In this study, spatial and temporal variation in fat content and temporal variation in maturation of North Sea herring were examined. Fulton’s K, a widely used condition index, was proven to be an inconsistent measure of individual herring fat content, whereas relative condition factor is a more accurate measure.  The Distell fish fatmeter was shown to be an accurate measure of individual herring muscle fat content and was used throughout the study. Individual herring biological and fat data were collected during the annual acoustic North Sea herring survey in 2006 – 2007. Analyses of these data showed that immature herring in the northern North Sea were larger and had higher fat contents than those in the south, in 2006.  This spatial gradient may be due to spatial variability in temperature and food abundance. Individual-level analyses using three years of field data demonstrated that North Sea herring must reach a length threshold of approximately 250 mm before the onset of maturation can occur.  However, stock-level analyses using data provided by the ICES herring stock assessment, indicated that maturation of North Sea herring is not affected by density-dependent factors or by mean North Sea surface temperatures.  This study demonstrates that the accuracy of different measures of condition should be tested before being used in research and that spatial and temporal variability in fat content should be considered when conducting studies on fish condition and other life history parameters.

Issued also as thesis, Université de Paris. / Bibliographical foot-notes. "Notice bibliographique": p. [5]-9, Bibliography: p.[11-20].

Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 120-131).

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves [98]-118).

The swimbladder of Atlantic and Pacific herring has a pneumatic duct arising from the stomach caecum and a direct posterior opening to the exterior. The thesis is advanced that these peculiarities are associated with differences in function which may be related to the life of the herring. Herring obtain swimbladder gas by swallowing air at the surface but not by secretion or bacterial gas generation over one week. Gas release from the swimbladder through the posterior duct occurs in response to pressure reduction, sympathomimetic drugs and atropine and is inhibited by spinal section or brain removal suggesting a gas release mechanism involving the central nervous system. Gas loss through the pneumatic duct is prevented by the swimbladder valve which opens in response to adrenalin. The swimbladder responds to adrenalin by moving its contained gas anteriorly and to pilocarpine by increasing internal gas pressure. The pneumatic duct, normally fluid filled, controls the applied pressure at which gas flow in either direction starts and finishes. This duct mechanically prevents the entry of particulate matter from the stomach and is able to remove air bubbles leaving a mean net force of 3.2 dynes/ml downwards to be compensated for by movements of the fish. As the herring swimbladder functions as a hydrostatic organ the low skeletal body content and high fat content results in a low swimbladder volume, so reducing the change in density with depth, an advantage to a fish undergoing diurnal vertical migrations. It was calculated that herring of Passamaquoddy Bay, N.B. can descend to their median daytime depth of 10 metres in August and 35 metres in February for sinking factors of 1016 and 1018 respectively. Predation may be reduced by the ability of herring to complete air uptake rapidly, to move upward without restriction by expelling any excess gas through the posterior duct and to liberate gas in times of stress in response to adrenaline so increasing body density and permitting rapid downward movement. Thus in many ways the herring because of its anatomical modifications has been able to adapt the physostome condition successfully to its marine environment. / Science, Faculty of / Zoology, Department of / Graduate

From the dark muscle of British Columbia herring a highly active enzyme capable of peroxidising unconjugated unsaturated fatty acids was isolated. This ‘lipoxidase’, which was shown to be a nitrogenous complex possessing no heavy metals or sulphydryl group as the active centre, is heat-labile and can act only in presence of activators such as certain iron-containing organic nitrogenous compounds. Two such compounds, namely haemoglobin and cytochrome ‘C’ were isolated. The enzyme exhibits optimum activity at 15°C. and pH 6.9. There is also an optimum concentration of enzyme, substrate, and of the activators for maximum enzyme activity. The presence of the activators appears to change the kinetics of the reactions. The inhibition of the enzymic reaction brought about by cyanide and azide is possibly due to the inactivation of the iron-containing activators rather than of the enzyme itself. / Science, Faculty of / Zoology, Department of / Graduate

No description available.

Pacific herring, Clupea harengus pallasi, possesses a pheromone in the milt and testes that triggers spawning behaviour in reproductively mature individuals of both sexes, and plays a role in synchronizing the school spawning that is distinctive of this species. The pheromone was found to be effective as a transient olfactory stimulus in eliciting a behavioural response that varied in the degree of expression and time course. Stimulus strength was found to influence the time course of the response, whereas differences in maturity, evident through examination of plasma levels of steroids, were correlated with a propensity to respond to the pheromone. Input from factors other than the spawning pheromone appear to be needed to elicit prolonged spawning; some of these factors also act through olfaction. Immediate effects of stress were not found to influence the response to the spawning pheromone. Plasma levels of reproductive steroids of herring during the spawning season were measured with radioimmunoassays. Peak levels of 17,20β-dihydroxy-4-pregnen-3-one (17,20β-P) were found to coincide with final maturation in females and the initiation of milt production in males, suggesting that this steroid is the maturation-inducing steroid of this species. Other features found to be distinctive of the reproductive physiology of the herring included low plasma levels of the unconjugated maturation-inducing steroid, high levels of 17α-progesterone (17-P) and 3α,17α-dihydroxy-5β-pregnan-20-one (3α,17-P-5β), and high levels of glucuronated steroids. Structural investigation of the pheromone with liquid chromatography/ mass spectrometry showed that it consists of at least two components which do not elicit a behavioural response individually. One of these compounds is sulphated 17,20β-P. The structure of proteinaceous hormones involved in controlling reproduction of the herring was also investigated. It was shown that this species possesses three forms of gonadotropin-releasing hormone (GnRH) in the brain, one with a structure that has not been reported before. These results indicate that the presence of three GnRH forms is a primitive, rather than derived, condition in the teleosts. The structure of the (β-subunit of gonadotropin II (GtH ll-β) of herring was also deduced by isolation of a cDNA for this molecule. The structure of the herring GtH ll-β was found to be quite different from other teleost molecules of this kind, and a phylogenetic analysis of known GtH ll-β structures suggests that the β-subunit of both mammalian gonadotropins may be most closely related to the β-subunit of teleost GtH-l. / Graduate

Egg weight and fecundity of Clyde spring-spawning and autumn-spawning herrings, Clupea harengus L., in the nothern North Sea and North Minch in different years were analysed. For Clyde spring-spawning herring high variation in egg weight was found and it was attributed to more than one spawning group spawning in the area. Annual variation in fecundity between 1963-1984 was found. Fecundity in 1984 was found to be about 10% higher than previous years. For autumn-spawning herring, fish spawn in the North Minch produce about 1.18 times heavier eggs than those spawning in the northern North Sea. Regional annual variation in fecundity between 1971-1984 was found. In 1984 fecundity of samples collected from Shetland was 1.12 higher than those of North Minch. Fecundity indices for Shetland samples were found to be 1.23 to 1.77 higher in 1984 than 1971-1973. Annual variation between 1971-1973 was also found. It was concluded that fecundity is a potential contributor to population regulation not necessarily related to population density. Monthly analysis of energy content of soma and gonad was carried out for Clyde spring-spawning herring. Differences in the magnitude and timing of energy allocated to the gonad was found between sexes. Energy budget was prepared for each sex at ages 2 and 3. No deficient of energy during winter was apparent due to gonad maturation and metabolic activity. Routine metabolic rate was measured in a group of herring in a respirometer. Oxygen consumption was estimated to be 31.3, 93.3 and 278.6 mgO2 kg-1 h-1 at 5, 10 and 15oC respectively. Standard oxygen consumption was derived from oxygen consumption and theoretical swimming speed to be 20.4, 59.5 and 164.8 mgO2 kg-1h-1 at 5, 10 and 15oC.

Thesis (M.S. in environmental science)--Washington State University, December 2009. / Title from PDF title page (viewed on Feb. 10, 2010). "School of Earth and Environmental Science." Includes bibliographical references (p. 31-34).