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A study was conducted to determine the effects of incubation salinity and temperature . and post-hatching temperature on salinity tolerance of Pacific herring (Clupea pallasi Valenciennes) larvae. Calorimetry experiments were also conducted on herring larvae that were incubated and reared in various combinations of salinity and temperature. In the salinity tolerance test, herring eggs were artificially fertilized in three salinities (13, 21 and 29°/ooS) at 6°C. Newly fertilized eggs were incubated in the same salinities as those in which they were fertilized at two levels of incubation temperature (6 and 12°C), making six incubation groups. During the peak of the hatching period, groups of larvae from each incubation group were exposed to a series of test salinities, ranging from 20 to 55°/ooS at three levels of post-hatching temperatures (6, 9 and 12°C). Salinity tolerance was measured by determining the mortality of larvae occurring in each test salinity over a period of 72 hours. Two approaches were employed: 1) time-mortality, and 2) dosage-mortality. The former provided estimates of the effective time to 50% mortality (ET₅₀), the latter, the effective dosage (salinity) to 50% mortality (ED₅₀). The ET₅₀ or ED₅₀ values were used as bases for comparison of the responses of larvae to incubation temperature and salinity, and post-hatching temperature. The results indicate that both incubation salinity and temperature exert a significant influence on the salinity tolerance of larvae. Eggs incubated in the highest salinity (29°/ooS) and lower temperature (6°C) produced larvae most tolerant to higher post-hatching salinities. Post-hatching temperature also showed a possible influence, although the trends seen were not statistically significant. Salinity tolerance of larvae hatching from the 6°C incubation temperature appeared to be maximized at post-hatching temperatures between 6 and 9°C; whereas, those larvae from the 12°C incubation temperature showed maximum salinity tolerance at 9 to 12°C post-hatching temperatures. The response. of. larvae to salinity may be a result of an irreversible non-genetic adaptation of the embryo to salinity and temperature during incubation. In the calorimetry experiments, samples of herring larvae were combusted in a microbomb calorimeter to determine caloric values. These larvae were hatched and reared in the same six combinations of incubation salinities and temperatures as those used in the main experiment. Larvae were sampled at day 0 (peak of hatching), 3, 6 and 9. Standard lengths, dry weights, ash-free dry weights and ash content of the larval samples were also taken. There was a considerable variability in the data for calorimetry of the herring larva. In general, larvae from all treatments, at hatching, averaged 6,586 cal/g ash-free dry weight and had a mean ash value of 8.25%, obtained by direct ashing. Mean standard length of larvae at the peak of hatching (day 0) ranged from 7.67 mm (12°C, 29°/ooS) to 9.93 mm (6°C, 13°/ooS). There was a trend towards larger larvae (greater standard length) at lower temperatures in lower salinities in all ages tested. Data on dry weights show a linear decrease in larval (body and yolk) weight from day 0 to day 9. Mean dry weight of larva at the peak of hatching ranged from 0.142 mg (6°C, 13°/OOS) to 0.162 mg (12°C, 21°/ooS; 12°C, 29°/ooS). At day 0, the largest larvae (in terms of dry weight) were found at higher temperatures in higher salinities, while at day 9 (past yolk-sac stage), the largest larvae were found at lower temperatures in lower salinities. The same trend was observed in terms of ash-free dry weight. / Science, Faculty of / Zoology, Department of / Graduate

This thesis focuses on the link between condition, defined as the magnitude of fat reserves, and maturation in two sub-populations of Atlantic herring (Clupea harengus L.). Histological, fatty acid (FA), univariate and multivariate analyses were used in a multi-scale approach to elucidate the relationship between body fat and maturity. Furthermore, the accuracy of commonly used proxies of condition and maturity was tested. No evidence was found to support the hypothesis that a threshold of fat must be exceeded for first maturation to occur; however, a size threshold was observed. During maturation, herring may be capable of both selectively incorporating certain FA into the ovary and also of synthesising FA within the ovary itself. Mesenteric fat was highly dynamic during maturation and likely plays a role in gonad development. Commonly used morphometric condition indices were not related to mesenteric fat and the relationship between morphometric indices and other more direct indices was dependent on maturity stage. Macroscopic maturity staging was unreliable and errors led to an under-estimation of the herring spawning stock biomass of up to 26%. A gonadosomatic index was validated which was able to discern between immature, mature and recovering fish more accurately than macroscopic staging. Few differences were found between North Sea autumn-spawning (NSAS) and Norwegian spring-spawning (NSS) herring in this study. The FA profiles of both sub-populations were similar over the maturity cycle and the effects of length and maturity stage on mesenteric fat were analogous for both populations. A photoperiod cue of first maturation was found for Atlantic herring. However, this cue differed between the subpopulations, with NSAS herring maturation being triggered by the spring equinox and NSS herring maturation being triggered later. A multi-scale approach was successfully employed to demonstrate that there is an intrinsic link between fat reserves and maturity in herring.

The distribution of herring (Clupea harengus pallasi) in the Northeast Pacific extends from southern California to northern Alaska. Studies on variation in herring life-history are limited to local characteristics and recruitment populations or relatively restricted regions of the Northeast Pacific. In this study I assessed herring life-history patterns and recruitment variation among 14 sites extending from Lynn Channel in Alaska to San Francisco Bay in California. Biological data were compiled from published and of state and provincial unpublished technical reports fisheries agencies in the northeast Pacific. Multivariate (PCA) and inferential statistical methods were applied in data analysis. Ordinations of length-and weight-at-age revealed no latitudinal patterns among the 14 herring sites. Among four sites for which environmental data were available, there were significant negative correlations between first PC scores of size and Ekman layer transport and sea-surface salinity (SSS). Reproductive characteristics of herring appeared to vary latitudinally. Herring from the more southerly sites tended to mature at an earlier age and smaller size and have a longer duration of spawning than herring from northerly sites. There were significant negative first PC scores of reproductive correlations between variables and Ekman transport, sea-surface temperature, and SSS. With the exception of Lynn and Seymour Channels in Alaska, the most northerly sites in this study, asymptotic to northern size (L[subscript]���) tended to increase from southern latitudes. With the exception of southern Strait of Georgia (British Columbia) herring and Tomales Bay (California) herring, growth coefficients (K) appeared to be higher in latitudes. L[subscript]��� was negatively correlated with SST. Recruitment variation at three sites was related to Ekman layer transport during the periods of spawning. At San Francisco Bay recruitment was negatively related to winter Ekman transport. At Sitka and Island, recruitment showed a southwestern Vancouver significant positive and negative correlation, respectively, Recruitment in northern and with spring Ekman transport. southern Strait of Georgia were negatively correlated with SST during fall. There was no correlation between recruitment and SSS for all sites. / Graduation date: 1997

The use of chemicals to disperse oil spills raises concerns for organisms living below the surface of the water. While decreasing the surface area of the slick, chemical dispersants increase the amount of oil in the water column, the surface-to-volume ratio of droplets, the partitioning to water of the toxic constituents of oil, and the bioavailability of oil to pelagic and benthic organisms. Chemical dispersion can increase the exposure to polycyclic aromatic hydrocarbons (PAH) by 100-fold. As a model for a full-scale spill at sea, a wave tank was used to simulate chemical and natural dispersion of spilled oil to determine if the concentrations of chemically dispersed oil were sufficient to cause toxicity to embryos of Atlantic herring (Clupea harengus). While the hydrocarbon concentrations of dispersed oil from the wave tank were not large, the exposure response relationship was consistent with that of laboratory-prepared dispersed oil. Additionally, the toxicities of chemically dispersed oil prepared in the lab to Pacific (Clupea pallasi) and Atlantic herring were compared to ensure that the wealth of literature available on Pacific herring could be used for assessing the risk of oil exposure to Atlantic herring. Exposures to low concentrations of dispersed oil for short periods (2.4 to 24 h) consistently increased the incidence of blue sac disease, and decreased the percentage of normal embryos at hatch, indicating that even brief exposures to oil could be detrimental to the survival and recruitment of herring. / Thesis (Master, Biology) -- Queen's University, 2011-05-06 16:59:51.507

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These (Ph.D.)--Dalhousie University, 2008. / Title from PDF title page. Abstract, table of contents in French and English. Available through UMI ProQuest Digital Dissertations. Includes bibliographical references (leaves 88-97). Also issued in print.

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