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Ralf
Riedel
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RALF
RIEDEL
Adjunct
Professor of Biology
M. S. in Fishery Science and
Technology, University of Rhode
Island
Emphasis: Selectivity of fish
harvesting gears
Ph.D in Ecology
University of Illinois U/C
Emphasis: Management of natural
resources
B.S. in Fisheries
Engineering
University of Pernambuco
Emphasis: Design of fish
harvesting gears.
tel. 619-594-0994
fax 619-594-5676
email:riedel@sunstroke.sdsu.edu
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RESEARCH INTERESTS
My professional interest include
research and teaching. My research
interests are described below. The
interaction with students and the
potential for contributing to
environmental literacy motivate my desire
for teaching.
Main Research Interest
I am mainly interested in investigating
the effects of fisheries on ecosystems.
Most of our research effort has been
directed at maximizing yields without much
emphasis on the consequences that actions
towards yield maximization will have on
the ecosystem. I am interested in
addressing the effects of current fishing
practices because they may lead to
irreversible consequences that are
detrimental to marine systems.
I have worked in the fishing industry
and realized first hand how damaging most
fishing practices can be. Bottom trawling
may affect the benthos either directly
(resuspending the sediment, scraping the
floor, or destruction of benthos) or
indirectly (mortality of fish and
long-term changes to the benthos).
Complexity and biodiversity may be reduced
and ecological services compromised when
biogenic and sedimentary structures on
fishing grounds are altered. Reduced
habitat complexity may also increase
vulnerability of exploited species to
predation.
Removal of top predators by pelagic
gear may affect the abundance of the
remaining organisms and the equilibrium of
the ecosystem. As an example, the
incidence of shark bycatches in fisheries
such as long-lines for tuna and billfishes
may impact the ecosystem irreversibly and
possibly affect catches of commercially
important species. Similarly, the bycatch
from small-meshed trawlers may cause a
shift in community structure favoring
non-commercial species.
There is little information on the
impact of fishing on non-commercial
species. Altering the basic productivity
and structure of the ecosystem by
harvesting a fraction of the biota may be
a reason why we have been faced with so
much uncertainty in fisheries management.
Incorporating the various components of
the ecosystem when managing fisheries
resources may improve our understanding of
fluctuations in fish abundance and be a
step toward resource sustainability.
The management of fisheries within
ecological principles by managing the
ecosystem may provide a better alternative
to resource sustainability. Ecosystem
management is an all-inclusive, possibly
more stable alternative to current
management practices. If ecosystem
management is to be successful,
experiments are required of the fishing
effects on habitat and species structure
in an attempt to address the
interconnections of marine systems.
Compromising the ecosystem to attain
management goals is short-sighted to say
the least. Given the current human
population explosion the oceans will not
be a solution to our protein problems.
Overexploiting our oceans based on our
putative needs will only aggravate the
ecological problems we are now facing.
Quantitative Fisheries
-Evaluation of anthropogenic and
environmental effects on fish
populations.
-Relative effects of environmental and
anthropogenic factors to evaluate the
degree of uncertainty when managing fish
stocks.
-Simulation models for stock assessment
and sustainable management.
Marine Ecology
-Inter-intraspecies interactions.
-Predator/prey as related to fisheries -
trophodynamics.
-Direct and indirect effects on ecosystems
of predator or prey removals (as when
overfishing takes place).
-Life-history of alternative fishery
resources.
Fish Behavior
-Fish migration and spatial/temporal
distribution (Seasonal and diel migrations
of fish; larval distributions according to
environmental factors).
-Fish behavior in the vicinity of
harvesting gears.
-Selection of fish harvesting gears.
Publications
DeAlteris, J. and R. Riedel. 1996.
Effect of size selection within and
between fishing gear type on the yield and
spawning biomass per recruit and catch per
unit of effort for a cohort of an
idealized ground fish. Journal of the
Northwestern Atlantic Fishery Science
19:73-82.
Perea, P., S. Sobaski, P. Bayley, R.
Riedel, and D. Philipp. 1996. Database
management and analysis of fisheries in
Illinois lakes: optimizing fisheries
management. Volume 1 Federal Grant
F-69-R-(7-9).
Riedel, R. and J. DeAlteris. 1995.
Factors affecting the performance of the
nordmore grate system: a bycatch reduction
device used in the Gulf of Maine shrimp
fishery, Fisheries Research
24:181-198.
Riedel, R., P. Bayley, and D. Austen.
Power analysis for annual variations in
largemouth bass abundance using a
temporally and spatially large-scale data
set: years-as-replicate vs.
lakes-as-replicate approaches. Transaction
of the American Fisheries Society. (In
Press)
Riedel, R., P. Bayley, and D. Austen.
Influences of environmental effects on the
dynamics of largemouth bass. Canadian
Journal of Fisheries and Aquatic Sciences.
(In Press)
Riedel, R., P. Bayley, and D. Austen.
Effects of sport fisheries management in
Illinois in determining largemouth bass
fluctuations. North American Journal of
Fisheries Management. (In Press)
Riedel, R., P. Bayley, and D. Austen.
Effects of water level fluctuations on
growth of largemouth bass: a management
alternative for mimicing flood pulses in
artificial lakes. North American Journal
of Fisheries Management. (In Press)
Riedel, R., P. Bayley, and D. Austen.
Variation in lake production for
largemouth bass: the usefulness of
morphoedaphic factors. Limnology and
Oceanography. (In Press)
Professional Experience
I recently accepted a position at San
Diego State University studying the Salton
Sea ecosystem, a saltwater lake of
economic and ecological importance in
California. The salinity of the lake has
been increasing during the last several
years and the success of restoring the
lake is intimately linked to understanding
the ecology of the various components of
its fauna and flora. The lake is a bird
sanctuary, providing one of the last
remaining stopover for migratory species
of birds, some of them endangered, like
the brown pelican. The lake also provides
the last refuge for the endangered desert
pupfish and possibly the razorback
sucker.
I have recently completed my work at
the Illinois Natural History Survey
(INHS). At the INHS, my duties were to
compile and analyze a statewide database
for management activities and fish
sampling conducted over the last 30 years
in Illinois state managed lakes. This work
involved: 1. working with all Illinois
district fisheries biologist in collecting
pertinent data for an evaluation of
management practices; 2. performing
analyses to model and investigate the
effects of natural and man-made factors on
the dynamics fish populations; 3.
developing computer programs to handle and
store large amounts of data; 4. physically
organize all information collected. I was
also involved in the mapping and
digitizing of Illinois lakes for
determination of lake morphometry, and
land-use patterns.
Teaching Experience
Course: Computer Applications in
Fishery Science.
Description: this course covered
the use of statistical and fisheries
software, it introduced students to
computer programming, and to the
functioning of computer hardware.
Period: Spring 1993.
Course: Genetics, Evolution, and
Biodiversity.
Description: this course covered
molecular and population genetics,
evolution, and plant/animal ecology and
anatomy.
Period: Fall 1996, Spring and Fall
1998.
Professional Experience
University: San Diego State
University
Position: Adjunct Faculty.
Period: 1999 -
Company: On-The-Job
Consulting
Position: Web page developer (ASP,
CGI, Perl, Java, SQL).
Period: 1998 - 1999
Company: Illinois Natural
History Survey
Position: Research assistant.
Period: 1993 - 1998
Company: CEBEL
Position: Software developer (C and
Clipper) and system analyst.
Period: 1988 - 1990
Company: Kowalsky Ind. Pescados
S/A
Position: Crew member in the shrimp
trawling, sardine purse seining, and pair
bottom trawling fisheries.
Company: Norte Pesca S/A
Position: Crew member in the
surface longlining fishery.
Company: Katsushio Suisan Kabushiki
Kaisha
Position: Gear Technologist in the
skipjack pole-and-line- fishery.
Period: 1986 - 1989
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