origina! scientific paper UDC 597.3/.5:591.16(262.3-11) EARLY LIFE HISTORY STAGES OF FAMILY CENTROLOPH1DAE IN THE EASTERN ADRIATIC jakov DUiCiC institute of Oceanography and fisheries, HR-21000 Split, P.O.BOX 500A ABSTRACT Use of early life history stages offish in systematic and ecological studies has increased in recent years. It is now recognized that eggs, larvae and juveniles present a wide array of characters that are largely independent of adult characters and suitable for a systematic analysis. Fisheries recruitment studies focus on the survival of eggs and larvae as the most important factor influencing variations in population abundance. A requisite to these studies is detailed infomation on the appearance of fish eggs and larvae in order to identify them in plankton samples. This paper reviews all available information on the early developmental stages of the family Centrolophidae found in the eastern Adriatic. Ke y words : early developmental stages, Centrolophidae, eastern Adriatic INTRODUCTION The importance of early-life-history studies to fisher­ies investigations and phylogenetic research has in­creased dramatically during the last decade. Early-life­history stages are now routinely used in fisheries studies to investigate the interannual variation in recruitment (Wooster, 1983}, and in studies of the phylogeny of fishes (Moser ef ai, 1984), The study of fish eggs, larvae and juveniles is a key component in research into the biology, systematics and even population dynamics of fishes, in that it provides information on spawning areas and periods of many species. By combining the location of eggs, larvae, juveniles and adults of a species with information on the surrounding environment, possible environmental effects on spawning (egg and larval transport, etc.) can be inferred. Studies of this type con­tribute to our understanding of the early stages of devel­opment of fishes, which for certain species are still completely unknown. Consideration of the factors that affect egg and larval survival is fundamental, since it is the early stages of development that will eventually de­termine the existence of good or bad year classes. This is one of the main thrusts of ichthyoplankton studies in those areas in which the requisite basic information is available (egg and larval surveys in spawning areas during the spawning season, etc.) for the species of in­terest. The object of this paper is to compile and present all available information on both the early development stages of the eggs and larvae of the family Centrolophi­dae found in the eastern Adriatic and possible spawning areas and seasons of some species of the family. MATERIAL AND METHODS The present paper sets out descriptions of the eggs, yolk-sac larvae, larvae and juveniles of the family Cen­trolophidae likely to be collected in plankton samples in the eastern Adriatic, together with information on the possible spawning areas and seasons for some species. The egg and larval descriptions have mostly been taken from the existing literature. In some cases the descrip­tions were done by the author himself based on material collected during surveys; in other instances the descrip­tions were published by other researchers, either for eggs, larvae and juveniles actually collected in the east-em Adriatic itself or for egg and larval material collected in other areas but for species that also inhabit the waters of the eastern Adriatic. Notochord (NL) length was mea­sured for preflexion and standard length (SL) for flexion larvae, and total length for larvae and juveniles (TL). 223 Fig. 1: Centrolophus niger (Gmelin, 1789). (A) egg; (B) yolk-sac larva, 4.4 mm TL; (C) larva, 5.0 mm TL; (D) larva, 5.4 mm TL; (E) larva, 5.6 mm TL; (F) larva, 6.7 mm TL; (G) larva 8.3 mm TL; (H) early juvenile, 17.2 mm TL (a fter Sanzo, 1932). SI. 1: Centrolophus niger (Gmelin, 1789). (A) ikra; (B) larva z rumenjakovo vrečko, 4,4 mm TL; (C) larva, 5,0 mm TL; (D) larva, 5,4 mm TL; (E) larva, 5,6 mm TL; (F) larva, 6,7 mm TL; (G) larva 8,3 mm TL; (Fl) mladostni osebek v zgodnji fazi, 17,2 mm TL (po Sanzu, 1932). Jakov DULtlC : EARLY LIFE HISTORY STAGES O F FAMILY CTNTROLOPHtDAEtN THE EASTERN ADRIATIC, 223-228 Fig. 2: Schedophiius medusophagus Cocco, 1839. (A) larva, 8.6 mm SL (after John & Karrer, 1987); (B) larva, 9.7 mm SL (original drawn by author); (C) larva, 11.8 mm SL (original drawn by author); (D) larva, 16.8 mm SL (after John & Karrer, 1987). SI. 2: Schedophiius medusophagus Cocco, 1839. (A) larva, 8,6 mm SL (po Johnu & Karrerju, 1987); (B) larva, 9,7 mm SL (izvirna risba je avtorjeva); (C) larva, 11,8 mm SL (izvirna risba je avtorjeva); (D) larva, 16,8 mm SL (po Johnu & Karrerju, 1987). Jakov DULClC: EARLY UFfi HISTORY STAGES OF FAMILY CENTROLORHIDAEIN THE EASTERN ADRIATIC, 223-223 RESULTS AND DISCUSSION Centroiophus niger (Gmelin, 1789) Eggs The eggs are spherical arid measure 1.20-1.24 mm in diameter, with an oil globule 0,32 mm in diameter. The yolk is segmented, the perivitelline space narrow, and the chorion smooth. Melanophores are visible over the surface of the oil globule after the embryo has formed, and a series of pigment patches are present on the em­bryo itself (fig. 1 A) (Sanzo, 1932). No eggs attributable to this species have been collected during any of the survey carried out in the eastern Adriatic. Larvae Regner (1982) found C. niger larvae at the station StonCica (43°00'N, 16°20'E) in the middle Adriatic in October and November with frequency 0.08%. Morphology The body is rather slender during the early stages, with body depth increasing with development. Body depth at the base of the pectoral fin is 13% of NL at 4.36 mm, 30% of SL at 8.32 mm TL, and 21% of St. at 17.2 m TL (Figs. 1 B, C, H). The gut is quite narrow and straight in the early stages, extending to 57% of NL in newly hatched larvae and to 59% of SL at 8.32 mm TL; gut diameter also Increases with growth. Head length also increases as development progresses, representing 20% of NL in first-feeding larvae and 33% of SL in postflexion larvae and early juveniles. Unlike other stromateoid species, the larvae of this species bear no spines on the preopercle. Pigmentation The basic pigmentation pattern in all stages of de­velopment consists of some stellate melanophores on the top of the head, melanophores along the dorsal and ventral margins of the body, a row of melanophores below the gut, and a cluster of pigment spots on the caudal tip. This latter pigmentation on the caudal tip is located on the finfold in preflexion larvae, but becomes embedded inside the body in postflexion larvae, in newly hatched larvae measuring 4.4 mm TL (Fig. IB), there are 4 large pigment patches on the dorsal margin of the body and another 4 on the ventral margin, some­what staggered with respect to the former. With growth these pigment spots on the contours of the body become smaller, particularly the ventral ones, which turn into a rather continuous series of small spots. In a 5.4 mm TL specimen (Fig. 1D) a longitudinal row of pigment spots begins to develop medially on the lateral walls of the tail. Pigmentation in early juveniles 17.2 mm TL (Fig. 1H) consists of small punctiform melanophores that spread over the entire body and on the proximal portion of the dorsal and anal fin rays. Notochordai flexion Notochordal flexion had already commenced in a 6.72 mm TL larvae (Fig. IF) described by Padoa (1956). Fin development The rays of the caudal fin are the first to develop completely, followed by those of the dorsal, anal, pel­vic, and pectoral fins. All the rays in the caudal, dorsal, anal, and pelvic fins were fully developed in a 8.32 mm TL specimen (Fig, 1G), but formation of the rays in the pectoral fins was still not complete even in a 17.2 mm TL specimens. Pelvic fin buds appeared in a 6.72 mm TL specimen (Padoa, 1956). There are 25 myomeres, 11 preanal and 14 cadual. Juvenile The specimen of the juvenile stage of the C niger was found by west of island of Vis, in the area of the Stonfiica observation station (43