Christopher G. Lowe

California State University, Long Beach | CSULB · Department of Biological Sciences

Ontogenetic changes in area use, habitat use, and trophic interactions play an important role in the ecology, demography, and ultimately population dynamics of many species. Assumed to be driven by shifting life‐history requirements, trophic niche shifts in white sharks (Carcharodon carcharias) are well documented, but the timing of the spatial nic...

Drones are an ecological tool used increasingly in shark research over the past decade. Due to their high-resolution camera and GPS systems, they have been used to estimate the sizes of animals using drone-based photogrammetry. Previous studies have used drone altitude to measure the target size accuracy of objects at the surface; however, target d...

In ecosystems, sharks can be predators, competitors, facilitators, nutrient transporters, and food. However, overfishing and other threats have greatly reduced shark populations, altering their roles and effects on ecosystems. We review these changes and implications for ecosystem function and management. Macropredatory sharks are often disproporti...

While juvenile white sharks (JWS) can display regional endothermy, the need to maintain internal temperatures within an energetically favorable range likely drives thermoregulatory movements to maximize growth and foraging efficiency. Many JWS from the northeastern Pacific population aggregate seasonally in nearshore nursery habitats throughout the...

Long-distance movements associated with environmental and ecological drivers are common in a wide array of mobile marine species. Understanding such movements and associated drivers is particularly important for management and conservation of threatened species, which may be exposed to anthropogenic threats throughout their range. Pacific nurse sha...

Seasonal upwelling in tropical coastal regions can create dynamic oceanographic conditions similar to temperate systems, which are known to influence the distribution and movement of marine species. Mobile marine species may seek warmer environments (i.e. exhibit behavioral thermoregulation) in response to stronger winds during the upwelling season...

Over one-third of elasmobranch fishes (sharks, rays, and skates) are threatened with extinction, mostly due to overfishing, habitat loss, and habitat degradation. Understanding the daily and seasonal movement patterns of these species can inform when and where populations are most susceptible to these threats, but these data are often lacking for n...

Juvenile white sharks (Carcharodon carcharias) typically aggregate along coastal beaches; however, high levels of recruitment and shifting oceanographic conditions may be causing habitat use expansions. Telemetry data indicate increased habitat use at the Northern Channel Islands (California, USA) by juvenile white shark that may be in response to...

Keystone species populations, including shark and ray taxonomic groups, are declining due to numerous threats. A better understanding of how individual belief structures inform pro-conservation behavioral intentions is therefore critical to foster support for their conservation and the greater biodiversity of world ecosystems. This study conducted...

Juvenile white sharks (JWS) of the Northeastern Pacific population are present in nearshore southern California waters and form mixed size class (~1.5–3 m) aggregations for weeks to months, often within 500 m of shore. These nearshore beach habitats are heavily used for human recreation (e.g., surfing, swimming, body boarding, wading, and standup p...

Organochlorine contaminants (OCs) accumulate in top predators, reaching high levels associated with negative physiological effects. Measuring OCs is key for assessing the accumulation of their loads and evaluating the efficiency of contaminant regulations. Some OCs generate specific signatures in certain areas, which allow us to track potential mov...

Game fish populations in North America face increasing pressure from recreational anglers, yet sublethal effects from mandatory catch‐and‐release regulations remain unknown for many targeted species. In southern California, Kelp Bass Paralabrax clathratus populations have significantly declined in recent decades, prompting changes in management and...

While the function of migration varies among species, environmental temperature is known to be one of the most important abiotic variables that drive animal migration; however, quantifying the thresholds and timing of the cues that influence a mass emigration is difficult, often due to lack of monitoring resolution, particularly for large, highly m...

Few published studies have measured the oxygen consumption rates of elasmobranchs larger than 1.5 m, with only one measured at temperatures below 10 °C. This study provides initial measurements of the metabolic rate of three juvenile Pacific sleeper sharks, SP1904, SP1908, and SP2005 (199 cm, 162 cm, 144 cm), which were caught and temporarily house...

High recreational catch rates of istiophorid billfishes in the eastern tropical Pacific (ETP) have led to substantial eco-tourism derived economic benefits for the countries in the region, prompting many countries to mandate catch-and-release practices for recreational anglers. Previous estimates of billfish post-release behaviours and recovery per...

The recent progress in deep learning has given rise to a non-invasive and effective approach for animal biometrics. These modern techniques allow researchers to track animal individuals on a large-scale image database. Typical approaches are suited to a closed-set recognition problem, which is to identify images of known objects only. However, such...

White sharks (Carcharodon carcharias) are the largest shark species to display regional endothermy. This capability likely facilitates exploitation of resources beyond thermal tolerance thresholds of potential sympatric competitors as well as sustained elevated swim speeds, but results in increased metabolic costs of adults, which has been document...

Juvenile common thresher sharks ( Alopias vulpinus) have been recently stranding along the California coastline. Using Illumina sequencing of the bacterial 16S rRNA gene along with necropsy, cytological, bacteriological, and histological techniques, we screened microbial communities and described lesions characterizing affected sharks with the purp...

Species occurrence records are vital data streams in marine conservation with a wide range of important applications. From 2001–2020, the Monterey Bay Aquarium led an international research collaboration to understand the life cycle, ecology, and behavior of white sharks ( Carcharodon carcharias ) in the southern California Current. The collaborati...

1. Fine-scale movement patterns are driven by both biotic (hunting, physiological needs) and abiotic (environmental conditions) factors. The energy balance governs all movement-related strategic decisions. 2. Marine environments can be better understood by considering the vertical component. From 24 acoustic trackings of 10 white sharks in Guadalup...

Many terrestrial and aquatic taxa are known to form periodic aggregations, whether across life history or solely during specific life stages, that are generally governed by the availability and distribution of resources. Associations between individuals during such aggregation events are considered random and not driven by social attraction or unde...

Structures installed to modify hydrology in waterways such as culverts can cause fragmentation across intertidal and subtidal areas, leading to increased habitat patchiness of previous interconnected habitats. This study aimed to understand the potential impacts of a 268-m culvert on habitat parameters in a large tidal bay and a coastal lagoon in S...

Acoustic telemetry (AT) is a rapidly evolving technique used to track the movements of aquatic animals. As the capacity of AT research expands it is important to optimize its relevance to management while still pursuing key ecological questions. A global review of AT literature revealed region-specific research priorities underscoring the breadth o...

To understand the ecology and environmental impact of free-ranging sharks, it is essential to investigate patterns and drivers of their behavior. Recently, the powerful representations learned by Deep Learning models have been utilized within a Bayesian non-parametric framework in order to learn non-Euclidean similarity metrics for classification....

Knowledge about top predators’ trophic ecology is crucial for defining their role in ecosystems, understanding habitat preferences, characterizing life stage-specific feeding habits, and evaluating their interaction with fisheries. In the northeastern Pacific, white sharks (Carcharodon carcharias) occupy coastal habitats during the early life stage...

Contaminant Exposure Models (CEMs) were developed to predict population-level tissue contaminant concentrations in fishes by pairing sediment-bound contaminant concentrations (DDTs, PCBs) and fine-scale acoustic telemetry data from a habitat-associated species (Vermilion Rockfish, Sebastes miniatus), nomadic flatfish species (Hornyhead Turbot, Pleu...

Using an intermittent respirometer, we measured the thermal sensitivity (metabolic Q10) and scaling relationship (b) of the round stingray, Urobatis halleri, based on their standard metabolic rates (SMR). A total of 33 individuals (mass range = 0.03–0.86 kg) were acclimated for over 14 days at three temperature treatments (15°, 23°, 27 °C) spanning...

Tiger sharks (Galeocerdo cuvier) play an important ecological role as top predators, yet knowledge of their reproductive ecology is scarce. Here, the authors report the first observation of a potential neonate G. cuvier at Cocos Island, a predator‐dominated oceanic island in the Eastern Tropical Pacific (ETP). The individual was detected using bait...

The global lockdown to mitigate COVID-19 pandemic health risks has altered human interactions with nature. Here, we report immediate impacts of changes in human activities on wildlife and environmental threats during the early lockdown months of 2020, based on 877 qualitative reports and 332 quantitative assessments from 89 different studies. Hundr...

Giant sea bass (Stereolepis gigas, Polyprionidae) are the largest reef-associated teleost in the northeastern Pacific, considered an important predator in Macrocystis kelp forest and rocky reef ecosystems. Because of the predictability of annual aggregations, giant sea bass (GSB) were fished throughout the twentieth century until they were nearly e...

Globally, one quarter of shark and ray species are threatened with extinction due to overfishing. Effective conservation and management can facilitate population recoveries. However, these efforts depend on robust data on movement patterns and stock structure, which are lacking for many threatened species, including the Critically Endangered soupfi...

Young-of-the-year (YOY) and juvenile-stage white sharks may use southern California nearshore beach habitats more extensively than previously known, within meters of some of the most heavily used beaches in the world. Such knowledge forms a critical component of species management and conservation plans, in addition to public safety and risk mitiga...

North Pacific marine heatwave, unprecedented sightings of juvenile white sharks (Carcharodon carcharias) emerged in central California. These records contradicted the species established life history, where juveniles remain in warmer waters in the southern California Current. This spatial shift is significant as it creates potential conflicts with...

Sharks are iconic and ecologically important predators found in every ocean. Because of their ecological role as predators, some considered apex predators, and concern over the stability of their populations due to direct and indirect overfishing, there has been an increasing amount of work focussed on shark conservation, and other elasmobranchs su...

This paper presents the feature extraction, selection and K-Nearest Neighbors (K-NN) algorithm to classify behaviors of sharks based on the data collected by tri-axial acceleration data loggers (ADLs). Because these behaviors are hard to observe in the wild and do not occur frequently, being able to adequately classify them is extremely challenging...

The giant sea bass Stereolepis gigas Ayres 1859 (GSB) is a critically endangered top marine predator in California. Since protection in 1982 and 1994, the population has appeared to increase, and individuals within a growing population may expand their ranges to new habitats to reduce intraspecific competition and increase foraging opportunities. I...

California horn sharks (Heterodontus francisci) are relatively small (122 cm maximum total length; TL), nocturnally active sharks that have been observed refuging in shelters during the day; however, little is known about how they select their daytime resting shelters, and what factors may drive their degree of shelter fidelity. Depending on body s...

California sheephead, Semic ossyphus pulcher, have experienced significant population declines in recent decades but have remained an important nearshore gamefish in southern California by hook and line anglers. Regulations in the recreational sector currently include a minimum size and bag limit; however, the resulting widespread catch and release...

Within Southern California, east Pacific green sea turtles (Chelonia mydas) forage year-round, taking advantage of diverse food resources, including seagrass, marine algae, and invertebrates. Assessing persistent organic pollutants (POP) in green turtle aggregations in the Seal Beach National Wildlife Refuge (SBNWR, n = 17) and San Diego Bay (SDB,...

Background: California horn sharks (Heterodontus francisci) are nocturnally active, non-obligate ram ventilating sharks in rocky reef habitats that play an important ecological role in regulating invertebrate communities. We predicted horn sharks would use an area restricted search (ARS) movement strategy to locate dense resource patches while min...

Wastewater outfall pipes are structures that may attract marine fishes, yet previous studies that address the risks of exposure to wastewater effluent rarely account for the movements of the species studied. This study used acoustic telemetry to quantify the movement patterns and habitat association of demersal species (Citharichthys sordidus, Pleu...

Off California, economically important nearshore reef fishes inhabit the shallow (<20 m) regions of offshore petroleum platforms on the San Pedro Shelf (SPS). It is essential to understand the degrees to which platforms support fish over time to indicate whether biological requirements (e.g., shelter, diet, reproduction) are being met. To determine...

Many batoid species will form aggregations while resting on the seafloor; however, the environmental variables that drive resting habitat selection behavior, and how it varies among species are not well understood. Bat rays (Myliobatis californica), shovelnose guitarfish (Pseudobatos productus), and round stingrays (Urobatis halleri) have been obse...

Hidden Markov models are prevalent in animal movement modelling, where they are widely used to infer behavioural modes and their drivers from various types of telemetry data. To allow for meaningful inference, observations need to be equally spaced in time, or otherwise regularly sampled, where the corresponding temporal resolution strongly affects...

Intense fishing pressure has led to changes in species composition, demography and the over‐exploitation of many coastal fishes. To restore populations, artificial reefs (ARs) are used with the assumption that new habitat will increase fish productivity. Kelp bass (Paralabrax clathratus), barred sand bass (P. nebulifer) and California sheephead (Se...

A strength of physiological ecology is its incorporation of aspects of both species’ ecology and physiology; this holistic approach is needed to address current and future anthropogenic stressors affecting elasmobranch fishes that range from overexploitation to the effects of climate change. For example, physiology is one of several key determinant...

While adult white sharks (Carcharodon carcharias) are apex predators with a circumglobal distribution, juvenile white sharks (JWS) feed primarily on bottom dwelling fishes and tend to be coastally associated. Despite the assumedly easier access to juveniles compared to large, migratory adults, limited information is available on the movements, envi...

Interpolated v. standardized positions. Linearly interpolated daily positions (A) and daily standardized positions (B) overlaid on top of the bathymetry data for Southern California. During periods when individuals were not detected, interpolated positions were often further from land, and less characteristic of assumed behavior. (TIFF)

Interpolated v. standardized habitat selection. When GLMs are run on both interpolated (blue) and daily standardized (red) positions there is a greater selection for habitats that are further from land (A). The increased probability for locations that are further from land can be attributed to unlikely interpolated paths. During movements, individu...

Environmental data. This is a description of the spatial environmental data used. (DOCX)

SPOT tag tracks for all sharks used in this study. (CSV)

Tracking durations. This is a table of the each individuals size, capture data, number of days detected and deployment duration. (XLSX)

Carnobacterium maltaromaticum is a well-known pathogen of bony fish. More recently, C. maltaromaticum have been isolated from the brain and inner ear of disorientated and stranded common thresher ( Alopias vulpinus ) and salmon shark ( Lamna ditropis ). While thresher shark strandings are recent, salmon sharks have been stranding for decades, sugge...

Foraging aggregations of east Pacific green sea turtles (Chelonia mydas) inhabit the Seal Beach National Wildlife Refuge (SBNWR) and San Diego Bay (SDB), two habitats in southern California, USA, located near urbanized areas. Both juvenile and adult green turtles forage in these areas and exhibit high site fidelity, which potentially exposes green...

White sharks, Carcharodon carcharias, are often described as elusive, with little information available due to the logistical difficulties of studying large marine predators that make long-distance migrations across ocean basins. Increased understanding of aggregation patterns, combined with recent advances in technology have, however, facilitated...

To improve ability to detect white sharks without the need for tags, or visual census, we developed a species-specific environmental DNA (eDNA) assay that targets a 163 bp fragment of the white shark (Carcharodon carcharias) mitochondrial cytochrome B gene on a digital droplet PCR (ddPCR) platform. We used this marker to detect white shark DNA in 2...

Length, mass and girth relationships are presented for 112 juvenile white sharks (JWS) Carcharodon carcharias caught in the Southern California Bight (SCB) nursery area between June 2008 and August 2017. No difference was found between male and female JWS length–mass relationships, but data suggest that JWS in the SCB gain more mass per unit length...

Background: Central place foragers (CPF) rest within a central place, and theory predicts that distance of patches from this central place sets the outer limits of the foraging arena. Many marine ectothermic predators behave like CPF animals, but never stop swimming, suggesting that predators will incur 'travelling' costs while resting. Currently,...