Spawning of Atlantic cod (Gadus morhua) in the northern Gulf of St. Lawrence: a study of adult and egg distributions and characteristics

1997 ◽  
Vol 54 (1) ◽  
pp. 198-210 ◽  
Author(s):  
P Ouellet ◽  
Y Lambert ◽  
M Castonguay
Keyword(s):  
Gadus Morhua ◽  
Developmental Stages ◽  
Atlantic Cod ◽  
Relative Proportion ◽  
Class Strength ◽  
Acoustic Surveys ◽  
Abundance And Distribution ◽  
Trawl Catches ◽  
Dominant Influence

From 1993 to 1995, Atlantic cod (Gadus morhua) egg abundance and distribution, fisheries acoustic surveys, and analysis of trawl catches provided evidence of spawning for the northern Gulf of St. Lawrence cod stock at the same location off Newfoundland's west coast. From the relative proportion of spent fish and various developmental stages of cod eggs, spawning could not have started before the end of March or early April. Spawning started while cod were in dense shoals following a prespawning migration from Cabot Strait. Larger cod started to spawn earlier than smaller cod. In May 1994, cod dispersed soon after spawning began, and most of the spawning activity probably occurred as the fish migrated and scattered within the northern Gulf. Stage I cod eggs were distributed throughout the water column but higher concentrations were observed within the cold (<0°C) layer of the Gulf each year. We propose that water temperature could have a dominant influence on determination of year-class strength in the northern Gulf via its effect on egg development and survival.

scholarly journals Photo-enhanced toxicity of crude oil on early developmental stages of Atlantic cod (Gadus morhua)

2022 ◽  
Vol 807 ◽  
pp. 150697
Author(s):  
Libe Aranguren-Abadía ◽  
Fekadu Yadetie ◽  
Carey E. Donald ◽  
Elin Sørhus ◽  
Lars Eirik Myklatun ◽  
...  
Keyword(s):  
Crude Oil ◽  
Gadus Morhua ◽  
Developmental Stages ◽  
Atlantic Cod ◽  
Early Developmental Stages ◽  
Early Developmental

Blood Changes in Atlantic Cod (Gadus morhua) Infected with Trypanosoma murmanensis

1977 ◽  
Vol 34 (11) ◽  
pp. 2185-2192 ◽  
Author(s):  
R. A. Khan
Keyword(s):  
Cell Count ◽  
Gadus Morhua ◽  
Developmental Stages ◽  
Atlantic Cod ◽  
White Cell Count ◽  
White Cell ◽  
Natural Conditions ◽  
Histological Changes ◽  
Erythrocyte Sedimentation ◽  
Hematological Changes

Blood samples for hematological and parasitological studies were obtained from 30 Atlantic cod (Gadus morhua) at intervals after infection with Trypanosoma murmanensis via leeches. Hematological procedures included estimation of hematocrit, hemoglobin, erythrocyte sedimentation rate (ESR), and differential white cell count. Tissues were also examined for histological changes. Results from the cod could be divided into two groups. In the first group of 10 cod (16–24 cm), coincident with the rise in parasitemia, hematocrit and hemoglobin levels decreased and the ESR increased following infection. Values did not return to normal levels by 92 days postinfection despite decreasing and somewhat irregular fluctuating parasitemias after 29 days. There was no apparent change in the differential white cell count. Increased hemopoiesis occurred in the kidney and various developmental stages of erythrocytic precursors were noted in peripheral blood. The fish appeared somewhat lethargic. In the second group of 20 cod (26–49 cm), hematological changes observed were slight and there was no evidence of decreased mobility. These results suggest that the blood changes observed in the group of small cod are sufficient to affect them similarly under natural conditions so that they could become more prone to predators, pollutants, or diseases. Key words: blood changes, Atlantic cod, trypanosomes

Small-scale spatial and temporal patterns in spawning of Atlantic cod (Gadus morhua) in coastal Newfoundland waters

2000 ◽  
Vol 57 (5) ◽  
pp. 1011-1024 ◽  
Author(s):  
Gareth L Lawson ◽  
George A Rose
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Temporal Patterns ◽  
Small Scale ◽  
Spatial And Temporal Patterns ◽  
Spawning Grounds ◽  
Acoustic Surveys ◽  
Placentia Bay ◽  
June July ◽  
Timing Of Spawning

Acoustic surveys were used to locate coastal Atlantic cod (Gadus morhua) spawning grounds and examine spatial and temporal patterns of spawning in Placentia Bay, Newfoundland, Canada. The same three grounds were used in 1997 and 1998 (Bar Haven in the inner bay and Cape St. Mary's and Oderin Bank in the outer bay). Grounds had densities >0.1 fish·m-2 over scales of 100 m and >13% of mature females in spawning condition. Ground use and spawning timing differed between years. Mean spawning female densities were highest at Cape St. Mary's in 1997 (1.6 × 10-2 fish·m-2) and Oderin Bank in 1998 (1.0 × 10-2 fish·m-2). At all grounds, spawning peaked earlier in 1997 (April) than in 1998 (June-July). In both years, cod spawned at sub- or near-zero temperatures. "Spawning columns" were observed at sites and times having high densities of spawning females. Sex ratios suggested that males arrived first and stayed later, while females followed when ready to spawn, accompanied by juveniles. Older females spawned earlier and later than younger females. Peaks in density of spawning females and the proportion of females spawning did not coincide. Hence, the location and timing of spawning cannot be quantified solely from the proportions of females in spawning condition.

scholarly journals Ossification of Atlantic cod ( Gadus morhua ) – Developmental stages revisited

Aquaculture ◽  
2017 ◽  
Vol 468 ◽  
pp. 524-533 ◽  
Author(s):  
Ø. Sæle ◽  
T. Haugen ◽  
Ø. Karlsen ◽  
T. van der Meeren ◽  
G. Bæverfjord ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Developmental Stages ◽  
Atlantic Cod

scholarly journals Methods and results of in situ target-strength measurements of Atlantic cod (Gadus morhua) during combined trawl-acoustic surveys

2009 ◽  
Vol 66 (6) ◽  
pp. 1225-1232 ◽  
Author(s):  
Viacheslav A. Ermolchev
Keyword(s):  
Gadus Morhua ◽  
Barents Sea ◽  
Atlantic Cod ◽  
Biological Data ◽  
Target Strength ◽  
Fish Length ◽  
The Barents Sea ◽  
Total Fish ◽  
Acoustic Surveys

Abstract Ermolchev, V. A., 2009. Methods and results of in situ target-strength measurements of Atlantic cod (Gadus morhua) during combined trawl-acoustic surveys. – ICES Journal of Marine Science, 66: 1225–1232. This paper presents methods for collecting acoustic and biological data, including in situ target-strength (TS) estimates of fish, with results presented for Atlantic cod (Gadus morhua) obtained from combined trawl-acoustic surveys. These include fish in the small, average, and maximum length classes, within the range 5–136 cm (total fish length, LT). The investigations were done using Simrad EK500/EK60 echosounders with split-beam transducers and special post-processing software. Based on an analysis of data collected in the Barents Sea during 1998–2007, a relationship TS = 25.2 log10(LT) − 74.8 was obtained for Atlantic cod at 38 kHz, with TS in dB and LT in centimetres. Seasonally, and for depths between 50 and 500 m, the variability in cod TS was 3.1 dB, decreasing with depth. The largest day–night difference in mean TS was in August–September, with changes as large as 1.0–1.7 dB. In the other seasons, the day–night difference was <1.0 dB.

scholarly journals Timing and determination of potential fecundity in Atlantic cod (Gadus morhua)

2006 ◽  
Vol 63 (2) ◽  
pp. 310-320 ◽  
Author(s):  
Jon Egil Skjæraasen ◽  
Trygve Nilsen ◽  
Olav S Kjesbu
Keyword(s):  
Egg Production ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Explanatory Power ◽  
Temporal Variations ◽  
Energy Reserves ◽  
Potential Fecundity ◽  
Time Determination ◽  
Spawning Periods

Studies using annual averages of lipid storage or estimated quality of the feeding season have shown that energy reserves influence egg production in Atlantic cod (Gadus morhua). However, vitellogenesis starts months before spawning. Therefore, energy reserves near the start of vitellogenesis might provide better proxies of fecundity and hence egg production than yearly averages. If so, proxies with large temporal variations (e.g., weight and lipid energy) should vary similarly in their predictive power, and females with different spawning periods should have their fecundity determined at different times. We exposed cod to two photoperiods to induce different spawning seasons. Growth before spawning was monitored, and potential fecundity was measured at the onset of spawning. The date yielding the greatest explanatory power differed between photoperiods. As proxies, length varied less and had lower explanatory power than weight. Lipid energy at the onset of spawning was a poor proxy. The greatest explanatory power was found ~3–4 months before spawning around the start of vitellogenesis, indicating that potential fecundity was highly influenced by female energy reserves at this time. Determination of potential fecundity early in vitellogenesis may be a common feature for determinate teleost spawners.

scholarly journals First feed affects the expressions of microRNA and their targets in Atlantic cod

2016 ◽  
Vol 115 (7) ◽  
pp. 1145-1154 ◽  
Author(s):  
Teshome Tilahun Bizuayehu ◽  
Tomasz Furmanek ◽  
Ørjan Karlsen ◽  
Terje van der Meeren ◽  
Rolf Brudvik Edvardsen ◽  
...  
Keyword(s):  
Gadus Morhua ◽  
Developmental Stages ◽  
Atlantic Cod ◽  
Fish Larvae ◽  
Artemia Salina ◽  
Differentially Expressed ◽  
Next Generation Sequencing Data ◽  
Sequencing Data ◽  
First Feeding ◽  
Differentially Expressed Mirna

AbstractTo our knowledge, there is no report on microRNA (miRNA) expression and their target analysis in relation to the type of the first feed and its effect on the further growth of fish. Atlantic cod (Gadus morhua) larvae have better growth and development performance when fed natural zooplankton as a start-feed, as compared with those fed typical aquaculture start-feeds. In our experiment, two groups of Atlantic cod larvae were fed reference feed (zooplankton, mostly copepods, filtered from a seawater pond) v. aquaculture feeds: enriched rotifers (Brachionus sp.) and later brine shrimp (Artemia salina). We examined the miRNA expressions of six defined developmental stages as determined and standardised by body length from first feeding for both diet groups. We found eight miRNA (miR-9, miR-19a, miR-130b, miR-146, miR-181a, miR-192, miR-206 and miR-11240) differentially expressed between the two feeding groups in at least one developmental stage. We verified the next-generation sequencing data using real-time RT-PCR. We found 397 putative targets (mRNA) to the differentially expressed miRNA; eighteen of these mRNA showed differential expression in at least one stage. The patterns of differentially expressed miRNA and their putative target mRNA were mostly inverse, but sometimes also concurrent. The predicted miRNA targets were involved in different pathways, including metabolic, phototransduction and signalling pathways. The results of this study provide new nutrigenomic information on the potential role of miRNA in mediating nutritional effects on growth during the start-feeding period in fish larvae.

Determination of apparent protein digestibility of live Artemia and a microparticulate diet in 8-week-old Atlantic cod Gadus morhua larvae

Aquaculture ◽  
2009 ◽  
Vol 288 (3-4) ◽  
pp. 290-298 ◽  
Author(s):  
Ronald B. Johnson ◽  
Matthew A. Cook ◽  
Peter M. Nicklason ◽  
Michael B. Rust
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Protein Digestibility ◽  
Microparticulate Diet

scholarly journals Stock structure of Atlantic cod (Gadus morhua) in West Greenland waters: implications of transport and migration

2004 ◽  
Vol 61 (6) ◽  
pp. 972-982 ◽  
Author(s):  
Marie Storr-Paulsen ◽  
Kai Wieland ◽  
Holger Hovgård ◽  
Hans-Joachim Rätz
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Stock Structure ◽  
West Greenland ◽  
The Past ◽  
Migration Behaviour ◽  
And Migration ◽  
Abundance And Distribution ◽  
Icelandic Waters

Abstract Atlantic cod in West Greenland waters have varied greatly in abundance and distribution in the past decades. Strong year classes yielded good catches inshore and offshore in the late 1980s, but since then cod have been nearly absent offshore and the inshore fishery has been depressed, though there has been a small increase inshore over the past few years. Different components contribute to the Greenland cod stock, and re-analysed tagging experiments indicate that migration behaviour differs between them. Inshore cod are sedentary, with almost no migration between different fjord systems. In contrast, there are many cases of alongshore migration of cod tagged on the offshore fishing banks. Further, observations have been made of occasional migrations from offshore to inshore, notably so in years of good recruitment originating from Icelandic waters.

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