Effect of enriched rotifers on growth, survival, and composition of larval Atlantic cod (Gadus morhua)

Abstract Recently, the nutritional requirements of marine finfish larvae have received considerable attention, and studies have shown that docosahexaenoic acid (DHA) affects the growth and survival of marine finfish larvae. We investigated the effects of different rotifer diets containing variable amounts of DHA on the growth and survival of larval Atlantic cod (Gadus morhua L.). Four different commercial rotifer enrichment formulations were used: spray-dried whole cells composed of Crypthecodinium sp. (ED1), spray-dried whole cells of Schizochytrium sp. (ED2), an oil emulsion (ED3) and ED1, and dried Chlorella at a 7:3 ratio by weight (ED4). The resultant rotifers contained a similar concentration of DHA (1.1–1.6% DW), but the level of DHA differed in proportion to EPA for each enrichment, and was designated ER1–4. Twelve 30-l aquaria were used with three replicates per treatment. Larvae were fed with rotifers from 3 to 43 days post-hatch (dph) at 4000 prey l−1. At the end of the experiment, no significant differences were found in body length and dry weight between the larvae reared on ER1 and ER2. However, larvae reared on ER3 were significantly smaller (both in length and weight) than larvae reared on ER1 and ER2. Larval survival on the ER2 treatment at 43 dph was significantly higher than on the other three treatments. Our results showed a positive effect of rotifer DHA proportions on growth and survival of cod larvae, and demonstrated that Atlantic cod larvae require a high ratio of dietary DHA to EPA.

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Turbulence enhances feeding of larval cod at low prey densities

ICES Journal of Marine Science ◽

10.1093/icesjms/fsu051 ◽

2014 ◽

Vol 71 (9) ◽

pp. 2515-2529 ◽

Cited By ~ 9

Author(s):

T. Kristiansen ◽

K. W. Vollset ◽

S. Sundby ◽

F. Vikebø

Keyword(s):

Vertical Distribution ◽

Growth Rates ◽

Gadus Morhua ◽

Atlantic Cod ◽

Larval Fish ◽

Larval Survival ◽

Growth And Survival ◽

First Feeding ◽

High Ingestion ◽

Biological Environment

Abstract The ability of larval fish to find food successfully after hatching is critical for their growth and survival during the early life stages. However, the feeding ecology of larval fish is strongly dependent on prevailing physical and biological conditions. Small changes in the prey distribution, turbulence, light, and ocean temperature can affect larval survival probabilities. This study combined physical and biological observations collected from Atlantic cod (Gadus morhua) spawning grounds from Lofoten, Norway, during the years 1991–1992 with an individual-based model (IBM) that is able to simulate behaviour, feeding, and growth. Observational data on the vertical distribution of larval cod revealed that they congregated at 10–25 m during the day, although the highest abundance of prey was generally in the upper 10 m. Using the behavioural component of the IBM, we analysed the mechanistic interactions between larval bioenergetics and the physical–biological environment and compared modelled with observed vertical larval cod distribution. During periods of both low and high prey densities, turbulence had a significant impact on larval cod feeding and growth rates as well as on larval vertical distribution. At low prey abundance (<5 nauplii l−1), turbulence enhanced encounter rates were very important for sustaining ingestion and growth rates for first-feeding larval cod. Our results suggest that turbulence allowed larval cod to sustain high ingestion rates even deeper in the water column, where prey densities are usually lower.

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Recent Growth, Biochemical Composition and Prey Field of Larval Haddock (Melanogrammus aeglefinus) and Atlantic Cod (Gadus morhua) on Georges Bank

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f87-003 ◽

1987 ◽

Vol 44 (1) ◽

pp. 14-25 ◽

Cited By ~ 100

Author(s):

L. J. Buckley ◽

R. G. Lough

Keyword(s):

Gadus Morhua ◽

Atlantic Cod ◽

Dry Weight ◽

Melanogrammus Aeglefinus ◽

Good Growth ◽

Georges Bank ◽

Larval Population ◽

Prey Biomass ◽

Recent Growth ◽

Haddock Melanogrammus Aeglefinus

A transect across southern Georges Bank in May 1983 showed higher levels of available prey for haddock (Melanogrammus aeglefinus) and cod (Gadus morhua) larvae at two stratified sites than at a well-mixed site. At the stratified sites, prey biomass was high (30–300 μg dry wt∙L−1) near the surface above the thermocline; values were lower and more uniform with depth (10–30 μg dry wt∙L−1) at the well-mixed site. Larval population centers generally coincided with prey biomass vertically. Recent growth in dry weight of haddock larvae as estimated by RNA–DNA ratio analysis was higher at the stratified sites (8–13%∙d−1) than at the well-mixed site (7%∙d−1). Larvae appeared to be in excellent condition at the stratified sites, but up to 50% of haddock larvae from the well-mixed site had RNA–DNA ratios in the range observed for starved larvae in the laboratory. Cod collected at the same site were in better condition and growing faster than haddock. The data support the hypotheses that (1) stratified conditions in the spring favor good growth and survival of haddock larvae and (2) cod larvae are better adapted to grow and survive in well-mixed waters at lower levels of available food than haddock larvae.

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

Journal of the Fisheries Research Board of Canada ◽

10.1139/f79-217 ◽

1979 ◽

Vol 36 (12) ◽

pp. 1497-1502 ◽

Cited By ~ 121

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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The influence of maternal effects in larval survival on fishery harvest reference points for two life-history patterns

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2013-0253 ◽

2014 ◽

Vol 71 (1) ◽

pp. 151-161 ◽

Cited By ~ 10

Author(s):

Paul D. Spencer ◽

Sarah B.M. Kraak ◽

Edward A. Trippel

Keyword(s):

Life History ◽

Pacific Ocean ◽

Maternal Effects ◽

Gadus Morhua ◽

Atlantic Cod ◽

Larval Survival ◽

Reference Points ◽

Life History Pattern ◽

Gadus Macrocephalus ◽

Potential Interactions

Increased larval viability with increased spawner age (i.e., maternal effects) have been observed in Atlantic cod (Gadus morhua) and Pacific rockfish (Sebastes spp.) stocks. Analytical results from a Beverton–Holt recruitment model indicate density-independent maternal effects affected the relative stock productivity and fishing rate reference points. We simulated populations based on Pacific cod (Gadus macrocephalus) and Pacific ocean perch (Sebastes alutus) to explore how estimates of reference points Fmsy and Fcrash are affected by maternal effects and potential interactions with life-history pattern, recruitment autocorrelation, and exploitation rate. Estimates of Fmsy and Fcrash were made from populations with maternal effects using either total larvae (proportional to eggs) or viable larvae (incorporating the maternal effect). Maternal effects have the largest impact upon estimated population productivity at high fishing rates. Estimates of Fmsy and Fcrash for cod were also affected by autocorrelated recruitment variability because of their reduced longevity compared with Pacific ocean perch. These results suggest the importance of evaluating the influence of maternal effects on estimated stock productivity on a case-by-case basis, particularly for depleted stocks composed of relatively young spawners.

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Use of the microalga Pavlova viridis as enrichment product for the feeding of Atlantic cod larvae (Gadus morhua)

Aquaculture ◽

10.1016/j.aquaculture.2015.01.011 ◽

2015 ◽

Vol 438 ◽

pp. 141-150 ◽

Cited By ~ 9

Author(s):

S. Rehberg-Haas ◽

S. Meyer ◽

M. Tielmann ◽

S. Lippemeier ◽

O. Vadstein ◽

...

Keyword(s):

Gadus Morhua ◽

Atlantic Cod ◽

Pavlova Viridis ◽

Atlantic Cod Larvae ◽

Enrichment Product

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Differential protein expression in early Atlantic cod larvae (Gadus morhua) in response to treatment with probiotic bacteria

Comparative Biochemistry and Physiology Part D Genomics and Proteomics ◽

10.1016/j.cbd.2009.06.001 ◽

2009 ◽

Vol 4 (4) ◽

pp. 249-254 ◽

Cited By ~ 7

Author(s):

Hólmfrídur Sveinsdóttir ◽

Agnar Steinarsson ◽

Ágústa Gudmundsdóttir

Keyword(s):

Protein Expression ◽

Gadus Morhua ◽

Atlantic Cod ◽

Probiotic Bacteria ◽

Response To Treatment ◽

Differential Protein Expression ◽

Differential Protein ◽

Atlantic Cod Larvae

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

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f99-088 ◽

1999 ◽

Vol 56 (9) ◽

pp. 1612-1623 ◽

Cited By ~ 43

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.

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Annual and spatial variability in endo- and ectoparasite infections of North Sea cod (Gadus morhua Linnaeus, 1758) larvae, post-larvae and juveniles

Acta Parasitologica ◽

10.2478/s11686-014-0244-0 ◽

2014 ◽

Vol 59 (2) ◽

Cited By ~ 3

Author(s):

Foojan Mehrdana ◽

Qusay Bahlool ◽

Alf Skovgaard ◽

Jesper Kuhn ◽

Per Kania ◽

...

Keyword(s):

Spatial Variability ◽

North Sea ◽

Gadus Morhua ◽

Sea Water ◽

Atlantic Cod ◽

The North ◽

Infection Pressure ◽

High Prevalence ◽

Atlantic Cod Larvae ◽

The North Sea

AbstractA parasitological investigation was performed on a total of 5380 Atlantic cod larvae, post-larvae and small juveniles sampled from the North Sea during a period of five years. The copepod Caligus elongatus (Von Nordmann, 1832) and the nematode Hysterothylacium aduncum (Rudolphi, 1802) were found at a relatively high prevalence of infection (4.6% and 5.2%, respectively). The infection by both parasites showed annual and spatial variability. C. elongatus showed a higher prevalence in 1992 compared to the following years, whereas the prevalence of H. aduncum increased from 1992 to 2001.We observed a relation between parasite distribution and parameters such as latitude and water depth. Adult digeneans (Lecithaster gibbosus and Derogenes varicus) and larval cestodes were also found with lower infection rates. Since changes of infection levels coincided with increasing North Sea water temperature in the studied period, it is hypothesized that temperature may affect parasite population levels. However, it is likely that other environmental factors may contribute to the observed variations. Absence of infection intensities higher than one nematode per fish in small larvae and post-larvae suggests that host survival may be affected by a high infection pressure. The relatively high levels of infection in the younger stages of cod, and the annual/spatial variability of these infections should be considered in the understanding of the early life dynamics of the species.

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