scholarly journals Survival of the fattest: linking body condition to prey availability and survivorship of killer whales

Ecosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Joshua D. Stewart ◽  
John W. Durban ◽  
Holly Fearnbach ◽  
Lance G. Barrett‐Lennard ◽  
Paige K. Casler ◽  
...  
Keyword(s):  
Body Condition ◽  
Prey Availability ◽  
Killer Whales

Morphometric discrimination of pelagic fish stocks challenged by variation in body condition

2017 ◽  
Vol 75 (2) ◽  
pp. 711-718
Author(s):  
George Geladakis ◽  
Nikolaos Nikolioudakis ◽  
George Koumoundouros ◽  
Stylianos Somarakis
Keyword(s):  
Body Condition ◽  
Prey Availability ◽  
Eastern Mediterranean ◽  
Morphological Differentiation ◽  
Shape Variation ◽  
Geometric Morphometric ◽  
Morphometric Characters ◽  
Mesozooplankton Biomass ◽  
Stock Discrimination ◽  
Principal Coordinates

Abstract Morphometric characters have traditionally been used to describe the population structure of fishes. Body shape variation, which is often environmentally induced, may provide a good record of short-term population structuring. However, factors unrelated to environmental or genetic influences on body morphology may complicate sampling and the use of morphometric features for stock discrimination. In the present study, we used geometric morphometric variables to compare the European sardine Sardina pilchardus putative stocks of the Aegean and Ionian Seas (eastern Mediterranean). Landmark data of fish collected at seven different sites were subjected to canonical analysis of principal coordinates (CAP). The average body condition of sardines from these sites was strongly and linearly related to corresponding scores along CAP1, the axis exhibiting the highest correlation with the morphometric data cloud. The average scores along CAP2 and CAP3 appeared to be linked to morphological differentiation related to temperature effects and prey availability (mesozooplankton biomass). Despite the primary and confounding effect of body condition, discrimination of different morphotypes corresponding to the Aegean and the Ionian Sea stocks was highly significant with 81% correct reallocations for the respective CAP model.

scholarly journals Linking killer whale survival and prey abundance: food limitation in the oceans' apex predator?

2009 ◽  
Vol 6 (1) ◽  
pp. 139-142 ◽  
Author(s):  
John K. B. Ford ◽  
Graeme M. Ellis ◽  
Peter F. Olesiuk ◽  
Kenneth C. Balcomb
Keyword(s):  
Prey Species ◽  
Killer Whale ◽  
Prey Availability ◽  
Trophic Position ◽  
Marine Ecosystem ◽  
Food Limitation ◽  
Ecosystem Dynamics ◽  
Foraging Strategies ◽  
Limiting Factor ◽  
Killer Whales

Killer whales ( Orcinus orca ) are large predators that occupy the top trophic position in the world's oceans and as such may have important roles in marine ecosystem dynamics. Although the possible top-down effects of killer whale predation on populations of their prey have received much recent attention, little is known of how the abundance of these predators may be limited by bottom-up processes. Here we show, using 25 years of demographic data from two populations of fish-eating killer whales in the northeastern Pacific Ocean, that population trends are driven largely by changes in survival, and that survival rates are strongly correlated with the availability of their principal prey species, Chinook salmon ( Oncorhynchus tshawytscha ). Our results suggest that, although these killer whales may consume a variety of fish species, they are highly specialized and dependent on this single salmonid species to an extent that it is a limiting factor in their population dynamics. Other ecologically specialized killer whale populations may be similarly constrained to a narrow range of prey species by culturally inherited foraging strategies, and thus are limited in their ability to adapt rapidly to changing prey availability.

scholarly journals Rapid weight loss in free ranging pygmy killer whales (Feresa attenuata) and the implications for anthropogenic disturbance of odontocetes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jens J. Currie ◽  
Martin van Aswegen ◽  
Stephanie H. Stack ◽  
Kristi L. West ◽  
Fabien Vivier ◽  
...  
Keyword(s):  
Body Condition ◽  
Anthropogenic Disturbance ◽  
Environmental Changes ◽  
Biological Effects ◽  
Body Volume ◽  
Rapid Weight Loss ◽  
Killer Whales ◽  
Total Body Mass ◽  
Total Body ◽  
Free Ranging

AbstractUnderstanding the impacts of foraging disruptions to odontocete body condition is fundamental to quantifying biological effects of human disturbance and environmental changes on cetacean populations. Here, reductions in body volume of free-ranging pygmy killer whales (Feresa attenuata) were calculated using repeated measurements of the same individuals obtained through Unoccupied Aerial System (UAS)-photogrammetry during a prolonged disruption in foraging activity arising from a 21-day stranding event. Stranded individuals were used to verify UAS-derived volume and length estimates through 3D-imaging, water displacement, and post-mortem measurements. We show that (a) UAS estimates of length were within 1.5% of actual body length and UAS volume estimates were within 10–13% of actual volume, (b) foraging disruption resulted in a daily decrease of 2% of total body mass/day, and (c) pygmy killer whales can lose up to 27% of their total body weight within 17 days. These findings highlight the use of UAS as a promising new method to remotely monitor changes in body condition and animal health, which can be used to determine the potential effects of anthropogenic disturbance and environmental change on free-ranging odontocetes.

scholarly journals Pathology findings and correlation with body condition index in stranded killer whales (Orcinus orca) in the northeastern Pacific and Hawaii from 2004 to 2013

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0242505
Author(s):  
Stephen Raverty ◽  
Judy St. Leger ◽  
Dawn P. Noren ◽  
Kathy Burek Huntington ◽  
David S. Rotstein ◽  
...  
Keyword(s):  
Infectious Disease ◽  
Cause Of Death ◽  
Body Length ◽  
Body Condition ◽  
Human Interaction ◽  
Orcinus Orca ◽  
Human Populations ◽  
Killer Whales ◽  
Human Interactions ◽  
Successful Recovery

Understanding health and mortality in killer whales (Orcinus orca) is crucial for management and conservation actions. We reviewed pathology reports from 53 animals that stranded in the eastern Pacific Ocean and Hawaii between 2004 and 2013 and used data from 35 animals that stranded from 2001 to 2017 to assess association with morphometrics, blubber thickness, body condition and cause of death. Of the 53 cases, cause of death was determined for 22 (42%) and nine additional animals demonstrated findings of significant importance for population health. Causes of calf mortalities included infectious disease, nutritional, and congenital malformations. Mortalities in sub-adults were due to trauma, malnutrition, and infectious disease and in adults due to bacterial infections, emaciation and blunt force trauma. Death related to human interaction was found in every age class. Important incidental findings included concurrent sarcocystosis and toxoplasmosis, uterine leiomyoma, vertebral periosteal proliferations, cookiecutter shark (Isistius sp.) bite wounds, excessive tooth wear and an ingested fish hook. Blubber thickness increased significantly with body length (all p < 0.001). In contrast, there was no relationship between body length and an index of body condition (BCI). BCI was higher in animals that died from trauma. This study establishes a baseline for understanding health, nutritional status and causes of mortality in stranded killer whales. Given the evidence of direct human interactions on all age classes, in order to be most successful recovery efforts should address the threat of human interactions, especially for small endangered groups of killer whales that occur in close proximity to large human populations, interact with recreational and commercial fishers and transit established shipping lanes.

Major hurricanes affect body condition of American crocodile Crocodylus acutus inhabiting Mexican Caribbean islands

2020 ◽  
Vol 651 ◽  
pp. 145-162
Author(s):  
D Labarre ◽  
P Charruau ◽  
WFJ Parsons ◽  
S Larocque-Desroches ◽  
JA Gallardo-Cruz
Keyword(s):  
Tropical Cyclones ◽  
Body Condition ◽  
Prey Availability ◽  
The Body ◽  
Population Characteristics ◽  
Long Term Effects ◽  
Caribbean Islands ◽  
Crocodylus Acutus ◽  
Major Hurricane ◽  
Reproductive Events

Recent models suggest that anthropogenic global warming will lead to an increase in the number of major hurricanes, which have strong effects on ecosystems and may modify animal population characteristics. The goal of this study was to assess the body condition of American crocodiles Crocodylus acutus of Cozumel and Banco Chinchorro islands, Mexico, and use it as a tool to better understand short- and long-term effects of hurricanes on crocodilian populations. Changes in body condition (Fulton’s K) of 392 crocodiles, captured between 2003 and 2015, were assessed and analyzed in response to a major hurricane through different environmental factors. Differences among populations and size classes, and between sexes, together with seasonal variation, were also evaluated. The body condition of crocodiles was generally good, with better condition for Banco Chinchorro, suggesting that these populations and the ecosystems they inhabit are healthy. Body condition for hatchlings and adults was higher than for other classes, with adults exhibiting the best condition. Body condition of Banco Chinchorro individuals varied seasonally, responding to reproductive events and environmental parameter fluctuations. We also found that C. acutus body condition is sensitive to the passage of tropical cyclones, most likely through their effects on salinity, temperature, and prey availability. Tropical cyclones have a 2fold effect on populations. In the short-term, crocodile health is negatively affected by disturbance, while the species seems to maintain and improve its body condition over the longer term. An increase in strong tropical cyclone frequency could impede the recovery of populations, while causing a continual decrease in crocodile body condition.

Declining spring usage of core habitat by endangered fish-eating killer whales reflects decreased availability of their primary prey

2018 ◽  
Vol 24 (2) ◽  
pp. 189 ◽  
Author(s):  
Monika W. Shields ◽  
Jimmie Lindell ◽  
Julie Woodruff
Keyword(s):  
British Columbia ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Prey Availability ◽  
The United States ◽  
Killer Whales ◽  
Salish Sea ◽  
Critical Habitat ◽  
Endangered Fish ◽  
The North

The salmon-eating Southern Resident killer whales (Orcinus orca) of the north-eastern Pacific Ocean are listed as endangered both in the United States and Canada. Their critical habitat has been defined as the region of the inland waters of Washington State and British Columbia known as the Salish Sea, where they have traditionally spent much of their time from spring through fall. Using reports from experienced observers to sightings networks, we tracked the daily presence of the Southern Residents in these waters from 1 April to 30 June from 1994 through 2016. We found that the escapement estimates of spring Chinook salmon (Oncorhynchus tshawytscha) on the Fraser River in British Columbia were a significant predictor of the cumulative presence/absence of the whales throughout the spring season. There was also a difference in both whale presence and salmon abundance before and after 2005, suggesting that the crash in Chinook salmon numbers has fallen below threshold where it is worthwhile for the whales to spend as much time in the Salish Sea. The use of the Salish Sea by the Southern Residents has declined in the spring months as they are either foraging for Chinook salmon elsewhere or are shifting to another prey species. In order to continue providing necessary protections to this endangered species, critical habitat designations must be re-evaluated as this population of killer whales shifts its range in response to prey availability.

scholarly journals Evidence for density-dependent changes in body condition and pregnancy rate of North Atlantic fin whales over four decades of varying environmental conditions

2013 ◽  
Vol 70 (6) ◽  
pp. 1273-1280 ◽  
Author(s):  
Rob Williams ◽  
Gisli A. Vikingsson ◽  
Astthor Gislason ◽  
Christina Lockyer ◽  
Leslie New ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Body Condition ◽  
North Atlantic ◽  
Environmental Conditions ◽  
Prey Availability ◽  
Prey Abundance ◽  
Density Dependent ◽  
Terrestrial Mammals ◽  
Per Capita ◽  
Fin Whales

Abstract Williams, R., Vikingsson, G. A., Gislason, A., Lockyer, C., New, L., Thomas, L., and Hammond, P. S. 2013. Evidence for density-dependent changes in body condition and pregnancy rate of North Atlantic fin whales over four decades of varying environmental conditions. – ICES Journal of Marine Science, 70: 1273–1280. A central theme in ecology is the search for pattern in the response of a species to changing environmental conditions. Natural resource management and endangered species conservation require an understanding of density-dependent and density-independent factors that regulate populations. Marine mammal populations are expected to express density dependence in the same way as terrestrial mammals, but logistical difficulties in data acquisition for many large whale species have hindered attempts to identify population-regulation mechanisms. We explored relationships between body condition (inferred from patterns in blubber thickness) and per capita prey abundance, and between pregnancy rate and body condition in North Atlantic fin whales as environmental conditions and population size varied between 1967 and 2010. Blubber thickness in both males and females declined at low per capita prey availability, and in breeding-age females, pregnancy rate declined at low blubber thickness, demonstrating a density-dependent response of pregnancy to prey limitation mediated through body condition. To the best of our knowledge, this is the first time a quantitative relationship among per capita prey abundance, body condition, and pregnancy rate has been documented for whales. As long-lived predators, marine mammals can act as indicators of the state of marine ecosystems. Improving our understanding of the relationships that link prey, body condition, and population parameters such as pregnancy rate and survival will become increasingly useful as these systems are affected by natural and anthropogenic change. Quantifying linkages among prey, fitness and vital rates will improve our ability to predict population consequences of subtle, sublethal impacts of ocean noise and other anthropogenic stressors.

scholarly journals Using aerial photogrammetry to detect changes in body condition of endangered southern resident killer whales

2018 ◽  
Vol 35 ◽  
pp. 175-180 ◽  
Author(s):  
H Fearnbach ◽  
JW Durban ◽  
DK Ellifrit ◽  
KC Balcomb
Keyword(s):  
Body Condition ◽  
Killer Whales ◽  
Aerial Photogrammetry
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