are likely to he reproductively isolated, there was insufficient data to justify separate distinct 

 population segment listings at that time. Therefore, until data supports splitting the population 

 segment, NMFS considers shortnose sturgeon within the Androscoggin River and Kennebec 

 Rivers to belong to a single distinct population segment composed of at least two breeding 

 populations. Justification for this determination is based on the 1987 shortnose sturgeon status 

 review and the recent joint USFWS/NMFS policy on distinct population segments 

 (February 7, 1996). 



SPECIES BIOLOGY 



The sturgeon family is among the most primitive of the bony fishes. The shortnose sturgeon 

 shares the same general external morphology of all sturgeon. Its elongated fusiform body is 

 moderately depressed, and its protractable subterminal mouth with barbels is well suited for 

 bottom feeding and a generally benthic existence. The body surface contains five rows of bony 

 plates or scutes. Shortnose sturgeon are relatively large, long-lived fish that utilize estuarine 

 habitats for feeding and freshwater habitats for spawning. The species is encountered less 

 frequently in marine habitats than the closely-related Atlantic sturgeon, suggesting that little 

 population mixing occurs. 



The shortnose sturgeon is the smallest of the three sturgeon species that occur in eastern North 

 America, having a maximum known total length of 143 cm and weight of 23 kg. Growth rate 

 and maximum size vary with latitude, with the fastest growth occurring among southern 

 populations. Maximum known age is 67 years for females, but males seldom exceed 30 years of 

 age. Sex ratio among young adults is 1 : 1 but changes to a predominance of females (4:1) for fish 

 larger than 90 cm fork length. 



Males and females mature at the same length (45 to 55 cm fork length) throughout their range. 

 However, age of maturation varies from north to south due to a slower growth rate in the north. 

 Males may mature at 2 to 3 years of age in Georgia, at age 3 to 5 from South Carolina to New- 

 York, and at age 10 to 1 1 in the St. John River, Canada. Females exhibit a similar trend and 

 mature at age 6 or younger in Georgia, at age 6 to 7 from South Carolina to New York, and at 

 age 13 in the St. Jolin River. Age of first spawning in males occurs 1 to 2 years after maturity, 

 but among females is delayed for up to 5 years. Approximate age of a female at first spawning 

 is 15 years in the St. John River, 1 1 years in the Hudson and Delaware Rivers, 7 to 14 years in 

 the South Carolina rivers, and 6 years or less in the Altamaha River, Georgia. Generally, females 

 spawn every three years, although males may spawn every year. 



Shortnose sturgeon are benthic feeders. Juveniles are believed to feed on benthic insects and 

 crustaceans. Mollusks and large crustaceans are the primary food of adult shortnose sturgeon. 



SPECIES DISTRIBUTION 



The shortnose sturgeon is anadromous, living mainly in the slower moving riverine waters or 

 nearshore marine waters, and migrating periodically into faster moving fresh water areas to 

 spawn. One partially landlocked population is known in the Holyoke Pool, Connecticut River, 

 and another landlocked group may exist in Lake Marion on the Santee River in South Carolina. 



Shortnose sturgeon occur in most major river systems along the eastern seaboard of the United 

 States. In the southern portion of the range, they are found in the St. Johns River in Florida; the 



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