Postlarva of the White Marlin, <I>Tetrapturus Albidus</I>, from the Florida Current Off the Carolinas

POSTLARVA OF THE WHITE MARLIN, TETRAPTURUS ALB/DUS, FROM THE FLORIDA CURRENT OFF THE CAROLINASl

DONALD P. DE SYLVA Institute of Marine Science, University of Miami

ABSTRACT A postlarval specimen of the white marlin is described for the first time. Counts and proportional measurements are given, and the color pattern is described. A provisional key is given for the late postlarvae and early juveniles of the Western Atlantic species of the family Istiophoridae.

INTRODUCTION Larval and juvenile stages of the marlins and sailfishes, family Istio- phoridae, from the Atlantic Ocean are poorly known. Larval istiophorids have been described from the Pacific by Yabe (1953), Ueyanagi (1957, et seq.), and Ucyanagi and Yabe (1959, 1960). Four species are known from the western Atlantic. The larvae of the sailfish, lstiophorus albicans (Latreille), were described by Voss (1953) and by Gehringer (1957). An advanced larval stage of the blue marlin, Makaira nigricans Lacepede, was described from Jamaica by Caldwell (1962), who overlooked the earlier descriptions of this species by Ueyanagi (1957, 1959) and Sun (1960). A larger specimen was identified by de Sylva (1958) from West End, Bahamas. Specimens figured by Gehringer (1957, Fig. 25) and identified tentatively as a spearfish, Tetrapturus belone Rafinesque, were identified by Ueyanagi (1959) as Makaira amp/a (Poey) [nigricans]. The spearfish listed by Robins and de Sylva (1961) from the western Atlantic as T. be/one is T. pfluegeri. The former species is believed to be restricted to the Mediterranean (Robins and de Sylva, 1963), the western Atlantic species being distinct from be/one and from the Pacific species T. angustirostris. Juvenile specimens of the western Atlantic species are shown in Robins and de Sylva (1961, Fig. 1; 1963, Fig. 1a) . The fourth known species, the white marlin, Tetrapturus albidus Poey, is known only from adults. The smallest specimen previously known to me, in the collection of the Institute of Marine Science, measures 955 mm body length, and was caught by Brian Caldwell off Miami on August 16, ] 957. The specimen has the adult characters nearly fully developed, with the pectoral fin and dorsal fin showing adult development. In the western North Atlantic, the four istiophorids are well marked and readily identifiable as adults (Robins and de Sylva, 1961, ]963). The longbill spearfish is characterized by its high dorsal-spine count (45-53), . and the anterior position of the anus, which is located about midway -I Contribution No. 456 from The Marine Laboratory, lnstitute of Marine Science, Univer- sity of Miami. The author gratefully acknowledges the support of the National Science Foundation, grant NSF G-23745. The material collected by R/V GERDA reported herein was obtained with the assistance of grant G-20355 from the National Science Foundation. 124 Bulletin of Marine Science of the Gulf and Caribbean [/3(1) between the base of the pelvic and anal fins. The blue marlin can be identified by the presence of a complex, branching lateral line (Gehringer, 1957, Fig. 25; LaMonte, 1958, PI. 75, Fig. 2; de Sylva, 1958, PI. 81, Figs. 1-3; Caldwell, 1962, Fig. 1), the short snout, and the posterior position of the anus. The sailfish and white marlin are similar in many respects, both having a long snout, a posteriorly placed anus, and a simple, single lateral line. The adults differ in the height, shape, and coloration of the dorsal and anal fins, and in pectoral fin length (Figs. 1, 2). There is a modal difference in the number of dorsal and anal spines, and anal and pectoral rays. The systematics of the family are still confused largely due to a lack of an adequate size series of the species. This is particularly true in the younger stages, and it has not been possible to arrive at identifications and descriptions of ontogenetic series. However, the specimen described subse- quently is of singular interest, and is apparently previously unrecognized.

MATERIAL Through the courtesy of Peter C. Wilson of the North Atlantic Fisheries Exploration and Gear Research Base, Bureau of Commercial Fisheries, U.S. Fish and Wildlife Service, East Boston, Massachusetts, we received a specimen of istiophorid for identification (Fig. 1). On the basis of the characters discussed below, the specimen is identified as a postlarva of the white marlin, Tetrapturus albidus. It was taken on 31 May 1961 by Mr. Wilson, with a light and dip net aboard the R/V CRAWFORD,at 2330 hours, at latitude 33°37'N, longitude 76°32'W, about J 00 miles east-south- east of Wilmington, North Carolina, at approximately the J OO-fathom curve. The weather was clear, the sea and wind calm; Sargassum patches, approximately 1 foot in diameter, were present about one per 10 square yards. The specimen has been catalogued in the collection of the Institute of Marine Science, University of Miami, UMML 11096. A postlarval specimen of sailfish figured for comparison (Fig. 3c) was collected at the surface with a nightlight and dipnet by a field party aboard the R/V GERDAon the night of 29-30 August 1962, 2120-0200 hours EST, at 25°20'N, 80000'W, GERDACruise G-6223, Sta. G-64, depth 220-230 fms. DESCRIPTION Proportional and meristic data are presented in Table 1. Measurements were taken with a micrometer caliper graduated to 0.1 mm. Meristic data were taken from the preserved specimen and from a radiograph. The dorsal profile at the nape is nearly straight, gradually becoming confluent with the straight profile along the dorsal base. The ventral outline is slightly convex. The lateral line is straight from a point at the base of spine 10 posteriorly to a point between spine 13 and J 4. It drops thereafter 1963] ae ~ylva: Postlarva of the White Marlin 125 to a point between spine 16 and 17 where it becomes nearly straight again, with a slightly downward-arching slope running posteriorly. The bill is slender and well developed, with the mandible well formed and much shorter than the bill. The pectoral fins are somewhat pointed. The tips of the caudal lobes are rounded, and the first anal fin is broadly rounded. The dorsal fin is high throughout its length, rising abruptly past the third spine and sloping gradually upward to about spine 11 (see Fig. 1). Coloration is brownish olive in formalin. The dorsal part of the body color is darkest midway between the dorsum and the lateral line, becoming somewhat paler along the sides and silvery white along the ventral surface. Four or five diffuse, dusky bands along the sides alternate with much narrower, obscure bands which are pale silvery. The head is colored as the body, but the maxillary is pale. The dorsal fin is uniformly dusky throughout. The spine tips and the edge of the interradial membrane immediately bordering the spine tips are translucent, giving a spotted effect to the fin edge. Four distinct ocelli are darker than the background color of the fin, with light borders about 1 mm wide. The first ocellus begins on the interradial membrane between spine 14 and 15, extending slightly past the edge of spine 16 and overlapping slightly onto the membrane. The ocellus is slightly deeper than wide, its diameter about 5 mm. The second ocellus begins on the interradial membrane between spine 20 and 21 and ends just touching spine 23. It is about 4 mm in diameter, and is slightly deeper than wide. The third ocellus begins on the interradial membrane between spine 27 and 28, ending on the membrane between spine 29 and 30. This is nearly circular, and measures about 4 mm. The fourth ocellus begins between spine 32 and 33, and ends between spine 34 and 35; this is circular and about 3 mm across. The caudal fin is dusky for the posterior three-fourths of the lobes, with a translucent region at the base of the lobes, roughly parallel with the caudal keels. The base of the caudal fin at the caudal peduncle is dark. The pectoral and pelvic fins are pale. The first four rays of the first anal fin are translucent, becoming abruptly dark olive on the middle rays throughout their length, the last few rays being translucent. The second dorsal and second anal fins are pale. A provisional key is presented to assist identification of young specimens of known istiophorid species in the western Atlantic, based upon published data and the writer's material (see Fig. 3); this key should suffice for specimens from about 50 to 500 mm in length:

1a. Anus placed far forward, approximately midway between bases of anal and pelvic fins; pelvic fins short, not reaching nearly to base of anal fin; dorsal fin unspotted or mottled; dorsal spine count high, 45-53, modally 49 (see Robins and de Sylva, ]963, Table 5) .. Longbill spearfish, Tetrapturus pfluegeri 1b. Anus placed close to anal fin base; pelvic fins long, reaching nearly to 126 Bulletin of Marine Science of the Gulf and Caribbean l]3(1) 1963] de Sylva: Postlarva of the White Marlin 127 128 Bulletin of Marine Science of the Gulf and Caribbean Jf3(1) TABLE 1 COMPARISON OF MORPHOMETRY AND COUNTS OF Tetrapturus albidus AND lstiophorus albicansl

T. albidus I. albicans Body length 124.9 126.9 First predorsal length 24.6 28.9 Second predorsal length 104.4 103.0 Prepectoral length 34.3 36.6 Prepelvic length 35.6 37.5 First preanal length 77.0 81.7 Second preanal length 100.2 103.9 Origin of first dorsal fin to origin of pectoral fin 14.3 12.0 Origin of first dorsal fin to origin of pelvic fin 17.8 15.5 Origin of second dorsal fin to origin of second anal fin 9.0 8.4 Tip of mandible to vent 73.5 77.0 Greatest depth of body 13.8 12.6 Depth at origin of first dorsal fin 12.9 12.6 Depth at origin of first anal fin 10.3 10.0 Least depth of caudal peduncle 3.6 3.6 Width at origin of pectoral fins 7.2 6.8 Width at origin of first anal fin 5.4 5.0 Width at origin of second anal fin 4.3 3.8 Width of caudal peduncle 2.0 2.1 Length of upper caudal keel 3.4 3.0 Length of lower caudal keel 3.5 2.7 Head length 34.6 36.7 Snout length 15.9 17.5 Bill length 37.9 61.5 Maxillary length 21.8 24.0 Orbit diameter (fleshy) 5.3 5.7 Depth of bill at tip of mandible 2.0 2.5 Width of bill at tip of mandible 2.1 2.5 Length of last ray in second dorsal fin 9.8 Length of last ray in second anal fin 11.8 Anterior height of first dorsal fin 32.8 Length of 25th spine of first dorsal fin 37.1 39.8 Anterior height of second dorsal fin 4.9 3.2 Height of first anal fin 20.2 8.5 Height of second anal fin 4.0 3.2 Length of pectoral fin 13.3 10.5 Length of pelvic fin 37.0 38.0 Origin of first dorsal fin to origin of second dorsal fin 81.3 74.4 Vent to origin of first anal fin 3.8 4.7 Spine count of first dorsal fin 43 47 Ray count of second dorsal fin 6 7 Spine count of first anal fin 17 18 Ray count of second anal fin 6 6 Ray count of pectoral fin 20-20 18 Vertebral count 12 + 12 ::: 24

]Measurements in mm as defined by Rivas, 1956. 1963] de Sylva: Postbrva of the White Marlin 129 base of anal fin; dorsal fin variously spotted or mottled; dorsal spine count relatively low, 38-49 2 2a. Lateral line complex, partly forming a reticulated pattern (see Gehringer, 1957, Fig. 25; LaMonte, 1958, PI. 75, Fig. 2; de Sylva, 1958, PI. 81, Figs. 1-3; Caldwell, 1962, Fig. 1); bill short, only slightly longer than the mandible · Blue marlin, Makaira nigricans 2b. Lateral line simple, forming a single unit (LaMonte, 1958, PI. 75, Fig. 3); bill long, greatly exceeding the length of the lower jaw 3 3a. Dorsal fin variously mottled, but without distinct ocelli at its base; anal fin pointed, pale, unmarked; dorsal spine count 40-49, modally 43 or 45; anal spine count 12-17, modally 13; dorsal soft-ray count 6-8, modally 7; anal soft-ray count 6-8, modally 7 (Voss, ]953, Fig. 4 and Gehringer, 1957, Fig. 15; see also Robins and de Sylva, ]963, Table 5, for frequency distribution) .... · Atlantic sailfish, lstiophorus albicans 3b. Dorsal fin variously mottled, but with four distinct ocelli near the base of dorsal fin (Fig. 1); anal fin broadly rounded, its middle rays dark; dorsal spine count 38-43, modally 42; anal spine count 13-19, modally 14 or 15; dorsal soft-ray count 5-7, modally 6; anal soft-ray count 5 or 6, modally 6 · White marlin, Tetrapturus albidus

Identification of adults of the western North Atlantic istiophorids is facilitated by data given by Robins and de Sylva (1961, ] 963), and only a few additional points need be made on the identification of the larger postlarvae and the juveniles. The forward position of the anus and the high dorsal spine count readily separate the longbill spearfish from the rest (Fig. 3a). The unusual nature of the lateral line of the blue marlin (Fig. 3d) is distinctive. The young stages of the white marlin (Fig. 3b) and sailfish (Fig. 3c) are quite similar, but they differ proportionately in the much longer bill of the sailfish (Table 1), and in the higher anal fin and longer pectoral fin of the white marlin. Other proportional differences cannot be resolved until a longer series is available. Mr. Jack W. Gehringer, U. S. Bureau of Commercial Fisheries, Bruns- wick, Georgia, has kindly made detailed measurements and counts of a small sailfish for comparison which are included in Table 1. This specimen was collected on 24 July 1960 by the M/V SILVER BAY, station 2201, at 34°34'N, 75°40'W, using a nightlight and dip net. The location of capture is about 50 miles east of Cape Lookout, North Carolina (Fig. 2). Coloration of the vertical fins of the sailfish and white marlin are distinctive. The white marlin dorsal fin has the four dorsal ocelli; the fin of the sailfish has nearly uniformly dark pigment, with no blotches or ocelli (Jack W. Gehringer, personal communication). The pigment on the middle rays of the anal fin of the white marlin is absent in the sailfish. Based on the Japanese literature and the scattered materials from the western North Atlantic, one striking feature of the family Istiophoridae is that the young of all species bear sail-like dorsal fins in the early stages. 130 Bulletin of Marine Science of the Gulf and Caribbean [13(1)

FIGURE 3. Schematic drawings of the juvenile and postlarval billfish of the western North Atlantic. a.-Longbill spearfish, 374 mm (from Robins and de Sylva, 1963). b.-White marlin, 124.9 mm. c.-Atlantic sailfish, 109 mm, GERDACruise G-6223, Sta. G-64. d.-Blue marlin, 177 mm (after Ueyanagi, 1957). Horizontal bar represents 5 em; al1lengths are body lengths (from tip cf bill to middle of caudal fork). 1963] de Sylva: Postlarva of the White Marlin 131 When an adequate series of small istiophorids becomes available, difference in the shape of the fins may be found to be specifically diagnostic. Researchers and field workers should, therefore, take care to retain all young sail-bearing istiophorids for study.

ACKNOWLEDGEMENTS Thanks are due Mr. Wilson for making available to me this postlarval specimen of Tetrapturus albidus and the data concerning it. I am grateful also to the staff of the Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, for providing collecting facilities. Jack W. Gehringer, U. S. Bureau of Commercial Fisheries, Brunswick, Georgia, generously supplied detailed measurements and counts of a postlarval sailfish for comparison.

LITERATURE CITED

CALDWELL, DAVID K. 1962. Postlarvae of the blue marlin, Makaira nigricans, from off Jamaica. Los Angeles County Mus. Contr. Sci., (53): 1-11. DE SYLVA, DONALD P. 1958. Juvenile blue marlin, Makaira ampla (Poey), from Miami, Florida, and West End, Bahamas. Bull. Amer. Mus. nat. Hist., 114 (5): 412- 415. GEHRINGER, JACK W. 1957. Observations on the development of the Atlantic sailfish lstiophorus american us (Cuv.), with notes on an unidentified species of istiophorid. Fish. Bull., Wash., 57 (110): 139-171. LAMONTE, FRANCESCA R. 1958. Scales of the Atlantic species of Makaira. Bull. Amer. Mus. nat Hist., 114 (5): 381-395. RIVAS, LUIS RENE 1956. Definitions and methods of measuring and counting in biJIfishes (Istiophoridae, Xiphiidae). Bull. Mar. Sci. Gulf & Carib., 6 (1): 59-73. ROBINS, C. RICHARD AND DONALD P. DE SYLVA 1961. Description and relationships of the Atlantic longbilI spearfish, Tetrap- turus belone Rafinesque. Bull. Mar. Sci. Gulf & Carib., 10 (4): 383-413. 1963. A new western Atlantic spearfish, Telrap/Urus pfluegeri, with a redescription of the Mediterranean spearfish, Telrapturus belone. Bull. Mar. Sci. Gulf & Carib., 13 (1): ~4-122. SUN, TSZI-GEN 1960. Larvae and juveniles of tunas, sailfishes, and swordfish (Thunnidae, lstiophoridae, Xiphiidae) from the central and western part of the Pacific Ocean. Trudy Inst. Okeana!., S.S.S.R., 41: 175-191. UEYANAGI, SHOJI 1957. Young of the black marlin, Eumakaira nigra Nakamura. Rep. Nankai reg. Fish. Res. Lab., (6): 91-102. 132 Bulletin of Marine Science of the Gulf and Caribbean [13(1) 1959. Larvae of the striped marlin, Makaira mitsukurii (Jordan et Snyder). Rep. Nankai reg. Fish. Res. Lab., (11): 130-146. 1962. On the larvae of the shortnosed spearfish, Tetrapturus angustirostris Tanaka. Rep. Nankai reg. Fish. Res. Lab., (16): 173-189. UEYANAGI, SHOJI AND HIROSHI YABE 1959. Larva of the black marlin, Eumakaira nigra Nakamura. Rep. Nankai reg. Fish. Res. Lab., (10): 151-169. 1960. On the larvae possibly referable to Marlina marlina (Jordan and Hill). Rec. oceanogr. Wks. Japan, 5 (2): 167-173. Voss, GILBERT L. 1953. A contribution to the life history and biology of the sailfish, /stio- phorus american us Cuv. and Va1., in Florida waters. Bull. Mar. Sci. Gulf & Carib., 3 (3): 206-240. Y ABE, HIROSHI 1953. On the larvae of the sailfish, lstiophorus orientalis, collected in the south-western Sea of Japan. Rep. Nankai reg. Fish. Res. Lab., (1): 1-10.