STOCK COMPOSITION OF THE NEW-YORK BIGHT ATLANTIC STURGEON FISHERY BASED ON ANALYSIS OF MITOCHONDRIAL-DNA

One of the few remaining fisheries for Atlantic sturgeon Acipenser oxy rinchus takes place during spring and fall in the New York Eight, but no information on the stock composition of this fishery is available. We used data from mitochondrial DNA (mtDNA) restriction fragment lengt h polymorphism analysis to estimate the relative contributions of sour ce stocks of Atlantic sturgeon to a New York Eight fishery sample (N = 112) collected in 1993 and 1994. Composite mtDNA haplotype frequencie s of source populations were first characterized with five informative restriction enzymes: Bgl I, Msp I, EcoR V, HinfI, and Hinc II. All St . Lawrence River, Quebec, and St. John River, New Brunswick, specimens had an identical haplotype (genotypic diversity = 0.0); for the purpo ses of mixed-stock analysis, both populations were pooled as the ''Can adian stock.'' Genotypic diversity ranged between 0.483 and 0.750 amon g samples from the Hudson River in New York, the Edisto River in South Carolina, and the Ogeechee, Altamaha, and Satilla rivers in Georgia. Chi-square analyses indicated that the Edisto, Savannah (Georgia), Oge echee, Altamaha, and Satilla River samples should be grouped as the '' southeastern stock,'' and that haplotype frequencies of the three sour ce stocks (Canadian, Hudson River, southeastern) were highly heterogen eous (P = 0.0000). Mixed-stock analysis with a constrained least-squar es approach under the conditional method indicated a 97.2% Hudson Rive r contribution, a 2.8% contribution by the southeastern stock, and a 0 .0% contribution by the Canadian stock; the unconditional method provi ded estimates of 99.1%, 0.9%, and 0.0%, respectively. Frequencies of m tDNA haplotypes of subadults (N = 30) from a seasonal aggregation of A tlantic sturgeon from the lower Delaware River were intermediate betwe en those of the Hudson River and southeastern stocks. This finding, to gether with ancillary information, suggests that the Delaware River ag gregation is primarily either a mixture of both the Hudson River and s outheastern stocks or of the Hudson River stock and a relict Delaware River stock.