Distribution and drift of Atlantic cod (Gadus morhua) eggs and larvae on the northeast Newfoundland Shelf

1997 ◽  
Vol 54 (3) ◽  
pp. 670-685 ◽  
Author(s):  
P Pepin ◽  
J A Helbig
Keyword(s):  
Spatial Patterns ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Stage I ◽  
Surface Currents ◽  
Adult Fish ◽  
Northern Limit ◽  
Mean And Variance ◽  
The Mean ◽  
Eggs And Larvae

We present the results of a study designed to ascertain the importance of variations in transport of cod eggs and larvae on the northeast Newfoundland Shelf. The distribution of cod eggs and larvae is described from a series of ichthyoplankton surveys. The mean and variance in surface currents were estimated from five experiments in which clusters of drogued satellite-tracked drifters were released at the presumed northern limit of the stock's range. These data were used to project the patterns of drift both backward and forward in time and thus the possible sources and destinations of eggs and larvae. Considering the development from the youngest (stage I) to the oldest stages (larvae), we saw a north-to-south and an offshore-to-inshore progression in spatial patterns of spawning and a continuing increase in the overall level of dispersion with increasing age of offspring. The data do not support the hypothesis that coastal or offshore areas represent simple sources or sinks of cod eggs and larvae. Transport plays an important but highly variable role that is coupled to the spawning distribution of adult fish and the availability of suitable conditions or habitats when the young begin to undergo metamorphosis and settle.

Nonrandom mating in a broadcast spawner: mate size influences reproductive success in Atlantic cod (Gadus morhua)

2007 ◽  
Vol 64 (2) ◽  
pp. 219-226 ◽  
Author(s):  
Sherrylynn Rowe ◽  
Jeffrey A Hutchings ◽  
Jon Egil Skjæraasen
Keyword(s):  
Body Size ◽  
Reproductive Success ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Negative Consequences ◽  
Nonrandom Mating ◽  
Individual Fitness ◽  
Mean And Variance ◽  
The Mean ◽  
Natural Breeding

We tested the hypothesis that reproductive success in Atlantic cod (Gadus morhua) is random with respect to similarity in body size between mates. Immediately prior to their natural breeding periods, groups of 52–93 cod from three Northwest Atlantic populations were transported to a large (15 m diameter, 4 m deep) tank where they spawned undisturbed at densities similar to those in nature. Based on microsatellite DNA-parentage assignment of 8913 offspring from four spawning groups, females and males achieved their highest reproductive success when breeding with mates that were larger than themselves. Our observations are consistent with the hypothesis that some form of intrasexual competition or mate choice is a constituent of the mating system of this species and that this can have an important influence on individual fitness. Our results further suggest that reductions in the mean and variance in body size of commercially exploited marine fishes concomitant with size-selective harvesting may have greater negative consequences for population recovery than previously thought.

Nearshore settlement and localized populations of age 0 Atlantic cod (Gadus morhua) in shallow coastal waters of Newfoundland

1998 ◽  
Vol 55 (6) ◽  
pp. 1317-1327 ◽  
Author(s):  
Scott M Grant ◽  
Joseph A Brown
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Indirect Evidence ◽  
Suitable Habitat ◽  
Site Variation ◽  
Mean And Variance ◽  
Eelgrass Habitat ◽  
The Mean ◽  
Catch Rates ◽  
Density Dependent Habitat Selection

Mark-recapture experiments and seasonal sampling were carried out to examine the nearshore movements, abundance, and behaviour patterns of age 0 Atlantic cod (Gadus morhua) in eelgrass (Zostera marina) and no-eelgrass habitat in Trinity Bay, Newfoundland, during 1994 and 1995. Cod remained localized, not moving further than a few hundred metres in eelgrass and no-eelgrass habitats for several weeks after settling from a pelagic habit, and may remain localized during their first winter. Observations from this study of bulk movements of marked and unmarked cod, high within-site variation in catch rates during the day, and significant day-night differences in the mean and variance of catch data, combined with results from related studies, provide indirect evidence that age 0 cod shoal during the day and disperse at night within the study area. Behaviour patterns exhibited by age 0 cod (restricted nearshore movements, diurnal shoaling, and preference for structurally complex habitat) are mechanisms for predator avoidance, suggesting that predation risk is high in coastal Newfoundland. A significant increase in abundance of age 0 cod in less suitable habitat (no-eelgrass cover) when settlement strength was high is consistent with the hypothesis of density-dependent habitat selection.

scholarly journals Effect of solar ultraviolet radiation (280–400 nm) on the eggs and larvae of Atlantic cod (Gadus morhua)

1999 ◽  
Vol 56 (6) ◽  
pp. 1058-1067 ◽  
Author(s):  
France Béland ◽  
Howard I Browman ◽  
Carolina Alonso Rodriguez ◽  
Jean-François St-Pierre
Keyword(s):  
Water Column ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Outdoor Exposure ◽  
Ultraviolet B ◽  
Solar Ultraviolet Radiation ◽  
Mortality Effect ◽  
Eggs And Larvae ◽  
Very High ◽  
Solar Ultraviolet

In the Gulf of St. Lawrence, Canada, solar ultraviolet B radiation (UV-B, 280-320 nm) penetrates a significant percentage of the summer mixed-layer water column: organisms residing in this layer, such as the eggs of Atlantic cod (Gadus morhua), are exposed to UV-B. In outdoor exposure experiments, Atlantic cod eggs were incubated in the presence versus the absence of UV-B and (or) UV-A (320-400 nm). We tested two hypotheses: H1, UV-B induces mortality in Atlantic cod eggs, and H2, UV-A either exacerbates or mitigates any such UV-B-induced mortality. Hypothesis H1 was supported: there was a significant mortality effect on Atlantic cod eggs exposed to UV-B at the surface and at a depth of 50 cm. Hypothesis H2 was not supported: there was no effect of UV-A. These experiments indicate that Atlantic cod eggs present in the first metre of the water column (likely only a small percentage of the total egg population) are susceptible to UV-B. However, UV-B must be viewed as only one among many environmental factors that produce the very high levels of mortality typically observed in the planktonic early life stages of marine fishes.

Biochemical composition and performance of Atlantic cod (Gadus morhua L.) eggs and larvae obtained from farmed and wild broodstocks

Aquaculture ◽  
2012 ◽  
Vol 324-325 ◽  
pp. 267-275 ◽  
Author(s):  
Carlos Frederico Ceccon Lanes ◽  
Teshome Tilahun Bizuayehu ◽  
Sylvie Bolla ◽  
Camila Martins ◽  
Jorge Manuel de Oliveira Fernandes ◽  
...  
Keyword(s):  
Biochemical Composition ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
And Performance ◽  
Eggs And Larvae

Some ectoparasitic trichodinids from Atlantic cod, Gadus morhua L., with a description of Trichodina cooperi n.sp.

1989 ◽  
Vol 67 (7) ◽  
pp. 1793-1800 ◽  
Author(s):  
S. L. Poynton ◽  
J. Lom
Keyword(s):  
Nova Scotia ◽  
Body Surface ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Geographic Range ◽  
The Body ◽  
Wild Fish ◽  
Eastern Canada ◽  
Mean Diameter ◽  
The Mean

Trichodina murmanica Polyanskiy, 1955 (= Trichodina domerguei subsp. saintjohnsi Lom and Laird, 1969) and Trichodina cooperi n.sp. were commonly encountered on skin and fins of Atlantic cod, Gadus morhua L., near Halifax, Nova Scotia, Canada. A third species of Trichodina, probably new, was recorded from the skin of one fish. This is believed to be the first report of the genus Trichodina from the body surface of gadoid fish from eastern Canada, and the known geographic range of T. murmanica is extended. Trichodina cooperi n.sp. has an adoral ciliary spiral of 370–380° and is relatively large, the mean diameter of the body is 110 μm, of the adhesive disc (with dark center), 95 μm, and of the denticulate ring, 59 μm. The denticulate ring consists of 24–29 denticles (usually 27), with 7–9 radial pins per denticle. Each denticle has a broad blade, a large central part, and a slightly curved thorn of moderate to broad width, with a central rib when mature. The thorn is approximately twice the length of the blade. The horseshoe-shaped macronucleus has a diameter of 80.0 μm and the micronucleus is in the +y position. Trichodina spp. infected 26% of 39 wild fish 20 to < 60 cm long. Most wild fish yielded less than five ciliates per 24 × 50 mm smear.

Survival of Northern Atlantic Cod (Gadus morhua) Eggs and Larvae when Exposed to Ice and Low Temperature

1992 ◽  
Vol 49 (12) ◽  
pp. 2588-2595 ◽  
Author(s):  
Paul F. Valerio ◽  
Sally V. Goddard ◽  
Ming H. Kao ◽  
Garth L. Fletcher
Keyword(s):  
Low Temperature ◽  
Newfoundland And Labrador ◽  
Direct Contact ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Ice Crystals ◽  
Freeze Resistance ◽  
Northern Cod ◽  
Northern Atlantic ◽  
Eggs And Larvae

Freeze resistance of eggs and larvae of Atlantic cod (Gadus morhua) from the northern cod stock was investigated to determine whether ice contact could affect survival during the spring spawning season off Newfoundland. Egg and larval homogenates did not appear to contain antifreeze proteins (mean freezing points −0.78 and −0.88 °C, respectively). However, cod eggs did not freeze at −1.8 °C in icy aerated seawater, could be undercooled to −4.0 °C in ice, and froze at temperatures between −4.1 and −1 7 °C; freeze resistance depended on the integrity of the chorion. Larvae withstood undercooling to −1.8 °C, provided they were not brought into direct contact with ice crystals, if directly touched with ice, larvae froze at −1.36 °C (feeding stage) or −1.34 °C (yolk-sac), approximately 0.5 °C lower than would be expected from the freezing temperatures of their body fluids. The nature of their external epithelium and delayed development of sensitive gill structures below 0 °C may contribute to larval freeze resistance. Cod eggs and larvae are found in spring off Newfoundland and Labrador, when sea temperatures can be as low as −1.8 °C and ice cover extensive. While cod eggs are remarkably freeze resistant, such environmental conditions may cause freezing mortalities in larval cod.

PACAP and nitric oxide inhibit contractions in the proximal intestine of the atlantic cod, Gadus morhua

2000 ◽  
Vol 203 (3) ◽  
pp. 575-583 ◽  
Author(s):  
C. Olsson ◽  
S. Holmgren
Keyword(s):  
Nitric Oxide ◽  
Smooth Muscle ◽  
Intestinal Motility ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Inhibitory Response ◽  
Nitric Oxide Donor ◽  
The Mean ◽  
Proximal Intestine ◽  
Spontaneous Contractions

The possible inhibitory roles of pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal polypeptide (VIP) and nitric oxide in the control of intestinal motility were investigated in the Atlantic cod, Gadus morhua. Circular and longitudinal smooth muscle preparations developed spontaneous contractions that were inhibited by atropine (10(−)(5)mol l(−)(1)). PACAP 27 and PACAP 38 (10(−)(7)mol l(−)(1)) reduced the amplitude of the contractions but did not usually affect the resting tension. In the circular preparations, the mean active force developed (above resting level; +/− s.e.m.) was reduced from 0. 62+/−0.18 mN to 0.03+/−0.03 mN (N=10) by PACAP 27 and from 0.53+/−0. 20 mN to 0.31+/−0.13 mN (N=7) by PACAP 38, while neither cod nor mammalian VIP (10(−)(10)-10(−)(6)mol l(−)(1)) had any effect. In the longitudinal preparations, PACAP 27 reduced the force developed from 1.58+/−0.22 mN to 0.44+/−0.25 mN (N=8) and PACAP 38 reduced it from 1.61+/−0.47 mN to 0.75+/−0.28 mN (N=5). The nitric oxide donor sodium nitroprusside (NaNP) almost abolished the contractions in the circular preparations, reducing the mean force developed from 0. 47+/−0.05 mN to 0.02+/−0.06 mN (10(−)(6)mol l(−)(1); N=9) and 0+/−0. 07 mN (10(−)(5)mol l(−)(1); N=8). In the longitudinal preparations, NaNP reduced the force developed from 2.03+/−0.36 mN to 0.33+/−0.22 mN (10(−)(6)mol l(−)(1); N=8) and 0.19+/−0.30 mN (10(−)(5)mol l(−)(1); N=8). The L-arginine analogue N(G)-nitro-L-arginine methyl ester (L-NAME; 3×10(−)(4)mol l(−)(1)) enhanced the contractions in both circular and longitudinal preparations, increasing the mean force developed from 0.51+/−0.12 mN to 0.94+/−0.21 mN (N=8) and from 1.49+/−0.36 mN to 3.34+/−0.67 mN (N=7), respectively. However, preincubation with L-NAME before a second addition of PACAP 27 (10(−)(7)mol l(−)(1)) did not affect the response to PACAP, neither did preincubation with the guanylate cyclase inhibitor 6-anilinoquinoline-5,8-quinone (LY83583; 10(−)(5)mol l(−)(1)), while the inhibitory response to NaNP (3×10(−)(7)mol l(−)(1)) was abolished by LY83583. The PACAP analogue PACAP 6–27 (3×10(−)(7)mol l(−)(1)) had no effect on the response to either NaNP (3×10(−)(7)mol l(−)(1)) or PACAP 27 (10(−)(8)mol l(−)(1)) in the circular preparations. These findings indicate the presence of both a cholinergic and a nitrergic tonus in the smooth muscle preparations of the cod. Although PACAP and NaNP both inhibit contractions, there is no evidence of any interactions between the two substances. In addition, NaNP, but not PACAP, probably acts via stimulating the production of cyclic GMP. In conclusion, both PACAP and nitric oxide may act as inhibitory transmitters, using distinct signalling pathways, in the control of intestinal motility in the Atlantic cod.

scholarly journals Quality of Nephrops as food for Atlantic cod (Gadus morhua L.) with possible implications for fisheries management

2004 ◽  
Vol 61 (6) ◽  
pp. 983-991 ◽  
Author(s):  
Björn Björnsson ◽  
Maria Álvaro Dongala Dombaxe
Keyword(s):  
Growth Rate ◽  
Gadus Morhua ◽  
Specific Growth ◽  
Condition Factor ◽  
Atlantic Cod ◽  
Gonadosomatic Index ◽  
Conversion Ratio ◽  
Food Conversion ◽  
The Mean

Abstract Nephrops was found to be of low quality as food for cod. In a laboratory experiment the mean specific growth rate of 1 kg cod was 0.184 and 0.415% d−1 when fed to satiation on Nephrops and capelin, respectively. This large difference in growth rate resulted not only from less intake of Nephrops (1.19 kg cod−1) than capelin (1.55 kg cod−1) but also because more Nephrops (4.6 kg) than capelin (2.2 kg) were required to produce each kilogramme of cod. Higher food conversion ratio was consistent with lower fat content of Nephrops (1.3%) than capelin (9.2%) but the exoskeleton also reduced the digestion rate of Nephrops. In the groups where Nephrops and capelin of equal mean weight were offered simultaneously, 40% of the diet consisted of Nephrops during the first week and 10% during the final seven weeks of the experiment. At the end of the experiment, condition factor, liver index, and gonadosomatic index were significantly lower for cod fed on Nephrops (0.967, 5.7, 7.1, respectively) than for those fed on capelin (1.086, 15.8, 11.2, respectively). These results suggests that predation by cod on Nephrops might be reduced by regular release of capelin or other similar food in the distributional areas of Nephrops.

Ultraviolet (280-400 nm)-induced DNA Damage in the Eggs and Larvae of Calanus finmarchicus G. (Copepoda) and Atlantic Cod (Gadus morhua) ¶

2007 ◽  
Vol 77 (4) ◽  
pp. 397-404 ◽  
Author(s):  
Howard I. Browman ◽  
Russell D. Vetter ◽  
Carolina Alonso Rodriguez ◽  
John J. Cullen ◽  
Richard F. Davis ◽  
...  
Keyword(s):  
Dna Damage ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Calanus Finmarchicus ◽  
Eggs And Larvae
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