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Full-Text Articles in Life Sciences
Maturity, Spawning, And Ovarian Cycle Of Atlantic Croaker, Micropogonias-Undulatus, In The Chesapeake Bay And Adjacent Coastal Waters, Luiz R. Barbieri, Mark E. Chittenden, Susan K. Lowerre-Barbieri
Maturity, Spawning, And Ovarian Cycle Of Atlantic Croaker, Micropogonias-Undulatus, In The Chesapeake Bay And Adjacent Coastal Waters, Luiz R. Barbieri, Mark E. Chittenden, Susan K. Lowerre-Barbieri
VIMS Articles
The reproductive biology of Atlantic croaker, Micropogonias undulatus, collected during 1990-91 from commercial catches in Chesapeake Bay and in Virginia and North Carolina coastal waters (n=3,091), was studied by using macroscopic and microscopic gonad staging, the gonadosomatic index, oocyte diameter distributions, and histological analysis. Atlantic croaker are multiple spawners with asynchronous oocyte development and indeterminate fecundity. Mean length at first maturity for males and females was 182 and 173 mm TL, respectively. More than 85% of both sexes were mature by the end of their first year and all were mature by age 2. Spawning extends over a protracted period …
Survival Of Juvenile Caribbean Spiny Lobster: Effects Of Shelter Size, Geographic Location And Conspecific Abundance, Jd Mintz, Rom Lipcius, Db Eggleson, Ms Seebo
Survival Of Juvenile Caribbean Spiny Lobster: Effects Of Shelter Size, Geographic Location And Conspecific Abundance, Jd Mintz, Rom Lipcius, Db Eggleson, Ms Seebo
VIMS Articles
The Caribbean spiny lobster Panulirus argus seeks structured shelter throughout its benthic phase, often forming aggregations within shelters. Casitas - concrete, low-relief, artificial shelters - are effective in aggregating lobsters, and are used to harvest spiny lobster in the Caribbean. However, casitas may also enhance populations of P. argus, by providing shelter from predation. In this study we examined the effects of various shelter features upon the survival of juvenile P. argus. Juvenile lobsters were tethered at several artificial shelter treatments in Florida Bay, Florida, USA, to test the efficacy of casitas as refuge from predation. Survival of juveniles was …
Interannual Variation In The Recruitment Pattern And Abundance Of Age-0 Summer Flounder, Paralichthys-Dentatus, In Virginia Estuaries, Brenda L. Norcross, David M. Wyanski
Interannual Variation In The Recruitment Pattern And Abundance Of Age-0 Summer Flounder, Paralichthys-Dentatus, In Virginia Estuaries, Brenda L. Norcross, David M. Wyanski
VIMS Articles
Capture of transforming larval and newly settled juvenile (age-0) summer flounder, Paralichthys dentatus, over four years (1986-1989) in the seaside salt marshes of Virginia's Eastern Shore and in the lower Chesapeake Bay verifies Virginia waters as a nursery area. Gear specific for juvenile flatfish was used and sampling was conducted in a broad range of habitats in all months. This study demonstrates a fluctuation in the timing of the appearance and magnitude of abundance of age-0 summer flounder in Virginia waters over a four-year sampling period. Age-0 summer flounder (11-27 mm TL) began entering the area in October 1986 and …
Age, Growth, And Mortality Of Atlantic Croaker, Micropogonias-Undulatus, In The Chesapeake Bay-Region, With A Discussion Of Apparent Geographic Changes In Population-Dynamics, Luiz R. Barbieri, Mark E. Chittenden, Cynthia M. Jones
Age, Growth, And Mortality Of Atlantic Croaker, Micropogonias-Undulatus, In The Chesapeake Bay-Region, With A Discussion Of Apparent Geographic Changes In Population-Dynamics, Luiz R. Barbieri, Mark E. Chittenden, Cynthia M. Jones
VIMS Articles
Atlantic croaker, Micropogonias undulatus, collected from commercial catches in Chesapeake Bay and in Virginia and North Carolina coastal waters during 1988-1991 (n=1,967) were aged from transverse otolith sections. Ages 1-8 were recorded, but eight-year-old fish were rare. Marginal increment analysis showed that for ages 1-7, annuli are formed once a year during the period April-May. Otolith age readings were precise: >99% agreement within and between readers. Observed lengths-at-age were highly variable and growth rate decreased after the first year. Despite the high variability in sizes-at-age, observed lengths for ages 1-7 fit the von Bertalanffy growth model (r2=0.99; n=753) well. No …
Experimental Monitoring Of Virginia Artificial Reefs Using Fishermen Catch Data, Ja Lucy, Cg Barr
Experimental Monitoring Of Virginia Artificial Reefs Using Fishermen Catch Data, Ja Lucy, Cg Barr
VIMS Articles
Catch and effort data were compiled in 1987-1988 from recreational fishing trips targeting artificial reefs and other structure sites in Virginia waters. Data were collected from boat-owning fishermen by a random telephone survey. Within target species groups, catch rates were compared among five fishing sites inside Chesapeake Bay and two offshore reefs. Fishermen's target species options were more diverse at estuarine (bay) sites, primarily the result of Sciaenidae species (Leiostomus xanthurus, Micropogonias undulatus, and Cynoscion regalis) and Paralichthys dentatus. The Gwynn's Island Test Reef, closest to mid-bay, provided significantly higher mean catch rates of L. xanthurus in 1988 than lower …
Technical Efficiency, Biological Considerations, And Management And Regulation Of The Sea-Scallop, Placopecten-Magellanicus (Gmelin, 1791) Fishery, James E. Kirkley, William D. Dupaul
Technical Efficiency, Biological Considerations, And Management And Regulation Of The Sea-Scallop, Placopecten-Magellanicus (Gmelin, 1791) Fishery, James E. Kirkley, William D. Dupaul
VIMS Articles
Achieving social and economic efficiency in a fishery requires that production be technically efficient. Yet, technical efficiency (TE) is rarely examined for a fishery. By the use of detailed trip-level data and information about resource conditions obtained from routine sampling, a stochastic frontier production model relating landings to days at sea, crew size, and resource conditions is specified and estimated for 10 Mid-Atlantic sea scallop (Placopecten magellanicus) dredge vessels. TE is shown to depend partly on the mix of controllable inputs such as days at sea and crew size but possibly more on uncontrollable factors such as resource conditions and …
Reproductive Activity Of Oysters, Crassostrea-Virginica (Gmelin, 1791) In The James River, Virginia, During 1987-1988, Roger L. Mann, Julia S. Rainer, Reinaldo Morales-Alamo
Reproductive Activity Of Oysters, Crassostrea-Virginica (Gmelin, 1791) In The James River, Virginia, During 1987-1988, Roger L. Mann, Julia S. Rainer, Reinaldo Morales-Alamo
VIMS Articles
Reproductive activity in oysters, Crassostrea virginica Gmelin, in the James River, Virginia, was examined for 1987 from weekly estimates for fecundity and egg viability in oysters collected from Wreck Shoal, and for 1988 from weekly estimates of fecundity, egg viability, gonad volume fraction, gonad thickness, and mean egg size in oysters collected from Horsehead Reef. Maximum and mean fecundity values from Wreck Shoal oysters were higher than from Horsehead oysters. No relationship was evident between fecundity and egg viability at Horsehead Reef. A strong temporal relationship was observed between egg viability and peak oyster settlement in the James in both …
A Comparison Of A Validated Otolith Method To Age Weakfish, Cynoscion-Regalis, With The Traditional Scale Method, Luiz R. Barbieri, Mark E. Chittenden, Susan K. Lowerre-Barbieri
A Comparison Of A Validated Otolith Method To Age Weakfish, Cynoscion-Regalis, With The Traditional Scale Method, Luiz R. Barbieri, Mark E. Chittenden, Susan K. Lowerre-Barbieri
VIMS Articles
Otoliths, scales, dorsal spines, and pectoral-fin rays were compared to ascertain the best hardpart for determining the age of weakfish, Cynoscion regalis. Each showed concentric marks, which could be interpreted as annuli. Sectioned otoliths, however, consistently showed the clearest marks, had 100% agreement between and within readers, and were validated by the marginal increment method for ages 1-5. This validated method of ageing weakfish was then compared with the traditionally used scale method. The scale method was less precise, as demonstrated by lower percent agreement, and generally assigned younger ages for fish older than age 6 (as determined by otoliths). …
Morphometric And Genetic Identification Of Eggs Of Spring-Spawning Sciaenids In Lower Chesapeake Bay, Louis B. Daniel Iii, John Graves
Morphometric And Genetic Identification Of Eggs Of Spring-Spawning Sciaenids In Lower Chesapeake Bay, Louis B. Daniel Iii, John Graves
VIMS Articles
Restriction-fragment length polymorphism (RFLP) analysis of mitochondrial mtDNA was used to identify morphologically similar eggs of spring spawning sciaenids in lower Chesapeake Bay. During spring 1990 and 1991, ichthyoplankton surveys were conducted in lower Chesapeake Bay to estimate seasonal egg production and population biomass of black drum, Pogonias cromis. Rearing experiments indicated that at least three species of sciaenid (silver perch, Bairdiella chrysoura; weakfish, Cynoscion regalis and P. cromis) were spawning in the survey area during both years. Specific identification of eggs based on previously published ranges of outside egg diameter (OED) were not reliable because of considerable overlap in …
Description Of Metamorphic Phases In The Oyster Crassostrea Virginica And Effects Of Hypoxia On Metamorphosis, Sm Baker, Roger L. Mann
Description Of Metamorphic Phases In The Oyster Crassostrea Virginica And Effects Of Hypoxia On Metamorphosis, Sm Baker, Roger L. Mann
VIMS Articles
Four phases of metamorphosis in the eastern oyster Crassostrea virginica were characterized:'settlers' have attached to the substrate but retain larval characteristics; metamorphosis and degeneration of the velum has begun in 'prodissoconch postlarvae'; in 'dissoconch postlarvae' shell growth beyond the prodissoconch has begun but the foot persists; and 'juveniles' have lost all larval organs and metamorphosis is complete. These phases were used in examining the metamorphic process during and following continuous and short-term exposures to hypoxia (1.5 mg O-2 l(-1), 20 % of air saturation) and microxia (< 0.07 mg O(2)l(-1), < 1 % of air saturation). We observed no abnormal development in the oysters, but development was delayed following 3 d exposures to hypoxia, and 2 and 3 d exposures to microxia. Under continuous exposure to microxia, oysters did not develop to the dissoconch postlarva or juvenile phases. Approximately 50 % of the control oysters died within the 2 wk period following settlement. Morality was virtually confined to the settler and prodissoconch postlarva phases. Short-term exposures to hypoxia (1 to 3 d) and microxia (1 d) had little effect on the median mortality time or final total mortality, compared to controls. Microxic treatments longer than 1 d did affect mortality and oysters continuously exposed to microxia had a median mortality time of 87 h. Short-term exposures to low oxygen did not have permanent effects on post-settlement growth rates. Oysters exposed to microxic treatments, however, appeared to have slower growth rates during the exposure period. We conclude that low oxygen conditions, in particular those that are microxic and last longer than 24 h, have detrimental effects on the development, growth, and mortality of post settlement oysters.