J. Howard McCormick

Effects of external radio transmitters on fish

Abstract Yellow perch (Perca flavescens) and largemouth bass (Micropterus salmoides) were studied to determine the effects of externally attached radio transmitter tags. Perch that had been tagged with dummy radio tags were more susceptible to predation and more sensitive to environmental stress than were controls. Feeding and respiration rates were similar among dummy tagged and control groups of perch over a 6-week period. The feeding rate of dummy tagged largemouth bass was lower than that of untagged fish over a 3.5-week period. On the basis of these studies, we conclude that weights of external transmitters in water should be less than 1.5% of the fish weight. Design considerations should include streamlining components and an anterior attachment wire at the extreme leading edge of an external transmitter to prevent entanglement of the tag in surrounding vegetation.

Temperature Requirements for Embryos and Larvae of the Northern Pike, Esox lucius (Linnaeus)

Abstract Several bioassay methods, responses, and end points were evaluated for use in determining the temperature requirements of northern pike embryos. Large differences in maximum embryo survival to hatch occurred among experiments that could not be attributed to effects of water temperature alone. Emphasis was placed on evaluating the relative effects of temperature on embryo survival by our correcting for differences in fertilization success among experiments. The most variable end point among experiments was the optimum temperature, while the most reproducible end point was the median tolerance limit (TL50). The lower and upper TL50s were 6.9 and 19.2 C for normal hatch and 6.3 and 19.9C for total hatch. The age of the embryo at the time of exposure had a great effect on these tolerance limits. Temperature shock, source of fish, and wet fertilization in hard and soft water had negligible effects on these tolerance limits. Recommendations were made for routine thermal bioassays for fish eggs. The 1-d...

Extreme Value Analysis of a Fish/Temperature Field Database

Abstract Extremes of water temperatures limit the presence of various fishes in streams and lakes. Upper extreme water temperatures and their uncertainties are determined by several statistical methods from a large field database. There are over 140 000 weekly mean fish/stream temperature matched pairs in the database. Three different techniques are employed to estimate upper extremes of habitat temperatures for 12 fish species. To quantify the uncertainty of the estimated extremes the bootstrap method, the method of moments and the residual method are applied. The data above the maximum growth temperature are matched well by a type III extremal or a three-parameter lognormal distribution. Standard error of the estimated extreme habitat temperatures depends on species and varies from 0.1°C to 0.6°C at the 95% cumulative probability of occurrence.

Oocyte atresia and reproductive success in fathead minnows (Pimephales promelas) exposed to acidified hardwater environments

The ovarian histology of fathead minnows (Pimephales promelas) chronically exposed to three levels of environmental pH was examined for evidence of reproductive impairment. Exposures occurred in three experimental runningwater channels receiving Mississippi River water. One of these channels was not acidified and two were dosed with H2SO4. The pH was approximately 8 in untreated river water and 6 and 5 in the two channels receiving H2SO4. Fish for ovarian examination were taken from these channels at four stages of the reproductive season: initiation of spawning (June 19), mid-spawning (July 12), end of spawning (August 14–15), and approximately 1 mo. post-spawning (September 19).The fish exhibited ovarian histological changes and depression of reproductive success which were directly associated with the level of environmental stress experienced. The association between these three factors was most consistent and pronounced if the fish were sampled near the end of the spawning season. When sampled at this time, reproductive impairment in a population was found when the ratio of the volume of atretic (resorbing) oocytes present in the ovary to the total ovarian volume exceeded 20% in all fish sampled. This was the case in the pH 5 channel fish sampled in August. At this same time, not all of the fish in the pH 6 channel exhibited such an accumulation of atretic oocytes, and egg deposition in that population was not reduced. None of the fish from the pH 8 channel were so affected nor was their reproduction.

Validation of a fish habitat model for lakes

Water temperatures and dissolved oxygen concentrations in 27 classes of lakes have been hindcast by simulation models and related to presence of coldwater, coolwater, and warmwater fishes in 3002 Minnesota lakes. A one-dimensional, dynamic water quality model driven by 25 years of daily weather data was used to model water temperature and dissolved oxygen profiles of these lakes. Fish presence data were available for these lakes from the Minnesota Lake Fisheries Data Base. Water temperature and dissolved oxygen criteria derived from a very large United States Environmental Protection Agency fish-temperature database and dissolved oxygen observations were used to define and link simulated water temperatures and dissolved oxygen conditions to suitability of habitats for coldwater, coolwater, and warmwater fish assemblages. Good agreement was found between fish presence and numerical simulations of fish habitat defined by water temperatures and dissolved oxygen concentrations. Generally water temperature and DO are good indicators of suitable fish habitat.

A Field and Laboratory Investigation of Acid Effects on Largemouth Bass, Rock Bass, Black Crappie, and Yellow Perch

Abstract One-half of Little Rock Lake, a small seepage lake in north-central Wisconsin, was gradually acidified by additions of sulfuric acid between August 1983 and November 1990. The ambient pH (6.1) of the lake was reduced at successive 2-year intervals to pH 5.6, 5.1, and 4.7. Responses of largemouth bass Micropterus salmoides, rock bass Ambloplites rupestris, black crappie Pomoxis nigromaculatus, and yellow perch Perca flavescens populations to the pH reductions were recorded and compared to the responses of these species during in situ bioassays and laboratory toxicity tests on embryos and larvae. Laboratory results obtained for largemouth bass and rock bass underestimated, black crappie results overestimated, and yellow perch results were similar to effects observed in field studies. In situ bioassays predicted field responses better than did laboratory toxicity tests. Laboratory results showed that monomeric A1 concentrations of approximately 50 μg/L, which were comparable to A1 concentrations in ...

Chronic effects of low ph and elevated aluminum on survival, maturation, spawning and embryo-larval development of the fathead minnow in soft water

Fathead minnows (Pimephales promelas) were exposed to a range of pH and A1 concentrations in soft water (8 mg Ca L−1) to determine effect levels at various life stages. The tested pH levels ranged from 8.0 through 5.2 and inorganic monomeric Al from 15 through 60 μg L−1. Reproductive processes including spawning, embryogenesis and early larval survival were more sensitive to acid stress than were juvenile growth and survival. Juvenile survival was significantly reduced at pH 5.2 + 60 μg Al L−1 (P <0.05). Spawning success was reduced at pH 6.0 and 5.5 (P <0.10) and failed completely at pH 5.2, regardless of Al concentration. An apparant beneficial effect of added Al was observed during spawning at pH 7.5 + 35 μg Al L−1, but this effect was not significantly greater than at pH 7.5 + 15 μg Al L−1. A significant (P <0.05) decrease in larval survival occurred at pH 6.0 + 15 μg Al L−1 and lower compared to the survival at pH 7.5 + 15 μg Al L−1. Aluminum at 30 μg L−1 provided protection resulting in short term increased embryo-larval survival at pH 5.5. The effect of parental exposure on progeny survival was assessed by an interchange of embryos from the spawning treatment to all tested exposure conditions. When reared at pH 8.0 + 15 μg Al L−1 through 6.0 + 15 μg Al L−1 or at pH 5.5 + 30 μg Al L−1, parental exposure did not significantly influence progeny survival. However, survival was significantly reduced among progeny from brood fish reared at pH 5.5 + 15 μg Al L−1 as compared to those spawned at pH 6.0 + 15 μg Al L−1 and above, or at pH 5.5 + 30 μg Al L−1 (P <0.05). Juvenile or 14 d larval growth effects were not detected under any exposure condition (P >0.05). Ultimately, fathead minnow young-of-the-year recruitment and production potential can be expected to diminish when environmental pH falls to 6.0, and to fail completely at 5.5 and lower.

Effects of Temperature on Hatching and Development of Ruffe (Gymnocephalus cernuus)

The ruffe (Gymnocephalus cernuus) was introduced into the estuary of the St. Louis River at the western end of Lake Superior in about 1986 and is now the numerically dominant trawl-caught fish in this ecosystem. To learn more about the early life history of this new North America species, we incubated ruffe embryos at 6, 11, 16, and 21°C. In this way we determined the effects of temperature on hatching success, rates of development, the times from fertilization to hatching, and from fertilization to swim-up stage. After cooling from 13–16°C and subsequent incubation at 6°C few embryos hatched and no normal larvae were produced. At 11, 16, and 21°C, hatching success ranged from 49–58%, and 66% of those that hatched survived to swim-up. The mean time from fertilization to hatching was 29, 11,6, and 4 days at 6, 11, 16, and 21°C, respectively. The time from fertilization to swim-up was 26, 14, and 9 days at 11, 16, and 21°C, respectively. We believe the information provided will be of value to those interested in the basic environmental biology of this new species to North America, and to those natural resource managers responsible for waters where this species is or will become present. This new information will aid natural resource managers in planning chemical control strategies so as to avoid scheduling treatment when the ruffes resistant egg stage may be extant; and also in aiding them to know when greater caution should be enforced so as to avoid extending their range through entrainment of the vulnerable swim-up larvae, e.g., during ships ballasting, with the possible consequence of transport to new sites of invasion.

Factors Contributing to First-Year Recruitment Failure of Fishes in Acidified Waters with Some Implications for Environmental Research

Abstract Factors that make fish particularly vulnerable to the effects of environmental acidification during their first year of life are examined. This perspective is based largely on the results of research carried on concurrently in the field (the Little Rock Lake, Wisconsin, acidification study, 1984–1990) and in the laboratory using water tailored to mimic that of Little Rock Lake. We discuss ways in which seasonal changes influence both the environmental challenges encountered by fishes and their ability to deal with those challenges. The vulnerability of a species may be based as much on its life history (e.g., synchrony of sensitive or resistant life stages with maximum pH challenges) as on its anatomy and physiology. The ordering of acid sensitivity of species or of life stages is based on a dynamic balancing of energy and ion uptake, storage, and loss. These processes, in turn, are linked to the length of the growing season (net uptake phase) and the winter fasting period (net loss phase). Each ...

Survival, Blood Osmolality, and Gill Morphology of Juvenile Yellow Perch, Rock Bass, Black Crappie, and Largemouth Bass Exposed to Acidified Soft Water

Abstract When exposed to a range of pH from 7.0 to 4.0 in soft water (1 mg Ca2+/L), juvenile rock bass Ambloplites rupestris, black crappie Pomoxis nigromaculatus, and largemouth bass Micropterus salmoides showed a capacity to osmoregulate and survive for up to 30 d at pH 4.5 and above. Juvenile yellow perch Perca flavescens maintained osmoregulatory control through 58 d at pH 5.0. All four species lost osmoregulatory control at pH 4.0, and death of fish ensued within a few days after blood osmolality declined to about 200 mosmol/kg or less (normal values, about 300 mosmol/kg). After 58 d of exposure to pH 4.0, mean blood osmolality of yellow perch was 218 mosmol/kg, and these fish were severely emaciated and moribund. Rock bass, black crappie, and largemouth bass all died by days 29, 16, and 9, respectively, when exposed to pH 4.0. However, when exposure to pH 4.0 was halted and pH was raised to 7.0 before death, blood osmolality returned to near-initial values within 15 d. Cessation of feeding also was ...