This project describes a portion of a long-term study of the behavioral ecology of sea otters. Sub-studies of this project include the development of an individual recognition program for sea otters, the construction of male sea otter activity and energy budgets, and the assessment of male sea otter territory quality. The Sea Otter Nose Matching Program, or "SONMaP", was developed to identify individual sea otters in Simpson Bay, Prince William Sound, Alaska, using a blotch-pattern recognition algorithm based on the shape and location of nose scars. The performance of the SONMaP program was tested using images of otters collected during the 2002-03 field seasons, and previously matched by visually comparing every image in a catalog of 1,638 animals. In 48.9% of the visually matched images, the program accurately selected the correct image in the first 10% of the catalog. Individual follows and instantaneous sampling were used during the summers of 2004-06, to observe male sea otter behavior. Six behaviors (foraging, grooming, interacting with other otters, patrolling, resting, and surface swimming) were observed during four time periods (dawn, day, dusk, night) to create 24-hr activity budgets. Male sea otters spent 27% of their time resting, 26% swimming, 19% grooming, 14% foraging, 9% patrolling and 5% interacting with other otters. Field Metabolic Rate (FMR) was estimated by combining the energetic costs for foraging, grooming, resting, and swimming behaviors of captive otters from Yeates et al. (2007) with these activity budgets. "Swimming" accounted for the greatest percentage (43%) of energy expended each day followed by grooming (23%), resting (15%), feeding (13%) and other (5%). With a peak summer sea otter density of 5.6 otters km-2, the low percentage of time spent foraging indicates that Simpson Bay is below equilibrium density. Territory quality was assessed for male sea otters using four attributes: territory size, shoreline enclosure, accessibility, and number of females observed feeding in each territory. Each attribute was coded with a score of 0-2, and total quality scores ranged from 0.14-1.96 (0.9 + 0.61 SD). High quality territories had large areas, moderate shoreline enclosure, high accessibility, and many foraging females.

Visitation to marine wildlife viewing tours has increased steadily in the last few decades. Despite concerns over negative impacts, one of the anticipated benefits to wildlife viewing is increased visitor support for marine conservation. In this study, sea otters were used as a case study to determine how wildlife viewing may alter visitor attitudes and behavioural intentions towards marine conservation. In particular, the effects of the inclusion of interpretation in marine wildlife observation were analysed. This study includes the experiences of marine wildlife visitors to boat-based tours in Tofino, on the west coast of Vancouver Island, as well as the experiences of visitors to the Vancouver Aquarium Marine Science Centre. A questionnaire was used to determine the importance of sea otters to wildlife viewing tours, how both aquarium and boat-based wildlife viewing experiences influence visitor learning, and what implications this has for marine conservation. Sea otters were found to be important incidentally-viewed species in the boat-based tours. Sea otters were oftentimes not the main draw, but visitors very much enjoyed their presence. The provision of interpretation on its own affected visitor attitudes and behavioural intentions. However, the most significant difference in the promotion of conservation attitudes and behaviours was when the observation of sea otters was coupled with interpretation regarding sea otters. The same trend was observed in both the boat-based tours in Tofino and the captive wildlife viewing at the aquarium. These results indicate that the most important role of the tour guide is in locating marine species, and providing targeted interpretation about the species during observation. Thus, marine wildlife tourism can increase overall visitor support for marine conservation through affecting attitudes and behaviours.

The purpose of this work was to examine the source and fate of hydrocarbons, the primary constituents of oil, in sea otter (Enhydra lutris) habitat on the west coast of British Columbia (BC), Canada and their fate in the sea otter food web. Oil pollution is the primary threat to this recovering population, reflecting their extreme vulnerability as a result of several unique life history characteristics, including the absence of a blubber layer, reliance on their fur for insulation, and the fact that their entire lives can be spent at sea. While the vulnerability of sea otters to acute oil exposure has been demonstrated, chronic hydrocarbon exposure through dietary processes is not well understood. We measured hydrocarbon (alkane, hopane and sterane biomarker, and polycyclic aromatic) concentrations in sediments, prey items, and live-captured sea otters using high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). Background signatures were characterized for remote sediment sites, with polycyclic aromatic hydrocarbon (PAH) patterns revealing the predominance of petrogenic sources. However, PAH concentrations were up to three orders of magnitude higher at two small harbour sites, with patterns reflecting weathered petroleum and the combustion of fossil fuels and biomass. Concentrations at these sites exceeded both national and provincial sediment quality guidelines for the protection of aquatic life. Despite differences in habitat and feeding ecology, all sea otter prey species sampled exhibited PAH patterns dominated by petrogenic low molecular weight (LMW) compounds, highlighting the likely importance of water as an exposure route. While biota-sediment accumulation factors (BSAFs) generally decreased with increasing octanol-water partitioning coefficients (log Kow) for parent PAHs, BSAFs for alkyl PAHs increased, indicative of bioaccumulation by invertebrates. Biomagnification factors (BMFs) indicated that while parent PAHs biodiluted in sea otters, consistent with metabolic elimination, some higher alkylated 3- and 4-ring PAHs biomagnified, challenging the commonly held view that PAHs dilute in food webs. This retention was reflected in estimated ∑PAH body burdens, in which alkyl PAHs comprised 89 ± 7% and 84 ± 10% of totals in male and female otters, respectively. While vertebrates are efficient metabolizers of parent PAHs, this apparent retention of some alkyl PAHs in sea otters raises concerns about the potential toxicological effects of these poorly understood compounds. This research suggests that sea otters may be vulnerable to PAH-related health risks as a consequence of their large dietary requirements (~25% of body weight per day), even when prey PAH concentrations are low.

Most of what is known about the ways in which strongly interacting species affect ecological communities stems from changes to community structure revealed in contemporary research. However, trophic downgrading has limited the temporal extent to which inferences can be drawn. The aim of my Dissertation was to expand on the strongly interacting species concept by examining species interactions at a historical scale, in a textbook example of a strongly interacting and keystone predator. The sea otter, Enhydra lutris, was driven to near-extinction but is recovering in parts of its range, providing a mosaic of areas with and without sea otters. This mosaic allowed for a series of natural experiments, which I conducted using behavioural observations, genetic tools, and archaeological methods, to examine sea otter effects spanning contemporary (last ~40 yrs.), and late-Holocene (~3500-150 yrs. ago) timeframes, and on an evolutionary scale that inferred middle-Pleistocene interactions. In Chapter 2, my coauthors and I found that sea otter use of clam-based niches increased as occupancy-time increased, and that bachelor groups of male otters primarily inhabited these niches, findings that informed and inspired subsequent questions. In Chapter 3, we found that where sea otters were established for 20-30 years, the disturbance to eelgrass (Zostera marina), caused by sea otters digging for clams and other infaunal prey, was correlated with ~25% greater eelgrass allelic richness than where otters were present <10 yrs, or absent. We posit that sea otter digging has long-influenced the genetic diversity and resilience of eelgrass – perhaps since the middle Pleistocene. In Chapter 4, we asked how two strongly interacting species – people and sea otters – co-existed for millennia where they both consumed clams. We used assemblages of live and otter-cracked butter clams (Saxidomus gigantea), to confirm the ecological effects that sea otters exert today. We measured clams from archaeological assemblages in areas densely populated with clam gardens – terraced beaches that enhance clam habitat and productivity – and found that sea otters reduced the sizes of ancient clams, acting as ecologically effective predators in the mid-to-late Holocene. However, clam harvests were stable for thousands of years, with or without otters. We suggest that clam gardening supported coexistence of people and otters in the past, and could function the same way today. Collectively, we found that a few, perhaps long-forgotten, interactions increased the breadth of the strongly interacting species concept. In Chapter 5, I suggest that such rediscoveries could occur in other systems. Many large vertebrates have suffered population declines, but the most insidious losses accompanying these, are the losses of ecological interactions that become unknowable, and thus cannot be intentionally restored. By searching out ancient interactions, long-forgotten relationships have the potential to be recovered, and to inform our understanding of contemporary systems. / Graduate / 2022-09-10

The coastal, indigenous communities around Alaska have subsisted on marine animals for generations, often focusing on large apex predators such as seals, sea lions, and whales. Three species of pinnipeds (harbor seal, Steller sea lion, northern fur seal) and the northern sea otter have all undergone significant population declines since the 1970s, some regions more than others. Archived vibrissae (whiskers) and body tissues from these four species were available from the Bering Sea and throughout the Gulf of Alaska from the 1990s and early 2000s. Tissues from these species are exceedingly difficult to obtain; thus, the archived tissues provided a finite and irreplaceable resource of data. Analysis of these archived tissues indicates which species, tissues, and gender bioaccumulate metals more readily. In this study twelve heavy metals (arsenic, cadmium, chromium, cobalt, copper, lead, manganese, mercury, nickel, selenium, vanadium, zinc) were analyzed in vibrissae from the four select species, and in body tissues from harbor seals and Steller sea lions. The samples were collected from three regions (southeastern, southcentral, and southwestern Alaska) during the 1990s through early 2000s. Significant differences of heavy metal concentrations in vibrissae were detected among elements (p2(110) = 454.81, p2(66) = 310.88, p