Wildlife, Fisheries, and Endangered Species Unit 3 AP Environmental Science (Chapter 14)

What are we trying 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.

Single-Species Wildlife Management Conservation and management often viewed each species as a single population in isolation. Assumptions: The population could be represented by a single number, its total size. Undisturbed by human activities, a population would grow to a fixed size, called the “carrying capacity”. Environment, except for human-induced changes, is constant.

Single-Species Wildlife Management This perception is illustrated by the S-shaped logistic growth equation. Two goals resulted: 1. For a species we intend to harvest: maximum sustainable yield 2. For a species we intend to conserve: remain at its carrying capacity

Single-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.

Single-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 ecosystem For a species that is threatened or endangered: minimum viable population

Logistic Growth Includes 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 individuals, the greater the competition and the slower the rate of growth. Eventually, a point is reached, called the “logistic carrying capacity”.

Carrying Capacity Has three definitions. 1. Logistical carrying capacity- the # of individuals is just sufficient for the available resources. 2. An abundance at which a population can sustain itself without any detrimental effects that would decrease the ability of that species to maintain that abundance. 3. Optimum sustainable population- the max population that can be sustained indefinitely.

Maximum Sustainable Yield Maximum number of organisms that can be harvested from a population and maintain population size Exactly one-half of the carrying capacity. Over estimating MSY will lead to overharvesting.

Maximum Sustainable Yield

The Grizzly Bear An endangered species US Fish and Wildlife Service must meet the requirements of ESA to restore the population Became endangered as a result of hunting and habitat loss. Removed because dangerous to humans and livestock

The 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.

The American Bison Bison have recovered Profitable for ranchers Currently 200,000- 300,000 Bison Estimates of original herds range from 10 – 50+ million After Civil War protest over the slaughter 15 years later only 1000+/- remained

Improved Approaches to Wildlife Management Four principles of wildlife conservation A safety factor in terms of population size, to allow for limitations of knowledge and the imperfections of procedures. Concern with 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.

Improved Approaches to Wildlife Management Principles broaden the scope from a narrow focus on a single species to inclusion of the ecological community and ecosystem.

Time Series and Historical Range Time series- set of population estimates over a number of years. Historical range variation- the known range of abundance of a population of species over some past time interval (rarely available) Analysis of these two trends show the probability of extinction for a species

Age Structure Information Shows the number of organisms in various age ranges so predictions can be made about the future of a population E.g. salmon from the Columbia River, WA Shift 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

Harvest Estimates Another method of estimating animal populations is to use the number harvested. Previous animal abundance can also be estimated by catch per unit effort Assumes same effort is exerted by hunters/harvesters per unit time as long as they have the same technology (Ex: same equipment used) If you know the total time spent hunting/harvesting and the catch per unit effort, you can roughly estimate total population

Fisheries Fish are an important food source 16% of the world’s protein In developing countries fish make up much larger percentages of the average diet Global fish harvests are on the rise Japan, China, Russia, Chile and the United States dominate fisheries Continental shelves make up only 10% of the ocean ecosystem but provide 90% of fish harvested

Continental Shelves Fish are abundant where food resources are abundant, like places of high algae growth Algae grow best in environments that have high concentrations of chemical elements like Nitrogen and Phosphorus Upwelling along coastlines and on the continental shelves keep up the steady supply of chemical nutrients

Global Fisheries

Fisheries The world’s fish harvest has increased greatly since the middle of the 20th century Increase in number of boats Improvements in technology Increases in aquaculture production

Aquaculture Fish harvest numbers more than doubled from 1960-1980 and nearly doubled again from 1980- 2000 largely due to increases in aquaculture Aquaculture currently provides more than 1/5 of all fish harvested

Fisheries Current trends from the catch per unit effort show evidence that fish populations are declining Suggests fishing depletes fish quickly Shows about an 80% decline in 15 years Large predatory fish are currently at less than 10% pre-industrial levels Commercial fisheries are mining a resource not sustaining it.

Chesapeake Bay Estuary Largest estuary in the United States Drains an area from New York to Maryland including 48 major rivers and 100 smaller ones Famous for oysters and crabs Breeding and spawning ground for many commercially valuable species Complex food webs Heavily influenced by runoff, exotic species, development, and alteration in salinity

Chesapeake Bay The bay area is being studied by ecologists to try and determine what environmental factors have led to the changes in fish species native to the estuary Many issues have arisen from the past management systems (based largely on the logistic curve model), and the open resource nature of fisheries (“tragedy of the commons”) Fishing gear also damages ecosystems. Trawling disturbs the sea floor while net and line fishing fail to catch just the target fish

Can fishing 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 worldwide Can create environmental problems E.g. Atlantic salmon fisheries cause water pollution from excrement and excess food, and can lead to a loss of genetic diversity. In 2000 Atlantic salmon were put on the endangered species list.

Current Status of Endangered Species The number of species listed as threatened or endangered is increasing International Union for Conservation of Nature maintains a list of endangered species called the Red List 21% of all known mammals at risk 12% of birds 28% of reptiles 30% of amphibians 37% of freshwater fish 35% of invertebrates 70% of plants

Current Status of Endangered Species The term endangered species as defined by the Endangered Species Act of 1973 “Any species which is in danger of extinction throughout all or a significant portion of its range…” With the exception of insect pests The term threatened species “Means any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.”

CITIES legislation Convention on International Trade in Endangered Species (1975) Legislation that ensures that international trade in plant and animal life does not threaten the survival of the species in the wild Believes in the ecological value of protecting all organisms, even those that are valued for economic reasons

How a species becomes extinct Local extinction Occurs when a species disappears from a part of its range but persist elsewhere. Global extinction Means a species can no longer be found anywhere

How a species becomes extinct Rate of extinctions has varied over geologic time From 580 million years ago until the industrial revolution about one species per year went extinct Rate of evolution of new species has usually equaled or slightly exceeded the rate of extinction Average longevity of a species 10 million years Certain periods of time have demonstrated catastrophic loss of species or rapid evolution of species in what is called “punctuated extinctions”

How humans influence extinction patterns By hunting or harvesting. By disrupting or eliminating habitats. By introducing exotic species. By creating pollution. Estimates are that 75% of the bird and mammal extinctions since 1600 have been caused by humans. This rate is 1,000 times higher than the extinction rate at the end of the Pleistocene epoch

Endangered Species Act of 1973 Since the U.S. Endangered Species Act was put into place conservation efforts have helped 43 species recover from “endangered” to “threatened” or removed from the list entirely An additional 33 and possibly more species have the potential soon to recover status

Can species be too abundant? Sometimes conservation efforts lead to negative side effects from the protection of species whose populations have been allowed to get too large The Marine Mammal Protection Act of 1972 led to the improvement of many marine mammals now not allowed to be hunted Sea lions have become so abundant in some areas that they pollute the water with their excrement and become a nuisance to human activity

Kirtland’s Warbler Many species are adapted to natural environmental change. If that change eliminated the species can become endangered Kirkland’s warbler in Michigan From 1951-1971 census of the species found it to be declining Build their nests in jack-pine woodlands that are between 6-12 years old

Kirtland’s Warbler Jack-pine trees ages 6-12 have dead branches close to the ground that promote the occurrence of forest fires After 1927 people were encourage to replace jack pine trees with economically useful species of trees in an effort to suppress fires Only the introduction of controlled burning and allowing jack pine to grow again saved the warbler species

Ecological Islands and Endangered Species An ecological island an area that is biologically isolated, so a species living there cannot mix w/ any other population of the same species. Mountain tops Ponds Real geographic islands

Ecological 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

Using Spatial Relationships to Conserve species Red-cockaded woodpecker An endangered species Nests in old dead or dying pines Feeds on pine bark beetle which hare a pest to the tree A new approach to conservation Overlay a map of one’s habitat requirements over a map of the other’s Co-occurrence can be compared and allow maintenance of all three species