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Geology topics

S. P. VanderKooi

Publications and source records attributed to S. P. VanderKooi.

29 records · Page 2Linked to original sources
USGS2001

The effects of electroshock on immune function and disease progression in juvenile spring chinook salmon

Although much is known about the effects of electroshock on fish physiology, consequences to the immune system and disease progression have not received attention. Our objectives were to determine the effects of electroshock on selected immune function in juvenile spring chinook salmon Oncorhynchus tshawytscha, the mechanism of any observed alteration, and the effects of electroshock on disease progression. We found that the ability of anterior kidney leukocytes to generate antibody-producing cells (APC) was suppressed 3 h after a pulsed-DC electroshock (300 V, 50 Hz, 8 ms pulse width) but recovered within 24 h. This response was similar in timing and magnitude to that of fish subjected to an acute handling stress. The mechanism of suppression is hypothesized to be via an elevation of plasma cortisol concentrations in response to stress. Other monitored immune functions, skin mucous lysozyme levels, and respiratory burst activity were not affected by exposure to electroshock. The progression of a Renibacterium salmoninarum (RS) infection may have been altered after exposure to an electroshock. The electroshock did not affect infection severity or the number of mortalities, but may have accelerated the time to death. The limited duration of APC suppression and lack of effects on lysozyme and respiratory burst, as well as infection severity and mortality levels in RS-infected fish, led us to conclude that electrofishing under the conditions we tested is a safe procedure in regards to immunity and disease.

Transactions of the American Fisheries Society↗
USGS2000

Preliminary study of gill NA+,K+-ATPase activity in juvenile spring chinook salmon following electroshock or handling stress

We compared gill Na+,K+-ATPase in subyearling and yearling spring chinook salmon Oncorhynchus tshawytscha 3 h, 24 h, and 7 d after exposure to either a short pulsed DC electroshock (300 V, 50 Hz, 8-ms pulse duration) or an acute handling stress. Mean gill Na+,K+-ATPase values ranged from 7.5 to 11.8 ??mol inorganic phosphate (Pi) ?? (mg protein)-1 ?? h-1. No significant differences were detected, with the exception of electroshocked subyearlings 7 d after treatment. Increased activity was attributed to the presence of two influential values. No significant differences were detected after removal of these observations, so the increase was not considered biologically significant. Inclusion of the outliers did not alter our interpretation of the results given that the observed increase was slight compared with the magnitude of changes reported under experimental conditions and in migrating juvenile salmonids. The treatment groups underwent a typical stress response and had significantly elevated cortisol and glucose levels 3 h after treatment. Recovery to control levels occurred within 24 h for cortisol and from 24 h to 7 d for glucose. Our results lead to the conclusion that neither acute electroshock nor acute handling stress alters Na+,K+-ATPase activity in juvenile spring chinook salmon.

North American Journal of Fisheries Management↗
USGS1999

Prevalence of Renibacterium salmoninarum in juvenile spring chinook salmon at Columbia and Snake river hatcheries, 1993-1996

We monitored the prevalence and severity of Renibacterium salmoninarum (RS) infections in juvenile hatchery spring chinook salmon Oncorhynchus tshawytscha at eight Columbia and Snake river hatcheries from 1993 through 1996. This study followed a prior study that monitored RS in the same hatcheries from 1988 through 1992. In the current study, we found that the prevalence of RS-positive fish declined at two hatcheries relative to the preceding 5 years. Prevalence dropped from near 90% in 1992 to below 50% at both sites by 1993 and was less than 20% at three locations in 1995. In contrast, prevalence increased at four of seven sites in 1993 and six of seven sites in 1994. This indicated that previously reported declines in RS prevalence at these locations might have been temporary. Our results showed that in 1993 the majority of fish at all monitored hatcheries had low RS-antigen levels and remained that way at most locations through 1996. These results suggest that certain hatchery practices may limit the severity of RS infections. Although elevations at two sites in 1994 and 1995 indicate reductions in RS were temporary in the short term, long-term monitoring will undoubtedly be required given the many factors that influence disease processes.

Journal of Aquatic Animal Health↗