Kinds, Distributions and Abundances of Sea Bass Larvae (Pisces: Serranidae) from the Eastern Gulf of Mexico

BULLETIN OF MARINE SCIENCE, 32(2): 511-522, 1982

KINDS, DISTRIBUTIONS AND ABUNDANCES OF SEA BASS LARVAE (PISCES: SERRANIDAE) FROM THE EASTERN GULF OF MEXICO

Edward D. Houde

ABSTRACT Occurrences, distributions and abundances of serranid larvae from the eastern Gulf of Mexico were described based on 505-lLmmesh bongo net collections made during 13 cruises in 1971-73. A diverse assemblage of serranid larvae was collected, totalling 5,350 individuals. Four subfamilies were represented and 11 genera and 14 species (or types) were identified. The most abundant serranid larva was Diplectrum formosum, followed by Hemanthias vivanus. Larvae of D. formosum were the fifth most common species of all fish larvae that were collected on the cruises and accounted for 55.5% of the serranids. Other common serranid larvae included Serraniculus pumilio, Centropristis ~'triata, Pronotogrammus aureorubens, Anthias Type I, epinepheline larvae and Rypticus spp. Larvae of serranids were collected over the entire shelf area in the eastern Gulf during all seasons, but species that occurred differed by area, season and depth zone. Apparent differences in annual mean abundances were observed for some species. Relationships between occurrences and surface temperature and salinity were examined. Spawning seasons were inferred from the larval occurrence data.

The sea basses (Serranidae) are a diverse group of perciform fishes that are well represented in tropical and temperate oceans of the world, with many species important to commercial and recreational fisheries. Spawning areas and seasons of serranids were poorly known in the eastern Gulf of Mexico. The objectives of this paper are to report the kinds and abundances of serranid larvae in the eastern Gulf as well as seasons and areas where they occur. Delineating distributions of pelagic larvae by area and time allows inferences to be made about adult distributions, spawning areas and spawning seasons. Larvae of most serranid species are unidentified and have not been recognized at the species level, but four major kinds of pelagic larvae often are collected in ichthyoplankton surveys. Following Kendall (1979), these larvae are assigned to four subfamilies: Serraninae, Anthiinae, Epinephelinae and Grammistinae. Ken- dall (1979) described these kinds of larvae and also provided many specific identifications. His work made it possible to identify much of the eastern Gulf of Mexico serranid material.

METHODS AND MATERIALS

A series of 13 ichthyoplankton survey cruises to the eastern Gulf of Mexico in 1971-73 provided samples from near the coast to the deep Gulf (Table 1). A total of 756 stations was sampled with a 61-cm, 505-lLm mesh bongo net in oblique tows from 200 m, or within 5 m of bottom, to surface. Houde and Chitty (1976), Houde (1977) and Houde et al. (1979) have described the survey plan, sampling methods and analytical procedures in detail. The major literature source for larval identifications was Kendall (1979). Most larvae of Diplectrum and all Centropristis larvae were assumed to be D. formosum and C. striata, respectively, based on reported adult occurrences and distributions in the eastern Gulf of Mexico (Miller 1959; Bortone, 1977). Larvae of groupers, Eipinephelus and Mycteroperca spp. usually could not be identified to genus or species, except for some large specimens of E. moria, which have distinctive dorsal and anal fin meristics (DXI, 16, 17; AlII, 9). Epinephelus mario is the most common grouper in the eastern Gulf; only the speckled hind (E. drummondhayi) has similar meristics and is known to have scattered occurrences in the area. Catches of larvae at each station were standardized to numbers under 10 m2 of sea surface (Houde

511 512 BULLETIN OF MARINE SCIENCE. VOL. 32, NO.2, 1982

Table I. Thirteen cruises to the eastern Gulf of Mexico from which abundances and distributions of serranid larvae were determined

Number Area Represented of by the Stations Cruises'!' Dates Stations (m' x 10')

l. 8C7113-TI7114 7-18 May 1971 123 120.48 2. GE7117 26 June-4 July 1971 27 101.10 3. 8C7120-TI121 7-25 Aug 1971 146 189.43 4. TI713l-8B7132 7-16 Nov 197] 64 72.99 5. 8B720]-GE7202 1-] I Feb 1972 30 148.85 6. GE7208 1-10 May 1972 30 ]24.88 7. IS7205 9-17 Sept 1972 34 104.59 8. IS7209 8-]6 Nov ]972 50 149.80 9. IS7303 19-27 Jan 1973 51 149.80 10. IS7308 9-17 May 1973 49 151.42 ]1. IS7311 27 June-6 July 1973 51 156.50 12. IS7313 3-13 Aug 1973 50 153.18 13. IS7320 6-14 Nov 1973 51 153.89

* Ship Codes: 8e = RN DAN BRAMAN; TI = RN TURSIOPS; 8B = RIV BELLOWS; GE = RIV GERDA; IS = RN COLUMBUS ISELIN.

1977). In this way mean abundances of larvae could be compared among years, seasons, depth zones and north-south sectors in the eastern Gulf. The survey area and stations that were sampled one or more times during the cruises are iUustrated in Figure l. Stations sampled on each of the cruises are not illustrated here but are illustrated in Houde et al. (1979). Comparisons of serranid larvae abundances between depth zones were made relative to the 50 m isobath. Comparisons between north and south sectors were made after dividing the survey area at latitude 2r15'N. Frequencies of station occurrences for common serranid larvae also were determined relative to depth zones, surface temperatures and surface salinities. Differences in mean abundances of larvae between depth zones and between north-south sectors were tested for significance in paired t-tests after transforming larval abundance estimates to log, (abundance ±0.0001). Differences were judged to be significant at the a '" 0.05 level.

RESULTS A total of 5,350 serranid larvae was collected in the 13 cruises. Serranids accounted for 4.7% of all fish larvae that were collected in the eastern Gulf of Mexico and 5.2% of larvae that were identified at least to the family level. Only Clupeidae, Gobiidae, Bothidae and Myctophidae contributed more larvae than Serranidae to the collections. Serranids were among the 10 most often collected families on 8 of the 13 cruises. Serranid larvae were collected at most of the stations in the eastern Gulf, an indication that spawning is widespread in the survey area. Larvae of the four subfamilies were present in eastern Gulf collections. Larval Serraninae were most common, contributing 3,653 larvae, 68.3% of the serranid larvae collected (Table 2). There were relatively few Anthiinae (512 larvae, 9.6%), Epinephelinae (146 larvae, 2.7%) and Grammistinae (202 larvae, 3.8%). Larval serranids that could not be identified to subfamily totalled 837 (15.6%). Eleven genera and 15 species (or types) were identified in the collections (Table 2). The number of larvae identified to species (or type) was 3,977, 74.3% of the serranid larvae that were collected. The most common species was the sand perch Diplectrum formosum. Its larvae comprised 55.5% of all serranid larvae in the collections. Diplectrum formosum was the fifth most frequently collected fish larvae identified to species for the 13 cruises. Only the clupeids Sardinella an- chovia and Opisthonema oglinum, the carangid Decapterus punctatus and the bothid Syacium papillosum were more common. Other common serranid larvae were Hemanthias viva nus (red barbier), Ser- HOUDE: SERRANlD LARVAE: EASTERN GULF OF MEXICO 513

~ + '~::=:_--:f-"" + ,;,' \ '. 10m + ,~, ,"!_... 1- '... ~\ -r\.. CI _ _ .••.._//,;1 _+- .•. ~, '~'.. +..-.. + .••."..I •• ~ - '" \ \ . ..--- + + \ -t \ '~-t + .. \.. .•.... + + + ' ....r .•.....+ , + -+ + + + +\ "", ....,... 50 m \ .•. ... +, + + + + -t1 .•. ,,\. \ + + + '+, ,,+ '" + + + + ~ \ \ \ ~ +", -i- ,,+ + -+ + ,+ ',100 rTt \ + + + + + ~, \ ~\ + --t- + + ~+ .. \' .. ~l 't -f~t + T +\ .. + + + "+\ + 1- +\, *I \.\ \ •• 200 'm+ ~ + \ + + +\ + l-+i-+-\-+++\ I \ I \ \+'+rl-++-t\ \ I' ,\\'\1 + + \ + t+ + \+ -+ + -+ \.\1 I I \ ' .• I + I + + \ --;- + + + " I I \ , + +: -+: + +\ + + + + \ ,.. \ \ : '\1-++\++++\+ I t \ \ + 1,+ , + -+ +1 + + + + \+ \ I I \ \\ 'I/ + -+ }+- + + + + \+\ + " \...... :-1', + +, + + + + /I 'q- :v ,it :- + + ~/ "'".~/ •••' ••••••.\.. • ,..__ ••.. J '"

86° 84° 82° 80° Figure I. Survey area, stations and depth contours for ichthyoplankton cruises to the eastern Gulf of Mexico, 1971-73. Not all stations were sampled on each of the 13 cruises. raniculus pumilio (pygmy sea bass) and Centropristis striata (black sea bass). Unidentified species of Rypticus (soapfishes) also were common as were larvae of Serranus spp. Larval groupers (Epinephelus or Mycteroperca spp.) occurred frequently but, except for five E. morio (red grouper) larvae, they could not be identified to species. Most unidentified serranids (Table 2) probably were serranines, based on subfamily characters given by Kendall (1979). They were not assigned to Serraninae because of uncertainty in their identification. Numbers collected and abundances of common serranid larvae varied among cruises (Table 3). Of the eight most common serranids only D. formosum occurred in all cruises. Hemanthias vivanus occurred in all except one cruise and S. pumilio was present in all but two of the cruises. Although nearly eight times more D.formosum than H. viva nus larvae were collected, their mean abundances (number under 10 m2) differed by only a factor of 3.4 (Table 3), primarily because H. viva nus occurred more frequently at deeper stations. Only D. formosum and H. viva nus mean abundances exceeded 1.0 under 10 m2 for the 13 cruises.

Areas of Occurrence Distributions of eight common serranid larvae, represented by stations when: larvae were collected at least once during the surveys, are illustrated in Figure 514 BULLETIN OF MARINE SCIENCE, VOL. 32, NO.2, 1982

Table 2. List of serranid larvae collected on 13 cruises to the eastern Gulf of Mexico, 1971-73 (Percentages of larvae within each subfamily are percents of total serranid larvae that were collected)

Larvae

Taxa Number Percent

Serraninae 3,653 68.3 Diplec/rum formosum 2,967 55.5 Dip/ectrum spp. 7 0.1 Centropristis striata 138 2.6 Serraniculus pumilia 355 6.6 Serra nus spp. 186 3.5 Anthiinae 512 9.6 An/Mas Type I 35 0.7 An/hias Type 2 3 <0.1 An/hias Type 3 11 0.2 An/hias spp. 13 0.2 P/ectran/hias garupellus 2 <0.1 Pronotogralnmus aureorubens 68 1.3 Hemanthias vivanus 379 7.] HemantMas sp. I <0.1 Epinephelinae /46 2.7 Epinephe/us moria 5 0.] Epinephe/us or Mycteroperca spp. 141 2.6 Grammistinae 202 3.8 Rypticus saponaceous 6 0.1 Rypticus macula/US I <0.1 Rypticus spp. 172 3.2 Liopropoma Type I 5 0.1 Liopropoma Type 2 I <0.1 Liopropoma spp. 17 0.3 Serranidae (unidentified) 837 /5.6 Total 5,350 /00.0

2. All of the larvae were widely distributed along the north-south axis of the eastern Gulf, although their abundances varied in that range. The serranine types (Diplectrum, Centropristis, Serraniculus) occurred most frequently where bottom depths were <50 m, while the anthiine types (Hemanthias, Pronotogrammus, Anthias) usually were found at stations >50 m deep. Larvae of groupers (Epi- nephelines) and soapfishes (Rypticus) occurred both nearshore and offshore in the eastern Gulf. The percentages of stations at which larvae occurred within three bottom depth categories served to show the differences in probability of occurrence (Table 4). Diplectrum formosum and S. pumilio had highest probability of occurrence where bottom depth was <50 m. Another serranine type, C. striata, occurred with nearly the same probability at <50 m and 50-100 m bottom depths. The anthiines, H. viva nus and Anthias Type I, occurred with highest probability where bottom depths exceeded 100 m, but P. aureorubens occurred with equal probability at 50-100 m and> 100 m depths. Rypticus spp. had its highest percentage occurrence at stations within the 50-100 m bottom depth zone. Percentage of positive stations for epinepheline larvae also was highest in the 50-100 m zone although these larvae occurred with only slightly lower probability where bottom depth was <50 m. Abundances of the larvae also differed with respect to depth. Mean abundances HOUDE: SERRANID LARVAE: EASTERN GULF OF MEXICO 515

Table 3. Numbers collected and estimated arithmetic mean abundances of eight taxa of sermnid larvae from 13 cruises to the eastern Gulf of Mexico, 1971-73

Diplecrrum formosum Serraniculus pumilia Centropristis striata Hemanthias l'ivutlus

Abundance Abundance Abundance Abundance Number (Number Number (Number Number (Number Number (Number Cruise'" of Larvae Under 10 m') of Larvae Under 10 m') of Larvae Under 10 m') of Larvae Under 10 m')

1 1,170 29.75 35 0.99 93 27.07 113 3.23 2 10 0.85 3 0.80 0 0.00 5 0.91 3 199 2.87 56 0.88 0 0.00 8 0.14 4 14 0.74 3 0.11 12 1.03 68 3.10 5 14 1.18 0 0.00 15 1.05 1 0.05 6 374 15.57 12 0.34 0 0.00 50 3.93 7 218 13.61 ]52 4.61 1 0.04 6 1.26 8 7 0.28 1 0.02 0 0.00 12 2.30 9 78 3.70 0 0.00 10 0.54 35 5.20 ]0 675 22.61 15 0.40 0 0.00 76 8.39 ]1 93 2.40 26 0.79 0 0.00 2 0.17 ]2 78 3.08 49 1.33 0 0.00 0 0.00 13 37 1.63 3 0.08 7 0.08 ] 0.17 Mean 7.56 0.80 0.30 2.22

* Refer to Table I for cruise details. for eight common serranids from each of the 13 cruises at bottom depths <50 m and >50 m (Table 5) were compared in a paired t-test!. The three serranine species were significantly more abundant at stations <50 m deep. The three anthiines were significantly more abundant at stations >50 m deep. In fact, An- thias Type I was not collected where bottom depth was <50 m. There were no significant differences in mean abundances between the depth zones for the epinepheline larvae or for Rypticus spp. When the cruise survey area (Fig. 1) was arbitrarily divided into northern and southern sectors at latitude 2rl5'N, there were significant differences in mean larval abundances of some serranids between the two areas (Table 6) [paired t-tests on loge(x + 0.0001) abundances]. Larvae of C. striata were significantly more abundant in the northern sector. Larvae of the anthiines H. viva nus and P. aureorubens were significantly more abundant in the southern sector. Higher abundance of anthiines in the south probably reflects the larger area there with bottom depths >50 m. The epinepheline mean abundances over the 13 cruises appeared to be higher in the south than the north (Table 6), but no significant difference was detected between cruise means. The eight most common kinds of serranid larvae differed seasonally in mean abundances (Table 7). Two of the three serranine types, D. formosum and S. pumiLio, were most abundant in spring and summer, while the third species, C. striata, was most abundant in winter and spring. All of the anthiines peaked in abundance during late winter or early spring; all were relatively rare in summer. EpinepheLine larvae were most abundant in spring-summer while Rypticus spp. had a peak summer abundance. The percentage frequency distributions of station occurrences relative to surface temperature for each of the eight kinds of larvae also indicated the seasonality of occurrences (Table 8). Diplectrum formosum and S. pumilio occurred most frequently at stations where surface temperatures were ~30°C, while C.

I The t-test was carried oul on log.,(x + 0.0001) transformed data that are summarized in Table 5. 516 BULLETIN OF MARINE SCIENCE. VOL. 32. NO.2. 1982

Table 3. Continued

Prollotogrammus aureorubells Anthias Type I EpinepheHne larvae Rypticus spp.

Abundance Abundance Abundance Abundance Number (Number Number (Number Number (Number Number (Number of Larvae Under 10 m') of Larvae Under 10 m') of Larvae Under 10 m') of Larvae Under 10 m')

29 0.55 2 0.Q7 32 0.55 2 0.04 1 0.09 1 0.17 0 0.00 7 0.82 3 0.08 2 0.04 0 0.00 48 0.64 0 0.00 15 0.54 0 0.00 1 0.03 5 0.49 0 0.00 1 0.07 0 0.00 11 1.02 0 0,00 29 1.65 1 0.03 0 0.00 0 0.00 24 3.70 69 3,15 7 0.91 8 1.63 \ 0.12 0 0.00 7 0.98 4 0.58 1 0.04 0 0.00 5 0.50 2\ 3.20 26 1.62 3 0.19 0 0.00 1 0,11 4 0.23 13 0.55 0 0.00 0 0,00 1 0.04 34 1.7\ 0 0.00 1 0.12 0 0.00 1 0.12 0.36 0,50 0.62 0,56 striata occurrences were most frequent where surface temperature was <22°C. All of the anthiine larvae occurred most often when surface temperatures ranged from 22-30°C. Rypticus spp. occurred most frequently at stations where surface temperature was ~30°C while epinepheline larvae were seen most often when surface temperatures were 22-26° and ~30°C. Surface salinities at stations that were sampled in the eastern Gulf usually were ~34%o, making it difficult to determine if occurrences of larvae were related to salinity. However, for six of the eight most common taxa percentage frequencies of station occurrences were highest where surface salinity was ~36%o (Table 9). Only D. formosum and H. vivanus larvae were common enough to determine whether changes in modal lengths occurred as seasons changed. During their seasons of peak larval abundance (Table 7), which probably coincide with peak spawning seasons, larval modal lengths were 2.1-3.0 mm SL for each species. In seasons when larvae were less abundant, and when recruitment of newly-hatched larvae into the population was lower, modal lengths for each species increased to 3.1-4.0 mm SL.

Table 4. Percentages of stations within three bottom depth zones that had positive occurrences for eight taxa of serranid larvae from 13 cruises to the eastern Gulf of Mexico (The number of stations sampled within each depth zone is given in parentheses)

Depth Zone

<50 m 50-100 m >Ioom Species (473) (143) (142)

Dip/ectrum farmasum 50.3 33.6 2.1 Serranicu/us pumilia 23,5 2.8 0.0 Centrapristis striata 6,8 9.1 1.4 Hemanthias vivanus 0,6 \6.8 26.1 Pranatagrammus aurearubens 0.2 11.2 11.3 Anthias Type 1 0,0 3.5 11.3 Epinepheline larvae 6,6 9.1 4.2 Rypticus spp. 9.9 20.3 3,5 HOUDE: SERRANID LARVAE: EASTERN GULF OF MEXICO 517

28'

26'

24'

"-'- ", "\"~ "\.:. 28' ..\:Y~'\. ", ••• Ip . . ,... \ .. I ••. \ . 26' • ! ••. \. I ••. \,' . ~. ·.·.·i.·. . \~.<,"i._: '--,- ._{::-::

24' 86' 84' 82' 80' 86' 84' 82" 80'

Figure 2. Stations at which eight taxa of serranid larvae occurred one or more times on 13 cruises to the eastern Gulf of Mexico, 1971-73.

Although sampling effort was not uniform among years there were apparent differences in annual mean abundances of some serranid larvae (Table 10). Larvae of the two most common species, D. formosum and H. vivanus, differed little in mean abundance from year to year. But, larvae of S. pumilio, P. aureorubens, epinepheline larvae and Rypticus spp. all had highest mean abundances in 1972. Only C. striata appeared to be most abundant in 1971 while Anthias Type I had its highest mean abundance in 1973.

DISCUSSION Although diverse, in the sense that many kinds of larvae occurred, the collections were dominated by a single serranid species, the sand perch D. formosum, which was widely distributed over shelf waters where bottom depth was <100 m. Finucane et a1. (1978) also reported Diplectrum sp. as the dominant serranid larva on the south Texas continental shelf, but its larvae were collected more frequently at depths >100 m in the Texas study than in the eastern Gulf. All except 7 Diplectrum larvae from the eastern Gulf were believed to be D. fo,.- mosum, based on Bortone's (1977) reported distributions of species in the genus. 518 BULLETIN OF MARINE SCIENCE, VOL. 32, NO.2, 1982

24' 86' 84' 82' BO' B6' 84' 82' 80' Figure 2. Continued.

It is possible that some of the larvae may have been D. bivittatum at stations on the southern edge of the survey area. That species is the only one that Bortone (1977) found to partially overlap D. formosum's area of distribution in the eastern Gulf. The dominance of serranid larvae by the single species, D.formosum, is similar to the situation observed by Leak (1981) for carangid larvae in the eastern Gulf, where a single abundant and widely distributed species, Decapterus punctatus, accounted for most of the larval carangids, even though many other less common species, more restricted in their areas of occurrence, were observed. The family Bothiidae also was diverse in the eastern Gulf (Dowd, 1978), but its species abundances were more evenJy distributed, Three species, Syacium pa- pilLosum, Etropus rimosus and Bothus robinsi were common and all occurred widely over the shelf area, Of the widely distributed and abundant species the serranid D. formosum, the carangid D. punctatus, and two of the bothids S. papilLosum and B. robinsi all spawned mainJy in spring-summer months and their larvae frequently occurred together (Houde et aI., 1979). All of those species continued to spawn in winter but the areas of larval occurrence were restricted then to the southern part of the survey area (Houde et aI., 1979). HOUDE: SERRANID LARVAE: EASTERN GULF OF MEXICO 519

Table 5. Estimated geometric mean abundances and .95 confidence limits of eight kinds of serranid larvae at <50 m and >50 m deep stations for 13 cruises to the eastern Gulf of Mexico, and outcome of a paired t-test to determine if abundance differed significantly

Mean Abundance (Number Under 10 m') Hest Result Species <50 m >50m (Probability)

Diplectrum formosum 1.35 ",; 2.03 ",; 3.04 0.23 ",; 0.60 ",; 1.56 P < .005 ** Serraniculus pumilio 0.19 ",; 0.50 ",; 1.29 0.01 ",; 0.03 ",; 0.06 P < .001 ** Centropristis striata 0.03 ",; 0.10 ",; 0.35 0.02 ",; 0.04 ",; 0.11 P < .05 * Hemantlzias vivanus 0.01 ",; 0.03 ",; 0.06 0.43 ",; 1.01 ",; 2.38 P < .001 ** Pronotogrammus aureorubens <0.0005 - ",; 0.02 ",; 0.29 P < .02 * Antlzias Type I 0.0000 - ",; 0.05 ",; 0.67 P < .001 ** Epinepheline larvae 0.05"'; 0.17 ",; 0.52 0.03 ",; 0.12 ",; 0.42 P> .20 n.s. Rypticus spp. 0.04 ",; 0.14 ",; 0.46 0.08 ",; 0.23 ",; 0.70 P> .20 n.S.

Two serranine larvae, in addition to D. formosum, were commonly collected. Larvae of the spring-summer spawner, pygmy sea bass S. pumilio, were widely distributed in eastern Gulf shelf waters where bottom depth was <50 m. In con- trast, larvae of the black sea bass C. striata occurred in winter and spring, indicating peak spawning at those times. Most larval C. striata were collected in the northeastern corner of the survey area where bottom depths were <50 m. It is possible that some Centropristis larvae collected offshore and at the southern- most stations were not C. striata, because C. ocyura and C. philadelphica are reported to occur in those areas (Miller, 1959). Centropristis sp. and S. pumilio larvae were reported from south Texas shelf waters (Finucane et aI., 1978) in the same seasons that they occurred in the eastern Gulf. Kendall (1972) described larvae of C. striata from the east coast of the United States and reported on their occurrences from North Carolina to New Jersey, where larvae have been collected from May to November, implying that the spawning season there differs from that in the eastern Gulf of Mexico. All of the anthiine type larvae were most abundant in winter and spring in areas where bottom depth was between 50 and 200 m. Although most spawning must occur in winter-spring, there is some spawning year-round, because a few specimens of all anthiine species or types were collected throughout the year. The red barbier Hemanthias viva nus is the only anthiine larva that was common in

Table 6. Estimated geometric mean abundances and .95 confidence limits in the northern and southern sectors of the survey area (Fig. 1) for eight kinds of serranid larvae collected in 13 cruises to the eastern Gulf of Mexico, and outcome of a paired t-test to determine if abundances differed significantly

Mean Abundance (Number Under 10 m') t-test Result Species North South (Probability)

Diplectrum formosum 0.81 ",; 1.33 ",; 2.19 1.33 ",; 1.91 ",; 2.74 .05 < P < .10 n.s. Serraniculus pumilio 0.10",; 0.28",; 0.77 0.06",; 0.22 ",; 0.77 P> .50 n.s. Centropristis striata 0.03 ",; 0.11 ",; 0.37 0.01 ",; 0.03 ",; 0.07 P < .05 * Hemantlzias vivanus 0.03",; 0.11",; 0.39 0.04 ",; 0.40 ",;4.48 P < .05 * Pronotogrammus aureorubens <0.01 - ",; 0.02 ",; 0.28 P < .02 * Antlzias Type I <0.03 - ",; 0.02 ",; 0.23 P = .20 n.s. Epinepheline larvae 0.03 ",; 0.09 ",; 0.29 0.06 ",; 0.19 ",; 0.63 .10 < P < .20 n.s. Rypticus spp. 0.05 ",; 0.17 ",; 0.53 0.06 ",; 0.18 ",; 0.58 P> .50 n.s. 520 BULLETIN OF MARINE SCIENCE. VOL. 32. NO.2, 1982

Tab]e 7. Unweighted mean seasonal abundances of eight taxa of serranid larvae from 13 cruises to the eastern Gulf of Mexico

Mean Abundance (Number Under 10 m')

Number Cenlro- Prolloro- of Dip{ectrum Serruniculus pristis Hema1l1hiwi grammus An/him; Epinepheline Ryp(icus Season Cruises formosum pumilio striata viva"u .•• aureorubens Type 1 larvae spp.

Jan-Mar 2 2.44 0,00 0.80 2.62 0.74 0.29 0.06 0.00 Apr-Jun 3 22.64 0.58 0.75 5.18 0.69 1.09 1.27 0.09 Jul-Sep 5 4.56 1.68 0.01 0.50 0.03 0.06 0,79 1.37 Oct-Dec 3 0.88 0.07 0.03 1.86 0.30 0.76 0.04 0.05

eastern Gulf collections. Finucane et al. (1978) collected both H. vivanus and Anthias sp. off south Texas, but these larvae apparently were relatively rare in that area. The groupers (epinephelines) apparently spawned mainly in spring, with some summer spawning also occurring in the eastern Gulf, based on larval collections. Only the red grouper Epinephelus moria was identified from five large, nearly metamorphosed larvae taken during two spring cruises where bottom depths were between 50 and 200 m. Moe (1969) found adut, eastern Gulf E. moria with mature gonads in spring. Unidentified epinepheline larvae might belong to any of several species of Epinephelus and Mycteroperca. Only 3.4% of the epinepheline larvae were identified to species. If epinepheline larvae could be identified, fluctuations in grouper stock abundances possibly could be evaluated, which would be helpful to agencies concerned with managing their fisheries in the eastern Gulf of Mexico. Larvae of grammistines, considered to belong to a subfamily within Serranidae by Kendall (1979), were common. Two distinct kinds of larvae occurred in the eastern Gulf. Most were Rypticus spp. and six large specimens were positively identified as R. saponaceous and one as R. maculatus based on Courtenay's (1967) keys. Rypticus spp. larvae occurred throughout the eastern Gulf where bottom depth was <200 m. The second kind of larva was Liopropoma spp. and two types were recognized. Liopropoma larvae occurred where bottom depths were >50 m. Larvae of grammistines were most abundant in summer, indicating spawning in that season. Larval serranids usually are among the most common larvae collected in ichthyoplankton surveys in the subtropical western Atlantic, but the larvae often are not identified at either the generic or specific level. Powles and Stender (1976)

Table 8. Percentages of stations within four surface temperature classes that had positive occurrences for eight taxa of serranid larvae from 13 cruises to the eastern Gulf of Mexico (The number of stations sampled in each temperature class is given in parentheses)

<22" 22-26" 26--30" ",30" Species (65) (323) (334) (36)

Diplectrum formosum 27.7 50.5 36.2 94.4 Serraniculus pumilio 0.0 ]5.8 ]7.7 58.3 Centropristis striata 27.7 9.6 1.5 0.0 Hemanthias vivanus 0.0 9.6 10.5 2.8 Pronotogrammus aureorubens 1.5 6.8 4.2 2.8 Anthias Type 1 0.0 2.8 3.3 0.0 Epinepheline larvae 0.0 10.8 3.6 8.3 Rypticus spp. 0.0 2.2 ]9.5 25.0 HOUDE: SERRANID LARVAE: EASTERN GULF OF MEXICO 521

Table 9. Percentages of stations within four surface salinity classes that had positive occurrences for eight taxa of serranid larvae from \3 cruises to the eastern Gulf of Mexico, 1971-73 (The number of stations sampled in each salinity class is given in parentheses)

<32%1l 32-34%ll 34-36"'/;, "'36"'/;, Species (28) (62) (387) (281)

Dip/ectrum farmasum 3.6 33.9 31.0 69.4 Serranicu/us pumilia 0.0 12.9 9.8 29.9 Centropristis striata 0.0 12.9 7.5 6.0 Hemanthias vivanus 3.6 1.6 1.8 20.6 Pranotogrammus aurearubens 3.6 0.0 0.8 12.1 Anthias Type I 0.0 0.0 1.3 7.8 Epinepheline larvae 0.0 1.6 4.4 4.6 Rypticus spp. 3.6 8.1 7.2 4.3 collected many serranid larvae in the South Atlantic Bight between Florida and North Carolina. Juarez (1975) collected serranid larvae in all seasons on the Campeche Banks in the southwestern Gulf of Mexico, but she did not identify the larvae except to note that, based on larval occurrences, epinephelines spawned in winter and that other serranids spawned in spring and summer. Fin- ucane et al. (1978) reported that serranid larvae were among the most abundant families from the south Texas shelf. They reported most of the larvae to be Diplectrum sp., a situation similar to that in the eastern Gulf. Larvae to Centro- pristis sp. also were common on the south Texas shelf. A better knowledge of serranid larval taxonomy is needed to help determine spawning areas and seasons, to define stock structure of important species or to monitor effects of environmental changes on stock abundances. Kendall's (1979) recent work was an important contribution but more good taxonomy is needed. This is particularly true for the epinephelines because of their commercial im- portance and for the serranines because of the great diversity in that subfamily. In this study nearly 16% of the larvae could not be identified to subfamily, although most of them probably were serranines, based on morphological features, particularly the relatively modest development of spination on the opercular-pre- opercular area and developing fins. Because D.formosum dominated the serranid larvae of the eastern Gulf and was one of the most abundant larvae collected, this easily identified species is one of a small group of species that could be used to monitor effects of environmental change on the Gulf ecosystem. Others would include the widely distributed and abundant larvae of Decapterus punctatus (Ca- rangidae) and Syacium papillosum (Bothidae).

Table 10. Unweighted mean annual abundances of eight taxa of serranid larvae from \3 cruises to the eastern Gulf of Mexico, 1971-73

Number Serrani- Centro- Pronoto- Epinephe. of DipJectrum eu/us prist;s Heman/hillS grammus AnthillS line Ryplicus Year Cruises formosum pumilia striata vivanw; aureorubens Type I Larvae spp.

1971 4 8.55 0.70 0.56 1.85 0.18 0.21 0.14 0.38 1972 4 7.66 1.24 0.27 1.89 0.61 0.41 1.39 0.80 1973 5 6.68 0.52 0.12 2.79 0.30 0.80 0.39 0.51 522 BULLETINOFMARINESCIENCE,VOL.32, NO.2, 1982

ACKNOWLEDGMENTS

Financial support was provided through a NOAA Sea Grant 04-3-158-27 and a Bureau of Land Management Contract AA550-CT7-28 to the University of Miami. Thanks go to S. A. Berkeley, C. E. Dowd and J. C. Leak for assistance in the laboratory and for help in preparing data for analysis. Dr. A. W. Kendall, Jr., provided comments and suggestions to improve a preliminary draft of the manuscript. Contribution No.1 136, Center for Environmenta] and Estuarine Studies of the University of Maryland.

LITERA TURE CITED

Bortone, S. A. 1977. Revision of the sea basses of the genus Diplectrum (Pisces: Serranidae). NOAA Tech. Rep. NMFS Circ. 404. 49 pp. Courtenay, W. K., Jr. 1967. Atlantic fishes of the genus Rypticus (Grammistidae). Proc. Acad. Nat. Sci. Phila. 119: 241-293. Dowd, C. E. 1978. Abundance and distribution of Bothidae (Pisces, Pleuronectiformes) larvae in the eastern Gulf of Mexico, 1971-72 and 1973. Master's thesis, Univ. Miami. 106 pp. Finucane, J. H., L. A. Collins, L. E. Barger, and J. B. McEachran. 1978. Ichthyoplankton/mackerel eggs and larvae. NOAA Final Rep. to Bur. Land Mgt., Environmental studies of the south Texas outer continental shelf. 1977. Bur. Land Mgt. Contract AA550-IA7-21, xxi plus 504 pp. Houde, E. D. 1977. Abundance and potential yield of the round herring, Etrumeus teres, and aspects of its early life history in the eastern Gulf of Mexico. Fish. Bull. U.S. 75: 61--89. ---, and N. Chitty. 1976. Seasonal abundance and distribution of zooplankton, fish eggs and fish larvae in the eastern Gulf of Mexico, 1972-74. NOAA Tech. Rep. NMFS SSRF-701. ]8 pp. --, J. C. Leak, C. E. Dowd, S. A. Berkeley, and W. J. Richards. 1979. Ichthyoplankton abundance and diversity in the eastern Gulf of Mexico. Rep. to Bur. Land Mgt., Contract AA550- CT7-28. NTIS PB-299839. xxxii plus 546 pp. Juarez, M. 1975. Distribuci6n cuantitativa y algunos aspectos cualitativos de] ictiop]ancton de] Banco de Campeche. Rev. Invest., INP 1: 27-71. Kendall, A. W., Jr. 1972. Description of black sea bass, Centropristis striata (Linnaeus), larvae and their occurrences north of Cape Lookout, North Carolina, in 1966. Fish. Bull. U.S. 70: 1243-1260. ---. 1979. Morphological comparisons of North American sea bass larvae (Pisces: Serranidae). NOAA Tech. Rep. NMFS Circ. 428. 50 pp. Leak, J. C. 1981. Distribution and abundance of Carangidae (Pisces, Perciformes) larvae in the eastern Gulf of Mexico, ]971-1974. BioI. Oceanogr. 1: 1-28. Miller, R. J. 1959. A review of the seabasses of the genus Centropristis (Serranidae). Tulane Stud. Zoo I. 7: 35-68. Moe, M. A., Jr. 1969. Biology of the red grouper Epinephelus morio (Valenciennes) from the eastern Gulf of Mexico. Fla. Dept. Natur. Resour. Prof. Pap. 10. 95 pp. Powles, H., and B. W. Stender. 1976. Observations on composition, seasonality and distribution of ichthyoplankton from MARMAP Cruises in the South Atlantic Bight in 1973. S. Carolina Mar. Resour. Center, Tech. Rep. 11. 47 pp.

DATE ACCEPTED: March 27, 1981.

ADDRESS: Division of Biology and Living Resources, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149. PRESENTAD- DRESS:Chesapeake Biological Laboratory, University of Maryland, P.O. Box 38, Solomons, Mary- land 20688.