Andrew W. Trites

University of British Columbia - Vancouver | UBC · Institute for the Oceans and Fisheries (IOF)

The ecological impact of environmental changes at high latitudes (e.g., increasing temperature, and decreased sea ice cover) on low-trophic species, such as bowhead whales, are poorly understood. Key to understanding the vulnerability of zooplanktivorous predators to climatic shifts in prey is knowing whether they can make behavioural or distributi...

Marine trophic ecology data are in high demand as natural resource agencies increasingly adopt ecosystem-based management strategies that account for complex species interactions. Harbour seal ( Phoca vitulina ) diet data are of particular interest because the species is an abundant predator in the northeast Pacific Ocean and Salish Sea ecosystem t...

Data sets composed of sequences of curves sampled at high frequencies in time are increasingly common in practice, but they can exhibit complicated dependence structures that cannot be modelled using common methods in functional data analysis. We detail a hierarchical approach that treats the curves as observations from a hidden Markov model. The d...

The decline of southern resident killer whales (Orcinus orca) may be due to a shortage of prey, but there is little data to test this hypothesis. We compared the availability of prey (Chinook salmon, Oncorhynchus tshawytscha) sought by southern residents in Juan de Fuca Strait during summer with the abundance and distribution of Chinook available t...

Although the ability of marine mammals to lower heart rates for extended periods when diving is well documented, it is unclear whether marine mammals have electrophysiological adaptations that extend beyond overall bradycardia. We analyzed electrocardiographic data from 50 species of terrestrial mammals and 19 species of marine mammals to determine...

Pinniped hearts have been well described via dissection, but in vivo measurements of cardiac structure, function, and electrophysiology are lacking. Electrocardiograms (ECGs) were recorded under anesthesia from eight Steller sea lions (Eumetopias jubatus), five northern fur seals (Callorhinus ursinus), and one walrus (Odobenus rosmarus) to investig...

Two competing hypotheses were proposed to explain why Steller sea lions had declined in the Gulf of Alaska, Bering Sea and Aleutian Islands. One of the theories was that young sea lions were starving because fisheries had reduced the abundance of groundfish—the overfishing hypothesis. The other was that these low-fat species of fish had increased i...

Photo-identification studies of transient killer whales (Orcinus orca) off western North America have primarily been conducted in the coastal inland waterways of Washington State, British Columbia, and southeastern Alaska. Less is known about transient killer whales along the outer coast and offshore waters of Oregon and central and northern Califo...

Availability of preferred salmonid prey and a sufficiently quiet acoustic environment in which to forage are critical to the survival of resident killer whales (Orcinus orca) in the northeastern Pacific. Although piscivorous killer whales rely on echolocation to locate and track prey, the relationship between echolocation, movement, and prey captur...

Climate-induced changes in calanoid copepod ( Calanus spp.) availability in traditional feeding areas might explain why a large proportion of the North Atlantic right whale Eubalaena glacialis population has fed in the Gulf of St. Lawrence (Canada) in recent years. However, little is known about the distribution of copepods in the gulf, and whether...

An array of predators that consume juvenile salmon (Oncorhynchus spp. Suckley‎, 1861)‎ may account for the poor returns of adult salmon to the Salish Sea. However, the Pacific great blue heron (Ardea herodias fannini Chapman, 1901) is rarely listed among the known salmon predators, despite being regularly seen near salmon streams. Investigating her...

Data sets comprised of sequences of curves sampled at high frequencies in time are increasingly common in practice, but they can exhibit complicated dependence structures that cannot be modelled using common methods of Functional Data Analysis (FDA). We detail a hierarchical approach which treats the curves as observations from a hidden Markov mode...

The full article is available in issue 20 of Carnivore Damage Prevention News: http://www.protectiondestroupeaux.ch/fileadmin/doc/International/CDP_and_General_Infos/CDPNews20_Nov2020.pdf

As zooplanktivorous predators, bowhead whales (Balaena mysticetus) must routinely locate patches of prey that are energy-rich enough to meet their metabolic needs. However, little is known about how the quality and quantity of prey might influence their feeding behaviours. We addressed this question using a new approach that included: (1) multi-sca...

Knowing size-at-age is important for determining food requirements and making inferences about the nutritional status of individuals and their populations. Accurate growth curves are also needed to quantify drug dosages to treat wounded or entangled animals. However, body sizes are often based on small numbers of measured animals that must be impro...

Pinnipeds have specific macronutrient (protein, lipid) requirements to satisfy physiological functions, yet little is known about how diet characteristics affect macronutrient digestibility. We measured relative and absolute lipid and protein digestibility in six female northern fur seals (Callorhinus ursinus (Linnaeus, 1758)) fed eight experimenta...

The North Atlantic right whale (Eubalaena glacialis, NARW) is an endangered cetacean which faces population decline from anthropogenic activities. Climate change may also be adding pressure on population recovery by shifting distribution of their preferred prey, Calanus copepods. The Gulf of St. Lawrence (GSL) in eastern Canada has been used as a f...

Climate change may affect the foraging success of bowhead whales Balaena mysti -cetusby altering the diversity and abundance of zooplankton species available as food. However,assessing climate-induced impacts first requires documenting feeding conditions under currentenvironmental conditions. We collected seasonal movement and dive-behaviour data f...

There is increasing evidence that predation by harbour seals on out-migrating salmon smolts may be responsible for the low return of adult coho and Chinook salmon in the Salish Sea. However, little attention has been given to understanding where and when this predation occurs and the extent to which it might be conducted by few or many seals in the...

Understanding variability in growth patterns of marine mammals provides insights into the health of individuals and status of populations. Body growth of gray whales (Eschrichtius robustus) has been described for particular life stages, but has not been quantified across all ages. We derived a comprehensive growth equation for gray whales by fittin...

These are the Abstracts of the 2019 annual meeting of SNVB, WA TWS, and NW PARC. I have two abstracts in this compilation: Olson et al., Density Management and Riparian Buffer Study update, pp 154-155; Weil and Olson, NW PARC update, pp 162-163.

Animal telemetry is a powerful tool for observing marine animals and the physical environments that they inhabit, from coastal and continental shelf ecosystems to polar seas and open oceans. Satellite-linked biologgers and networks of acoustic receivers allow animals to be reliably monitored over scales of tens of meters to thousands of kilometers,...

The Guadalupe fur seal Arctocephalus townsendi was intensively hunted and considered extinct by the end of the 1800s. However, small numbers ( < 20 seals) were reported on Guadalupe Island (Mexico) in the mid-1950s and were observed at a second location (San Benito Islands, Mexico) in the late 1990s. Sporadic counts at these 2 sites have followed a...

The Guadalupe fur seal (Arctocephalus townsendi) was intensively hunted and considered extinct by the end of the 1800s. However, small numbers (<20 seals) were reported on Guadalupe Island (Mexico) in the mid-1950s and were observed at a second location (San Benito Islands, Mexico) in the late 1990s. Sporadic counts at these two sites have followed...

Foraging strategies and their resulting efficiency (energy gain to cost ratio) affect animals’ survival and reproductive success and can be linked to population dynamics. However, they have rarely been studied quantitatively in free-ranging animals. We investigated foraging strategies and efficiencies of wild northern fur seals Callorhinus ursinus...

Predation risk and competition among conspecifics significantly affect survival of juvenile salmon, but are rarely incorporated into models that predict recruitment in salmon populations. Using densities of harbour seals (Phoca vitulina) and numbers of hatchery-released Chinook salmon (Oncorhynchus tshawytscha) smolts as covariates in spatially str...

Most stocks of Atlantic cod (Gadus morhua) in the Northwest Atlantic collapsed in the early 1990s, with little sign of recovery since then. In the southern Gulf of St. Lawrence (sGSL), the failed recovery is due to severe increases in the natural mortality of adult Atlantic cod. We examined the role of predation by grey seals (Halichoerus grypus) i...

Decreased health may have lowered the birth and survival rates of Steller sea lions ( Eumetopias jubatus) in the Gulf of Alaska and Aleutian Islands over the past 30 yr. Reference ranges for clinical hematology and serum chemistry parameters needed to assess the health of wild sea lion populations are limited. Here, blood parameters were serially m...

[This corrects the article DOI: 10.1371/journal.pone.0186156.].

ABSTRACT: Accurately estimating predators’ diets at relevant spatial and temporal scales is key to understanding animals’ energetics and fitness, particularly in populations whose decline might be related to their diet such as northern fur seals Callorhinus ursinus. Our goals were to improve the accuracy of diet estimates and extend understanding o...

Animal-borne instruments have become a standard tool for collecting important data from marine mammals. However, few studies have examined whether placement of these data loggers affects the behavior and energetics of individual animals, potentially leading to biasing data. We measured the effect of two types of relatively small data loggers (<1% o...

Bowhead whales (Balaena mysticetus) have a nearly circumpolar distribution, and occasionally occupy warmer shallow coastal areas during summertime that may facilitate molting. However, relatively little is known about the occurrence of molting and associated behaviors in bowhead whales. We opportunistically observed whales in Cumberland Sound, Nuna...

sUAS video of one bowhead whale rubbing on a large rock in Brown Harbour on 7 August 2016. This individual (A) was observed with three other individuals that subsequently engaged in rubbing behavior (Fig 6). (MOV)

sUAS data for 83 unique bowhead whales used to determine body length (m), sloughing amount (0 = none, 1 = <33%, 2 = 33–66%, 3 = >66% and <100% and 4 = 100%), sloughing type (0 = none, 1 = light gray lines from probable rock-rubbing behavior, 3 = covered) and whether the mouth was closed (e.g., 0), slightly open (1), wide open (2), or indeterminable...

Ecosystem-based management requires a clear understanding of marine ecosystem functioning, particularly the transfer of energy (consumption) to higher trophic levels. However, robust estimates of consumption are generally hampered by a dearth of data for predators (diet and abundance), and by methodological weaknesses. We undertook a comprehensive...

Polar oceans are poorly monitored despite the important role they play in regulating Earth’s climate system. Marine mammals equipped with biologging devices are now being used to fill the data gaps in these logistically difficult to sample regions. Since 2002, instrumented animals have been generating exceptionally large data sets of oceanographic...

Details on the methods used to measure metabolic rates with Doubly-Labeled Water in Antarctic fur seals. (DOCX)

Prey capture attempts (PrCA) by lactating Antarctic fur seals detected from back acceleration compared to PrCAs detected from head acceleration signals. Each dot represents one animal. The dotted line shows the results of regression model PrCABack = 34. 25 + 1.00 × PrCAHead (R2 = 0.90, p slope < 10−15). (TIF)

The efficiency with which individuals extract energy from their environment defines their survival and reproductive success, and thus their selective contribution to the population. Individuals that forage more efficiently (i.e., when energy gained exceeds energy expended) are likely to be more successful at raising viable offspring than individual...

Background We sought to quantitatively describe the fine-scale foraging behavior of northern resident killer whales (Orcinus orca), a population of fish-eating killer whales that feeds almost exclusively on Pacific salmon (Oncorhynchus spp.). To reconstruct the underwater movements of these specialist predators, we deployed 34 biologging Dtags on 3...

Three rays opportunistically obtained near Margarita Island, Venezuela, were identified as lesser devil rays Mobula cf. hypostoma, but their disc widths were between 207 and 230 cm, which is almost double the reported maximum disc width of 120 cm for this species. These morphometric data suggest that lesser devil rays are either larger than previou...

Marine mammals are characterized as having physiological specializations that maximize the use of oxygen stores to prolong time spent under water. However, it has been difficult to undertake the requisite controlled studies to determine the physiological limitations and trade-offs that marine mammals face while diving in the wild under varying envi...

ABSTRACT: Previous research has presented contradictory evidence on the ability of overall dynamic body acceleration (ODBA) to predict mass-corrected oxygen consumption (sV ̇ O2) in air- breathing diving vertebrates. We investigated a potential source of these discrepancies by partitioning the ODBA−sV ̇ O2 relationship over 3 phases of the dive cyc...

Knowing the species and life stages of prey that predators consume is important for understanding the impacts that predation may have on prey populations, but traditional methods for determining diets often cannot provide sufficient detail. We combined data from two methods of scat analysis (DNA metabarcoding and morphological prey ID) to quantify...

Time and energy are the two most important currencies in animal bioenergetics. How much time animals spend engaged in different activities with specific energetic costs ultimately defines their likelihood of surviving and successfully reproducing. However, it is extremely difficult to determine the energetic costs of independent activities for free...

Flipper strokes have been proposed as proxies to estimate the energy expended by marine vertebrates while foraging at sea, but this has never been validated on free-ranging otariids (fur seals and sea lions). Our goal was to investigate how well flipper strokes correlate with energy expenditure in 33 foraging northern and Antarctic fur seals equipp...

Bayesian Melding (BM) and downscaling are two Bayesian approaches commonly used to combine data from different sources for statistical inference. We extend these two approaches to combine accurate but sparse direct observations with another set of high-resolution but biased calculated observations. We use our methods to estimate the path of a movin...

Energy expenditure is an important component of foraging ecology, but is extremely difficult to estimate in free-ranging animals and depends on how animals partition their time between different activities during foraging. Acceleration data has emerged as a new way to determine energy expenditure at a fine scale but needs to be tested and validated...

Forces due to propulsion should approximate forces due to hydrodynamic drag for animals horizontally swimming at a constant speed with negligible buoyancy forces. Propulsive forces should also correlate with energy expenditures associated with locomotion-an important cost of foraging. As such, biologging tags containing accelerometers are being use...

This zipped folder contains a set of summary spreadsheet files, two for each animal. The files with names ending in NewAnalysis contain the data used to construct the APBA and ODBA plots. The files ending with “JP edits” contain calculations relating to drag and energy expenditures. Also included is C++ source code required to apply the GIDA method...

Unpacked raw openTag files are provided for animal F00BO,. Also, a set of csv files, one for each dive included in the study. Each file contains a 50Hz time series. Provided are calibrated accelerometer and gyro measurements, together with the estimated gravity vector, and the estimated dynamic accelerations by the different methods. The small file...

Unpacked raw openTag files are provided for animal F97SI. Same components as S2. (ZIP)

Unpacked raw openTag files are provided for animal F97HA. Same components as S2. (ZIP)

Unpacked raw openTag files are provided for animal F97SI. Same components as S2. (ZIP)

Aerial surveys are sometimes used to assess the densities of wide-ranging whales, as well as changes in their distributions in response to human activity. Such surveys also provide data used to estimate numbers of animals exposed to different received levels of seismic sound, as required by regulators. However, estimates of abundance are often bias...

Recent studies of stranded marine mammals indicate that exposure to underwater military sonar may induce pathophysiological responses consistent with decompression sickness (DCS). However, DCS has been difficult to diagnose in marine mammals. We investigated whether blood microparticles (MPs, measured as number/μl plasma), which increase in respons...

Quantification of costs associated with foraging contributes to understanding the energetic impact that changes in prey availability have on the energy balance of an animal and the fitness of populations. However, estimating the costs of foraging is difficult for breath-hold divers, such as Steller sea lions, that feed underwater. We developed mode...

DNA metabarcoding is a powerful new tool allowing characterization of species assemblages using high-throughput amplicon sequencing. The utility of DNA metabarcoding for quantifying relative species abundances is currently limited by both biological and technical biases which influence sequence read counts. We tested the idea of sequencing 50/50 mi...