Presentation on theme: "Chapter 14: Wildlife, Fisheries, and Endangered Species"— Presentation transcript:
1Chapter 14: Wildlife, Fisheries, and Endangered Species
2Wildlife, Fisheries, and Endangered Species Common history of exploitation, management and conservationWhen saving a species, what is it we really want to save?1. A wild creature in a wild habitat, as a symbol to us of wilderness.2. A wild creature in a managed habitat.3. A population in a zoo.4. Genetic material only.
3Wildlife, Fisheries, and Endangered Species Involves science and valuesMany reasons for wishing to save endangered species.Policies and actions differ widely depending on goal chosen.
4Single-Species Wildlife Management Conservation and management often viewed each species as a single population in isolation.1. The population could be represented by a single number, its total size.2. Undisturbed by human activities, a population would grow to a fixed size, called the “carrying capacity”.3. Environment, except for human-induced changes, is constant.
5Single-Species Wildlife Management This perception illustrated by the S-shaped logistic growth equation.Two goals resulted:1. For a species we intend to harvest: maximum sustainable yield2. For a species we intend to conserve: remain at its carrying capacity
7Single-Species Wildlife Management This approach failed.None of the assumptions were true.Population cannot be represented only by a single number.Do not remain at a fixed carrying capacity.The environment is not constant.
8Single-Species Wildlife Management Necessary to include an ecosystem and landscape context for conservation and management.New goals:For a species to be harvested: sustain a harvestable population in a sustainable ecosystemFor a species that is threatened or endangered: minimum viable population
9Logistic Growth Curve Include the following ideas: A population that is small in relation to its resources grows at a nearly exponential rate.Competition among individuals in the population slows the growth rate.The greater the # of ind, the greater the competition and the slower the rate of growth.Eventually, a point is reached, called the “logistic carrying capacity”.
10Logistic Growth CurveAt this level, the # of births in a unit time equals the number of deaths, and the population is constant.A population can be described simply by its total #.Therefore, all individuals are equal.The environment is assumed to be constant.
11Carrying Capacity Has three definitions. 1. Logistical carrying capacity- the # of ind is just sufficient for the available resources.2. An abundance at which a population can sustain itself w/o any detrimental effects that would decrease the ability of that species to maintain that abundance.3. Optimum sustainable population- the max pop that can be sustained indefinitely.
12Logistic Growth CurveAnother key concept is that the population size that provides the max sustainable yieldExactly one-half of the carrying capacity.Other estimating MSY will lead to overharvesting.
15The Grizzly Bear An endangered species US Fish and Wildlife Service must meet the requirements of ESABecame endangered as a result of hunting and habitat loss.Removed because dangerous to humans and livestock
17The Grizzly Bear Restore to what? Past abundance (this is unknown) Also lack good estimates of present abundanceEstimates include 1,200 in contiguous states, 32,000 in Alaska and 25,000 in CanadaBased on Lewis and Clarks records (and a number of assumptions)The # of grizzly bears in 1805 in the US was 12,000Another approach is to ask what the min viable pop is.
18The American Bison Brought close to extinction for 2 reasons Hunted to make coats that were fashionable in Europe.Killed as part of a warfare against the Plains peoples.
21The American Bison Bison have recovered Profitable for ranchersCurrently 200, ,000 BisonEstimates of original herds range for 10s of millions to > 50 millionAfter Civil War protest over the slaughter15 years later only 1000+/- remained
22Improved Approaches to Wildlife Management Four principles of wildlife conservationA safety factor in terms of population size, to allow for limitations of knowledge and the imperfections of procedures.Concern w/ the entire community of organisms and all the renewable resources.Maintenance of the ecosystem of which the wildlife are a part.Continual monitoring, analysis, and assessment.
23Improved Approaches to Wildlife Management Principles broaden the scope from a narrow focus on a single species to inclusion of the ecological community and ecosystem.
24Time Series and Historical Range of Variation set of estimates over a # of years.Historical range variation-the known range of abundance of a population of species over some past time intervalE.g. American whooping crane
27Age Structure as Useful Information An additional key to successful wildlife management.E.g. salmon from the Columbia River, WAShift in catch towards younger ages, along with an overall decline in catch, suggests that the fish were being exploited to a point at which they were not reaching older ages.Early sign of overexploitation
28Harvests as an Estimate of Numbers Another method of estimating animal populations is to use the # harvested.Previous animal abundance can also be estimated byCatch per unit effortAssumes same effort by all per unit time (same tech)So if you know the total time spent in hunting and catch per unit effort, you can estimate total popE.g. bowhead whale
37The Decline of Fish Populations Evidence that fish populations were declining came from the catch per unit effort.Suggests fishing depletes fish quicklyAbout 80% decline in 15 yearsCommercial fisheries are mining a resource not sustaining it.
40The Decline of Fish Populations Chesapeake BayFamous for oysters and crabsBreeding and spawning ground for many commercially valuable speciesFood webs very complexAlso influenced by runoff, introductions, development, alteration in salinity
43The Decline of Fish Populations Crisis has arisen for one of the living resources most subjected to science-based management.Management based on logistic growth curveFisheries subjected to the “tragedy of the commons”
45The Decline of Fish Populations Fishing gear can be destructive to habitat.Ground-trawling equipment destroys the ocean floorLong-line fishing kills sea turtles and other non-target surface animalsLarge tuna nets have killed dolphins.
46Can Fishing Ever be Sustainable? Few wild biological resources can sustain a harvest at a level that meets even low requirements for a growing business.We can turn to farming fish (aquaculture)Important food source in China, growing worldwideCan create environmental problemsE.g. Atlantic salmon fisheries cause water pollution and loss of genetic diversity
47The Current Status of Endangered Species The # of species listed as threatened or endangered increasingIUCN maintains a list known as the Red List20% of all know mammals at risk31% of amphibians3% of fish12.5% of plants recently extinct or endangered
49The Current Status of Endangered Species The term endangered species as defined by the ESA“Any species which is in danger of extinction throughout all or a significant portion of its range…”With the exception of insect pestsThe term threatened species“Means any species which is likely to become an endangered species w/in the foreseeable future throughout all or a significant portion of its range.”
50How a Species Becomes Endangered and Extinct Local extinctionOccurs when a species disappears from a part of its range but persist elsewhere.Global extinctionMeans a species can no longer be found anywhere
51How a Species Becomes Endangered and Extinct Rate of extinctions has varied over geologic timeFrom 580 million years ago until industrial revolution about one species per yearRate of evolution of new species =or > the rate of extinctionAverage longevity of a species 10 million yearsOther periods of “punctuated extinctions”
55How People Cause Extinctions and Affect Biological Diversity By hunting or harvesting.By disrupting or eliminating habitats.By introducing exotic species.By creating pollution.
56How People Cause Extinctions and Affect Biological Diversity The IUCN estimates 75% of the extinction of birds and mammals since 1600 have been caused by humans.Current extinction rate estimated to be 1,000 times greater than extinction rate in Pleistocene
57Good News Species whose status has improved Elephant seal Sea otter Many bird species effects by DDT, including bald eagle, brown pelican, white pelican, osprey and peregrine falcon.Blue whaleGray whale
58Can a Species be too Abundant? Sea lions now number 50,000 and have become a problem in S.F. and S.B. HarborsMountain lions in CaliforniaBoth mountain lion and human population growingPeople building in lion habitatAttacks more common
59The Kirtland’s Warbler and Environmental Change Many species are adapted to natural environmental change.If change eliminated the species can become endangeredKirkland’s warbler in MichiganFrom found to be decliningNest in jack-pine woodlands that are between 6-12 years old
61The Kirtland’s Warbler and Environmental Change Jack pine adapted to fireCones open only after they are heatedTrees intolerant of shadeAbundance of dead branchesKirkland’s warbler requires change at short intervalsFire approximately every years
63The Kirtland’s Warbler and Environmental Change Fire suppression became the practice in 1927 and area replaced with economically useful species.Now the Recovery Plan calls for prescribed burns
64Ecological Islands and Endangered Species An ecological islandan area that is biologically isolated, so a species living there cannot mix w/ any other population of the same species.Mountain topsPondsReal geographic islands
68Ecological Islands and Endangered Species Almost every park is a biological island.How large must an ecological island be to ensure survival of a species?Depends on species requirements
69Using Spatial Relationships to Conserve Endangered Species Red-cockaded woodpeckerAn endangered speciesNests in old dead or dying pinesFeeds on pine bark beetle which hare a pest to the treeA new approach to conservationOverlay a map of one’s habitat requirements over a map of the other’sCo-occurrence can be compared and allow maintenance of all three specie