Northeast Gulf Science Volume 3 Article 5 Number 2 Number 2

12-1979 Maturation of the Calico , gibbus, Determined by Ovarian Color Changes George C. Miller National Marine Fisheries Service

Donald M. Allen National Marine Fisheries Service

T.J. Costello National Marine Fisheries Service

J. Harold Hudson U.S. Geological Survey

DOI: 10.18785/negs.0302.05 Follow this and additional works at: https://aquila.usm.edu/goms

Recommended Citation Miller, G. C., D. M. Allen, T. Costello and J. Hudson. 1979. Maturation of the Calico Scallop, , Determined by Ovarian Color Changes. Northeast Gulf Science 3 (2). Retrieved from https://aquila.usm.edu/goms/vol3/iss2/5

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Northeast Gulf Sciences Vol. 3, No.2, p. 96-103 December 1979

MATURATION OF THE CALICO SCALLOP, Argopecten gibbus, DETERMINED BY OVARIAN COLOR CHANGES 1

George C. Miller, Donald M. Allen, and T.J. Costello Southeast Fisheries Center National Marine Fisheries Service, NOAA 75 Virginia Beach Drive Miami, FL 33149 and J. Harold Hudson U.S. Geological Survey Fisher Island. Station Miami Beach, FL 33139

ABSTRACT:: Ovarian color was described for the calico scallop, Argopecten gibbus, by sizes and seasons from May 1970 to October 1971 on the Cape Canaveral grounds, Florida. Seven stages of ovarian development were recognized primarily by color and sequence of development and graded from immature to ripe to spent. as small as 20 mm shell height can be ripe. There were distinct changes in developmental stage by season. Most scallops were ripe·from January to May; in August, large scallops were spent or developing and small scallops were immature. Based on seasonal occurrence of ripe and partially spawned scallops, spawning extended primarily from about November to July and was intense from January to May. There was no spawning in August. Variations occurred in the spawning pattern between years.

The calico scallop, Argopecten gibbus, (1) rate of development; a benthic marine mollusk found in the (2) developmental stages by season; western North Atlantic Ocean, is most and abundant at depths from 28 to 65 m (3) spawning. (15 to 36 fm). Commercial beds of the Other factors that might influence calico scallop are fished off North ovarian color were also determined. Carolina and off the east and west coasts Color changes in scallop ovaries with of Florida (Allen and Costello, 1972). maturation and spawning have been The biology of the calico scallop was reported previously. In the sea scallop, studied by the Bureau of Commercial Placopecten magellanicus, the sexes Fisheries, Tropical Atlantic Biological are separate; the ovaries are brilliant Laboratory (now National Marine Fish­ coral red when ripe, pale pink when eries Service, Miami Laboratory) from partially spent, and clear when spent 1969 to 1971. One objective of the study (Posgay and Norman, 1958). Posgay et al. was to describe color changes in ovarian (1962) listed the following stages of tissue of the calico scallop and to relate development by ovarian color for the sea those changes to matnri ty of the ovaries. scallop: Ovarian color was then used to recognize and delimit the following aspects of Stage 1: Immature, sexes indistin­ gonads trans- maturation: quishable, lucent. 1 Contribution Number 80-llM, Southeast Stage II: Immature, developing, light Fisheries Center, National Marine Fisheries Service, NOAA, Miami, FL 33149, pink. 96 Published by The Aquila Digital Community, 1979 1 Gulf of Mexico Science, Vol. 3 [1979], No. 2, Art. 5

Maturation of the calico scallop 97

Stage III: Immature, orange-pink to noticeable. Coloration and incidence orange-red. increased into fall and winter and by Stage N: Mature, ripe, coral-red. February ovaries were predominantly Stage V: Mature, partially spent, color reddish-orange or ripe. The majority still bright. of ovaries taken in April were bright Stage VI: Mature, spent, sexes diffi­ reddish-orange. June ovaries were cult to distinguish, dull gray­ largely uncolored." orange. From the progression of color changes, Color was also used to describe ovarian Roe et al. ( 1971) concluded that the development in the hermaphroditic bay maturation period "begins in August scallop, , a species and ends in March or April." closely related to the calico scallop. Ripe calico scallops, which had orange­ Belding ( 1910) reported that with devel­ red ovaries, were induced to spawn in the opment the ovaries change "from an in­ laboratory and produced viable eggs, discernible pink to a deep orange color." larvae, and juveniles (Costello et al. According to Gutsell ( 1931 ), the ovaries (1973). are pink or red when ripe. Costello et al. (1957) reported that the ovaries were METHODS bright orange-pink when ripe and pale after spawning. Castagna and Duggan A study site for calico scallops on the (1971) found that ripe ovaries were Cape Canaveral grounds, Florida, desig­ reddish-orange, although black epi­ nated Buoy 2, was established at latitude thelium sometimes obscured the initial 28°49.l'N and longitude 80°29.0W in color change of the ovaries. Sastry ( 1963) a depth of 22m (12 fm) (Figure 1). A distinguished the following stages of scallop bed located immediately west of development by ovarian color: Buoy 2 was sampled seasonally by two Stage I: Immature, sexes indistin­ 5-min tows of a 3m (10 ft) otter trawl guishable, transparent. (trynet) equipped with a double-tickler Stage II: Immature, sexes indistin- chain between the trawl doors. Buoy 2 guishable, translucent. was the primary source of scallops for Stage III: Immature, pale orange. the ovarian color study, and 11 samples Stage IV: Mature, ripe, bright orange. were obtained there from May 1970 to Stage V: Mature, partially spent, pale October 1971 (Figure 2). Each sample orange. contained at least 10 scallops selected Stage VI: Mature, spent, sexes indis­ over the size range of those caught, tinguishable, light brown. except that for July 1970, which con­ In the hermaphroditic calico scallop, tained 9 scallops. In May, June, and Roe et aL (1971) observed that ovarian August 1971, each sample included 10 color changes occurred with maturation. additional scallops less than 41 mm shell Undeveloped ovaries were whitish, rest­ height is a straight line measurement ing ovaries whitish-yellow, maturing of the greatest distance between the ovaries yellow-orange, and ripe ovaries umbo and the ventral margin) to estab­ bright reddish-orange. They noted that: lish minimum size at maturity. The live 'Yellow-orange coloration was seen scallops were opened 1 to 2 hours after in very few scallops during the August capture and the color of the ovaries was cruise, but by September the rate and observed. In March 1971, an additional incidence of color change was highly 10 scallops were kept alive in running https://aquila.usm.edu/goms/vol3/iss2/5 2 DOI: 10.18785/negs.0302.05 Miller et al.: Maturation of the Calico Scallop, Argopecten gibbus, Determined b

98 G. C. Miller et al.

RESULTS

N Relation of Ovarian Color to Develop­ BUOY 2 2a~ so' .... ,A mental Stages: ········· ... // \\\ By reference to work of earlier \'; \ investigators and from our laboratory ·~t9-1t. and field observations, we were able to relate ovarian color to maturation stages. ······· As points of departure we observed the

CAPE color and texture of ovaries of: CANAVERAL j

/..... ·~ ( 1) young, immature scallops raised from the egg in the laboratory: (2) ripe scallops before they spawned in the

so" so' so· Jo' so" 20' W laboratory and produced healthy, viable eggs; (3) those same scallops (2) after they partially Figure 1. Location of calico scallop sampling site spawned in the laboratory. at Buoy 2 off Cape Canaveral, F1orida. (4) young, immature scallops in the field; (5) small, mature scallops which had recently spawned and were in a spent condition: seawater for about 16 hours after which (6) ripe scallops in the field; and the ovaries were compared to those (7) those same scallops (6) after they partially examined soon after capture. Additional, spawned in holding tanks in the field. random observations of ovarian color were made on small and large scallops The ovarian colors distinguished in collected at several sites on the Cape our samples were taken over an 18- Canaveral scallop grounds. To follow month period, May 1970 to October 1971, development through t1me of live and are shown by shell height by season individual scallops, the ovarian colors in Figure 2. The colors were initially were observed through the gaping valves separated into four groups: ( 1) drab, with of the live scallops. ovaries lacking orange or red pigmenta­ We recognized that for comparing tion; (2) brownish-orange, Pantone 156- ovarian colors, a standard would be 158; (3) reddish-orange, Pantone 163- required. The standard we used was the 165; and (4) dark orange-red, Pantone Pantone Color® Specifier, 2 which 170-172. designates color by number, not by name. An additional color may indicate in­ The color names we apply to the Pan tone fection of scallops by nematodes or numbers do not follow a previously trematodes. Dissection of a scallop gonad established system. When the ovaries colored irridescent orange revealed that were parasitized, or of a drab color, i.e., gonadal tissue was destroyed and that lacking orange or red pigments, wd did the ovary and testis were occupied by not assign a Pantone number. more than 50 reddish, immature nema­ todes (unidentified). Bisexual differenti­ ation by color was obliterated. The 2 Designers Edition of the Pan tone Matching irridescent color was not identifiable to Systems of Pan tone, Inc., New York, N.Y. Reference to trade names does not imply endorsement by the any Pantone color and was easily dis­ National Marine Fisheries Service, NOAA. tinguishable from that of normal ripe

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Maturation of the calico scallop 99

STAGES could, however, be separated into single 70 • 1 stages. 65 p 5 • 7 Drab ovaries of the calico scallop, like • 2 • • • • _,_ 60 • 7-f-ll- • 2 ' ' the bay scallop (Sastry, 1963), repre­ • • • 7 55 • ~ 1-• 2 l- 1 3 -· 7 sented two stages, the beginning and end 2 ' 3 50 ' 5 ' ' of maturation. Drab ovaries represented 7 ' ' 5 ' 7 3 • " l ...l3- 45 5 " 1- the immature stage of juvenile scallops • 4 7 3 e 37 • 7 and the spent stage of mature scallops. E 40 t---1-! :-t--- 1--•- 'j- l- o= I q- I ·- 5 We were able to distinguish the spent =g 35 • • ' L 1- 5 ' I "' I I stage from the immature stage in late = 2 515 :j 30 'l'-' 1--;-l-1- • 5 f-j"ls I 441 I spring and summer by our knowledge "' I I 7ls 11125= 75 I 5 I I 7' of scallop size and growth. .I 20 Brownish-orange ovaries represented I 15 two stages well-separated in time. The MAY JUL AUG NOV JAN MAR APR MAY JUN AUG OCT 1970 1971 STAGE DEVELOPMENT COLOR early developing stage occurred in the fall 1 IMMATURE DRAB 2 EARLY D£VELOPING 156·158 following the spent stage of summer; the 3 LATE DEVELOPING 163•165 4 RIPE 170·172 5 EARLY PARTIALLY SPAWNED 163·U>S late partially spawned stage occurred 6 LATE PARTIALLY SPAWNED 156 158 7 SPENT DRAB p PARASITIZED BY NEMATODES just before the spent stage, in late spring and early summer. Figure 2. Ovarian colors, developmental stages, Reddish-orange ovaries represented and sizes of calico scallops from Buoy 2 off Cape two stages: the late developing stage Canaveral, F1orida, May 1970 to October 1971. occurred in late fall or early winter just before the ovaries became ripe; the early scallop ovaries (Figure 3). The parasitic partially spawned stage (Figure 4) infection prevented interpretation of occurred after partial spawning and near ovarian development by color in some the end of the spawning season in late specimens. A nematode, Sulcascaris spring and summer. Since we observed sulcata, has been reported from the this color following partial spawning in gonads of calico scallops by Lichtenfels et the laboratory and field, and very few al. (1978) but these authors did not scallops were seen with this color from · mention associated color changes in the January to April, we concluded that scallop gonads. However, similar color reddish-orange (early partially spawned) changes have been observed in Gulf of rapidly reverts to dark orange-red (ripe). Mexico mollusks infected by trematode From the above information, we estab­ sporocysts (Dr. E.W. Cake, Jr., Gulf Coast lished seven stages of ovarian develop­ Research Laboratory, pers. comm.). ment for the calico scallop: Based on our knowledge of calico scallop life history, and from scallop samples taken sequentially at Buoy 2, we Stage 1: Immature, drab, were able to follow the maturation cycle Stage 2: Early developing, brownish-orange of age groups and distinguish between (Pantone 156-158). developmental stages having' the same Stage 3: Late developing, reddish-orange (Pan tone 163-165). color. We found that, except for dark Stage 4: Ripe, dark orange-red (Pantone 170- orange-red, which represented a single 172). developmental stage (ripe), the remain­ Stage 5: Early partially spawned, reddish­ orange (Pantone 163-165). ing ovarian colors (drab, brownish­ Stage 6: Late partially spawned, brownish­ orange, and reddish-orange) each repre­ orange (Pantone 156-158). sented two developmental stages which Stage 7: Spent, drab. https://aquila.usm.edu/goms/vol3/iss2/5 4 DOI: 10.18785/negs.0302.05 Miller et al.: Maturation of the Calico Scallop, Argopecten gibbus, Determined b

100 G. C. Miller et al.

Table 1. Ovarian development stages of calico scallops (by percent) from Buoy 2 off Cape Canaveral, Florida, May 1970 to October 1971. 1970 1971 Developmental Stage and Color May July Aug, Nov. Jan. Mar. Apr. May June Aug. Oct.

Stage 1: Immature, drab~ 0 25 20 50 10 0 10 0 0 15 20 Stage 2: Early developing, 0 0 40 0 0 0 0 0 0 5 0 brownish -orange, Pantone 156-158. Stage 3: Late developing 0 0 20 0 0 0 0 0 0 5 70 reddish-orange, Pantone 163-165.

Stage 4: Ripe, dark ora~e- 20 12 0 50 90 100 80 80 0 0 0 red, Pantone 170-172. Stage 5: Early partially 30 38 0 0 0 0 10 5 45 0 0 spawned, reddish- orange, Pantone 163-165. Stage 6: Late, partially 50 12 0 0 0 0 0 0 5 0 0 spawned, brownish- orange, Pantone 156-158. Stage 7: Spent, drab. 0 12 20 0 0 0 0 15 50 75 10

Total Percent 100 99 100 100 100 100 100 100 100 100 100 •Lacking orange or red pigmentation, so not assigned a Pantone number.

These developmental stages were used partially spawned scallops as compared to determine scallop maturation as with a large percentage of ripe scallops related to rate of development, season, (Table 1 ). The high percentage of ripe and spawning. ovaries observed through several months suggests that the calico scallop may be Rate of Development: an intermittent spawner, spawning We determined changes in ovarian many times during the period it is ripe, development with time, based on field as has been indicated for the bay scallop and laboratory observations. Scallops by Castagna and Duggan (1971). changed from early developing to late At Buoy 2, calico scallops that set in developing in 8 to 14 days. We speculate winter or early spring (1970-71) were that scallops can change from late devel­ ripe, partially spawned, or spent in May oping to ripe within a month. From ripe 1971 (less than 42 mm shell height); to early partially spawned takes place partially spawned or spent in June (less within 12 hours. Even after spawning than 48 mm); and generally spent in for several hours, scallops can remain August (35 to 52 mm) (Figure 2). The early partially spawned, rather than above sizes by season were determined changing to late partially spawned. We from length frequencies of scallops on speculate further that early partially the bed at Buoy 2 (Miller and Hudson, spawned scallops may rapidly revert to manuscript in preparation). a ripe condition, since in some months The smallest ripe scallop observed was there was only a small percentage of early 23.0 mm shell height. However scallops

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Maturation of the calico scallop 101

Figure 3. Comparison of normal calico scallop gonad (left) and gonad infected with nematodes (right).

Figure 4 . Comparison of ripe. dark orange-red (right) and early partially spawned. reddish-orange (left) calico scallop ovaries. https://aquila.usm.edu/goms/vol3/iss2/5 6 DOI: 10.18785/negs.0302.05 Miller et al.: Maturation of the Calico Scallop, Argopecten gibbus, Determined b

102 G. C. Miller et al.

19.0 to 21.0 mm were in the late develop­ November, spawning had apparently ing stage. Therefore, considering the begun (50% were ripe) and probably rate of ovarian development from late increased in December (inferred because developing to ripe, scallops at least as 90% were ripe in January). small as 20.0 mm, 71 days old (Allen, Scallops that set in winter and early 1979), could be ripe. spring will spawn one or more times in spring and early summer at ages 4 to 7 Developmental Stages by Season: months and will spawn again in winter, Calico scallops undergo distinct spring, and early summer at ages 11 to 18 changes in developmental stages by months. Scallops that set in late spring season. Differences in stages by season or early summer will spawn the following between years were perhaps related to winter, spring and early summer at ages environmental variations. Seasonal 6 to 13 months. A few very old scallops of development from May 1970 to October this late setting may spawn at 18 months 1971 is shown in Figure 2 and Table 1; of age in early winter. the following observations refer to months of both years. Scallops were ripe, partially spawned, or spent in May. In DISCUSSION AND CONCLUSIONS August, large scallops (35 mm shell There were variations between years in height or more) were spent or developing, the spawning patterns of calico scallops and small scallops (less than 35 mm) on the Cape Canaveral grounds. In 1970, were primarily immature. In October, only 20% ofthe scallops were ripe in May, large scallops (40 mm or more) were while in 1971, 80% of the scallops were generally in the late developing stage ripe in May. In August 1970, 60% of the and small scallops (less than 40 mm) re­ scallops were in developing stages, mained immature. In November, large whereas in August 1971, only 10% of the scallops (45 mm or more) were ripe, and scallops were developing. The difference small scallops (less than 45 mm) were in rate of ovarian development and time immature. In January, nearly all scallops of spawning between 1970 and 1971 may of the older age group were ripe and have been due to variations in the annual remained in this condition, except for temperature cycle. For both years, a high probable partial spawnings, until May. proportion of scallops had ripe or par­ tially spawned ovaries from about Spawning: January to May, indicating major While samples were not taken in all spawning during that time period. months from May 1970 to October 1971, There is evidence that the general spawning intensity through an annual seasonal spawning pattern, as deter­ cycle can be estimated. Calico scallops mined from our study at Buoy 2, is wide­ with ripe and partially spawned ovaries spread on the Cape Canaveral grounds. indicated proximity to spawning time From investigations of calico scallops on (Table 1 ). Based on percentages of ripe the Cape Canaveral grounds in 1967 and and partially spawned ovaries by month, 1968, Roe etaL (1971) stated "Spawning spawning intensity was apparently begins in February or early March and highest from January to May, decreased continues to June." Furthermore, in in June and July, and was non-existent March and April 1970 and 1971, a high in August and perhaps in September. In incidence of "bright orange-red" ovaries. October, a high proportion of scallops indicating ripe or early partially spawned was close to spawning condition. By scallops, was reported among commer-

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Maturation of the calico scallop 103

cial sized scallops in the Cape Canaveral Costello, D.P., M.E. Davidson, A. Eggers, area by scallop fishermen. In June 1971, M.H. Fox, and C. Henley. 1957. Methods scallops sampled over a wide area on the for obtaining and handling marine cape Canaveral grounds were observed eggs and embryos. Marine Biological to be 40 to 60% spent. (Leonard L. May. Laboratory, Woods Hole, Mass. 24 7 p. National Marine Fisheries Service, pers. Costello, T.J.. J.H. Hudson, J.L. Dupuy, comm.). and S. Rivkin. 1973. Larval culture of Based on collections of scallop spat the calico scallop, Argopecten gibbus. (Allen, 1979) and scallop length -frequen­ Proc. Nat Shellfish. Assoc. 63:72-76. cies (Miller and Hudson, manuscript in Gutsell, J.S. 1931. Natural history of the preparation) on the Cape Canaveral bay scallop. Bull. U.S. Bureau. Fish. grounds, the major recruitment of 46:569-632. scallops occurs from about January to Lichtenfels, J.R., J.W. Bier, and PA June. The recruitment period therefore Madden. 1978. Larval anisakid (Sul­ relates well with the spawning period cascaris) nematodes from Atlantic determined from the annual ovarian molluscs with marine turtles as defin­ developmental pattern. itive hosts. Trans. Amer. Micros. Soc. 97:199-207. ACKNOWLEDGMENTS Miller, G.C. and J.H. Hudson. Age and We thank the following, formerly of growth of the calico scallop, Argopecten the Bureau of Commercial Fisheries, for gibbus. Manuscript in preparation. their assistance in the laboratory and National Marine Fisheries Service, field: Billy R. Drummond. Abraham J. Southeast Fisheries Center, Miami Barrett, Anthony F. Serra. and Captain Laboratory, Miami, FL 33149. J.B. Randall. Posgay, JA, AS. Merrill, L.R Porter, Jr., H.W. Jensen, and F.E. Nichyparowich. LITERATURE CITED 1962. Sea scallop program. Pages 36- 46. In Bureau of Commercial Fisheries Allen, D.M. 1979. Biological aspects of Biological Laboratory, Woods Hole, the calico scallop, Argopecten gibbus, Mass., annual report for the year end­ determined by spat monitoring. The ing June 30, 1961. U.S. Fish Wildl. Serv. Nautilus 93:107-119. Circ. 137. ___ . and T .J. Costello. 1972. The ----·· and KD. Norman. 1958. calico scallop, Argopecten gibbus. An observation on the spawning of NOAA Tech. Rep. NMFS SSRF-656, the sea scallop, Placopecten magel­ 19 p. lanicus (Gmelin), on Georges Bank. Belding, D.L. 1910. A report upon the Limnol. Oceanogr. 3:4 78. scallop fishery of Massachusetts, in­ Roe, RB., R Cummins, Jr., and H.R cluding the habits, life history of Bullis, Jr. 1971. Calico scallop distribu­ Pecten irradtans, its rate of growth, tion, abundance, and yield off eastern and other facts of economic value. Florida, 1967-1968. Fish. Bull., U. S. Wright & Potter Printing Co., Boston, 69:399-409. 150p. Sastry, AN. 1963. Reproduction of the Castagna. M., and W. Duggan. 1971. Rear­ bay scallop, Aequipecten irradtans ing the bay scallop, Aequtpecten ir­ Lamarck. Influence of temperature on radtans. Proc. Nat. Shellfish. Assoc. maturation and spawning. ::Uol. Bull. 61:80-85. 125:146-153. https://aquila.usm.edu/goms/vol3/iss2/5 8 DOI: 10.18785/negs.0302.05