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Geology topics

L. A. Hanson

Publications and source records attributed to L. A. Hanson.

2 recordsLinked to original sources

Status and reproduction of Gulf coast strain walleye in a Tombigbee River tributary

Walleye (Sander vitreus [Mitchill]) are native to rivers and streams in the Mobile River basin in Mississippi and Alabama. These populations comprise a genetically unique strain (Gulf coast walleye, GCW) and represent the southernmost distribution of walleye in the United States. Luxapallila Creek was considered an important spawning site for GCW prior to and shortly after impoundment of the Tombigbee River in 1980. Extensive sampling in Luxapallila Creek in 2001 and 2002 collected only one larval walleye. Microsatellite DNA analysis suggested 14 of 16 adult walleye from Luxapallila Creek were hatchery-produced fish or their progeny. Controlled angling catch rates of adult walleye have declined since 1997. The scarcity of wild-spawned walleye and the similarity of wild-caught and hatchery broodstock walleye indicates that the GCW population in, or spawning in, Luxapallila Creek is sustained by stocking and recruitment from these stocked fish may be diminishing.

Southeastern Naturalist

Diet related anemia in channel catfish: Case history and laboratory induction

Severe anemia among fingerling to adult channel catfish (Ictalurus punctatus) and blue catfish (Ictalurus furcatus) was reported by 39 of 166 catfish farmers in west‐central Alabama in 1983. The hematocrits of moribund fish in ponds ranged from 0 to 5%. Weekly mortalities as high as 5% in individual ponds were recorded. The gills of affected fish were pale or white, the kidneys and spleen were pink, and the liver was gray to tan. In 27 of 29 ponds where the type or brand of feed was changed, deaths ceased within 1 week. However, the disease was noted among fish regardless of the major brand or type of feed used. Under laboratory conditions, the feeding of diets from affected farms induced anemia in fry, but not in subadults. The cause of the anemia was associated with an unidentified factor or factors in diets.

Progressive Fish-Culturist