7.•

200 300 400 500

TOTAL LENGTH (mm)

Figure 2-Length frequencies of male and female Menticirrhus americanus by maturity stage. See Table 1 for maturity

stage criteria.

9
10
5] 24 Jul 80 0 51 t----FBO~ .... F79--;------+-1--i +-F781"i'6 Feb 810 t-F79~ . 0=30 . ...#1A~~_ 0=204 tq.. q

10 15Aug80N 5] 1 2 Mar 81 N I---F80~ "-F79----1 0=267 5311", A~ • 1r:!"'tvtp n=101 .

5] FOO 1--"9---1 16Mara1D f-----l F78 n=60

5] A • ., .tp..~.. . F78 11 Sep 80 N

t- F79 ..j H 0=14

0° 0

5] 1 7 Apr 81 N r--F80--l J---F79----l

......1:/'4 ? -40f\AMf AMf

n=125

5] 1----F79-f 25 Sep 800

..~. F18 n=79

5] 20 Apr 81 0

rF.,8g~ Ic>'ro /,F794 0=58

5] GOct80N

1--F79-1 F78? 0=15

b ""'I 5] ~F8(]~ 4 May 81 N

1/---F79-1F78 n=188

5] F78 21 Oct 800 otMh<j/»

F80 .... ,-t1--F79 -U----l 0=70 .".r"'IJ"". 5] 19 May 81 0 "F80~ F78

1-581-1 ~~F79--l?H 0=129

5] 3 Nov 80 N (!\ " ,bN\:.1 ...... I

1 1-F79- '1.- F78 -f n=52 •.. .o!'y.A. 10 7 Jun 81 N

0=243

5] 18 NovaO 0

F80 F7' 0=2

5] I-F80~~ 1 DecBON 5] +-581--; ~F79-1 F78 16 Jun 81 0

0=137 0=172 o A.. ,t- F78 ---4 ofv'b Iv rH I

5] ? F78 15 Dec 80 0 5] 581 1 Jul 81 N I----:-F79-'1----4 FOO 0=81 'g~;~' 0=83

"'~,

10 7 Jan 81 N 5] 22 Jul 81 0

0=298 '1 5817 .. s:1,,~ ~~~9'" "81 0=77

5] ~-lI--F80~ .. F791 6 Aug 81 N

F78 0=155

5] 21 Jan 81 0 • • +1$-40 ,.. I--F80"'?1---F79---4~ 0=82

"'l0 po ~4' 5] 581 ? f-:-- F'O-t~ 18 Aug 810

'1 S81?~ n=91

5] 2 Feb 81 N ~M""'a AF~f--F79---i~F78~ 0 100 200 300 400 500 1 n=200 ~""P,".,

5] '-F80~1~ 16 Feb81 D

n=204 ....c-f'.t&,r#. . 0 100 200 300 400 500

11
oO~-..J....-:-:l0""0c----"'---2"'0""0c---L---,3:-!0:::0-......l..-....,,!400

Fall 1979

400

Fall 1980

200 300

Spring 1981

Max

M"+ 95% Urn;"

Min

10'N10'jIF'M'A'M'j JI A sial

"1980 1981

300

100

300

200

2

Fall 1978

JIF1MIAIMiJ jIA'SIO

1979

Max

M"+ 95% Urn;"

Min

A1S'0IN'01

1978

300

100

200

300

--E

E

J:

IZ

W

...I

...I

c(

Io

I200

100

100 200 300 400

-=-N--' I "'0--"-:j--'j=FTI-=-M"':'"TI-A""""-:M""""'---'j--'-:j-Ol-:A""""I-:S::-r-:O"""'i-:N-'-'I

1979 1980

200

100

F I M A M

1981

J

2

1~~~<::...13

J I A 'S

AGE (days)

Figure 4-Regressions of total length (mm) on age (days) used to calculate hatching dates for spring and fall groups of Menticirrhus americanus off

Freeport, Texas. All regressions were significant at " = 0.07 or higher, and collections used are summarized in Table 3.

Figure S-Regressions of gonad weight (g) on total length (mm) by month for female Menticirrhus americanus, Octoher 1977-August

1981. Regression statistics are presented in Table 6.

12
150

100 Sep 79

n=51

Mar 80

n=70

Sep 80

n=57

Mar 81

n=96

50

12345678

Apr 81

n=116

Jun 81

n=314

May 81

n=211

5 678

12345678

12345678

Oct 80

n=51

Nov 80

n=44

12345678

12345678

12345678

2345678

1 Dec 80

n=127

Apr 80

n=523

Jun 80

n=289

May 80

n=608

5 678

567 8

12345678

12345678

Oct 79

n=27

Nov 79

n=20

12345678

12345678

12345678

50

50

50

150

100

100

150

Dec 79

100 n=63

150

>

u

z

w

::J

o

w

a:

LL

Jul 81

n=86

Aug 81

n=117

12345678

12345678

Feb 81

n=266

Jan 81

n=190

12345678

Jul 80

n=172

Aug 80

n=209

12345678

Jan 80

n=267

Feb 80

n=261

12345678

50

50

100

150

150

100

MATURITY STAGE

Figure 6--Monthly maturity stage compositions for female Menticirrhus americanus. Maturity stages (see Table 1): 1 =Immature; 2 =Maturing

virgin; 3 = Early developing; 4 = Late developing; 5 = Gravid; 6 = Ripe; 7 = Spawning/Spent; 8 = Resting.

13
16

3 n Females tl95%

110 Mean Limit

1

Range

30

9 60 62

110 7 '6 37

60

5 1S 19 42

3. 13

! 92 6S 42

32 89 59 37 3911

3 4S

!~, j 60 63

[Jt€J 30

I~t 1

7:

3

:' :~62

15

)(

w

C

Z

U

j::

e:(

o

Ul

o

C

e:(

Z

o

Cl

Z

e:(

w

9. 2. Males

Figure 7-Mean gonadosomatic indices, ranges, and 95% confidence intervals by

cruise for Menlicirrhus americanus in early developing and later maturity stages.

Sample sizes are depicted for each cruise.

COLLECTION PERIOD

70

60

POOLED

50 0 1977

A 1978

0 1979

· 1980

40 • 1981

• ABSENT

• 30

0

Ia::

w 20 Q.

:r

lU . e:( 10 • U

3

o

A

8 •

•

.

+

0 o~

. • • o e : " Figure 8-Mean catch per tow (number of individuals) by depth for Menlicirrhus americanus off

Freeport, Texas, each year and pooled, October

1977-August 1981.

o 10 20 30 40 50 60

DEPTH (m)

70 80 90 100
400

455

C/KOl

2'

9M

n=31

13M

n=22

5M

n=337

C/KOl

2'

"

CJKO 1

2

ClI=0.3

I--l----l

CIl...O.8

f--1------;

.

ClI:O.l ClKO.l

f--l------i I- 2--1

200 *"cl: a 6'360 •

Sep-Noy

C/KO.l C/I: 1.1

07 I---l~

.,.wM /,w""

100

5] IBM

n=11

5] 22-27M n=40

C/I:l0? C/1=13

,~1~;1~01

C/1:47 ClI=35

5 ]1-_C_/Kf-'0_.1_f-f'~O,---;...-:-i-------c----'-'''i-_--'j>'---''~,-+C , ~o _ """ 1~.."=..0_.'~'_3~M 0=202 I, I I , ,

5] 16M n=257

Dec-Jan Apr-May

5M 45 5M 10

n=891 n=1973

30

15

2'

Ctt"06

5] f-2--i

20 9M

n=818

9M 15

n"326 5]

10

16M

n"226 C/I=26 ?

CIl..,O'J-- l~ C11=04

~o~ ~2~

ClI'O 2 CIl·2.' ClI'O' 13M t-0......j t----:'1-----i 1--2---; n=72

10

10

10

15

20

5]""_~_~_~~.....""'o.+~_CrW..O_'~'_B~M ClI:10

I---l----i l2 n=24 ,........ 5 ]__n=16

'...,BM~-,~-,~_pCl",,-" r--l----i

ph ..0'i"'6po--A.~--r--..., 0,

>

o

z

W

::J

o

W

a:

I<.

5] 22-27M

n=151

o 100

f-O-l

ClI=0.6

~'''04 1-2".

Feb-Mar

5] 22-27M C/KO.l C/KO.l

0=4 r----l~ 21

0!:--r-"'"7100~-r--:;2tOO:;--"""--;;3~00~'-'---:;;400

Jun-Aug

15 30

10

5M

n"735

20

10 ClI=O 9 Clf=O 1

1--'---; 21

5M

n"1300.

5]1-~~C~/l_'0_.2-'1-'I....£C",/l",~",1.8:'=F'-'CJI:/l","l".6 1--50-11---0--+-1--1..........C\-"=_0_'....,..._'_3~M t-2--l 0=128

, 4'4~&,

5 ]""_-r-_C_I.... K~0_'....

~o-{ CI,......'~0""3"';><....."'CI...'.~'~.0....,...--r--'-B...,M 0=44

,so ,M.Il!p"""",'---i

9M

n~2BO

Clf=4.6

5] C/I=7~2 t-o- ---l CJf=1.0

r- 50- - --l I---l---j C/KO 1

, 0'1!66~ 2,1

Clf'" 2 CII-O.8

5]1__~CI~'~~0~.4rf-e>L~0-r_-lr_:.=r_,-----j="'fI'C~I .~ ..AK....0,....,-'-6~M 0=303

" ," p " ,

9M

n=393

CJf=O 1

2

C/I=O 6 C/l=26 C/I=O 3 ?

!--0---i r-.-'-----l r--2------;

Clf<. 0 1

o

13M

n=68

16M

n=318

10

10

5]1._'_BrM_~_~_-,C;.:"u",,-8,,+' n=52

1---:---1...,

.. ., ......1--2~ CW02

.:..,.......~_~ 5] 22-27M

, 0=178

o 100

CJl=O.4

ClI·~C/KO., ~O~ 21

n,' 200 300 ' 400

C/.....O I

o

100

Clf=OS

1--1---l ClI=0.1

200

~2~300 400

TOTAL LENGTH (mm)

Figure 9-Length frequencies and catch per unit effort (C/f, expressed as mean number of individuals per 16-min tow) by depth for Menticirrhus americanus off Freeport,

Texas, October 1977-August 1981. Data were pooled over the 4-year period because length frequencies within listed periods were similar each year. Designated ages

are for fall-spawned fIsh except where noted as spring (8). Age designation for each fall cohort changed after August.

15
120

100

110

100

80

90 (")

>

c:

(,) 80

Z c:

60 w r

::l

70 >

n=9447 -l 0 60 <; W

a:: m

LL. 50 40 "'C

m

40 :II

(")

m 30 Z

20 -l

20

10

50 100 150 200 250 300 350 400 450 500

TOTAL LENGTH (mm)

Figure 10-Length frequencies and cumulative percentage of all Mentici"hus americanus collected off Freeport,

Texas, October 1977-August 1981.

Table I-Maturity stages assigned to male and female Mentici"hus americanu•• Gravid, ripe, and spawning/spent stages were difficult to distinguish in males and

were pooled.

Stage

I.

Maturing virgin

3. Early developing

4. Late developing

5-7. Ripening/Spawning

8. Resting

Description

MALES

Sex undetermined. Testes very small or indistinguiShable.

Testes translucent-red, occupy less than 10% of body

cavity.

Testes opaque to grey, occupy 10-15 %of body cavity.

Testes pale yellow, occupy 15-25% of body cavity.

Stages not readily separated. Testes pale yellow,

occupy 25 % or more of body cavity. Edges of testes

crenulated.

Testes greyish, reduced in size, occupy less than 10%

of body cavity.

16

Stage

I. Immature

2. Maturing virgin

3. Early developing

4. Late developing

5. Gravid

6. Ripe

7. Spawning/Spent

8. Resting

Description
Table 2-Growth data by spawned group for Menticirrhus americanus from the Gulf off Freeport, Texas. Night and day cruises are indicated by N or D. Observed

size ranges correspond to those indicated by horizontal bars in Figure 3 and derme group boundaries used in growth calculations. Age is scaled to the hatching

date derived from indicated equation numbers corresponding to those in Figure 4 and Table 3.

Observed 95% 99% Age (days)

Collection size range limits on limits on and

date n (mm) X S2 means observations hatching date

Spring 1979

15 May 79 D 1 79 79.0 0.0

10 Jun 79 N 3 62-73 68.0 3\.0 54.2-8\.8 12.7-123.3

9 Jul 79 N II 66-I16 90.1 298.9 78.5-101.7 35.3-144.9

22 Aug 79 D 1 73 73.0 0.0

24 Sep 79 N 4 69-116 95.8 494.9 6O.4-13\.2 -34.1-225.7

Spring 1980

II Jul 80 N I 80 80.0 0.0

13 Aug 80 N 2 60-68 64.0 32.0 13.2-114.8 -296.1-424.1 EQUATION

Spring 1981 2 3

2 Mar 81 N 1 44 44.0 0.0 59

15' May 81 D 14 38-81 56.9 102.4 51.1-62.7 26.4-87.4 137 72 29

7 Jun 81 N 109 26-103 76.4 214.2 73.6-79.2 37.9-114.9 156 91 48

16 Jun 81 D 44 65-117 91.5 142.8 87.9-95.1 59.3-123.7 165 100 57

1 Jul 81 N 28 96-124 108.7 56.7 105.8-11 \.6 87.8-129.6 180 115 72

22 Ju1 81 D 8 102-138 122.9 170.4 I12.0-133.8 77.2-168.6 201 136 93

6 Aug 81 N 93 84-145 12\.6 167.5 118.9-124.3 87.6-155.6 216 151 108

18 Aug 81 D 5 98-I15 104.8 7\.7 94.3-115.3 65.8-143.8 2 Jan 8 Mar 20 Apr

Fall 1976

8 May 78 D 1 295 295.0 0.0

12 Oct 78 N 1 271 27\.0 0.0

30 Nov 78 N 23 237-308 264.7 410.0 255.9-273.5 207.6-32\.8

19 Dec 78 D 10 255-348 283.1 840.8 252.4-303.8 188.9-377.3

24 Feb 79 D 4 247-294 268.0 558.0 230.4-305.6 130.0-406.0

14 Mar 79 N 1 291 29\.0 0.0

Fall 1977

14 Apr 78 D 6 111-208 154.7 1186.7 118.5-190.9 15.8-293.6

8 May 78 D 16 133-215 178.2 498.4 166.3-190.1 112.4-244.0

15 Sep 78 D 1 181 18\.0 0.0

12 Oct 78 N 3 167-191 182.3 177.3 149.2-215.4 50.1-314.5

30 Nov 78 N 261 146-221 178.9 229.9 177.1-180.7 129.0-228.3

19 Dec 78 D 132 163-225 186.0 242.0 183.3-188.7 145.9-226.1

24 Feb 79 D 86 170-224 193.6 186.0 190.7-196.5 157.7-229.5

14 Mar 79 N 14 200-241 213.6 106.7 207.6-219.6 182.5-244.7

5 Apr 79 N 82 176-278 200.2 399.6 196.8-204.6 147.5-252.9

20 Apr 79 D 115 181-267 208.6 363.5 205.1-212.1 158.6-258.6

15 May 79 N 98 185-281 219.8 425.4 215.7-223.9 165.6-274.0

10 Jun 79 N 106 201-279 233.9 356.0 230.3-237.5 184.4-283.4

24 Jun 79 D 9 212-256 235.7 192.5 225.0-246.4 J89.2-282.2

9 Jul 79 N 8 218-274 239.0 348.0 237.7-240.3 173.8-304.3

22 Aug 79 D 1 262 262.0 0.0

24 Sep 79 D 4 262-284 276.0 92.7 260.7-291.3 219.8-332.2

5 Oct 79 N 4 262-287 274.0 108.7 257.4-290.6 213.0-334.9

19 Oct 79 D 4 268-305 284.0 244.7 259.2-308.9 192.6-375.4

6 Nov 79 N 3 271-305 285.3 310.3 24\.6-329.0 110.5-460.1

18 Nov 79 D 2 300-308 304.0 32.0 253.2-354.8 -56.1-664.1

4Dec79N 3 287-300 293.7 42.3 277.5-309.9 229.1-358.3

14 Dec 79 D 3 282-332 304.7 641.3 24\.8-367.6 53.4-556.0

3 Jan 80 N 5 274-300 286.2 142.2 27 \.4-30 \.0 231.3-341.1

16 Jan 80 D II 273-311 287.6 135.7 279.8-295.4 250.7-324.5

4 Feb 80 N 9 266-317 283.1 345.6 268.8-297.4 220.7-345.5

15 Feb 80 D 5 264-349 293.4 1150.8 25\.3-335.5 137.2-449.6

8 Mar 80 N I 311 31\.0 0.0

20 Mar 80 D 1 317 317.0 0.0

1 Apr 80 N 6 299-331 31\.2 163.8 297.8-324.6 259.6-362.8

16 Apr 80 D 1 323 323.0 0.0

5 May 80 N 1 312 312.0 0.0

2 Jun 80 N 1 318 318.0 0.0

11 Jul 80 N 11 344 344.0 0.0

Fall 1978

30 Nov 78 N 117 45-145 107.7 63\.9 103.1-112.3 4\.8-173.6

19 Dec 78 D 162 78-158 126.8 32\.4 124.0-129.6 9\.6-16\.9 EQUATION

24 Feb 79 D 58 102-162 140.5 23\.2 136.5-144.5 100.0-18\.0 2

5 Apr 79 N 268 67-175 129.9 378.7 127.6-132.3 78.8-180.0 243 95

20 Apr 79 D 341 80-180 142.8 335.7 140.5-144.3 95.2-189.6 258 110

17
Table 2-(Continued).

Observed 95% 99% Age (days)

Collection size range limits on limits on and

date " (mm) i S2 means observations hatching date

EQUATION

Fall 1978 (Continued) 2

15 May 79 N 400 92-179 138.2 348.9 136.4-140.0 90.1-186.3 283 135

10 Jun 79 N 82 131-198 167.8 227.1 164.5-171.1 128.1-207.5 309 161

24 Jun 79 D 6 160-190 173.7 108.3 162.8-184.6 131.7-215.7 323 175

9 Jul 79 N 186 125-195 156.0 162.4 154.2-157.8 123.2-188.8 190

22 Ju1 79 D 13 131-192 162.8 348.5 151.5-174.1 105.8-219.8 203

22 Aug 79 N 34 120-212 146.1 577.8 137.7-154.5 80.2-212.0 234

24 Sep 79 D 122 144-243 186.4 466.3 182.5-190.3 129.8-242.9 5 Aug 31 Dec 5 Oct 79 N 42 125-238 192.2 808.9 183.3-201.1 115.4-269.0

19 Oct 79 D 16 144-245 212.1 961.3 195.6-228.6 120.7-303.5

6 Nov 79 N 38 151-251 210.8 1025.2 200.3-221.3 124.0-297.6

18 Nov 79 D 9 195-258 234.0 472.0 217.3-250.7 161.1-306.9

4Dec79N 17 155-255 208.1 994.2 191.9-224.3 116.0-300.2

14 Dec 79 D 20 163-251 207.1 862.7 202.6-211.6 123.5-290.7

3 Jan 80 N 58 175-266 225.0 717.5 218.0-232.0 153.6-296.4

16 Jan 80 D 68 183-265 224.9 441.8 219.8-230.0 169.2-280.6

4 Feb 80 N 67 167-264 215.9 623.2 209.8-222.0 149.7-282.1

15 Feb 80 D 56 171-247 210.7 446.6 205.0-216.3 154.3-267.1

8 Mar 80 N 56 180-287 224.2 666.3 217.3-231.1 155.3-293.1

20 Mar 80 D 23 195-292 236.7 1103.8 235.5-237.9 143.0-330.4

I Apr 80 N 30 176-284 221.7 842.1 210.9-232.5 141.7-301.7

16 Apr 80 D 38 204-281 236.5 298.4 229.2-243.8 175.9-297.1

5 May 80 N 28 193-288 228.7 573.8 219.4-238.0 162.3-295.1

19 May 80 D 16 193-300 247.6 1086.6 230.0-265.2 150.5-344.7

2 Jun 80 N 32 212-300 244.9 541.0 236.5-253.3 181.0-308.8

19 Jun 80 D 2 228-238 233.0 50.0 169.5-296.5 -217.1-683.1

11 Ju1 80 N 21 206-277 243.7 381.3 234.8-252.6 188.1-299.3

13 Aug 80 N II 205-275 242.0 605.6 225.5-258.5 164.0-320.0

II Sep 80 N 2 252-260 256.0 32.0 205.2-306.8 -104.1-616.1

25 Sep 80 D I 247 247.0 0.0

6 Oct 80 N I 246 246.0 0.0

21 Oct 80 D 4 241-269 257.0 160.0 242.8-271.2 183.1-330.9

3 Nov 80 5 264-328 304.6 644.8 273.1-336.1 187.7-421.5

1Dec80N 9 253-319 276.8 510.2 259.5-294.1 201.0-352.6

15 Dec 80 D 3 301-332 319.7 270.3 278.8-360.5 156.0-482.9

7 Jan 81 N II 273-329 292.1 332.9 279.8-304.4 234.3-350.6

21 Jan 81 D 8 285-321 299.7 148.5 289.5-309.9 257.1-342.3

2 Feb 81 N 10 266-300 276.4 109.4 268.9-283.9 242.4-310.4

16 Feb 81 D 6 338-382 354.2 277.0 336.7-371.7 287.1-421.3

16 Mar 81 D 3 315-318 316.3 2.3 312.5-320. I 301.2-331.4

4 May 81 N I 322 322.0 0.0

16 Jun 81 D 2 318-334 326.0 128.0 224.4-427.6 -394.2-1046.2

22 Ju1 81 D I 343 343.0 0.0

Fall 1979

5 Oct 79 N 2 51-87 74.0 338.0 -91.2-239.2 -1096.3-1244.3

6 Nov 79 N 7 75-121 102.1 275.8 86.7-117.5 40.5-163.7

18 Nov 79 D 2 101-145 123.0 968.0 -156.5-402.5 -1857.5-2103.5

4 Dec 79 N 10 56-144 120.6 616.9 102.8-138.4 39.9-201.3

14 Dec 79 D 40 54-150 118.8 397.8 112.4-125.2 65.5-173.1

3 Jan 80 N 109 48-141 110.7 424.5 106.8-114.6 56.6-164.8

16 Jan 80 D 10 94-144 125.1 192.5 115.2-135.0 80.0-170.2

4 Feb 80 N 87 42-143 82.9 896.1 76.5-89.3 18.5-147.3 87 232

15 Feb 80 D 426 49-150 103.1 425.5 101.1-105.1 50.0-156.2 98 243

8 Mar 80 N 199 61-163 10l.l 439.2 98.2-104.0 46.6-155.6 119 264

20 Mar 80 D 47 66-175 123.9 689.0 116.2-131.6 53.6-194.2 131 276

I Apr 80 N 202 68-166 120.5 344.2 117.9-123.1 73.0-168.0 143 288

16 Apr 80 D 391 77-187 137.7 296.0 136.0-139.4 93.4-182.0 158 303

5 May 80 N 187 89-174 135.5 293.1 133.5-138.5 91.4-179.6 177 322

19 May 80 D 517 66-180 121.2 469.7 119.3-123.1 65.4-177.0 191 336

2 Jun 80 N 352 99-192 137.5 360.7 135.5-139.5 88.6-186.4 205 350

19 Jun 80 D 23 113-181 152.7 246.4 145.9-159.5 108.4-197.0 222 367

II Ju1 80 N 208 116-192 146.1 190.7 144.2-148.0 110.5-181.7 245

24 Ju1 80 D 30 123-166 141.2 148.7 136.6-145.8 107.7-174.7 258

13 Aug 80 N 254 87-191 1330 554.0 130.1-135.9 72.4-193.6 278

II Sep 80 N 12 143-188 161.3 248.6 151.3-171.3 112.3-210.3 8 Nov 17 Jun

25 Sep 80 D 78 115-208 162.0 438.5 157.3-166.7 106.7-217.3

6 Oct 80 N 14 158-229 187.3 468.7 174.8-199.8 122.1-252.5

21 Oct 80 D 56 151-231 186.3 450.8 180.6-192.0 129.6-243.0

18
Table 2-(Continued).

Observed 95% 99% Age (days)

Collection size range limits on limits on and

date n (mm) X S2 means observations hatching dale

Fall 1979 (Continued)

3 Nov 80 N 38 157-225 192.9 394.7 186.4-199.4 138.8-247.0

18 Nov 80 D I 21 I 211.0 0.0

IDec80N 99 152-242 191.3 490.1 186.9-195.7 133.1-249.5

15 Dec 80 D 77 193-284 238.5 509.8 234.2-242.8 178.9-298.1

7 Jan 81 N 92 165-267 215.1 789.8 209.3-220.9 141.2-289.0

21 Jan 81 D 53 175-277 227.3 587.0 220.6-234.0 162.5-292.1

2 Feb 81 N 55 171-252 207.2 457.2 201.4-213.0 150.1-264.3

16 Feb 81 D 121 176-272 226.2 744.9 221.3-231.1 154.8-297.6

2 Mar 81 N 73 180-292 221.0 644.6 215.1-226.9 153.8-288.2

16 Mar 81 D 48 175-267 223.6 5788 216.7-230.6 159.1-288.1

7 Apr 81 N 50 189-309 238.3 1059.1 229.1-247.5 151.1-325.4

20 Apr 81 D 33 186-297 222.4 698.1 213.0-231.8 150. 1-294.7

4 May 81 N 30 207-306 243. I 758.0 232.8-253.4 167.2-319.0

19 May 81 D 30 202-273 233.6 426.7 225.9-241.3 176.7-290.5

7 Jun 81 N 16 222-294 254.2 695.7 240.1-268.3 176.5-331.9

16 Jun 81 D 40 219-300 243.8 377.0 237.6-250.0 191.3-296.3

I Jul 81 N 15 247-285 264.9 125.6 258.7-271.1 231.5-298.3

22 Ju1 81 D 21 245-301 265.8 223.8 259.0-272.6 223.2-310.4

6 Aug 81 N 7 249-287 265.7 146.6 254.5-276.9 220.8-310.6

18 Aug 81 D 8 259-308 278.1 262.7 264.5-291.7 221.4-334.8

Fall 1980

21 Oct 80 D I 71 71.0 0.0

3 Nov 80 N 5 88-118 103.8 219.2 85.4-122.2 35.6-172.0

18 Nov 80 D I 78 78.0 0.0

IDec80N 21 71-121 106.1 254.0 98.8-113.4 60.8-151.4

15 Dec 80 D I 105 105.0 0.0

7 Jan 81 N 180 50-148 111.0 593.6 107.4-114.6 48.2-173.8 EQUATiON

21 Jan 8\ D 15 87-145 110.3 259.5 101.4-1\9.2 62.3-158.3 2 3 4

2 Feb 81 N 131 47-157 106.7 955.4 101.4-112.0 27.1-186.3 175

16 Feb 81 D 54 61-159 124.2 593.1 117.6-130.8 59.1-189.3 189

2 Mar 81 N 26 70-160 110.0 621.2 99.9-120.1 40.5-179.5 203 165 150

16 Mar 81 D 9 103-135 119.0 180.7 108.9-129.1 73.9-1641 217 179 164

7 Apr 81 N 74 58-164 118.5 578.5 112.9-124.1 54.9-182.1 239 201 186 152

20 Apr 81 D 25 87-172 1317 446.5 101.3-162.1 72.6-190.8 252 214 199 165

4 May 81 N 153 86-174 124.1 408.3 119.3-128.9 72.0-176.2 266 228 213 179

19 May 81 D 93 110-195 155.3 360.7 151.4-159.2 105.4-205.2 281 243 228 194

7 Jun 81 N 109 130-200 162.3 318.8 158.9-165.7 115.4-209.2 300 262 247 213

16 Jun 81 D 85 135-215 176.8 493.8 172.0-181.6 118.2-235.4 309 271 256 222

I Jul 81 N 40 150-236 189.7 590.1 181.9-197.5 124.0-255.4 324 286 271 237

22 Jul 81 D 45 164-235 204.0 444.2 197.7-210.3 147.3-260.7 345 307 292 258

6 Aug 81 N 54 163-238 200.4 398.6 195.0-205.8 146.8-254.0 360 322 307 273

18 Aug 81 D 54 165-248 199.1 687.9 191.9-206.3 129.0-269.2 334

I I Aug 20 Sep 3 Oct 5 Nov

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Table 3-Summary of iterative process used to calculate hatching dates and set time scales for growth calculations on Menticirrhus americanus. Equations describe regressions of observed mean total length on age in days, from Table 2. Initial age values and growth equations were scaled to 1

October and 1 February hatching dates for fall and spring spawned groups. All regressions were significant at a = 0.07 or higher. Equation numbers

in parentheses refer to regression lines in Figure 4. No hatching date calculations were made for Fall 76 and Fall 77 cohorts because few of these

nsh were captured within 12 months of their hatching date.

Collection period Initial growth Initial Final growth Hatching

(equation number) equation x-intercept equation lOOr 2 date

Spring 1981

2 Mar 81- 6 Aug 81 (1) TL=0.560 Age+ 15.9 -29 TL=0.560 Age-0.31 86.2 2 Jan 81

19 May 81- 6 Aug 81 (2) TL=0.867 Age-4.39 5 TL=0.867 Age+0.22 92.7 8 Mar 81

19 May 81- 6 Aug 81 (3) TL= -0.009 Age2 +3 583 Age-225.9 79 TL= -0.009 Age2 +2.137 Age+0.02 98.4 20 Apr 81

Fall 1978

24 Feb 79-24 Jun 79 TL=0.344 Age+76.80 -223 TL=0.344 Age+0.07 63.0 25 Nov 77

24 Feb 79-22 Aug 79 TL=0.153 Age+ 114.5 -746 TL=0.153 Age+0.03 30.3 4 Sep 76

5 Apr 79-24 Jun 79 (I) TL=0.532 Age+46.24 -87 TL=0.532 Age-0.18 86.5 5 Aug 78

5 Apr 79-22 Aug 79 (2) TL=-0.005 Age2 +2.59 Age-'45.2 65 TL= -0.005 Age2 + 1.84 Age-O.60 72.5 31 Dec 78

Fall 1979

4 Feb 80-19 Jun 80 (I) TL=0.408 Age+42.24 -106 TL=0.408 Age -0.00 78.7 17 Jun 79

4 Feb 80-11 Jul 80 TL=0.171 Age+93.55 -548 TL=0.171 Age+0.03 41.6 3 Jun 78

4 Feb 80-24 Jul 80 TL=0.166 Age+94.15 -566 TL=166 Age+O.06 45.3 15 May 78

4 Feb 80-13 Aug 80 (2) TL= -0.003 Age2 + 1.45 Age-52.3 39 TL= -0.003 Age2 + 1.24 Age+0.16 84.7 9 Nov 79

4 Feb 80-13 Aug 80 (3) TL= -0.003 Age2 + 1.70 Age- 7 6.79 50 TL= -0.003 Age2 + 1.38 Age-0.05 92.3 20 Nov 79

Fall 1980

2 Feb 81- 6 Aug 81 (I) TL=0.557 Age+27.6 -50 TL=0.557 Age-0.25 89.4 II Aug 80

2 Mar 81- 6 Aug 81 (3) TL=0.680 Age-22.7 33 TL=0.681 Age-0.18 91.1 3 Oct 80

2 Mar 81-18 Aug 81 (2) TL=0.630 Age+63.6 -10 TL=0.630 Age+0.28 93.6 20 Sep 80

7 Apr 81- 6 Aug 81 (4) TL=0.780 Age-26.7 36 TL=0.780 Age+0.43 90.2 5 Nov 80

Table 4-Calculations to estimate duration of spawning periods of Menticirrhus americanus, during 1978-81. Mean 99% conndence limits

were calculated from data in Table 2 for the listed interval of collection dates. Equation numbers used to preduct initial and nnal sizes for

growth increments are those in Figure 4 and Table 3.

Mean 99% Time Spawning

Interval of Predicted total length o:onfidence interval Growth interval Growth/day duration

Collection dates Initial Final on observations increment (days) (mm) (days)

Spring 1981

I. 19 May- 6 Aug 81 76.41 120.65 67.3 44.2 76 0.56 120

1. 19 May- 6 Aug 81 49.50 125.18 67.3 75.7 76 1.00 68

3. 19 May- 6 Aug 81 62.64 131.14 67.3 68.5 76 0.90 75

Fall 1978

I. 24 Feb-15 May 79 107.92 148.78 92.9 40.9 77 0.53 174

2. 24 Feb-15 May 79 11356 164.76 92.9 51.2 77 0.67 139

Fall 1979

1. 4 Feb-19 May 80 64.45 127.56 112.1 63.1 104 0.61 184

2. 4 Feb-19 May 80 94.66 IJ7.09 112.1 42.4 104 0.41 275

3. 4 Feb-19 May 80 87.50 151.15 112.1 63.7 104 0.61 183

Fall 1980

I. 2 Feb-19 May 81 97.23 150.1'1 121.0 59.0 106 0.56 217

2. 2 Feb-19 May 81 86.59 153.37 1:1.0 66.8 106 0.63 192

3. 2 Feb-19 May 81 82.90 15508 1210 72.2 106 0.68 178

4. 2 Feb-19 May 81 69.85 152.53 121.0 82.7 106 0.78 155

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Table 5-Total length (mm) statistics for Menticirrhus amencanus by maturity Table 6-Regression statistics of gonad weight (g) on total length (mm)

stage and sex. Confidence limits are for observations. for female Menticirrhus americanus captured off Freeport, Texas,

October 1977-August 1981. Regressions were significant at a = 0.06

99% or higher and are shown in Figure 5.

Observed confidence

Stage n X S size range limit Collection

month n r 2 Equation

Immature

2,556 112 21.5 31-183 56-167 SEPT.-NOV.

Male Sep 79 24 0.678 0.0612 TL - 11.87

Maturing virgin 763 \6\ 26.7 109-250 92-229 Oct 79 22 0.579 0.0207 TL- 3.81

Early developing 540 195 31.3 130-303 114-275 Nov 79 13 0.800 0.0690 TL - 14.97

Late developing 116 225 26.4 140-287 156-294 Sep 80 23 0.734 0.0261 TL- 4.47

Ripening/Spawning 2 222 9.2 215-228 -364-807 Oct 80 28 0.471 0.0044 TL - 0.59

Resting 27 238 19.6 208-271 183-292 Nov 80 28 0.584 0.0511 TL - 10.05

Female DEC.-FEB.

Maturing virgin 162 162 24.2 120-241 99-224 Dec 79 13 0.703 0.0198 TL - 3.57

Early developing 341 233 32.1 146-343 \51-316 Jan 80 44 0.577 0.0224 TL- 4.20

Late developing 96 258 29.6 205-345 180-336 Feb 80 7 0.873 0.1002 TL - 18.63

Gravid 28 262 31.0 207-339 176-348 Dec 80 84 0.550 0.0170 TL - 3.17

Ripe 27 265 35.1 203-333 167-362 Jan 81 87 0.727 0.0188 TL- 3.59

Spawning/Spent 14 258 39.4 190-324 140-377 Feb 81 101 0.559 0.0480 TL - 9.74

Resting 180 248 28.6 162-325 174-321 MAR.-MAY

Mar 80 26 0.769 0.2306 TL - 46.70

Apr 80 49 0.700 0.1981 TL - 37.94

May 80 24 0.715 0.1092 TL - 20.51

Mar 81 65 0.602 0.1689 TL - 34.34

Apr 81 40 0.831 0.1140 TL - 21.61

May 81 24 0.792 0.1216 TL - 25.24

JUNE-AUG.

Jun 80 16 0.829 0.0740 TL - 14.93

Jul 80 8 0.815 0.1087 TL - 24.51

Aug 80 6 0.619 0.0545 TL - 11.27

Jun 81 61 0.640 0.0567 TL - 10.85

Jul 81 44 0.823 0.0805 TL - 16.01

Aug 81 33 0.764 0.0681 TL - \3.33

Table 7-0bserved mean total length (mm) at 6 months, Ages I and II, for fall-spawned cohorts of Menticirrhus americanus off Freeport, Texas.

Mean sizes and confidence limits at Ages I and II were calculated from mean size statistics (Table 2) for the period September-November and assume

a September-November hatching date; collections from August were substituted in 1981 when fall cruises were not made. Mean size statistics at

6 months were calculated from data (Table 2) for the period March-May, and 99% confidence limits for observations were calculated as means

of upper and lower limits given in Table 2.

--------------------------- 6 months Age I Age II

No. of No. of No. of

means in calc. 99% limits means in calc. 99% limits means in calc. 99% limits

Cohort of X X on observ. of X X on observ. of X X on observ.

1976 2 267.9 208-322

1977 2 166.5 64-269 3 180.7 90-372 5 284.7 184-376

1978 3 137.0 88-185 5 207.1 128-317 5 262.1 185-376

1979 6 123.3 89-199 6 183.5 122-134 I 278.1 221-335

1980 6 126.4 70-\83 2 199.8 138-262

Pooled mean 4 138.3 78-209 4 192.8 119-271 4 272 200-352

Table 8-Regressions of weight-length, girth-length, and length-length for Menticirrhus americanus, with supporting statistics. Regressions were significant at a

= 0.05. The symbol v is from Ricker's (1973) GM regression. Measures are grams and millimeters.

Mean

TL square Corrected total

Equation n range IOOr 2 error SSx SSy X y v

Immatures Log lO TW = -5.61 + 3.24 Log lo TL 2,556 31-183 96.2 0.004 23.4 255.1 2.04 0.99 3.30

Males Loglo TW = -5.95 + 3.40 Log lo TL \,448 109-303 97.6 0.002 11.0 130.0 2.25 1.69 3.44

Females Loglo TW = -5.94 + 3.39 Log lo TL 1,697 120-345 98.6 0.002 20.0 232.4 2.28 1.79 3.41

Males + females + immatures Log lo TW = -5.79 + 3.33 Loglo TL 5,701 31-345 98.8 0.003 128.4 1,438.2 2.17 1.42 3.35

Males + females LoglO TW = -5.93 + 3.39 Log lo TL 3,145 109-345 98.3 0.002 31.7 369.9 2.26 1.74 3.42

TL = 7.40 ·f 1.18 SL 5,701 31-345 99.8 5.06 11,522,762 16.072,558 125.0 155.1 1.18

SL --6.19 + 0.85 TL 5,701 31-345 99.8 3.63 16,072,558 11,522,762 ]55.1 125.0 0.85

G = -11.53 + 0.61 TL 5,701 31-345 98.0 21.14 16,072,558 6,144,025 155.1 83.4 0.62

TL = 21.60 + 1.60 G 5,701 31.345 98.0 55.30 6,144,025 16,072,558 83.4 155.1 1.62

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