Early life history of the American conger eel ... - ResearchGate

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480Fig. 2A–C Conger oceanicus.Illustration of the head (A),anal region (B) and caudal fin(C) of a metamorphosingleptocephalus (total length:84.0 mm; preanal length/totallength: 0.58)2001), which have been shown to deposit incrementsdaily. Based on previous studies on otolith microstructureand microchemistry of fishes that have a leptocephaluslarval stage (see ‘‘Discussion’’), the age atwhich increments showed a rapid increase in widthsimultaneous with a marked decrease in Sr:Ca ratios wasregarded as the onset of metamorphosis for this species.Since all the individuals captured were still in metamorphosis,the duration of this stage could not bedetermined. For the early metamorphic leptocephali(preanal length/total length, PAL/TL‡0.63), the numberof increments between the hatch check and the otolithedge was regarded as the age at recruitment. Unfortunately,for late metamorphic leptocephali (PAL/TL
481Fig. 3A–D Conger oceanicus. SEM micrographs showing theotolith microstructure of an early metamorphosing conger eelleptocephalus (total length: 96.0 mm; preanal length/total length:0.63): A whole view (boxes with letters correspond, respectively, topanels B, C and D); B otolith core and surrounding zone; Cboundary between the developing leptocephalus growth andmetamorphic zones; D otolith edge (P primordium; HC hatchcheck; DLGZ developing leptocephalus growth zone; WIZ wideincrement zone; ICTZ increment countable terminal zone)until a relatively constant minimum value (0.65 lm) wasreached, at about 80 days (phase II). This inner portionof the otolith’s ICZ, which includes phases I and II, isnamed the developing leptocephalus growth zone(DLGZ) (Fig. 3C). In a third phase, the incrementswiden abruptly (to a maximum of 1.20–1.50 lm); thisphase, depending on the specimen, could occur between70 and 120 days. This wide increment zone (WIZ) occurredover about 20–40 days, after that the incrementwidth decreased (increment countable terminal zone,ICTZ) (phase IV) (Fig. 3C, D). In the late metamorphicleptocephali (PAL/TL
Page 1 and 2: Marine Biology (2004) 145: 477-488D
Page 3: 479Table 1 Conger oceanicus.Collect
Page 7 and 8: 483Fig. 6 Conger oceanicus. Profile
Page 9 and 10: 485Fig. 8 Conger oceanicus. SEM mic
Page 11 and 12: 487Fahay 1998). The ingression of C

Early life history of the American conger eel ... - ResearchGate

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