Geology topics

Joseph J. Cech

Publications and source records attributed to Joseph J. Cech.

4 recordsLinked to original sources

USGS2016

Reconnecting fragmented sturgeon populations in North American rivers

The majority of large North American rivers are fragmented by dams that interrupt migrations of wide-ranging fishes like sturgeons. Reconnecting habitat is viewed as an important means of protecting sturgeon species in U.S. rivers because these species have lost between 5% and 60% of their historical ranges. Unfortunately, facilities designed to pass other fishes have rarely worked well for sturgeons. The most successful passage facilities were sized appropriately for sturgeons and accommodated bottom-oriented species. For upstream passage, facilities with large entrances, full-depth guidance systems, large lifts, or wide fishways without obstructions or tight turns worked well. However, facilitating upstream migration is only half the battle. Broader recovery for linked sturgeon populations requires safe “round-trip” passage involving multiple dams. The most successful downstream passage facilities included nature-like fishways, large canal bypasses, and bottom-draw sluice gates. We outline an adaptive approach to implementing passage that begins with temporary programs and structures and monitors success both at the scale of individual fish at individual dams and the scale of metapopulations in a river basin. The challenge will be to learn from past efforts and reconnect North American sturgeon populations in a way that promotes range expansion and facilitates population recovery.

Fisheries↗

USGS2000

Tidal influence on spatial dynamics of leopard sharks, Triakis semifasciata, in Tomales Bay, California

We used ultrasonic telemetry to determine the movement directions and movement rates of leopard sharks, Triakis semifasciata , in Tomales Bay, California. To analyze tide and time of day effects, we surgically implanted transmitters in the peritoneal cavities of one male and five female leopard sharks, which we located during summer for three to five sampling sessions lasting 12 to 24 h each. All leopard sharks showed strong movement direction patterns with tide. During incoming tides, sharks moved significantly (p<0.0001) towards the inner bay, apparently to exploit the extensive inner bay muddy littoral zones' food resources. On outgoing tides, sharks showed significant (p<0.0001) movements towards the outer bay. During high tide, there was no discernible pattern to their movements (p=0.092). Shark movement rates were significantly (p<0.0001) greater during dark periods (mean±SE: 10.5±1.0 m min −1 ), compared with fully lighted ones (6.7±0.5 m min −1 ). Movement rates of longer sharks tended to be greater than those of shorter ones (range means±SE: 5.8±0.6 m min −1 for the 91 cm shark, to 12.8±1.6 m min −1 for the 119 cm shark), but the leopard sharks' overall mean movement rate (8.1±0.5 m min −1 ) was slower than other (more pelagic) sharks.

Environmental Biology of Fishes↗

USGS1994

Northern squawfish Ptychochelius oregonensis, O2 consumption rate: Effects of temperature and body size

Northern squawfish, Ptychocheilus oregonensis (live weight range 0.361–1.973 kg), O 2 consumption was measured with temperature-controlled, flow-through respirometers for >24 h. Mean standard O 2 consumption rate of northern squawfish increased with acclimation temperature: 24.3, 49.1, 75.0, and 89.4 mg∙kg −0.67 ∙h −1 at 9, 15, 18, and 21 °C, respectively. Q 10 analysis showed that O 2 consumption rate temperature sensitivity was greatest at the intermediate acclimation temperatures (15–18 °C, Q 10 = 4.10), moderate at the lower acclimation temperatures (9–15 °C, Q 10 = 3.23), and lowest at the higher acclimation temperatures (18–21 °C, Q 10 = 1.80). Overall Q 10 was 2.96 (9–21 °C). Body size ( W , grams) and temperature ( T , degrees Celcius) were related to O 2 consumption ( , grams per gram per day) by W −0.285 ∙ e 0.105 T . Northern squawfish red to white muscle ratios significantly exceeded those of rainbow trout, Oncorhynchus mykiss , in cross sections at 50 and 75% of standard length. High metabolic rates and red to white muscle ratios argue for comparability of northern squawfish with active predators such as sympatric rainbow trout.

Canadian Journal of Fisheries and Aquatic Sciences↗

USGS1994

Temperature and CO2 Effects on Blood O2 Equilibria in Northern Squawfish, Ptychocheilus oregonensis

In vitro blood O 2 equilibrium curves were constructed at 9, 15, 18, and 21 °C from temperature-acclimated northern squawfish, Ptychocheilus oregonensis . At low (<1 mm Hg, 1 mm Hg = 133.32 Pa), P 50 s generally showed variable increases with temperature from 3.6 mm Hg at 9 °C to 8.7 mm Hg at 21 °C, leading to whole-blood temperature effects (Δ H , kilocalories per mole O 2 ) ranging from a low +4.4 at 15–18 °C to a peak −21.2 at 18–21 °C. High- (7.6 mm Hg) conditions decreased blood pH and increased P 50 s at each temperature (Bohr factor). Bohr factors (Φ) ranged from −0.46 at 21 °C to −0.70 at 18 °C. Considered together, Δ H and Φ values suggest an optimal temperature range of 15–18 °C for hemoglobin O 2 loading and unloading in northern squawfish. Nonbicarbonate buffer values ranged from −10.04 at 21 °C to −14.13 at 9 °C. Overall, the high O 2 affinities and hyperbolic blood O 2 equilibrium curves of northern squawfish resemble those of other large cyprinids (e.g., common carp, Cyprinus carpio , tench, Tinca tinca , Sacramento blackfish, Orthodon microlepidotus ) indicating a better ability to tolerate hypoxic environments than sympatric rainbow trout, Oncorhynchus mykiss . High northern squawfish blood O 2 capacities and Φs suggest high aerobic capacity, especially at temperatures <21 °C.

Canadian Journal of Fisheries and Aquatic Sciences↗