Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Spawning

Discipline
Institution
Publication Year
Publication
Publication Type

Articles 1 - 30 of 31

Full-Text Articles in Physical Sciences and Mathematics

Investigation Of Retention Versus Export Of Planktonic Fish Eggs In The Northeastern Gulf Of Mexico, Bich Vi Viviane Nguyen Mar 2020

Investigation Of Retention Versus Export Of Planktonic Fish Eggs In The Northeastern Gulf Of Mexico, Bich Vi Viviane Nguyen

USF Tampa Graduate Theses and Dissertations

Planktonic fish eggs can be reliably identified with DNA barcoding, and their distribution and abundance can be monitored. Passive drifting fish eggs can be advected by ocean currents and as a result, can either be locally retained or exported away from the West Florida Shelf (WFS). Investigating their retention or export helps in the interpretation of egg abundance trends and in understanding their distribution in long-term surveys. The present investigation was performed in two steps using a combination of biological and physical oceanographic methods. First, fish fecundity of three species (Red Snapper, Vermilion Snapper, and Sand Perch) was assessed, first, …


How Corals Avoid Mating Between Different Species, Amanda Kempton Jan 2020

How Corals Avoid Mating Between Different Species, Amanda Kempton

Scientific Communication News

No abstract provided.


Dredging Activity And Associated Sound Have Negligible Effects On Adult Atlantic Sturgeon Migration To Spawning Habitat In A Large Coastal River, Matthew Balazik, Michael Barber, Safra Altman, Kevin Reine, Alan Katzenmeyer, Aaron Bunch, Greg Garman Jan 2020

Dredging Activity And Associated Sound Have Negligible Effects On Adult Atlantic Sturgeon Migration To Spawning Habitat In A Large Coastal River, Matthew Balazik, Michael Barber, Safra Altman, Kevin Reine, Alan Katzenmeyer, Aaron Bunch, Greg Garman

Rice Rivers Center Research

Dredging is considered a major threat/impedance to anadromous fish migrating to spawning habitat. Due to the perceived threat caused by dredging, environmental windows that restrict dredge operations are enforced within many rivers along the east coast. However, it is generally unknown how anadromous fish react to encountering an active dredge during spawning migrations. Atlantic sturgeon (ATS) are an endangered, anadromous species along the Atlantic slope of North America. To determine if and how an active dredge may affect ATS spawning migration, a Vemco Positioning System array was deployed around an active hydraulic-cutterhead dredge that adult ATS must traverse to reach …


Characterization Of Pallid Sturgeon (Scaphirhynchus Albus) Spawning Habitat In The Lower Missouri River, Caroline M. Elliott, Aaron J. Delonay, Kimberly Chojnacki, Robert B. Jacobson Jan 2020

Characterization Of Pallid Sturgeon (Scaphirhynchus Albus) Spawning Habitat In The Lower Missouri River, Caroline M. Elliott, Aaron J. Delonay, Kimberly Chojnacki, Robert B. Jacobson

United States Geological Survey: Staff Publications

Acipenseriformes (sturgeons and paddlefish) globally have declined throughout their range due to river fragmentation, habitat loss, overfishing, and degradation of water quality. In North America, pallid sturgeon (Scaphirhynchus albus) populations have experienced poor to no recruitment, or substantial levels of hybridization with the closely related shovelnose sturgeon (S. platorynchus). The Lower Missouri River is the only portion of the species’ range where successful reproduction and recruitment of genetically pure pallid sturgeon have been documented. This paper documents spawning habitat and behavior on the Lower Missouri River, which comprises over 1,300 km of unfragmented river habitat. The …


Spawning Characteristics Of Yellow Perch During Periods Of Water Level Fluctuations In A Hydropower Reservoir, Kyle J. Matt Jan 2020

Spawning Characteristics Of Yellow Perch During Periods Of Water Level Fluctuations In A Hydropower Reservoir, Kyle J. Matt

Graduate Theses, Dissertations, and Problem Reports

Water level fluctuations alter reservoir ecosystems causing direct and indirect effects on fish populations. The dewatering of eggs, a direct impact of lake level drawdowns, can affect reproductive success of species that spawn in littoral zones, such as Yellow Perch. I examined relationships between water level fluctuations and spawning characteristics of Yellow Perch in a Central Appalachian hydropower reservoir, where water levels were permitted to be drawn down to 4 m and 2.1 m below the full pool elevation in March and April, respectively. Daily presences of egg masses were recorded on artificial spawning structures at two sites for the …


Dna Barcoding Of Fish Eggs In The Gulf Of Mexico, Makenzie Burrows Mar 2019

Dna Barcoding Of Fish Eggs In The Gulf Of Mexico, Makenzie Burrows

USF Tampa Graduate Theses and Dissertations

DNA barcoding of fish eggs is a relatively new technique that enables more accurate identification of early life stages of ecologically and economically important fish species. Using DNA barcoding of individual planktonic percomorph eggs, this thesis determines putative spawning locations of neritic and oceanic fish species in the Gulf of Mexico (GoM). Surveys at 40 stations in the Gulf of Mexico showed a clear delineation of spawning sites, with neritic fish eggs generally found on continental shelves, and oceanic fish eggs found at the surface of deeper waters. However, samples collected between Florida and Cuba revealed exceptions to this trend …


Persistence Of Stream Restoration With Large Wood, Redwood National And State Parks, California, Diedra L. Rodriguez Jan 2018

Persistence Of Stream Restoration With Large Wood, Redwood National And State Parks, California, Diedra L. Rodriguez

Cal Poly Humboldt theses and projects

The conservation and recovery of anadromous salmonids (Oncorhynchus sp.) depend on stream restoration and protection of freshwater habitats. In-stream large wood dictates channel morphology, increases retention of terrestrial inputs such as organic matter, nutrients and sediment, and enhances the quality of fish habitat. Historic land use/land cover changes have resulted in aquatic systems devoid of large wood. Restoration by placement of large wood jams is intended to restore physical and biological processes. An important question for scientists and restoration managers, in addition to the initial effectiveness of restoration, is the persistence and fate of large wood installations. In this …


Reproductive Characteristics Of Landlocked Fall Chinook Salmon From Lake Oahe, South Dakota, Kelsen L. Young, Michael E. Barnes, Jeremy L. Kientz Dec 2016

Reproductive Characteristics Of Landlocked Fall Chinook Salmon From Lake Oahe, South Dakota, Kelsen L. Young, Michael E. Barnes, Jeremy L. Kientz

The Prairie Naturalist

Lake Oahe, South Dakota, USA, landlocked fall Chinook salmon (Oncorhynchus tshawytscha) reproductive characteristics were examined over a 27 year period, from 1988 to 2015. Mean total lengths of spawning females ranged from 665 mm (1995) to 812 mm (2015) with considerable year-to-year variation. Post-spawn female weights varied, ranging from 2.02 kg (2000) to 5.55 kg (2015), with an overall mean of 3.04 kg. Fecundity peaked at 4,555 eggs per female in 2003, which was just 3 years after a low of 2,011 eggs per female in 2000. Relative fecundity based on female weight was greatest at 1,211 eggs/kg …


No Reef Is An Island: Integrating Coral Reef Connectivity Data Into The Design Of Regional-Scale Marine Protected Area Networks, Steven R. Schill, George T. Raber, Jason J. Roberts, Eric A. Treml, Jorge Brenner, Patrick N. Halpin Dec 2015

No Reef Is An Island: Integrating Coral Reef Connectivity Data Into The Design Of Regional-Scale Marine Protected Area Networks, Steven R. Schill, George T. Raber, Jason J. Roberts, Eric A. Treml, Jorge Brenner, Patrick N. Halpin

Faculty Publications

We integrated coral reef connectivity data for the Caribbean and Gulf of Mexico into a conservation decision-making framework for designing a regional scale marine protected area (MPA) network that provides insight into ecological and political contexts. We used an ocean circulation model and regional coral reef data to simulate eight spawning events from 2008–2011, applying a maximum 30-day pelagic larval duration and 20% mortality rate. Coral larval dispersal patterns were analyzed between coral reefs across jurisdictional marine zones to identify spatial relationships between larval sources and destinations within countries and territories across the region. We applied our results in Marxan, …


Reproductive Phase Determination In Male Meagre (Argyrosomus Regius, Sciaenidae): Testis Development And Histologic Corroboration Of A Gross Anatomical Scale, Nuno Prista, Leonel Gordo, José Lino Costa, Maria José Costa, Cynthia Jones Jan 2014

Reproductive Phase Determination In Male Meagre (Argyrosomus Regius, Sciaenidae): Testis Development And Histologic Corroboration Of A Gross Anatomical Scale, Nuno Prista, Leonel Gordo, José Lino Costa, Maria José Costa, Cynthia Jones

OES Faculty Publications

Reproductive stage determination of male gonads has received sparse attention in fish biology literature with few studies detailing the building of gross anatomical- and histologic scales. The meagre (Argyrosomus regius) is one of the world's largest sciaenids and supports a significant regional fishery in European and North African waters whose reproductive patterns are yet to be fully investigated. In the present study, we derive a macroscopic grading system for meagre testis using semi-quantitative graphs that feature the testis variability along the species size range and time of the year. We then describe the histological stages and reproductive phases of male …


Effects Of Environmental Variables On The Reproduction Of Quagga Mussels (Dreissena Rostriformis Bugensis) In Lake Mead, Nv/Az, Richard Steven Ianniello May 2013

Effects Of Environmental Variables On The Reproduction Of Quagga Mussels (Dreissena Rostriformis Bugensis) In Lake Mead, Nv/Az, Richard Steven Ianniello

UNLV Theses, Dissertations, Professional Papers, and Capstones

In 2007, quagga mussels (Dreissena rostriformis bugensis) were found in Lake Mead and have spread downstream on the Colorado River and to other lakes and reservoirs in the Southwestern United States. The quagga mussel's extremely quick colonization of Lake Mead and annual veliger abundance trends provide evidence that the quagga mussels in the Southwest have different reproductive behavior than in previous habitats. This study is one of the first to specifically examine quagga mussel reproduction in the Southwest and examines how quagga mussel reproduction varies at sites known to have different temperatures and other environmental variables resulting from the input …


Modeling Studies Of Antarctic Krill (Euphausia Superba) Survival During Transport Across The Scotia Sea And Environs, Bettina Andrea Fach Apr 2013

Modeling Studies Of Antarctic Krill (Euphausia Superba) Survival During Transport Across The Scotia Sea And Environs, Bettina Andrea Fach

OES Theses and Dissertations

The Antarctic krill (Euphausia superba) populations at South Georgia, which is in the eastern Scotia Sea, are hypothesized to be sustained by import of individuals from upstream regions, such as the western Antarctic Peninsula. To test this hypothesis a modeling framework consisting of the Harvard Ocean Prediction System (HOPS) and a time-dependent, size-structured, physiologically-based krill growth model was developed. The simulated circulation fields obtained from HOPS were used with drifter studies to determine regions and pathways that allow transport of Antarctic krill to South Georgia. Pelagic phytoplankton concentrations along the simulated drifter trajectories were extracted from historical Coastal …


Essential Spawning Habitat For Atlantic Sturgeon In The James River, Virginia., Geoffrey Austin Aug 2012

Essential Spawning Habitat For Atlantic Sturgeon In The James River, Virginia., Geoffrey Austin

Theses and Dissertations

Substrate composition plays a critical role in determining the spawning success of Atlantic sturgeon. A benthic analysis of the tidal freshwater portion of the James River, Virginia, was performed to locate and protect remaining sturgeon spawning habitat within the James River system. I modeled structural habitat, substrate distribution, and river bathymetry from Richmond, Virginia to the Appomattox River confluence. A classification model was developed to describe the dominant substrate type (mud/silt, sand, gravel, bedrock) using side scan sonar data collected from August 2011-Febuary 2012. River depth, bottom imagery, substrate density (hardness), and ground truth substrate samples were interpolated into a …


A Study Of The Spawning Ecology And Early Life History Survival Of Bonneville Cutthroat Trout, Phaedra E. Budy, Sarah Wood, Brett B. Roper May 2012

A Study Of The Spawning Ecology And Early Life History Survival Of Bonneville Cutthroat Trout, Phaedra E. Budy, Sarah Wood, Brett B. Roper

Watershed Sciences Faculty Publications

We completed a large-scale field experiment in four tributaries of the Logan River, Utah, where the largest metapopulation of imperiled Bonneville cutthroat trout Oncorhynchus clarkii utah persists. We documented the spatial and temporal distributions of spawners, quantified substrate use versus substrate availability, and evaluated differences in hatch and emergence fry success between and among sites in relation to habitat characteristics. We observed considerable variability in the timing, magnitude, and duration of spawning among study areas (streams), in part as a function of a variable, multipeaked hydrograph. Nevertheless, across study areas, >70% of redds were constructed on the final descending limb …


Spawning, Veliger Growth And Desiccation Of Dreissena Bugensis, Lynn Schwaebe May 2012

Spawning, Veliger Growth And Desiccation Of Dreissena Bugensis, Lynn Schwaebe

UNLV Theses, Dissertations, Professional Papers, and Capstones

Quagga (Dreissena bugensis) mussel veliger growth was compared under two dietary conditions: 1) only seston present in Lake Mead water; and 2) Lake Mead seston plus algae (Isochrysis galbana). Shell length, width, and area were compared as a function of time for the two treatments. It was expected that mussels would exhibit faster growth when supplemented with I. galbana than with Lake Mead water alone. However, no significant difference was observed between the control and I. galbana treatments. This result was unexpected and may have been caused by water quality, the nutritional content of Lake Mead seston, and/or over feeding. …


Modeling The Dispersal Of Eastern Oyster (Crassostrea Virginica) Larvae In Delaware Bay, Diego A. Narvaez, John M. Klinck, Eric N. Powell, Eileen E. Hofmann, John Wilkin, Dale B. Haidvogel Jan 2012

Modeling The Dispersal Of Eastern Oyster (Crassostrea Virginica) Larvae In Delaware Bay, Diego A. Narvaez, John M. Klinck, Eric N. Powell, Eileen E. Hofmann, John Wilkin, Dale B. Haidvogel

CCPO Publications

The interactions of circulation and growth processes in determining the horizontal distribution of eastern oyster (Crassostrea virginica) larvae in the Delaware Bay estuary were investigated with a coupled circulation-individual-based larvae model that used environmental conditions from the spawning seasons (mid-June to mid-September) of 1984, 1985, 1986, 2000, and 2001. Particles, representing oyster larvae, were released at five-day intervals from areas in Delaware Bay that correspond to natural oyster reefs. The simulated larval development time was used to estimate potential larval success, determined by the percent of larvae that successfully reached settlement size (330 µm) within the planktonic larval …


Shelf-Scale Mapping Of Fish Distribution Using Active And Passive Acoustics, Carrie Christy Wall Jan 2012

Shelf-Scale Mapping Of Fish Distribution Using Active And Passive Acoustics, Carrie Christy Wall

USF Tampa Graduate Theses and Dissertations

Fish sound production has been associated with courtship and spawning behavior. Acoustic recordings of fish sounds can be used to identify distribution and behavior. Passive acoustic monitoring (PAM) can record large amounts of acoustic data in a specific area for days to years. These data can be collected in remote locations under potentially unsafe seas throughout a 24-hour period providing datasets unattainable using observer-based methods. However, the instruments must withstand the caustic ocean environment and be retrieved to obtain the recorded data. This can prove difficult due to the risk of PAMs being lost, stolen or damaged, especially in highly …


The Effect Of Stream Restoration On Preferred Cutthroat Trout Habitat In The Strawberry River, Utah, Nicolas R. Braithwaite May 2011

The Effect Of Stream Restoration On Preferred Cutthroat Trout Habitat In The Strawberry River, Utah, Nicolas R. Braithwaite

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Stream restoration has become a popular management tool for attempting to increase and/or restore fish populations by improving habitat. A section of the Strawberry River, Utah recently underwent a stream restoration project, where the main goals of the project included increasing spawning activity, rearing potential, and resident populations of Bear Lake cutthroat trout Oncorhynchus clarkia utah. The impact of the restoration project on cutthroat trout was investigated by first characterizing preferred habitat for different life stages, investigating habitat as a limiting factor in the system, and then assessing the quality of available habitat by comparing restored/unrestored sections of stream …


Reproduction And Genetic Detection Of Veligers In Changing Dreissena Populations In The Great Lakes, Jeffrey L. Ram, Aos S. Karim, Payel Acharya, Pranav Jagtap, Sonal Purohit, Donna R. Kashian Jan 2011

Reproduction And Genetic Detection Of Veligers In Changing Dreissena Populations In The Great Lakes, Jeffrey L. Ram, Aos S. Karim, Payel Acharya, Pranav Jagtap, Sonal Purohit, Donna R. Kashian

Environmental Science and Geology Faculty Research Publications

Dreissenid bivalves, Dreissena polymorpha (zebra mussel) and Dreissena bugensis (quagga mussel) are biofouling species that invaded the Great Lakes region of North America from source populations in Europe in the 1980s. Initially, D. polymorpha spread faster and farther; however, D. bugensis have recently displaced D. polymorpha in many areas of the Great Lakes and was the first to be found west of the Continental Divide. Early detection of dreissenids is important in anticipating and preventing potentially high economic impacts. To study population dynamics and to enhance detection methods, we assessed “spawnability” using a serotonin bioassay and developed a new, sensitive, …


Slides: Development Of Shale: Water Resource Concerns And Policy Considerations, Katy Dunlap Nov 2010

Slides: Development Of Shale: Water Resource Concerns And Policy Considerations, Katy Dunlap

Shale Plays in the Intermountain West: Legal and Policy Issues (November 12)

Presenter: Katy Dunlap, Eastern Water Project Director, Trout Unlimited, Inc., Burdett, NY

24 slides


Spawning-Related Movements Of Barred Sand Bass Paralabrax Nebulifer, In Southern California: Interpretations From Two Decades Of Historical Tag And Recapture Data, E. T. Jarvis, Christi Linardich, C. F. Valle Jan 2010

Spawning-Related Movements Of Barred Sand Bass Paralabrax Nebulifer, In Southern California: Interpretations From Two Decades Of Historical Tag And Recapture Data, E. T. Jarvis, Christi Linardich, C. F. Valle

Biological Sciences Faculty Publications

During the 1960s and 1990s, the California Department of Fish and Game tagged 8,634 barred sand bass in southern California, and 972 fish (11%) were recaptured. Tag returns suggest barred sand bass are transient aggregate spawners that form spawning aggregations consisting of both resident and migrant individuals. Spawning residency at a historic spawning location was estimated by the frequency of returns over time; most same-year returns (82%, n  =  141) were recaptured within a 7 to 35-day period. The maximum recapture distance was 92 km. The average (± SD) non-spawning season recapture distance from peak spawning season tagging locations was …


Slides: Finding Flows: Fish Still Need Water Everyday, Melinda Kassen Jun 2009

Slides: Finding Flows: Fish Still Need Water Everyday, Melinda Kassen

Western Water Law, Policy and Management: Ripples, Currents, and New Channels for Inquiry (Martz Summer Conference, June 3-5)

Presenter: Melinda Kassen, Director of the Western Water Project, Trout Unlimited

12 slides


Paddlefish Egg Deposition In The Lower Yellowstone River, Montana And North Dakota, Shannon E. Miller, Dennis L. Scarnecchia, Steven R. Fain Aug 2008

Paddlefish Egg Deposition In The Lower Yellowstone River, Montana And North Dakota, Shannon E. Miller, Dennis L. Scarnecchia, Steven R. Fain

The Prairie Naturalist

We used passive egg collectors during May, June, and July of2003 and 2004 in the lower 50 river kiiometers (rkm) of the Yellowstone River, eastern Montana and western North Dakota, to detect egg deposition by spawning paddle fish (Polyodon spathula). Sampling yielded 292 eggs (46 in 2003 and 246 in 2004). All egg collections in 2003 occurred on the descending limb of the spring hydrograph but 99% of egg collections in 2004 occurred before the spring hydrograph began to descend. Catch-per-unit-effort (CPUE) in 2004 was about four times that of 2003. A combination of river conditions, in addition …


Influence Of Temperature And Discharge On Reproductive Timing Of Common Carp In A Northern Great Plains River, Tim Resseguie, Steve Kelsch Mar 2008

Influence Of Temperature And Discharge On Reproductive Timing Of Common Carp In A Northern Great Plains River, Tim Resseguie, Steve Kelsch

The Prairie Naturalist

Reproductive timing of common carp (Cyprinus carpio) was examined in the Red River of the North and compared with environmental factors that might have triggered spawning during 1999 and 2000. We estimated spawn dates for individual common carp larvae collected in the drift by back-calculating from datc of capture and by accounting for developmental stage at capture and water temperature during the period of egg incubation. Reproductive timing was compared with discharge and water temperature to determine which of these likely might be a synchronizing cue for spawning of common carp in the Red River basin. In both years of …


Maps Of The Klamath Basin And Key Water-Related Events In The Upper Klamath Basin, University Of Colorado Boulder. Natural Resources Law Center Jun 2003

Maps Of The Klamath Basin And Key Water-Related Events In The Upper Klamath Basin, University Of Colorado Boulder. Natural Resources Law Center

Water Negotiation Workshop (June 4-5)

5 pages.

Contents:

Maps of Klamath Basin -- Key water-related events in the Upper Klamath Basin

Excerpted from: Ron Hathaway & Teresa Welch, Water Allocation in the Klamath Reclamation Project, 2001: An Assessment of Natural Resource, Economic, Social, and Institutional Issues with a Focus on the Upper Klamath Basin 31-34, 43 (Oregon State University, University of California, reprinted May 2003). Full report available in Klamath Waters Digital Library at http://digitallib.oit.edu/cdm/ref/collection/kwl/id/9442.


Fluctuations In Chinook Salmon (Oncorhynchus Tshawytscha) Counts At Three Lower Columbia River Spawning Sites, Eric Michael Loomis May 2003

Fluctuations In Chinook Salmon (Oncorhynchus Tshawytscha) Counts At Three Lower Columbia River Spawning Sites, Eric Michael Loomis

UNLV Theses, Dissertations, Professional Papers, and Capstones

Several hypotheses were developed to explore the pronounced increase in Chinook salmon (Oncorhynchus tshawytscha) returning to spawning grounds at the Cowlitz, Kalama, and Lewis Rivers, three tributaries of the lower Columbia River. The study was conducted using data compiled over a ten-year span from 1991-2001. Preliminary indications are that trends in climate are linked to these increases, with the absence of El Niño events and fluctuations in winter precipitation as likely explanations of these phenomena. The unique nature of Chinook life cycles causes them to utilize a variety of habitats that require ideal conditions for maximum survival rates. Correlations between …


Use Of Fluorescence Microscopy In An Assay Of Sperm Density For The Gorgonian Coral, Plexaura Kuna, Timothy D. Swain, K. Kim, H. R. Lasker Jun 1997

Use Of Fluorescence Microscopy In An Assay Of Sperm Density For The Gorgonian Coral, Plexaura Kuna, Timothy D. Swain, K. Kim, H. R. Lasker

Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures

The density of sperm in the water column during the broadcast spawning events of marine invertebrates is often undetermined or reported in terms of fertilization potential. The density of sperm during such events can be determined by directly counting numbers of spermatozoa using a modification of the acridine orange direct count (AODC) technique for enumerating bacteria. A number of variables in the handling and processing of samples may bias estimates. Sample collection in glass and rapid fixation and filtration are necessary for reproducible estimates. Once filtered, samples are stable for many months, and counts on filters that were poorly stained …


Early Life History Of Yellow Perch In Eastern South Dakota Lakes, Shannon Fisher Jan 1996

Early Life History Of Yellow Perch In Eastern South Dakota Lakes, Shannon Fisher

Electronic Theses and Dissertations

Yellow perch Perea flavescens are a popular South Dakota sportfish; however, inconsistent recruitment creates highly variable and unpredictable perch fishery quality. Before fishery managers can begin to develop and assess strategies to stabilize yellow perch recruitment, a better understanding of their early life history is required. I selected two natural lakes with differing yellow perch population types and monitored brood stock, spawning habits, and larval and juvenile life history patterns during 1995 and 1996. Pelican Lake was selected as a representative yellow perch population exhibiting inconsistent recruitment and Pickerel Lake as a population with relatively consistent recruitment. Yellow perch tended …


Lake Trout Spawning In Lake Tahoe: Egg Incubation In Deepwater Macrophyte Beds, D. A. Beauchamp, B. C. Allen, R. C. Richards, Wayne A. Wurtsbaugh, C. R. Goldman Jan 1992

Lake Trout Spawning In Lake Tahoe: Egg Incubation In Deepwater Macrophyte Beds, D. A. Beauchamp, B. C. Allen, R. C. Richards, Wayne A. Wurtsbaugh, C. R. Goldman

Watershed Sciences Faculty Publications

Although most populations of lake trout Salvelinus namaycush spawn over rocky shoals, use of these substrates by lake trout has not yet been found in Lake Tahoe. Large cobble substrate exists at depths less than 20 m, and steep, fractured, rocky substrate can be found in isolated areas from the surface down to at least 100 m, but no evidence of spawning activity in these areas has been found. Instead, at least a portion of the population spawns on deepwater mounds (40–60 m deep) over beds of the macrophyte Chara delicatula. This is the first known report of lake trout …


Estimates Of Spawning Stock Size Of Blue Crab, Callinectes Sapidus, In Chesapeake Bay, 1986-1987, Cynthia M. Jones, John R. Mcconaugha, Patrick J. Geer, Michael H. Prager Jan 1990

Estimates Of Spawning Stock Size Of Blue Crab, Callinectes Sapidus, In Chesapeake Bay, 1986-1987, Cynthia M. Jones, John R. Mcconaugha, Patrick J. Geer, Michael H. Prager

OES Faculty Publications

The 1986 spawning stock exhibited a single abundance peak, increasing from 1.0×105 individuals in early July to 9.3×106 in late July, maintaining high levels throughout the summer, and declining in the fall to 7.4×105 individuals. The 1987 spawning stock showed 2 peaks of abundance. The population reached the lesser peak, 1.0×106 individuals, in late July; the greater peak, 1.5×106, in late August. By late September, the population had declined to 6.5×105 individuals. The peak abundance of the 1987 female spawning stock was only 16% as great as the peak abundance in 1986; the 1987 spawning stock size in 1986. Variability …