if multiple users utilize all the growth of a renewable resource
conservation only works if all users participate
otherwise, the conservationists' share is simply taken by non-conservationists
the larger the common property the more difficult the problem becomes
an international high-seas fishery examplifies the situation
removal of fisheries from common property is a necessary step in management (if possible)
e.g. with taxes, licensing, fisher quotas, etc.
yet very difficult to adopt these policies in a free-market economy
even more so in international waters
Other Commercial Fishery Problems
High processing cost after the fish are caught
High initial investment, yet operators are at the mercy of local, state, and federal regulation
e.g. fisher invest life savings in one type of gear, yet it may be banned the next year
High-risk occupation: losses of equipment and/or catch frequent
Small changes in retail price of fishes has a great economic impact
e.g. fish: $5/lb of which fisher makes some $0.30/lb; if $4.70/lb goes for processing and distribution and the retail price falls to $4.85/lb, the fisher losses 1/2 his profits
Economic squeeze
cost of fishing increases, yet prices recieved for fish often remain stable because of low demand, rising distribution, and processing costs, foriegn compettion, and competition from agriculture
this leads to economic marginality
i.e. the fisher is just getting by economically
usually results in greater fishing efforts
economic marginality leads to biological marginality
i.e. the populations are so reduced that their ability to regenerate is diminished
because most of the fishing fleets are under the same economic conditions
leads straight back to the "tragedy of the commons"
small operators using conventional gear have largely been replaced by large operators that are technologically sophisticated
i.e. smaller boats servicing a mothership
Like so many other facets of a technological society, the military has had a large impact on fisheries.
largely due to the development of SONAR, new navigational technology, synthetic fibers(nets), ocean-going vessels
the world's production of fish rose from a pre-war figure of 20 million metric tons (MMT) to 70 MMT by the early 1970's
production then leveled off and even now declines
concern for the natural limits of fish production has spurred the development of aquaculture(another branch of fisheries science)
Conservation and Management of Resource Organisms
Fisheries Management Policy (regulations)
Knowledge of exploited animal populations
distribution
spawning grounds
basic biology including reproductive biology
growth
morphology
behavior
physiology
population parameters
age composition
recruitment
mortality
Knowledge of the exploited animals ecology
physical factors which limit the population
fish relationship with water chemistry
temperature
bottom conditions e.g. substrate type
currents
seasonal changes
pollution
Biotic factors which limit the population
interrelationships among species
competitive interactions
food webs
Knowledge of humans as predators (food webs)
numbers of fishers (# of licenses)
time spent fishing (effort and catch)
Enforcement of regulations
policing
conservation officers
Penalties
meaningful (usually involve time) education programs, etc.
Practical steps toward the Conservation of Aquatic Resources
National Environmental Policy Act (NEPA): 1969
establish policies that utilize an interdiscplinary approach which integrates the concerns of the natural and social sciences when making policies that have an impact on human environment
environmental impact statements are required in every proposal for legislation
Marine Mammal Protection Act: 1972
prohibits the taking of marine mammals (with few exceptions)
Endangered Species Act: 1973
established worldwide list of endangered and threatened species, and strigent requirements for their protection and the protection of their habitats
Fishery Conservation and Management Act: 1976
established 200 miles exclusive economic zone (EEZ)
gives individual nations with coastal zones control of fishing rights up to 200 miles offshore
Fisheries Scientist; the types of work they do and where they do it
Descriptive and Experimental Biology
qualitative and quantitative documentation
experiments that show cause and effect
e.g. A. Ichthyology (other taxa too)
biogeography
systematics
physiology
endocronology
behavior
reproduction
migration
genetics
****Molecular biology can be a part of any of the above or not****
A. Ecology
limnology
oceanography
hydrology
population biology
population dynamics
models
community ecology
competition
trophic relationships
e.g. food webs
conservation biology
e.g. long-term monitoring
Social Services
Economics
Law
Fish Preservation
Chemistry
Microbiologists of fish flesh
Fisheries scientist may be basic or applied researchers
Characteristics of Basic Research
Basic researchers are primarily university faculty, students, and to a lesser extent, government agencies
Basic research is rarely about fisheries research per-say
it covers topics which may be useful to a fishery
e.g. food prefence work basic to understanding a species has practical application
researchers typically work alone or in small groups (theory, data collection, analysis, report writing)
Basic research usually searches for generality
Funding is relatively difficult
Essential: forms the basis fo scientific knowlegde
Applied Research
research used to solve a specific problem
basic research forms the foundation for applied research
examples of applied research problems in fisheries management
Assesment of fish stocks
migration
reproduction
growth, abundance, effects of fishing, and environmental change
Control of fishing
effects of regulations on biological and social variables, enforcement problems
Aqua-culture: control of reproduction(endocrinology)
behavior and physiology (responses to gear) location systems, effectiveness of gear, fishing stradegy, fish flesh preservation, marketing
Stock Enhancement
fits between assesment and aqua-culture
Control of Introduced Species
fits between assesment of fish stocks and environmental protection
Recovery of endangered species
fits between assesment, environmental protection, and aqua-culture
Characteristics of Applied Research
Applied research is primarily performed by government labs, agencies, and institutions
Research goal is usually not an end in itself
usually a step toward the solution of a specific practical problem
Work is usually done by a team on a very specific schedule
Research is narrow in scope
Funding is relatively abundant
Essential to a successful resource-human interaction
In application
Fisheries decisions involve many factors and the people working on the problems have diverse views
Agencies try to cover many views and work as a team
Decisions are almost always tentative because the problems are dynamic
Decisions are constantly reviewed and altered
The Aquatic Environment
Water covers approximately 71% of the Earth's service
approximately 98% of the water is in the oceans
only about 0.02% occurs as freshwater, as atmospheric vapor, inland water, and circulating groundwater
the balance is found in ice on the poles and on landmasses
The Water Cycle
Rain or Snow from atmosphere
Evaporation
A. ground
B. lakes and streams
C. ocean
(Goto 1)
Transpiration from plants (goto 1)
Drainage above and below ground (goto 2b and/or 2c)
Lotic Environments: Streams and Rivers
i.e. running water
Classification of Stream Order
First Order streams are the terminal twigs, the headwaters of a stream system
at least two streams of any given order are required to form the next higher order stream
there are problems with classification due to intermidancy in headwater reaches that reduce the accuracy of categorization
10th Order rivers are rare (e.g. Mississippi River, probably the only one in North America)
a stream network occupies a catchment area which is usually the same as a drainage area
however, note that a drainage area may be larger than a catchment area if an adjacent catchment area is tapped from underground
Lentic Environments: Standing Water
stratification occurs seasonally in most shallow, freshwater lakes
only a thin surface layer is warmed through radiation by the sun
90% of heat is absorbed within 4 to 20 meters (depends on the turbidity of the water)
heat is conducted downward through mixing
stratification results in no mixing of the upper and lower layers of the water
it occurs due to the temperatuer and density differences between layers
note that water is most dense at approximately 4 degrees C
either colder or warmer temperatures result in less dense water
Typical Pattern(s) of stratification
Late Spring and Summer
water at surface heats up
differential temperatures at surface and bottom cause a density differential
light summer winds are insufficient to overcome the density differential
stratification results
the upper mixed warm layer is the epilimnion
the lower unmixed cold layer is the hypolimnion
Note: Littoral zone extends to the edge of the rooted plants. The trophogenic zone is defined by the presence of photosynthesis.
Fall
air temperature declines and so does the temperature at the water's surface
density differential is reduced
fall usually produces stronger winds
even light winds are usually (lake specific) enough for mixing (if shallow)
Winter
ice covers the lake
results in reverse stratification
i.e. coldest water is now on top
Early Spring
temperature increase
ice melts
density differential is reduced
easily mixed by wind
thus a typical temperate lake will have two periods of stratification and two periods of mixing per year
late spring, summer, and winter stratification
early spring and fall mixing
Turn-over: loss of stratification
Oxygen is used up in the hypolimnion
note that photosynthesis is occuring at great rates in the warm and light penetrated epilimnion
dead material and waste fall to the hypolimnion
microbes utilize oxygen decomposition
may also form a zone of deoxygenation (where only anaerobic bacteria live)
the size of this zone is important in determining the operational size of the lake
very important in shallow water
e.g. calm water for a few days
stratification
bottom water may have a rapid deoxygenation
possible for the whole water depth in shallow warm-water fish ponds
may result in great loss of fish stock
loss of stock may also happen by deoxygenation if small lake is covered with ice/snow too long
only a small amount of photosynthesis occurs through the ice and snow
oxygen problems are complicated by the fact that oxygen saturation varies with both temperature and salinity
saturation concentration decreases with increases in temperature and salinity
thus warm-water ponds may be difficult to manage from this standpoint
Species
Minimum Dissolved Oxygen Requirement
Tilipia
3mg/L
Salmonids
5-6mg/L
Mahimahi(juv)
5-6mg/L
saturation concentration of marine water (i.e. 35% NaCl) at 27 degrees C is 6.7mg/L
Oceans
average depth is 3800m or approximately 4.5 times the average elevation of land
greatest depth in trenches
e.g. Mariana Trench: 11,000m deep
fishing takes place in relatively shallow water (<500m)
approximately 91% of the ocean floor is beyond the reach of most commercial fishing gear
most fishes are found over continental shelves and most fishing takes place there
shelf margins, on average, are about 130m deep, but 200m is often used as the demarkation
most fishing occurs on the shores for both benthic and pelagic species
shelves follow terrestrial topography
widest off coastal plain, narrowest off mountain regions
range in width from 0-1300km
the major shelves (and fishing grounds) are found off NW Europe, off Alaska, and Eastern Asia, off South America east of Argentina, and off North America between Cape Hatteras and Newfoundland
beyond shelves, continental slopes lead to deep water
Currents
they transport heat, dissolved materials(nutrients) and solids
all three can be ecologically important
temperature and solids play important roles in determining habitat type and thus what species may live in an area
temperature is fairly obvious
niche dimension
bottom type is also very important
sandy bottome, rocky bottom, etc.
nich dimension
nutrients will largely determine they primary productivity which will lead largely determine the carrying capacity of the environment
Causes of Currents
wind is the primary force of surface currents in oceans and lakes
shearing forces of the wind drive the water
ocean waves travel thousands of miles
in lakes the water travels to the far shore where it "piles-up"
in general circulation in lakes is highly variable and will be lake specific where it is going to depend on lake shape, depth, and the strength, steadiness,a nd fetch of the wind
epilimnion becomes slightly decreased toward the wind and slightly increased on the far shore
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