scholarly journals Coarse woody habitat does not predict largemouth bass young of year mortality during the open-water season

2019 ◽  
Vol 76 (6) ◽  
pp. 998-1005 ◽  
Author(s):  
Jacob P. Ziegler ◽  
Colin J. Dassow ◽  
Stuart E. Jones ◽  
Alexander J. Ross ◽  
Christopher T. Solomon

Littoral structure is often assumed to provide refuge to young of year (YOY) freshwater fish species, but empirical in situ tests of this relationship are lacking. We estimated mortality rates of YOY largemouth bass (Micropterus salmoides) over the open-water season in 13 lakes in northern Wisconsin and Michigan using repeated snorkel surveys. Our goal was to test the hypothesis that mortality rate is negatively related to the abundance of littoral coarse woody habitat, which ranged from 3 to 1500 pieces of wood per kilometre of shoreline in these lakes. Instantaneous mortality rates were well-constrained and ranged from 0.04 to 0.19 among the 13 lakes. Mortality was not related to coarse woody habitat abundance. Our results suggest that the relationship between coarse woody habitat and YOY mortality might not be as strong or universal as is often assumed.

2018 ◽  
Vol 75 (1) ◽  
pp. 106-115 ◽  
Author(s):  
Gretchen J.A. Hansen ◽  
Stephen R. Midway ◽  
Tyler Wagner

Lakes respond heterogeneously to climate, with implications for fisheries management. We analyzed walleye (Sander vitreus) recruitment to age-0 in 359 lakes in Wisconsin, USA, to (i) quantify the relationship between annual water temperature degree days (DD) and walleye recruitment success and (ii) identify the influence of lake characteristics — area, conductivity, largemouth bass (Micropterus salmoides) catch rates, and mean DD — on this relationship. The relationship between walleye recruitment and annual DD varied among lakes and was not distinguishable from zero overall (posterior mean = −0.11, 90% CI = −0.34, 0.15). DD effects on recruitment were negative in 198 lakes (55%) and positive in 161 (45%). The effect of annual DD was most negative in lakes with high largemouth bass densities, and, on average, the probability of recruitment was highest in large lakes with low largemouth bass densities. Conductivity and mean DD influenced neither recruitment nor the effect of annual DD. Walleye recruitment was most resilient to warming in lakes with few largemouth bass, suggesting that the effects of climate change depend on lake-specific food-web and habitat contexts.


1984 ◽  
Vol 246 (4) ◽  
pp. R479-R486 ◽  
Author(s):  
L. I. Crawshaw

The importance of low ambient temperature in the physiology of winter dormancy was studied in the brown bullhead (Ictalurus nebulosus) and the largemouth bass (Micropterus salmoides). The bullheads frequently entered a sleep-like state at low temperatures; the likelihood of being aroused from this state was inversely proportional to the ambient temperature. Spontaneous activity for both species was relatively constant from 17 to 7 degrees C; at lower temperatures activity decreased. The selected temperature was lowered in both species as a consequence of acclimation to 3 degrees C; if given the opportunity, fish of both species moved to temperatures above 25 degrees C within 1 day in spite of the consequent acid-base and metabolic imbalances. In bass, food intake was very low for acclimation temperatures of 8 degrees C and below; at higher temperatures the relationship between food intake and acclimation temperature required 4 wk to stabilize. Quiescent brown bullheads exhibited discontinuous breathing. Alteration of brain temperature with implanted thermodes indicated that the main locus of control of this breathing pattern is in the medulla; lesser influences emanate from the anterior hypothalamus and the midbrain. Metabolism was measured at a series of acclimation temperatures between 3 and 17 degrees C for both species. No evidence of a discontinuous function (metabolic shutdown) was seen for either species.


2020 ◽  
Vol 23 (1) ◽  
pp. 55-60
Author(s):  
Yoko Imaizumi

AbstractUsing vital statistics in Japan (1995–2008), 154,578 live-born twin pairs (128,236 monozygotic [MZ] and 180,920 dizygotic [DZ]) were identified. The proportion of severe discordance among live-born twin births was twice as high in Japanese than Caucasian infants. There were 1858 MZ and 1620 DZ infant deaths. Computation of the relationship between infant mortality rate and birth weight discordance among the twins was performed. Discordance levels were classified into seven groups: <5%, five groups from 5–9% to 25–29%, and ≥30%.The mortality rate was significantly higher in MZ than DZ twins for discordances except at 5–9% and 10–14%. The lowest rate for MZ twins was at 5–9% (7.5 per 1000 live twins) and significantly increased from 10–14% (9.4) to ≥30% (83.4), while the lowest rate for DZ twins was at <5% (6.7), which significantly increased at 10–14% (8.0) and from 25–29% (12.1) to ≥30% (35.5). The relationship was also computed in two gestational age groups (<28 and ≥28 weeks). For births at <28 weeks, three discordances (after 20–24%) in MZ twins were associated with adverse mortality rate. For births at ≥28 weeks, the same relationship was obtained after 10–14% in MZ and after 20–24% in DZ twins. The relationship from 2002 to 2008 showed that the mortality rates significantly increased after 10–14% for both types of twins. In conclusion, five discordance levels in MZ and three levels in DZ twins were associated with adverse mortality rates.


1990 ◽  
Vol 47 (12) ◽  
pp. 2358-2363 ◽  
Author(s):  
M. R. Meador ◽  
W. E. Kelso

Plasma osmotic and electrolyte concentrations as well as branchial Na+/K+ and Mg++ ATPase activities were determined in the field for largemouth bass, Micropterus salmoides, from a brackish marsh and freshwater lake in southcentral Louisiana. Laboratory experiments were conducted to evaluate plasma chemistry and gill ATPase activities of largemouth bass from both locations exposed to 0, 4, 8, and 12‰ salinity. No significant differences in physiological responses were detected between marsh and freshwater largemouth bass exposed to 0, 4, or 12‰. Exposure to 12‰ salinity resulted in osmotic stress in largemouth bass from both locations. At 8‰, marsh largemouth bass had significantly higher plasma solutes and lower gill ATPase activities than freshwater fish. Different physiological responses by marsh and freshwater largemouth bass during exposure to 8‰ salinity indicated that marsh largemouth bass have adapted to environments of variable salinity by reducing active ion transport and tolerating elevated plasma son levels.


1999 ◽  
Vol 56 (8) ◽  
pp. 1362-1369 ◽  
Author(s):  
Scott M Reid ◽  
Michael G Fox ◽  
Thomas H Whillans

In situ and laboratory feeding trials coupled with stomach content analysis of largemouth bass (Micropterus salmoides) were performed to examine how turbidity influences the size selectivity and capture rates of prey. No significant differences in the capture success of adult largemouth bass preying on northern redbelly dace (Phoxinus eos) were observed during in situ feeding trials in two Lake Ontario coastal wetlands differing in turbidity level (2.3 and 20 nephlometric turbity units (NTU)). During 1-h laboratory feeding trials, the overall number of fathead minnows (Pimephales promelas) captured was not significantly different among 1-, 18-, and 37-NTU treatments. However, at 70 NTU, the number of fathead minnows captured was significantly lower than that at the lowest turbidity treatment. Selection by juvenile largemouth bass of the smallest size-class of fathead minnow decreased as turbidity increased. No significant differences in piscivory were apparent between juvenile largemouth bass collected from turbid and clear habitats. Stomach content comparisons of juvenile largemouth bass seined from six clear and turbid habitats suggest that piscivory is primarily regulated by the availability of vulnerable size-classes of prey fish, as opposed to water clarity.


1985 ◽  
Vol 59 (3) ◽  
pp. 706-709 ◽  
Author(s):  
D. A. DuBose ◽  
J. McCreary ◽  
L. Sowders

Reticuloendothelial system (RES) clearance function correlates with the mortality rate associated with stresses that can induce shock. Likewise, experimental rat heat stress (ERHS) mortality rate is altered by modulation of RES function. Since plasma fibronectin (PF) in many instances appears to mediate in vivo phagocytosis by the RES, the relationship between mean plasma fibronectin level (MPFL) and ERHS mortality was examined. A comparison of MPFLs prior to ERHS revealed that rats which ultimately comprised the survival group had a MPFL of 269.0 +/- 11.2 micrograms/ml, whereas that of the nonsurvivors was 252.9 +/- 11.9 micrograms/ml. Both groups had elevated MPFLs up to 12 h following ERHS. However, after this time, MPFL began to decline. The decline was more severe for the nonsurvivors, with MPFLs at 15, 18, and 20.3 h significantly (P less than 0.01) lower than the values for the survival group. Even the lowest MPFL (256.0 +/- 30.7 micrograms/ml) noted for the survival group was still significantly (P less than 0.01) higher than the value (159.3 +/- 13.3 micrograms/ml) determined for agonal samples collected from nonsurvivors. Furthermore, grouping rats according to their preheat PF level demonstrated that rats with levels exceeding 300 micrograms/ml had significantly (P less than 0.05) reduced mortality rates (12.5 vs. 51.3%) compared with rats with levels below this value. It was concluded that elevated PF levels prior to ERHS correlated with thermotolerance.


2020 ◽  
Vol 77 (3) ◽  
pp. 520-533
Author(s):  
Christopher J. Sullivan ◽  
Daniel A. Isermann ◽  
Kaitlin E. Whitlock ◽  
Jonathan F. Hansen

Climate-related changes in fish communities can present new challenges for fishery managers who must address declines in cool- and cold-water sportfish while dealing with increased abundance of warm-water sportfish. We used largemouth bass (Micropterus salmoides) in Wisconsin lakes as model populations to determine whether angler harvest provides a realistic method for reducing abundance of a popular warm-water sportfish that has become more prevalent and has prompted management concerns around the globe. Model results indicate largemouth bass will be resilient to increased fishing mortality. Furthermore, high rates of voluntary catch-and-release occurring in most largemouth bass fisheries likely preclude fishing mortality rates required to reduce bass abundance at meaningful levels (≥25% reductions). Increasing fishing mortality in these scenarios may require more “stimulus” than merely providing anglers with greater harvest opportunities via less stringent harvest regulations. Angler harvest could result in populations dominated by small fish, a scenario that may be undesirable to anglers, but could provide ecological benefits in certain situations.


1989 ◽  
Vol 46 (12) ◽  
pp. 2203-2209 ◽  
Author(s):  
Donald J. Hail ◽  
Timothy J. Ehlinger

The top predator (largemouth bass, Micropterus salmoides) in eutrophic Wintergreen Lake, Michigan, was eliminated by successive winterkills in 1978 and 1979. Within 2 yr, the golden shiner (Notemigonus crysoleucas), a facultative planktivore, dominated the fish community. The zooplankton, previously consisting of large Daphnia pulex and D. galeata mendotae, concomitantly shifted to a community consisting of smaller species: Bosmina and small copepods. In situ fish enclosure experiments in 1981 and 1982 revealed that the large Daphnia species would grow in Wintergreen Lake in the absence of the golden shiner. Golden shiners exhibit both a particulate and filtering mode of planktivory on large and small zooplankton, respectively. This flexible feeding behavior suggests that golden shiners are able to prevent the reestablishment of Daphnia, while Bosmina and the other small zooplankton support a high and apparently stable golden shiner density.


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