10-06-2005, 01:18 PM
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#2
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King Salmon
Join Date: Jun 2003
Location: woodstock
Posts: 10,511
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Re: Sealions / Columbia River Spring Chinook??
This might be good news.
Quote:
San Miguel Island
Population assessment studies of California sea lions and northern fur seals were conducted from May through September at San Miguel Island, California. The field research in 2002 was a continuation of long-term studies of survival, recruitment, natality, and health of California sea lions and northern fur seals.
In 2002, total production for California sea lions was 23,604, which represents a 1.5% increase from 2001. The observed pup mortality rate was 21.8% by 3 months of age. We began a study investigating the causes of California sea lion pup mortality in the first year of life in June 2002. We collected up to 30 fresh dead California sea lion pups once each month between June and September and conducted a complete necropsy on each pup. Hookworm infection rates were near 100% . It is likely that these infections are a significant cause of mortality of California sea lion pups and may have a population level effect on the dynamics of the population if the high incidence and mortality continue over several more years. We plan to continue to monitor the health of the population to document the population response to this density-dependent parasite.
In September, 500 sea lion pups were branded marking the 15th year of branding at San Miguel Island. The branding study continues to provide data for estimation of age-specific survival and natality and recruitment rates of sea lions and will provide insight into the impacts of environmental changes and disease on the vital parameters of the population. In 2002, a total of 7,092 observations of 1,695 individually branded California sea lions, ages 1 to 15, were recorded between June and August 2002. The number of females with pups decreased 14% from 2001. The decrease in the number of pupping females may reflect adult female mortality related to a large-scale demoic acid event in the spring of 2002. More than 400 adult and juvenile sea lions were stranded along the central California coast. Most of those animals that were transferred to rehabilitation centers died due to demoic acid toxicity in the brain.
In 2002, total production of northern fur seals on San Miguel Island was 1,947, a 4.3% decrease from 2001. The northern fur seal pup production has slowly increased since the 80% decrease in pup production in 1998, but in 2002 production was still 37% below 1997 production. The slow recovery of the population from the 1997-98 El Niño event indicates that adult mortality occurred then, in addition to pup and juvenile mortality, and that full recovery of the population may be several years in the future.
Resights of tagged fur seals are also providing information on age-specific survival and recruitment of the small population at San Miguel Island. In September, 300 northern fur seal pups were tagged to continue long-term studies for estimation of vital parameters of this population.
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Mother nature knows how to deal with over population.
salmon hugger
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salmon hugger
"A curious thing happens when fish stocks decline: People who aren't aware of the old levels accept the new ones as normal. Over generations, societies adjust their expectations downward to match prevailing conditions." Kennedy Wame
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AnnaDraMoss
Linear Mode
