Steven G. George

NONLETHAL ACQUISITION OF LARGE LIVER SAMPLES FROM FREE-RANGING RIVER STURGEON (SCAPHIRHYNCHUS) USING SINGLE-ENTRY ENDOSCOPIC BIOPSY FORCEPS

Harvesting of liver samples for toxicologic and other laboratory analyses is frequently undertaken in free-ranging fish to evaluate accumulations of various pollutants and chemicals. However, commonly used, lethal techniques for collecting liver tissues are unacceptable when dealing with protected species. We report the use of a nonlethal, single-entry, endoscopic technique using saline infusion to examine and collect large liver samples using optical biopsy forceps from 16 free-ranging sturgeon (Scaphirhynchus spp.) during 25 and 27 January 2010. Under tricaine methanesulfonate anesthesia and following the introduction of the optical biopsy forceps (with a 5-mm telescope) through a 1–2-cm ventral midline skin incision, liver examination and collection of biopsies averaging 0.9 g, ranging up to 1.4 g, and representing up to 12% of total liver tissue were successful. All fish made uneventful recoveries and necropsy examinations the following day failed to indicate any significant hemorrhage or iatrogenic trauma. We recommend the use of large optical biopsy forceps as a practical, nonlethal alternative for collection of large liver biopsies from sturgeon and other fish.

Rostrum Size of Paddlefish (Polyodon spathula)(Acipenseriformes: Polyodontidae) from the Mississippi Delta

Abstract Paddlefish rostra vary in size and shape suggesting existence of multiple morphotypes. Measurements for 118 adult paddlefish from a Mississippi delta river indicate that the rostrum becomes shorter, narrower, and straighter as a fish grows. Negative allometric growth of rostra, and high variation within size classes, may obscure existence of distinctive rostral morphotypes.

A Paddlefish Entrained by the 2011 Mississippi River Flood: Rescue, Recapture, and Inferred Swim Speed

Abstract We observed a large adult Paddlefish entrained from the Mississippi River through the Bonnet Carré spillway, south Louisiana, which was injured and underweight. We captured, measured (23 metrics), and tagged the fish. After it had spent a week at large on the floodway, we recaptured and released it back into the Mississippi River. The specimen was re-captured eight months later in northern Mississippi, 627 km upriver from where it was released. Distance traveled and water velocities in the river indicate that the fish was traveling at least 90–197 cm/s for prolonged periods, equivalent to gross speeds of 77–170 km/d. This incident suggests that a large entrained fish, trapped for several days in a hyperthermic and hypoxic habitat, can be viable when returned to the river. It also demonstrated that rescue efforts could reduce impacts of spillway operations to fish populations, and that comprehensive field assessment of fish morphology can be benign t o fish.

First Recorded Occurrence of Oncorhynchus mykiss (Rainbow Trout) in Louisiana

Abstract An individual of Oncorhynchus mykiss (Rainbow Trout) was collected in a diversion canal of the Mississippi River known as Davis Pond located at river kilometer (RKM) 191.03 in St. Charles Parish near Luling, LA. This locality is the southern-most record for Rainbow Trout in the Mississippi River Basin and represents a range extension of 733.5 RKM south from the previous southern-most locality at Lake Whittington, Bolivar County, MS. The collection we report here also represents the first documented record of Rainbow Trout in Louisiana.