Influence of growth and survival costs of reproduction on Atlantic cod, Gadus morhua, population growth rate

1999 ◽  
Vol 56 (9) ◽  
pp. 1612-1623 ◽  
Author(s):  
Jeffrey A Hutchings
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Environmental Stochasticity ◽  
Individual Growth ◽  
Growth And Survival ◽  
Individual Growth Rate ◽  
Age Structured ◽  
Reproductive Rates

A stochastic, age-structured life history model was used to examine how age at maturity (theta), pre- (Zimm) and postreproductive (Zmat) mortality, and postreproductive growth rate can affect maximum reproductive rates of fish at low population size. Simulations suggest that annual (r) and per-generation (R0) metrics of population growth for Newfoundland's northern Grand Bank Atlantic cod, Gadus morhua, are primarily influenced by changes to mortality prior to and following reproduction. At observed weights at age and Zmat = 0.2, r ranged between 0.135 and 0.164 for cod maturing at between 4 and 7 years. Incremental increases in either Zimm or Zmat of 0.1 were associated with 0.03-0.05 reductions in r. To effect similar reductions, individual growth rate would have to decline by approximately one half. At observed weights at age, increases in Zmat from 0.20 to 0.45 increased the probability of negative per-generation growth from 3 to 26% for cod maturing at 4 years and from 6 to 46% for cod maturing at 7 years. Thus, even in the absence of fishing mortality, little or no population growth by Atlantic cod may not be unexpected in the presence of environmental stochasticity, particularly when accompanied by increases in mortality and declining individual growth.

Demography of an Estuarine Amphipod (Gammarus lawrencianus) Experimentally Selected for High "r": A Model of the Genetic Effects of Environmental Change

1981 ◽  
Vol 38 (9) ◽  
pp. 1120-1127 ◽  
Author(s):  
R. W. Doyle ◽  
W. Hunte
Keyword(s):  
Growth Rate ◽  
Population Growth ◽  
Life History Strategy ◽  
Intrinsic Rate ◽  
Individual Growth ◽  
Population Growth Rates ◽  
Phenotypic Correlations ◽  
Demographic Traits ◽  
Marine Crustacean ◽  
Individual Growth Rate

The estuarine amphipod Gammarus lawrencianus was subjected to prolonged selection (3 years; 26 generations) for high population growth rates. The demography of the selected population was studied in detail and compared under laboratory conditions with animals derived from a control (wild) population collected in the same area 3 years later. In the lab-adapted population the intrinsic rate of population growth r increased by 72% as the result of changes in age at maturation, survivorship, and fecundity. The variance of these traits decreased and Crow's (1958) index of total selection (variance of fitness/mean fitness squared) is proposed as a quantitative and operational measure of genetic adaptation to a changed environment. Possible limitations on adaptation were investigated by examining the correlations among demographic traits within the lab-adapted population. Some phenotypic correlations were determined directly and others by an indirect technique using information from full siblings. Individual growth rate was negatively correlated both with survival and fecundity. Individual growth rate and age at sexual maturity were also negatively correlated. Negative phenotypic correlations between traits may indicate limitations on long-term adaptation. We conclude that significant evolutionary changes in the demographic traits of this (and presumably other) marine crustacean can occur within a time scale of interest to ecologists and aquaculturalists.Key words: adaptation, amphipod, aquaculture, Crustacea, evolution, Gammarus, genetics, life history, strategy

scholarly journals Effect of Stocking Density on Growth and Survival Rate of Giant Gouramy (Osphrenemus gouramy Lac.) Seed

2009 ◽  
Vol 8 (2) ◽  
pp. 199 ◽  
Author(s):  
S. Sarah ◽  
. Widanarni ◽  
Agus Oman Sudrajat
Keyword(s):  
Growth Rate ◽  
Survival Rate ◽  
Feed Efficiency ◽  
Stocking Density ◽  
Individual Growth ◽  
Daily Growth Rate ◽  
Daily Growth ◽  
Fish Yield ◽  
Growth And Survival ◽  
Individual Growth Rate

<p>This experiment was conducted to study the stocking density effect on growth and survival rate of giant gouramy seed in the aquarium. Fish were stocked at the density of 2.5; 5.0; 7.5 and 10 individual/l with average initial weight and length were 0.013 g and 5.56 mm, respectively. Fish were fed with silkworm (<em>Tubifex</em> sp.) <em>ad libitum</em> in the morning and evening for 22 days of experiment. Aquarium was siphoned and water was changed everyday for maintaining good water quality. Result showed that survival rate remain high in all treatment (93.5 - 95.5%). Increasing stocking density from 2.5 to 10 individual/I did not affect survival rate. On the other hand growth rate and feed efficiency decreased, while fish yield increased. Stocking density of 2,5 individual/l gave  the highest daily growth rate, individual growth rate, growth in length and feed efficiency of 12.94%, 0.0081 g/day, 16.84 mm and 12.51%; respectively. The highest value for fish yield (0,0360 g/l/day) was obtained from stocking density of 10 individual/l</p> <p>Key words: stocking density, seed, survival rate, growth rate, giant gouramy <em>Osphrenemus goramy</em></p> <p> </p> <p>ABSTRAK</p> <p>Keterbatasan pengadaan benih ikan gurame (<em>Osphronemus gourame </em>Lac.) disebabkan oleh tidak seimbangnya jumlah benih yang tersedia dengan kebutuhan usaha pembesaran. Teknik pembenihan yang digunakan sampai saat ini relatif sederhana dengan cara tradisional. Pemeliharaan gurame secara terkontrol di akuarium dapat menjawab tantangan dalam teknologi pembenihan gurame sekaligus sebagai sarana pola budidaya secara bertahap yang sedang berkembang saat ini. Produksi yang tinggi akan dicapai dengan pemeliharaan pada kepadatan yang tinggi. Pada keadaan lingkungan yang baik dan pakan yang mencukupi, peningkatan kepadatan akan disertai dengan peningkatan hasil. Jumlah ikan yang ditebar pada penelitian ini disesuaikan berdasarkan perlakuan yaitu 2,5; 5,0; 7,5 dan 10 ekor/l. Pengamatan terhadap ikan dilakukan sampai hari ke-22. Hasil pengamatan menunjukkan bahwa peningkatan kepadatan 2,5 - 10 ekor/l pada pemeliharaan benih gurame di akuarium mempengaruhi pertumbuhan, hasil dan efisiensi pakan, namun tidak berpengaruh terhadap kelangsungan hidup. Dengan meningkatnya padat penebaran, laju pertumbuhan dan efisiensi pakan semakin menurun, sedangkan hasil (<em>yield</em>) semakin meningkat. Padat penebaran 2,5 ekor/l menghasilkan laju pertumbuhan harian, laju pertumbuhan individu, pertumbuhan panjang mutlak dan efisiensi pakan tertinggi, masing-masing mencapai 12,94 %, 0,0081 g/hari, 16,84 mm dan 12,51 %. Sedangkan nilai tertinggi untuk hasil (<em>yield</em>) sebesar 0,0360 g/l/hari diperoleh pada padat penebaran 10,0 ekor/l.</p> <p>Kata kunci : padat tebar, pembenihan, gurame dan <em>Osphronemus gouramy</em></p>

Life history consequences of overexploitation to population recovery in Northwest Atlantic cod (Gadus morhua)

2005 ◽  
Vol 62 (4) ◽  
pp. 824-832 ◽  
Author(s):  
Jeffrey A Hutchings
Keyword(s):  
Life History ◽  
Population Growth ◽  
Gadus Morhua ◽  
Life History Traits ◽  
Atlantic Cod ◽  
Hatching Rate ◽  
Northwest Atlantic ◽  
Annual Population ◽  
Age Structured ◽  
Negative Impacts

Changes to life history traits are often concomitant with prolonged periods of exploitation. In the Northwest Atlantic, 30- to 40-year declines of more than 90% of Atlantic cod (Gadus morhua) have been associated with significant reductions in age and length at maturity, changes most parsimoniously explained as genetic responses to fishing. Increased survival costs of reproduction associated with earlier maturity, resulting in higher natural mortality and shorter life span, negatively affect population growth rate and rate of recovery. Coupled with lower hatching rate among first-time spawners and smaller size at maturity, a modest reduction in age from 6 to 4 years can reduce annual population growth in Atlantic cod by 25%–30%, based on the output of a stochastic, age-structured life history model. Earlier maturity more than doubles the probability of negative population growth every generation. These results underscore the potential for fishing-induced changes to life history traits alone to generate slow or negligible recovery in marine fishes, exacerbating negative impacts on population growth resulting from ecosystem-level alterations to interspecific competition and predation.

scholarly journals The effect of growth rate on otolith-based discrimination of cod (Gadus morhua) ecotypes

PLoS ONE ◽  
2021 ◽  
Vol 16 (9) ◽  
pp. e0247630
Author(s):  
Einar Pétur Jónsson ◽  
Steven E. Campana ◽  
Jón Sólmundsson ◽  
Klara B. Jakobsdóttir ◽  
Hlynur Bárðarson
Keyword(s):  
Growth Rate ◽  
Gadus Morhua ◽  
Sampling Period ◽  
Individual Growth ◽  
Discrete Wavelet ◽  
Shape Variation ◽  
Otolith Shape ◽  
Individual Growth Rate ◽  
The Individual ◽  
The Relationship

Otolith shape has previously been used to identify ecotypes within the Icelandic cod (Gadus morhua) stock, using DST profiles to validate the results. Fish otolith shape variation has repeatedly been found to be largely determined by growth rate. To examine the effect of growth rate on the relationship between otolith shape and cod ecotypes (using the Pan I genotype as a proxy for ecotype), 826 archived sagittal otoliths collected over a 58 year sampling period were retrieved, the individual growth rate calculated, and otolith shape described using both Normalized Elliptic Fourier transform and Discrete Wavelet transform. Discriminant functions of otolith shape successfully classified ecotype, whether using Fourier or Wavelet descriptors, but only when excluding a heterozygous genotype from the analysis. The otolith shape variability of this genotype lowered the classification success, while otolith shape, in turn, was significantly affected by growth rate and cohort. Growth rate differences previously reported for the ecotypes were present, but were less marked than expected and indeed, growth rate variance attributable to ecotype identity was dwarfed by cohort- and location-related variance in growth. Such a strong effect of growth rate suggests that cod ecotype discrimination based on otolith shape is sensitive to both temporal and spatial variations in growth, which can mask the effect of ecotype-related growth rate differences on otolith shape.

scholarly journals Otolith-based discrimination of cod ecotypes and the effect of growth rate

2021 ◽  
Author(s):  
Einar Pétur Jónsson ◽  
Steven E. Campana ◽  
Jón Sólmundsson ◽  
Klara B. Jakobsdóttir ◽  
Hlynur Bárðarson
Keyword(s):  
Growth Rate ◽  
Gadus Morhua ◽  
Sampling Period ◽  
Individual Growth ◽  
Discrete Wavelet ◽  
Shape Variation ◽  
Otolith Shape ◽  
Individual Growth Rate ◽  
The Individual ◽  
The Relationship

AbstractOtolith shape has previously been used to identify ecotypes within the Icelandic cod (Gadus morhua) stock, using DST profiles to validate the results. Fish otolith shape variation has repeatedly been found to be largely determined by growth rate. To examine the effect of growth rate on the relationship between otolith shape and cod ecotypes (using the Pan I genotype as a proxy for ecotype), 826 archived sagittal otoliths collected over a 52 year sampling period were retrieved, the individual growth rate calculated, and otolith shape described using both Normalized Elliptic Fourier transform and Discrete Wavelet transform. Discriminant functions of otolith shape yielded high ecotype classification success, whether using Fourier or Wavelet descriptors, but only when excluding a heterozygous genotype from the analysis. The otolith shape variability of this genotype lowered the classification success, while otolith shape, in turn, was significantly affected by growth rate and cohort. Growth rate differences previously reported for the ecotypes were present, but were less marked than expected and indeed, growth rate variance attributable to ecotype identity was dwarfed by cohort- and location-related variance in growth. Such a strong effect of growth rate suggests that cod ecotype discrimination based on otolith shape is sensitive to both temporal and spatial variations in growth, which can mask the effect of ecotype-related growth rate differences on otolith shape.

scholarly journals How should enzyme activities be used in fish growth studies?

1995 ◽  
Vol 198 (7) ◽  
pp. 1493-1497 ◽  
Author(s):  
D Pelletier ◽  
P Blier ◽  
JD Dutil ◽  
H Guderley
Keyword(s):  
Growth Rate ◽  
Gadus Morhua ◽  
White Muscle ◽  
Citrate Synthase ◽  
Atlantic Cod ◽  
Muscle Protein ◽  
Dry Mass ◽  
Fish Growth ◽  
Individual Growth ◽  
Oxidative Enzymes

The activity of glycolytic and oxidative enzymes was monitored in the white muscle of Atlantic cod Gadus morhua experiencing different growth rates. A strong positive relationship between the activity of two glycolytic enzymes and individual growth rate was observed regardless of whether the enzyme activity was expressed as units per gram wet mass, units per gram dry mass or with respect to muscle protein and DNA content. The most sensitive response to growth rate was observed when pyruvate kinase and lactate dehydrogenase activities were expressed as units per microgram DNA, and this may be useful as an indicator of growth rate in wild fish. In contrast, no relationship between the activities of oxidative enzymes and growth rate was observed when cytochrome c oxidase and citrate synthase activities were expressed as units per gram protein. Apparently, the aerobic capacity of white muscle in cod is not specifically increased to match growth rate.

Relationships Between RNA–DNA Ratio, Prey Density, and Growth Rate in Atlantic Cod (Gadus morhua) Larvae

1979 ◽  
Vol 36 (12) ◽  
pp. 1497-1502 ◽  
Author(s):  
L. J. Buckley
Keyword(s):  
Growth Rate ◽  
Nutritional Status ◽  
Growth Rates ◽  
Prey Density ◽  
Gadus Morhua ◽  
Slow Growth ◽  
Atlantic Cod ◽  
Larval Fish ◽  
Dry Weight ◽  
Dna And Rna

The protein, DNA, and RNA content of larvae maintained at 1.0 plankter/mL increased at the rates of 9.3, 9.9, and 9.8% per day, respectively, for the 5 wk after hatching. Protein reserves of larvae held at 0 or 0.2 plankters/mL were depleted by 45 and 35%, respectively, prior to death 12–13 d after hatching. Starved larvae had similar protein concentrations (percent of dry weight), lower RNA concentrations, and higher DNA concentrations than fed larvae. Larvae held at higher plankton densities had higher RNA–DNA ratios and faster growth rates than larvae held at lower plankton densities. The RNA–DNA ratio was significantly correlated (P < 0.01) with the protein growth rate. The RNA–DNA ratio appears to be a useful index of nutritional status in larval Atlantic cod (Gadus morhua) and may be useful for determining if cod larvae were in a period of rapid or slow growth at the time of capture. Key words: RNA–DNA ratio, starvation, protein, nucleic acids, growth, larval fish, Atlantic cod

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