The condition of juvenile fish relates to their overall health and is a strong predictor of survival and eventual recruitment. Condition can be quantified and interpreted in a variety of ways covering different time scales and levels of biological organization. Here I (i) quantify interannual variability in the condition in Young-of-Year (YOY) Pacific herring (Clupea pallasi) in the Strait of Georgia, BC, from 2013-2016, and (ii) examine the extent to which the condition of an individual fish varies depending on which condition metric is used. Chapter 1 provides a general background on the concept of measuring condition in fish, as well as the basic biology of Pacific herring and their importance in Strait of Georgia ecosystem. In Chapter 2, I report the condition of YOY herring from 2013-2016 using six metrics: (i) Fulton’s K, (ii) the residuals from a length:weight regression, (iii) the RNA:DNA ratio, (iv) recent growth estimated via otolith microstructure analysis, (v) lipid content, and (vi) the ratio of two essential acids DHA:EPA. Four of these metrics (Fulton’s K, length:weight residuals, and growth from RNA:DNA and otolith increments) indicate a decrease in condition over the four years. In contrast, lipid content suggests an increase across the four years, while DHA:EPA suggests a decrease in 2015 but no change over the other three years. The observed interannual variability in condition can be partly linked to unfavourable changes in temperature and zooplankton community composition in 2015 and 2016, and to the propensity of juvenile fish to prioritize energy storage over somatic growth before a period of prey scarcity, such as their first winter. This dataset is further examined in Chapter 3, wherein I examine variability in condition of individual fish based on the different metrics used. Individual herring are ranked based on their scores from the six different metrics of condition, and the distribution of these rankings are examined to assess the degree of intercorrelation among the metrics. Based on this model, as well as pairwise Spearman rank correlations between the six metrics, I conclude that there is little intercorrelation between metrics, and that a fish that scores highly in terms of condition in any one metric will not necessarily score highly for the other metrics. These findings underscore the importance of choosing condition metrics carefully, based on the nature of the question being asked. / Graduate / 2019-07-04

For marine fishes, the early larval phase is considered a critical stage for survivorship and recruitment. The spatial and temporal dynamics of larval fish assemblages can influence their success and trophic structure of marine communities and entire ecosystems. This thesis will provide the first characterization of larval fish assemblage in the Strait of Georgia (SoG) in terms of diversity, abundance and composition, and their variability over multiple temporal scales, as well as the first quantification of variability in larval fish distribution in the SoG across multiple spatial scales. On the interdecadal scale, a significant decrease in larval abundance of several dominant fish taxa (Pacific hake, walleye Pollock, northern smoothtongue and rockfishes) contributed to a decline in total larval abundance and turnover in the composition structure between the early 1980s and the late 2000s. In contrast, both abundance and the relative composition of flatfishes and several demersal forage fish taxa increased during the same period. On interannual scales, abundance, diversity and community structure of the spring larval assemblages varied dramatically through 2007-2010, a period which alternated between strong La Niña and El Niño events. Higher overall larval concentrations were associated with warm conditions in the SoG in 2007 and 2010, while the lowest larval concentration was associated with cooler condition in 2009. Examination of associations between larval fish assemblages and environmental fluctuations suggests a potential influence of large-scale climate processes between the early 1980s and the late 2000s, but a primary association with local environmental factors on interannual scales. Spatial patterns in larval density of three dominant fish taxa (Pacific herring, Pacific hake and northern smoothtongue) were mostly structured on predefined broad (> 40km) and medium (20~40km) scales. Although their scale-dependent associations with environmental factors varied interannually, larval distributions in the central-southern SoG were generally associated with salinity, temperature and vertical stability of water column in the upper layer (0-50m). Our results emphasize the role of local estuarine circulation in structuring hierarchical spatial distributions of planktonic fish larvae in the SoG. These findings will provide considerable implications in fisheries resource management and conservation strategies. / Graduate / 0416 / 0329 / guanlu129@gmail.com

The bathypelagic copepods Spinocalanus brevicaudatus, Scaphocalanus brevicornis and Heterorhabdus tanneri have established relatively large, permanent breeding populations in Bute and Jervis Inlet, British Columbia. They are found only rarely in the shallower Strait of Georgia. The preference shown by Spinocalanus brevicaudatus and Scaphocalanus brevicornis was attributed to the deep living habits of breeding adults. The reason for H. tanneri's preference of deep water was not apparent from the distribution study. Two general patterns of vertical distribution were seen among the calanoid capepods in the inlets. The common interzonal species such as Calanus glacialis preferred a definite depth interval near mid-water. The deep-living species such as Spinocalanus brevicaudatus were found throughout the water column below the thermocline, in about equal numbers. Maximum numbers usually occurred in the depth interval immediately below the thermocline. Only females of Metridia pacifica showed a strong diurnal migration pattern in July. This migration became less intense near the head of Bute Inlet. The vertical distribution and migration patterns of Spinocalanus brevicaudatus, Scaphocalanus brevicornis and H. tanneri appeared to increase the chances of secual encounters in these relativelyt rare species. The interzonal and deep-living species showed contrasting life-histories. The interzonal species exhibited a well-defined breeding season, with adults maturing in the winter, and young appearing in the spring. The deep-living species did not show a yearly breeding cycle. Females dominated the population at all times of year, and a relatively small percentage of males and females were always present. A reduction in the male:female sex ratio occurred during or after the last moult in Spinocalanus brevicaudatus and Scaphocalanus brevicornis. In the animals the male has reduced mouth parts and probably dies soon after mating. H. tanneri males do not have reduced mouth parts. This species had a sex ratio close to unity at all times. An increase in total copepod numbers was observed with increasing distance from the head of Bute Inlet. An increase in the percentage of juveniles in the population of most species was also observed with increasing distance from the inlet head. Spinccalanus brevicaudctus, Scaphocalanus brevicornis and H. tanneri are redescribed. Comantenna columbiae is described for the first time. / Graduate

Ocean optical studies have been conducted extensively in open ocean waters but less so in coastal waters where the influence of human population is increasing dramatically. The waters of the Strait of Georgia, British Columbia, Canada, are very important to the rearing of young salmon and herring, and to the fishing industry of British Columbia overall. The oceanography and plankton communities of the Strait have been researched extensively, however the forces behind the frequent occurrence of phytoplankton blooms in these waters still causes debate among researchers. In order to shed some light onto this topic and increase our knowledge of the characteristics of the waters of the Strait of Georgia, optical and bio-physical data were measured in the euphotic waters of the Strait in late spring and early summer of 2006. Hyperspectral optical data were measured for the first time in these waters using in situ optical profilers to collect inherent optical properties and radiometric quantities that were later used to derive apparent optical properties. The inherent optical properties included absorption coefficient, spectral beam attenuation coefficient, chromophoric dissolved organic matter absorption coefficient, particulate absorption coefficient, and particulate scattering coefficient. In situ irradiances and radiances were used to derive various diffuse attenuation coefficients. Water masses in the euphotic zone of the Strait of Georgia were then classified into three optical water masses according to their inherent optical properties using a clustering algorithm. OM1 waters were characterized by high and spectrally-invariant particulate scattering due to inorganic particles carried by the Fraser River plume. Absorption and scattering showed some spectral dependence in OM2 waters, with particles and chromophoric dissolved organic matter contributing equally to light absorption. The deepest waters, OM3, were the least influenced by the Fraser River, and the contribution of chromophoric dissolved organic matter to absorption was greater than in OM1 and OM2. A radiative transfer model, Hydrolight, was used to model some of the optical properties that were not collected in situ and then used to assess the magnitude of light available to phytoplankton in the Strait. Based on the minimum light requirements for photosynthesis of two of the main phytoplankton species in the Strait, the analysis presented here showed that there was enough light available for photosynthesis in the photosynthetically-available radiation range for the two phytoplankton species in all three optical water masses.

In this thesis, I constrain rupture scenarios of active crustal faults in the southern Strait of Georgia and Boundary Bay in order to assess their tsunamigenic potential. The NW-SE-trending Drayton Harbor, Birch Bay, and Sandy Point faults had been previously identified on the southern side of Boundary Bay from aeromagnetic, LiDAR, and paleoseismic data; all show evidence of abrupt vertical Holocene displacements. South of Boundary Bay, the E-W-trending Skipjack Island fault zone was recently mapped on the basis of multibeam sonar imagery and seismic reflection data, with evidence for Holocene offsets of the seafloor and subsurface sediments. In addition, the Fraser River Delta fault had been hypothesized on the basis of a line of pockmarks and fluid seeps. Since these faults have only been recently mapped and identified as active, there is little information available on their structure, rupture style, and past large earthquakes. This makes it difficult to constrain rupture models to predict how fault slip could displace the seafloor during a large earthquake, for input to tsunami models. I analyzed relocated earthquake hypocentres, earthquake mechanisms, bathymetry, topography, and aeromagnetic, seismic reflection, and magnetotelluric data, to constrain the location, strike, dip, and rupture width of each fault. Correlations between datasets enabled mapping of northwestward extensions of the Sandy Point and Birch Bay faults, as well as delineating the previously unmapped Fraser River Delta fault. These offshore faults appear to be associated with infilled basement valleys in the subsurface, perhaps due to differential glacial erosion of weakened fault zone material. The Drayton Harbor fault could not be definitively mapped across Boundary Bay, so was excluded from the rupture modelling. Rupture styles were constrained using a combination of earthquake mechanisms, stress orientations, other evidence of regional compression, and vertical paleoseismic offsets. Where possible, paleoseismic displacements in past earthquakes were used to constrain the amount of fault slip for scenario earthquakes; empirical relations between fault slip and fault length or area were used to estimate displacements for the Skipjack Island and Fraser River Delta faults. The Birch Bay, Sandy Point, Skipjack Island, and Fraser River Delta faults all pose a significant tsunami risk to communities surrounding the southern Strait of Georgia and Boundary Bay. Considering both the originally mapped and extended lengths, the Birch Bay and Sandy Point faults could rupture in reverse-faulting earthquakes up to Mw 6.7-7.4 and 6.8-7.5, respectively, with seafloor uplift up to 2-2.5 m triggering damaging tsunami waves (up to at least 2.5 m) that could arrive onshore with little to no warning after the shaking begins. Similarly, the Fraser River Delta fault could host reverse or dextral-reverse slip earthquakes up to Mw 7.0-7.6, with seafloor uplift of 0.6-3.5 m. Ruptures on the Skipjack Island fault would likely have a larger strike-slip component; earthquakes of Mw 6.9-7.3 produce modelled seafloor uplift of 0.5-1.9 m. These results suggest that large tsunamigenic earthquakes on crustal faults in the southern Strait of Georgia should be included in future seismic and tsunami hazard assessments on both sides of the international border. / Graduate

In the Gulf Islands and Salish Sea Regions of British Columbia the Parks Canada Agency (PCA) currently operates Gulf Islands National Park Reserve (GINPR) and is in the development phase for the proposed Southern Strait of Georgia National Marine Conservation Area Reserve (SSGNMCAR). Protected areas such as these are meant to protect the ecological and cultural heritage of the region on behalf of all Canadians. As the government runs and expands their protected areas in the region it is important to look at their relationship with Indigenous communities in particular, as the PCA mandate requires the agency to work in “partnership” with Indigenous communities (Parks Canada 2017). The region is home to nearly 20 First Nations groups including the three W̱SÁNEĆ First Nations of the W̱SÁNEĆ Leadership Council (WLC). The WLC is an Indigenous government that has publicly stated their perception of a strained relationship with the PCA beginning before the formal establishment of GINPR in 2003. Through historical analysis; interviews with employees from the PCA and members of the W̱SÁNEĆ community; and a review of several aspects of site management and establishment in the region – this thesis explores the changing relationship between the PCA and W̱SÁNEĆ First Nations. Through this thesis I collect and discuss recommendations from W̱SÁNEĆ community members, and develop several myself, for the PCA to consider developing to improve the partnership between the two bodies. Potentially a partnership could lead towards formalized and lasting co-operative decision-making practice in the region’s cultural and natural heritage management. / Graduate

Intra-archipelago waterways, including tidal strait networks, present a complex set of barriers to, and conduits for sediment transport between marine basins. Tidal straits may also be the least well understood tide-dominated sedimentary environment. To address these issues, currents, sediment transport pathways, and seabed sedimentology & geomorphology were studied in the central Salish Sea (Gulf and San Juan Islands region) of British Columbia, Canada and Washington State, USA. A variety of data types were integrated: 3D & 2D tidal models, multibeam bathymetry & backscatter, seabed video, grab samples, cores and seismic reflection. This dissertation included the first regional sediment transport modelling study of the central Salish Sea. Lagrangian particle dispersal simulations were driven by 2D tidal hydrodynamics (~59-days). It was found that flood-tide dominance through narrow intra-archipelago connecting straits resulted in the transfer of sediment into the inland Strait of Georgia, an apparent sediment sink. The formative/maintenance processes at a variety of seabed landforms, including a banner bank with giant dunes, were explained with modelled tides and sediment transport. Deglacial history and modern lateral sedimentological and morphological transitions were also considered. Based on this modern environment, adjustments to the tidal strait facies model were identified. In addition, erosion and deposition patterns across the banner bank (dune complex) were monitored with 8-repeat multibeam sonar surveys (~10 years). With these data, spatially variable bathymetric change detection techniques were explored: A) a cell-by-cell probabilistic depth uncertainty-based threshold (t-test); and B) coherent clusters of change pixels identified with the local Moran's Ii spatial autocorrelation statistic. Uncertainty about volumetric change is a considerable challenge in seabed change research, compared to terrestrial studies. Consideration of volumetric change confidence intervals tempers interpretations and communicates metadata. Techniques A & B may both be used to restrict volumetric change calculations in area, to exclude low relative bathymetric change signal areas. / Graduate / 2018-12-07