Showing papers on "Atlantic cod published in 1985"
TL;DR: There was a highly significant correlation between genetic and geographic distance for the samples from the Atlantic suggesting that a substantial gene flow has occurred between these stocks with geographic distance being an inhibiting factor.
Abstract: The amount of genetic differentiation between stocks of Atlantic cod (Gadus morhua) was estimated from electrophoretically detectable protein loci expressed in skeletal muscle and liver. Variant al...
219 citations
TL;DR: The ability of larvae to capture artemia nauplii was related to the size of their mouth gape, itself a function of larval size, which may help them survive the shift to exogenous feeding better than those from small eggs.
Abstract: The size of Atlantic cod eggs declines during the spawning season, and the potential effects of this on larval development were studied. Eggs from 12 females were artificially fertilized and incubated in separate aquaria. Egg diameter was correlated significantly (P < 0.05) with egg dry weight. The standard length of unfed larvae continued to increase a few days beyond yolk exhaustion, whereas the increase in muscle tissue (myotome height) reached its maximum at the time of yolk exhaustion. Egg dry weight was significantly correlated with larva dry weight, standard length, myotome height, and the size of the mouth gape. The ability of larvae to capture artemia nauplii was related to the size of their mouth gape, itself a function of larval size. Atlantic cod larvae from large eggs may survive the shift to exogenous feeding better than those from small eggs. Late-spawned Atlantic cod larvae may have a lower survival potential than those spawned earlier in the season.
153 citations
TL;DR: Four isozymes of cytochrome P-450 were purified to varying degrees of homogeneity from liver microsomes of cod, a marine teleost fish, and showed differences in the rate and optimal pH for conversion of this substrate, and in optical properties.
114 citations
TL;DR: The population declined during summer probably due to cannibalism and predation from birds, and a first attempt to augment the fishery for Atlantic cod was made in the Austevoll region.
Abstract: In March-April 1983, 2.5 × 106 yolk-sac Atlantic cod larvae were released in a dammed estuarine pond. One month later, more than half a million metamorphosed. The larvae and metamorphosed juveniles depleted the natural food supply by mid-May, but the fish accepted small pellets containing 30% krill meal dispensed from automatic feeders. From mid-June, young Atlantic cod primarily ate the pellets, supplemented with minor amounts of wild calanoid and harpacticoid copepods. The population declined during summer probably due to cannibalism and predation from birds. No outbreaks of disease were observed, and infestation with parasites (nematodes) was less than 20%. Altogether, 75,000 juvenile Atlantic cod were captured alive from late May to October. By October, about 20,000 15-cm-long juveniles were tagged and released in the Austevoll region in a first attempt to augment the fishery for Atlantic cod.
81 citations
TL;DR: The muscle from postspawning Atlantic cod caught during the influx of capelin were unique in exhibiting a rapid and relatively low ultimate pH together with a stable pH after the onset of rigor mortis.
Abstract: Soft textured fillets from postspawning Atlantic cod caught during the influx of capelin exhibited significantly more drip than fillets from fish caught at other times of the 1983 inshore fishing season. The extent and rate of pH decline, protein, collagen and temperature of the muscle were not distinctive in fish caught during the influx of capelin. The muscle from these fish were unique in exhibiting a rapid and relatively low ultimate pH together with a stable pH after the onset of rigor mortis. The number of capelin present in the stomach of cod at the time of catch was positively related (r = 0.92) to the amount of free drip recovered from the fillets.
63 citations
TL;DR: A hypothesis of a three-part density-dependent mechanism controlling fecundity is postulated for Atlantic cod reared in the laboratory over 10 months, for each of two consecutive years, 1978–1980.
33 citations
01 Mar 1985
TL;DR: Genotypes atLDH-3 andPGI-1 are not selectively neutral, and allele frequency differences at these two loci between groups of cod in nature should not be interpreted as markers of reproductive isolation.
Abstract: Genotypes atLDH-3 (lactate dehydrogenase) andPGI-1 (phosphoglucoisomerase) in 263 0-group specimens of Atlantic cod(Gadus morhua) caught in Trondheimsfjorden, Norway, in fall 1983 showed significantly different survival rates during 72 days in captivity. The heterozygote was nominally superior at both loci, and there was a significant accumulation of double heterozygotes among the survivors. Apparently,LDH-3 andPGI-1 are not selectively neutral, and allele frequency differences at these two loci between groups of cod in nature should not be interpreted as markers of reproductive isolation. The results are related to current concepts of cod population structure.
26 citations
01 Mar 1985
TL;DR: The results appear to support recent reports on considerable selection effects at HbI, and stress the unreliability of allele frequencies at this locus for use in studies of the genetic population structure of cod.
Abstract: A total of 262 specimens (0-, and 1-group) of Atlantic cod(Gadus morhua) representing 4 different yearclasses were caught in Trondheimsfjorden, Norway, during 1977–1984. They were genotyped by agar gel electrophoresis for the polymorphic haemoglobin locusHbI (Sick, 1961). The analyses revealed a highly significant (P=0.0003) heterogeneity ofHbI allele frequencies between yearclasses. The difference in the frequency of theHbI-1 allele between the first (1977) and the last (1983) yearclass amounted to 0.18 (±0.07). The results appear to support recent reports on considerable selection effects atHbI, and stress the unreliability of allele frequencies at this locus for use in studies of the genetic population structure of cod.
16 citations
TL;DR: The effects of viral ERYthrocytic necrosis (VEN) on clinical blood parameters and erythrocyte metabolism were investigated in Atlantic cod and Atlantic herring and no effects on plasma electrolyte or protein concentrations in either species were detected.
Abstract: The effects of viral erythrocytic necrosis (VEN) on clinical blood parameters and erythrocyte metabolism were investigated in Atlantic cod (Gadus morphua) and Atlantic herring (Clupea harengus h.). VEN-infected cod and herring exhibited lower hematocrits (HCT) and erythrocyte counts (E) in comparison to uninfected fish. In addition, VEN-infected cod, but not herring, had significantly lower hemoglobin concentrations (HB). No effects on plasma electrolyte or protein concentrations in either species were detected. Several metabolic changes were noted in VEN-infected erythrocytes. Infected cod erythrocytes had significantly lower lactate dehydrogenase (LDH) and glucose-6-phosphate dehydrogenase (G-6-PD) activities than erythrocytes from uninfected fish. No alterations in citrate synthetase (CS) activity were observed. No effects on LDH, G-6-PD, or CS activity were detected in VEN-infected herring. In VEN-infected cod erythrocytes the ATP levels were decreased approximately 50% compared to uninfected fish. In contrast, VEN infection in herring was associated with an elevation of ATP levels by approximately 33%.
11 citations
01 Jan 1985
2 citations
TL;DR: Gastrin/CCK-like peptides are present in endocrine cells and enteric nerves in the gastrointestinal canal of the Atlantic cod and there is a tendency that gastrin 17 (nonsulphated) is more potent than CCK 8, but less potent than pentagastrin.