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Fishery Bulletin 98(1) 



lected and processed without sacrifice of fish. They 

 have been used in the past to age Atlantic sturgeon, 

 but authors have described difficulty in aging older 

 fish (>20 yr; Magnin, 1964; Huff, 1975; Dovel and 

 Berggren, 1983). Aging based upon fin spines has 

 been validated for white sturgeon, Acipenser trans- 

 montanus (Brennan, 1988; Brennan and Cailliet, 

 1991) and lake sturgeon, A. fulvescens (Rossiter et al., 

 1995); however, no studies have validated the period- 

 icity of annulus deposition in Atlantic sturgeon. 



Otoliths are often preferred for estimating fish 

 age, but rate of otolith annulus formation has not 

 been evaluated in sturgeons. Greeley ( 1937) enumer- 

 ated ridges on the external surface of otoliths with- 

 out examination of an internal section. Subsequent 

 studies have indicated that annuli on an internal 

 section of otoliths do not provide age estimates as 

 precise as those from fin-spine sections (Schneberger 

 and Woodbury, 1944; Brennan and Cailliet, 1991). 

 Otolithic material, however, does not resorb, which 

 is desirable for accurate aging, especially of long- 

 lived fishes. 



The objectives of this study were to identify an 

 appropriate calcified structure and develop a precise 

 and unbiased method for determining age of Atlan- 

 tic sturgeon and to model growth rates of Hudson 

 River Atlantic sturgeon on the basis of juvenile and 

 adult fish collected in 1992-96. 



Materials and methods 



Adult Atlantic sturgeon were collected during 1992- 

 95 from fishery harvests in the Hudson River and 

 New York Bight, in cooperation with New York State 

 Department of Environmental Conservation and 

 New Jersey Department of Environmental Protec- 

 tion. Fish were collected by using drift and anchored 

 gill nets (25-36 cm stretched mesh) and otter trawls. 

 During the period of collection, a minimum size limit 

 of 152 cm total length (TL) was imposed on the New 



York fishery. In New Jersey, the minimum size limit 

 of 107 cm TL was replaced with a 152-cm size limit 

 in 1993. 



We collected pectoral-fin spines from sturgeon 

 smaller than the minimum commercial size limit 

 (<149 cm TL) in the Hudson River during 1993-95, 

 using monofilament anchored gill nets (3—13 cm 

 stretched mesh). Because few fish less than 152 cm 

 were collected, other mid-Atlantic Bight regions were 

 sampled. Fin spines were obtained from sturgeon 

 collected from Chesapeake Bay commercial pound 

 nets and gill nets in 1996 (n = ll), from National 

 Marine Fisheries Service trawl surveys in the Mid- 

 Atlantic Bight (1994 and 1996; n=4), and from U.S. 

 Fish and Wildlife Service gillnet surveys of the Dela- 

 ware Bay (/z=8). Because the Hudson River stock is 

 the dominant reproducing stock in the Mid-Atlantic 

 area (Waldman et al., 1996), subadults from areas 

 other than the Hudson River were assumed to be 

 predominantly of Hudson River origin. 



Removal and preparation of hard parts 



Pectoral-fin spines ( n =634 ) were removed at the point 

 of articulation, air-dried, and sectioned less than one 

 centimeter distal to the articulation point. Soft tissue 

 adhering to the fin spines was allowed to decom- 

 pose through microbial decay. A one-centimeter- 

 wide section of each fin spine was then embedded 

 in a block of Spurr epoxy, sectioned with an Isomet 

 saw (Buehler, Lake Bluff, IL), and mounted on glass 

 slides (see Secor et al., 1991). Some fin spines (64%) 

 were not embedded but were sectioned with a jew- 

 eller's saw. All sections were mounted with thermo- 

 plastic glue on glass slides and polished with an 

 automated poHshing wheel ( MINIMET 1000, Buehler, 

 Lake Bluff, IL) with fine grit carborundum paper and 

 a 0.3-)im alumina slurry on a polishing cloth. Final 

 sections were 1-2 mm thick. 



Sagittal otoliths were removed from the severed 

 heads of Atlantic sturgeon collected in 1994-95 



