Growth dynamics of a ctenophore (Mnemiopsis) in relation to variable food supply. I. Carbon biomass, feeding, egg production, growth and assimilation efficiency

1989 ◽  
Vol 11 (3) ◽  
pp. 535-552 ◽  
Author(s):  
Michael R. Reeve ◽  
Mary Ann Syms ◽  
Patricia Kremer
Keyword(s):  
Food Supply ◽  
Egg Production ◽  
Assimilation Efficiency ◽  
Growth Dynamics ◽  
Carbon Biomass ◽  
Production Growth

scholarly journals Economic Analysis of Commercial Layer Production Decisions for Family Farm Operators

1973 ◽  
Vol 5 (1) ◽  
pp. 147-152
Author(s):  
G. Chris Lance
Keyword(s):  
Vertical Integration ◽  
Egg Production ◽  
Production Contracts ◽  
Production Growth ◽  
Different Types ◽  
The Sixties ◽  
Retail Prices ◽  
Farm Operators ◽  
Independent Ownership ◽  
Small Producers

Egg production in Georgia traditionally was by small producers with eggs marketed through retail stores. Beginning in the early 1960's feed millers, egg distributors and broiler integrators began shifting from broilers and other enterprises to commercial egg production. Growth of the industry through the decade of the sixties developed into two different types of production and marketing structures. Industry leaders primarily interested in selling feed, and handling eggs encouraged expansion of independent ownership of flocks by small producers. Independent producers purchased feed and started pullets at retail prices and sold eggs on a grade-yield basis to processor-distributors. Other industry leaders encouraged vertical integration by offering production contracts. Contract producers provided facilities and labor for egg production and received a fixed payment per unit from the integrator. The integrators owned the layers and provided feed, medication and supervision for flocks.

scholarly journals Effects of temperature and phytoplankton community composition on subitaneous and resting egg production rates of Acartia omorii in Tokyo Bay

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ayumi Tsunashima ◽  
Hiroshi Itoh ◽  
Toshiya Katano
Keyword(s):  
Water Temperature ◽  
Community Composition ◽  
Egg Production ◽  
Phytoplankton Community ◽  
Tokyo Bay ◽  
Production Rates ◽  
Phytoplankton Community Composition ◽  
Carbon Biomass ◽  
Effects Of Temperature ◽  
Second Peak

AbstractTo clarify the effects of temperature and phytoplankton community composition on Acartia omorii (Copepoda: Calanoida) egg production, its abundance and egg production rates were investigated from 2016 to 2018 in Tokyo Bay, Japan. Abundance was high from March to May (> 3.0 × 104 individuals m−3) and low or undetected from late June to December (≤ 0.4 × 104 individuals m−3). In 2018, most eggs were subitaneous until April; diapause eggs appeared in May when the water temperature exceeded 20 °C. The weight-specific egg production rate (SEPR, Cegg Cfemale−1 day−1) had two peaks. In the first peak in January, > 90% of eggs were subitaneous; in contrast, in the second peak in May, 60% of eggs were unhatched, including diapause eggs. The first peak of subitaneous eggs may contribute to planktonic population development from March to May. In contrast the second peak of diapause eggs probably enhances their recurrence in the next winter. Multiple regression analysis revealed that subitaneous SEPR showed a negative response, whereas diapause SEPR showed a positive response to temperature. Subitaneous SEPR positively correlated with the proportion of small diatoms in phytoplankton carbon biomass, whereas unhatched SEPR positively correlated with the proportion of inedible preys in large diatoms and dinoflagellates. Edible diatoms may induce subitaneous egg production, whereas low-food availability may induce diapause egg production. These results suggest that phytoplankton composition and water temperature have strong impacts on the dynamics of A. omorii via egg production.

A comparison of the size at maturity of female American lobsters (Homarus americanus) over three decades and across coastal areas of the Gulf of Maine using ovarian staging

2021 ◽  
Author(s):  
Jesica D Waller ◽  
Kathleen M Reardon ◽  
Sarah E Caron ◽  
Blaise P Jenner ◽  
Erin L Summers ◽  
...  
Keyword(s):  
Egg Production ◽  
Gulf Of Maine ◽  
Stock Assessment ◽  
Coastal Region ◽  
Homarus Americanus ◽  
Growth Patterns ◽  
American Lobster ◽  
Size At Maturity ◽  
Management Measures ◽  
Production Growth

Abstract The carapace length (CL) at which American lobster (Homarus americanus) females reach maturity can be used to evaluate egg production, growth patterns, and the overall health of lobster stocks. The female maturity datasets used to represent Gulf of Maine (GOM) lobsters in the 2015 Atlantic States Marine Fisheries Commission American Lobster Stock Assessment were collected in the 1990s by the Maine Department of Marine Resources at two coastal sites. Many studies have demonstrated an inverse relationship between temperature and the size at maturity in female lobsters, and GOM waters have warmed significantly over this period. To update these GOM maturity datasets, we used ovarian staging to determine the maturity status of over 1200 females from fives sites over 3 years. Broad application of this methodology in tandem with key growth measurements on females 50–120 mm CL allowed us to characterize reproductive development and generate maturity ogives (proportion mature at a given CL). We observed a latitudinal gradient in the size at maturity across this coastal region of the GOM and quantified a decrease in this size over 25 years. These findings have implications for future stock assessment approaches and management measures implemented to sustain this valuable fishery.

Feeding ecology of Apocyclops procerus (Copepoda, Cyclopoida) under experimental conditions

Crustaceana ◽  
2015 ◽  
Vol 88 (3) ◽  
pp. 283-297
Author(s):  
M. Guenther ◽  
R. Durst ◽  
W. S. Felismino ◽  
V. T. Pessoa ◽  
S. Neumann-Leitão
Keyword(s):  
Food Supply ◽  
Egg Production ◽  
Feeding Habits ◽  
Adult Life ◽  
Isochrysis Galbana ◽  
First Record ◽  
Chaetoceros Muelleri ◽  
Experimental Conditions ◽  
Adult Life Span ◽  
Copepoda Cyclopoida

Copepods are key links between primary producers and higher pelagics. We investigated, for the first time, under laboratory conditions, some aspects of the reproductive behaviour and feeding preferences of Apocyclops procerus (Copepoda: Cyclopoida) under different conditions of salinity and food supply. This is also its first record for Pernambuco (NE Brazil). The females carry their eggs until their eclosion and present several cycles of egg production without being further fecundated. Egg production and adult life span were not affected by differences in salinity or food supply. Offspring predation was also observed. From the three microalgae species offered to A. procerus individuals, Thalassiosira weissflogii, Chaetoceros muelleri (Ochrophyta) and Isochrysis galbana (Haptophyta), the small round-shaped I. galbana was preferred over the large and spiny diatoms, in spite of its lower nutritional value. The high salinity tolerance and apparently omnivorous feeding habits of A. procerus may enable it to predominate in estuarine waters.

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