| dc.description.abstract | Exploitation of northern stocks of the crayfish Orconectes
virilis (Hagen) produced significant alterations in several
population parameters. High fishing efforts increased per capita
fecundity, young-of-year (YOY) production, and age- and sex-specific
growth, and altered mortality patterns. Climatic variation, measured as arbitrarily defined weather variables, did not influence life history parameters in the exploited population. However, short-term temperature fluctuations affected YOY production and future reproductive potential in the control lake. The control population in Shallow Lake exhibited strong
density dependence in regulating both mortality and growth rates
of pre-recruit age classes. Behavioural dominance by maturing
males (age I-to-age II) effectively controlled juvenile life
history parameters , i.e., egg-to-YOY and YOY-to-age I mortality
and growth. As a result a dynamic oscillatory relationship
existed between annual age I-to-age II male growth and female
year-class strength, which in turn correlated with cohort egg
production. Exploitation of Dock Lake's population broke down
this process so that year-class strength directly correlated with
annual growth but cohort egg production varied independently. The
amount harvested, using passive fishing gear, proportionately
increased with increases in nominal effort. However interactions
between sampling intensity, duration of harvest and behavioural
responses resulted in a upper limit to the percent of the
exploitable stock that that could be removed by this fishery.
Rlteration of life history parameters contributed to population
resilience and stability as fishing pressure increased. | |
