A Case Study on the removal of
sharks and wolves
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Ian Craick
Bernice Longouo
Jeremy Raynor
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Apex predators are the top level predators in an ecosystem.
This means that they have no natural predators
Humans become predators – upset the natural balance
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What is removal?
How are predators removed?
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Ecosystems Services
Ecosystem dynamics and function
Energy and nutrient flow
Human Health
The importance of predation
- predators have a fundamental influence on structure and
function of ecosystem
- Predators influence prey population and community
-Predation affect prey behavior. Presence of predator allow
prey to use behavioral mechanism to reduce predation risk.
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Large shark populations down by about 90% or more
regionally
Found out of 547 species studies 20% were threatened
(sharks, rays, chimaeras)
Difficult to measure due to mobility and low populations of
Nicholas Dulvy 2006
target species
Heithaus et al. 2008
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How do apex predators influence Nutrients flow?
Mainly through Biologic factors
Two methods:
-Top Down Control
-Trophic Cascades
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Changes in top predators influence the abundance and
behavior of organisms in lower trophic levels
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Top predators influence trophic levels two or more levels
below them
Post 1999
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Wolf removal has seen major spikes in Deer, Elk, Moose
and other prey populations
Wolf re-introduction has seen decreases in prey populations
and significant increases in foliage
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Last Wolves exterminated in 1926 within the park
Re-introduced in 1994-95
Pack reached a record high of approximately 40 individuals
Elk populations rise when wolves are exterminated,
decreased after peak (resource limited) then decreased to
~pre-extermination levels after re-introduction of wolves
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Shark presence shapes prey behavior
Shark Bay, Australia
Behavior changes
-Spatial
-Temporal
Fear – Politics – Apathy – Ignorance - Greed
North American Gray wolf
(canus lupus)
Ripple et al 2005
Black Tip Shark population
off the East Coast of the
United States
Heithaus et al. 2008 article FIU
Shark Finning
Fear – Ideas of sharks as competitors and dangerous
Money – Shark fin soup market growth in China
Accidental Catch (bycatch) Long Lines, Trolling, Siene Netting
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Defenders of Wildlife Wolf Video Clip
Last month, Idaho’s Governor
Otter signed a bill creating a
$400,000-per-year wolf
extermination fund.
State-funded culling programs
Approximately 1,300 Wolves have been killed in Idaho alone since 2011
There ARE solutions
 There ARE things YOU can do to help
Scientifically proven equations for success
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MPA (Marine Protected Areas)
National Parks
IUCN Red List (International Union for Conservation of Nature)
CITES (International Trade Regulations)
Magnuson-Stevens Act (Fishery Conservation, Mgmt. USA)
Shark Finning Prohibition Act (USA)
ESA - Endangered Species Act (USA)
Biodiversity Hot Spots
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Education based on Long Term Scientific Studies
Advocacy based on the facts, environmental lobbyists
Awareness & Action:
Know the issue from multiple perspectives (Volunteer)
Know the history and current situation (Investigate)
Make a difference voice your opinion & support research
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Abesamis, R A, and G R. Russ. "Density-dependent Spillover from a Marine
Reserve: Long-Term Evidence." Ecological Applications. 15.5 (2005):
1798-1812. Print.
Beschta, R L, and W J. Ripple. "River Channel Dynamics Following Extirpation of
Wolves in Northwestern Yellowstone National Park, Usa." Earth Surface
Processes and Landforms : the Journal of the British Geomorphological
Research Group. 31.12 (2006): 1525-1539. Print.
Dulvy, Nicholas K. "Conservation Biology: Strict Marine Protected Areas Prevent
Reef Shark Declines." Current Biology. 16.23 (2006). Print.
Graham, Nicholas A. J, Mark D. Spalding, and Charles R. C. Sheppard. "Reef
Shark Declines in Remote Atolls Highlight the Need for Multi-Faceted
Conservation Action."Aquatic Conservation: Marine and Freshwater
Ecosystems. 20.5 (2010): 543-548. Print.
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Heithaus, MR, A Frid, AJ Wirsing, and B Worm. "Predicting Ecological
Consequences of Marine Top Predator Declines." Trends in Ecology &
Evolution. 23.4 (2008): 202-10. Print.
Kareiva, Peter. “Conservation Biology: Beyond Marine Protected Areas”
Current Biology. 16.14 (2006). Print.
Knip, D.M, M.R Heupel, and C.A Simpfendorfer. "Evaluating Marine Protected
Areas for the Conservation of Tropical Coastal Sharks." Biological
Conservation. 148.1 (2012): 200-209. Print.
Ripple, William J., and Robert L. Beschta. "Linking wolves and plants: Aldo
Leopold on trophic cascades." BioScience 55.7 (2005): 613-621.
Robbins, William D, Mizue Hisano, Sean R. Connolly, and J H. Choat. "Ongoing
Collapse of Coral-Reef Shark Populations." Current Biology. 16.23 (2006):
2314-2319. Print.
Post, Eric, et al. "Ecosystem consequences of wolf behavioral response to
climate." Nature 401.6756 (1999): 905-907.
A Case Study on the removal of
sharks and wolves
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“To keep every cog and wheel is the first precaution
in intelligent tinkering” –Aldo Leopold
Ian Craick
Bernice Longouo
Jeremy Raynor