299 



Abstract-Not catches from 1985-86 

 1(1 1991-9.") at Fivers Island. North Caro- 

 lina, indicated that glass-ccl stage Ainer- 

 ican eels {AngiiilUi rostrata) were re- 

 cruited to the estuary from November 

 to early May. with peak numbers in 

 January. February, and March. There 

 was no declining trend in recruitment 

 over the years of sampling. Except for 

 one year, there was no clear seasonal 

 decrease in mean length. But shorter 

 glass eels were older than longer glass 

 eels, as judged by age within the glass 

 eel growth zone of the otolith, suggest- 

 ing that smaller fish took longer to 

 arrive. The mean age of glass eels col- 

 lected from the lower estuary and a 

 freshwater site 9.5 km upriver differed 

 by 8.4 d (36.2 vs. 44.6, respectively). 

 Outer increments (30-35) of the oto- 

 lith gi-owth zone of glass eels from 

 North Carolina were significantly wider 

 than corresponding increments of oto- 

 liths from New Brunswick. Mean total 

 ages of North Carolina, New Jersey, 

 and New Brunswick elvers were 175.4. 

 201.2, and 209.3 d, corresponding to 

 mean lengths of 55.9, 60.9. and 58. 1 mm 

 TL. respectively. The mean durations 

 of glass-eel growth zones (44.6, 62.3, 

 and 69.8) were in close agreement with 

 those from previous studies, but total 

 ages were not. This suggested that per- 

 haps some finer (leptocephalus stage) 

 increments were not detected by light 

 microscopy, differences occurred in sea- 

 sonal increment deposition, or absorp- 

 tion of the otolith material may have 

 taken place during metamorphosis, ren- 

 dering the aging of larvae inaccurate. 

 Judging from the long recruitment 

 period and seasonal uniformity in both 

 mean age and length found in our study, 

 the spawning period of American eels 

 may be somewhat more protracted than 

 previously considered. 



Recruitment season, size, and age of 

 young American eels (Anguilla rostrata) 

 entering an estuary near Beaufort, North Carolina 



Perce M. Powles 



Biology Department 



Trent University 



Peterborough 



Ontano, K9J 7B8, Canada 



E-mail address: ppowlesiq trenlu ca 



Stanley M. Warlen 



Center for Coastal Fisheries and Habitat Research 



National Ocean Service, NOAA 



101 Pivers Island Road 



Beaufort, North Carolina 28516-9722 



Manuscript accepted 16 August 2001. 

 Fish. Bull. 100:299-306 (2002). 



The life history of the American eel {An- 

 guilla rostrata ) is both fascinating and 

 mysterious. It spawns in the Sargasso 

 Sea and the young willow leaf-shaped 

 leptocephalus lai-va disperses over great 

 distances before it metamorphoses into a 

 transparent glass eel. This stage reaches 

 the estuaries of North America where it 

 typically ascends rivers and streams as 

 an elver, becoming progressively more 

 pigmented as the run progresses. This 

 stage is followed by the juvenile or 

 yellow eel, and finally by the silver or 

 maturing adult (Able and Fahay, 1998). 

 Eel physiology and ecology are still not 

 completely understood, although much 

 has been learned since the early 1900s. 

 Schmidt (1922) discovered the general 

 area of spawning in the Sargasso Sea, 

 and Kleckner et al. 1 1983 ) further demar- 

 cated breeding to an area defined by 

 thermal front boundaries. Comparini 

 and Rodino (1982) used electrophoretic 

 analysis on American and European eel 

 (Anguilla anguilla) leptoeephali to con- 

 firm that both spawn in the Sargasso 

 Sea. 



Based on oceanographic surveys and 

 entrance times into rivers, estimates 

 of migration time to North America 

 of young A. rostrata range from 250 

 days to one year, corresponding with a 

 peak spawning time of February and 

 March (McCleave et al., 1987; Haro 

 and Kreuger, 1988). Many studies have 



described seasonal sizes of European 

 glass eels and elvers entering estuar- 

 ies, but similar long-term data sets for 

 the American species are uncommon. 

 Elvers enter estuaries along the coast of 

 North America progressively from south 

 to north, becoming larger with increas- 

 ing latitude (Haro and Ki-euger, 1988), 

 and for many (but not all) areas, sizes 

 have been recorded. We document the 

 recruitment period and variations in its 

 seasonality for the Beaufort, NC, region 

 for the 1985-86 to 1994-95 seasons. 



Michaud et al. (1988) documented 

 the sizes but not the ages of American 

 eel elvers entering a Quebec river Jes- 

 sop ( 1998) used large samples from the 

 Nova Scotian elver fishery to show sea- 

 sonal declines in length and weight and 

 an increase in pigmentation of newly 

 arrived elvers. Wang and Tzeng (1998) 

 used SEM (scanning electron micros- 

 copy) and elemental analysis of oto- 

 liths to determine ages of elvers taken 

 from Haiti, north to Nova Scotia. They 

 also estimated the length in days of 

 the leptocephalus and glass-eel stages 

 from the same sites. Helfman et al., 

 (1984) described the length range of 

 glass eels entering a Georgia river in 

 February. Although most earlier work- 

 ers (e.g. Vladykov, 1966; Eldred, 1968, 

 and others) did not have long-term da- 

 ta series, their samples are useful for 

 comparisons with current data. 



