Perch In Lakes Research Articles

Blood Oxygen Capacity Differences in Yellow Perch (Perca flavescens) from Northern Wisconsin Lakes Differing in pH

Whether chronic exposure to environmental acidity reduces oxygen loading in fish is still uncertain. We evaluated this question by looking for evidence of adaptations to hypoxia in a population of yellow perch (Perca flavescens) isolated in a well-oxygenated, naturally acidic lake. Perch were sampled directly from this naturally acidic lake (pH 4.5) and two circumneutral lakes, one of which experiences low oxygen. Fish were bled rapidly via cardiac puncture. Hemoglobin, hematocrit, and erythrocyte number were determined by standard methods. Hemoglobin concentrations were highest in perch from the acid lake (6.4 g/dL) intermediate in the neutral lake with anoxic zones (5.7 g/dL) and lowest in the well-oxygenated neutral lake (4.8 g/dL). Increased hemoglobin per red cell accounted for this trend. Slightly larger hematocrits in acid lake perch (41.2 versus 36.2) were achieved through small increases in red cell number and volume. Evidence suggests that these results are part of an adaptational response different from the hematological responses of fish to acute acid exposure.

Acid stress in respect to calcium and magnesium concentrations in the plasma of perch during maturation and spawning

Plasma calcium and magnesium concentrations in perch,Perca fluviatilis, were monitored in an acid lake, Lake Iso Tenhetty (pH ∼5, Al concentrations 0.3–0.5 mg l-1) compared with a nearby reference lake, Lake Paijanne, in Southern Finland. The effect of acid stress could be noticed as 1/3 lower fecundity of perch in the acid lake. Plasma Ca concentrations were temporarily lower in the middle of the winter in the fish of the acid lake, and in April–May samples the situation was opposite. Plasma Mg concentration was also lower in the perch from the acid lake in midwinter months, when compared with the double as high values (∼3 mmol l-1) from the reference lake. Elevated level of plasma Mg have been reported for fish in cold acclimation especially in winter. Thus overwintering may be specially stressing for some specimens in acid waters. Also ova did contain clearly less magnesium in the midwinter sample from the acid lake perch compared with the reference lake sample. This difference, however, was no more to be found later in spring. Mg content in the ova of perch was in both cases high, which may be necessary to the breeding in comparable acid waters. According to the literature fish cannot increase their magnesium content directly from the water. Mortality for the reference lake embryos was lower than those of the acid lake when incubated in the acid lake. No physiological acclimation inside the fish could be demonstrated in this case.

Metacercarial distribution of Apophallus brevis (Heterophyidae) in yellow perch (Perca flavescens) from the Heming Lake study area

During a fish parasite survey in 1980 and 1981, 395 yellow perch (Perca flavescens) were removed from the Heming Lake study area (54°53′ N, 101°07′ W). Encysted Apophallus brevis metacercariae were found in the body musculature of perch from six lakes as well as the eye and body musculature of perch in Heming Lake. Species identity was confirmed with experimental infections in ring-billed (Larus delawarensis) and herring (Larus argentatus) gulls. No significant differences were found in prevalences or mean intensities of A. brevis metacercariae between male and female perch in Heming Lake. Prevalence levels remained high in most age-classes of Heming Lake perch and mean intensity differences were not significant for all ages beyond 1 year old. Slight variations from these Heming Lake results were found in other lakes. Prevalence levels of A. brevis in Heming Lake perch remained more or less constant during the open water seasons. Mean intensities dropped significantly from June to July and increased in August and October. Monthly fluctuations are probably the result of recruitment of the parasite and a loss of heavily infected hosts. The variance to mean ratios of A. brevis in perch from Heming, Home, and Demarch lakes showed that these parasite populations were overdispersed, and the distribution of each was found to fit the negative binomial. The authors question the use of variance to mean ratios or other statistics dealing with overdispersion in predicting loss or recruitment for all parasite systems.

Effects of lethal acidity on plasma sodium concentrations in yellow perch ( Perca flavescens) from a naturally acidic and a naturally alkaline lake

1. 1. In situ plasma sodium concentrations of yellow perch ( Perca fluvescens) from naturally acidic Wharton lake (pH 4.6) and naturally alkaline Trout lake (pH 7.9) were similar. 2. 2. Exposure to lethal acidity (pH 3.2) for 48 hr resulted in significant but similar decreases in plasma sodium levels in both populations, even though Whartor lake perch were known to survive significantly longer than Trout lake perch at low pH. 3. 3. This suggests that the observed differences in acidity tolerance between the two populations are not due to differences in rates of plasma sodium decrease.

Effect of High Winds on Eggs of Yellow Perch, Perca flavescens, in Oneida Lake, New York

Abstract As a result of one day of high winds, large quantities of eggs of yellow perch, Perca flavescens, were washed ashore at a number of locations in the windward shoreline of Oneida Lake. A single large windrow, just downwind from a major spawning area, contained almost one percent of the estimated egg potential of the lake's perch population. Damage to the dislodged egg masses appeared most severe in areas with rubble bottoms.

TREATMENT FOR ERYSIPELOID BY LOCAL INJECTIONS OF SPECIFIC SERUM

The presence of erysipeloid in the region of the Great Lakes and its successful treatment by the intragluteal injection of specific serum (Mulford) have recently been recorded. 1 The purpose of this report is to bring to attention another case of this infection and to record the results of treatment by the local injection of specific serum. REPORT OF CASE History.— A white man, aged 26, was first seen on July 16, 1930. Ten days previously, while working in a general biologic laboratory, he had been bitten on the left palm by a turtle. During the following two days he had handled many decomposing lake perch. Two days afterward he noticed redness, tenderness, swelling and pain about the site of the injury, accompanied by red streaks that extended up the left forearm and a tender gland in the left axilla. Hot packs had been applied to the hand and forearm,