Geology topics

D. Pugh

Publications and source records attributed to D. Pugh.

3 recordsLinked to original sources

USGS2011

Passage and behaviour of cultured Lake Sturgeon in a prototype side-baffle fish ladder: I. Ladder hydraulics and fish ascent

Research and development of a fish ladder for sturgeons requires understanding ladder hydraulics and sturgeon behaviour in the ladder to insure the ladder is safe and provides effective passage. After years of research and development, we designed and constructed a full‐scale prototype side‐baffle ladder inside a spiral flume (38.3 m long × 1 m wide × 1 m high) on a 6% (1 : 16.5) slope with a 1.92‐m rise in elevation (bottom to top) to test use by sturgeons. Twenty‐eight triangular side baffles, each extending part way across the flume, alternated from inside wall to outside wall down the ladder creating two major flow habitats: a continuous, sinusoidal flow down the ladder through the vertical openings of side‐baffles and an eddy below each side baffle. Ascent and behaviour was observed on 22 cultured Lake Sturgeon = LS ( Acipenser fulvescens ) repeatedly tested in groups as juveniles (as small as 105.1 cm TL, mean) or as adults (mean TL, 118 cm) during four periods (fall 2002 and 2003; spring 2003 and 2007). Percent of juveniles entering the ladder that ascended to the top was greater in spring (72.7%) than in fall (40.9–45.5%) and 90.9% of 11 adults, which ascended as juveniles, ascended to the top. Six LS (27.3%) never swam to the top and seven (31.8%) swam to the top in all tests, indicating great variability among individuals for ascent drive. Some LS swam directly to the top in <1 min, but most rested in an eddy during ascent. Juveniles swimming through outside wall baffle slots (mean velocity, 1.2 m s −1 ) swam at 1.8–2.2 body lengths s −1 and 3.2–3.3 tail beats s −1 , either at or approaching prolonged swimming speed. The side‐baffle ladder was stream‐like and provided key factors for a sturgeon ladder: a continuous flow and no full cross‐channel walls, abundant eddies for resting, an acceptable water depth, and a water velocity fish could ascend swimming 2 bl s −1 . A side‐baffle ladder passes LS and other moderate‐swimming fishes.

Journal of Applied Ichthyology↗

USGS2011

Using a semi-natural stream to produce young sturgeons for conservation stocking: Maintaining natural selection during spawning and rearing

Young sturgeons used for conservation stocking are presently produced using the same methods used for commercial culture. To determine if young sturgeons could be produced without relaxing natural selection factors, we developed a semi‐natural stream where we annually studied mating of wild shortnose sturgeon ( Acipenser brevirostrum ) observed movement of gametes released freely during spawning, and estimated the number of larvae produced by various densities of spawned eggs. The stream had a bottom area of 18.8 m 2 , a rubble–gravel bottom, and a mean bottom current at 0.6 depth during spawning of 48 cm s −1 (range, 17–126 cm s −1 ). Wild adults successfully spawned in the stream each year for 7 years (2002–2008). Some females and males were more successful during spawning than others, suggesting an unequal fitness during spawning among wild individuals, which is different than the controlled spawning fitness of individuals in hatcheries. Male and female gametes spawned naturally must connect quickly in the fast current or fail, a selection factor absent in hatcheries. The number of larvae produced was inversely related to spawned egg density m −2 ( R 2 = 0.65) and the maximum number of larvae produced was 8000–16 000 (425–851 larvae m −2 of bottom). Artificial spawning streams have the potential to contribute to sturgeon restoration.

Journal of Applied Ichthyology↗

USGS2007

Use of laboratory studies to develop a dispersal model for Missouri River pallid sturgeon early life intervals

Understanding the drift dynamics of pallid sturgeon (Scaphirhynchus albus) early life intervals is critical to evaluating damming effects on sturgeons. However, studying dispersal behavior is difficult in rivers. In stream tanks, we studied the effect of velocity on dispersal and holding ability, estimated swimming height, and used the data to estimate drift distance of pallid sturgeon. Dispersal was by days 0-10 embryos until fish developed into larvae on day 11 after 200 CTU (daily cumulative temperature units). Embryos in tanks with a mean channel velocity of 30.1 cm s-1 and a side eddy could not hold position in the eddy, so current controlled dispersal. Late embryos (days 6-10 fish) dispersed more passes per hour than early embryos (days 0-5 fish) and held position in side eddies when channel velocities were 17.3 cm s-1 or 21.1 cm s-1. Day and night swim-up and drift by embryos is an effective adaptation to disperse fish in channel flow and return fish from side eddies to the channel. Early embryos swam <0.50 cm above the bottom and late embryos swam higher (mean, 90 cm). A passive drift model using a near bottom velocity of 32 cm s-1 predicted that embryos dispersing for 11 days in channel flow would travel 304 km. Embryos spawned at Fort Peck Dam, Missouri River, must stop dispersal in <330 km or enter Lake Sakakawea, where survival is likely poor. The model suggests there may be a mismatch between embryo dispersal distance and location of suitable rearing habitat. This situation may be common for pallid sturgeon in dammed rivers. ?? 2007 Blackwell Verlag.

Journal of Applied Ichthyology↗