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Wagner T.,Michigan State University | Jones M.L.,Michigan State University | Ebener M.P.,Chippewa Ottawa Resource Authority | Arts M.T.,Environment Canada | And 4 more authors.
Journal of Great Lakes Research | Year: 2010

We examined the spatial and temporal dynamics of health indicators in four lake whitefish (Coregonus clupeaformis) stocks located in northern lakes Michigan and Huron from 2003 to 2006. The specific objectives were to (1) quantify spatial and temporal variability in health indicators; (2) examine relationships among nutritional indicators and stock-specific spatial and temporal dynamics of pathogen prevalence and intensity of infection; and (3) examine relationships between indicators measured on individual fish and stock-specific estimates of natural mortality. The percent of the total variation attributed to spatial and temporal sources varied greatly depending on the health indicator examined. The most notable pattern was a downward trend in the concentration of highly unsaturated fatty acids (HUFAs), observed in all stocks, in the polar lipid fraction of lake whitefish dorsal muscle tissue over the three study years. Variation among stocks and years for some indicators were correlated with the prevalence and intensity of the swimbladder nematode Cystidicola farionis, suggesting that our measures of fish health were related, at some level, with disease dynamics. We did not find relationships between spatial patterns in fish health indicators and estimates of natural mortality rates for the stocks. Our research highlights the complexity of the interactions between fish nutritional status, disease dynamics, and natural mortality in wild fish populations. Additional research that identifies thresholds of health indicators, below (or above) which survival may be reduced, will greatly help in understanding the relationship between indicators measured on individual fish and potential population-level effects. © 2009.


Faisal M.,Michigan State University | Fayed W.,Michigan State University | Fayed W.,Alexandria University | Brenden T.O.,Michigan State University | And 4 more authors.
Journal of Great Lakes Research | Year: 2010

We estimated the prevalence, intensity, and abundance of swimbladder nematode infection in 1281 lake whitefish (Coregonus clupeaformis) collected from four sites in northern lakes Huron (Cheboygan and DeTour Village) and Michigan (Big Bay de Noc and Naubinway) from fall 2003 through summer 2006. Morphological examination of nematode egg, larval, and mature stages through light and scanning electron microscopy revealed characteristics consistent with that of Cystidicola farionis Fischer 1798. Total C. farionis prevalence was 26.94%, while the mean intensity and abundance of infection was 26.72 and 7.21 nematodes/fish, respectively. Although we detected C. farionis in all four stocks that were examined, Lake Huron stocks generally had higher prevalence, intensity, and abundance of infection than Lake Michigan stocks. A distinct seasonal fluctuation in prevalence, abundance, and intensity of C. farionis was observed, which does not coincide with reported C. farionis development in other fish species. Lake whitefish that were heavily infected with C. farionis were found to have thickened swimbladder walls with deteriorated mucosa lining, which could affect swimbladder function. Whether C. farionis infection may be negatively impacting lake whitefish stocks in the Great Lakes is unclear; continued monitoring of C. farionis infection should be conducted to measure responses of lake whitefish stocks to infection levels. © 2010 Elsevier B.V.


Ebener M.P.,Inter Tribal Fisheries and Assessment Program | Brenden T.O.,Michigan State University | Wright G.M.,Nunns Creek Fishery Enhancement Facility | Jones M.L.,Michigan State University | Faisal M.,Michigan State University
Journal of Great Lakes Research | Year: 2010

Adult lake whitefish were tagged and released from the Big Bay de Noc (BBN) and Naubinway (NAB) stocks in northern Lake Michigan, and the Detour (DET) and Cheboygan (CHB) stocks in northern Lake Huron during 2003-2006 to describe their spatial and temporal distributions. The contemporary spatial distributions were compared with past distributions of the BBN and NAB stocks. Sixty-two percent of BBN tag recoveries occurred in Wisconsin waters during winter, spring and summer, but 83% of fall tag recoveries were made near the tagging site. Eighty-eight percent of the NAB tag recoveries were made in the management unit of tagging and 7% occurred into northern Lake Huron. Over 90% of the DET stock remained in the vicinity of the tagging sites regardless of the season, while 75% of the CHB tag recoveries were made in northwestern Lake Huron and 17% were made in Ontario. Based on regression tree analysis, there were strong stock, season, and year effects on movement distances, with weaker effects due tosex and length attagging. Spatial distribution of the BBN stock changed from 1978-1982 to 2003-2008, but spatial distribution of the NAB stock did not. Substantial differences in movement and distribution existed among the four stocks, large seasonal differences in spatial distribution were found within some stocks, and lake whitefish exhibited strong spawning sitefidelity. Present management unit boundaries are inappropriate for managing three of our four stocks, and agencies should consider developing single harvest limits for both northern Lake Huron and western Lake Michigan. © 2010 Elsevier B.V.


Faisal M.,Michigan State University | Loch T.P.,Michigan State University | Brenden T.O.,Michigan State University | Eissa A.E.,Cairo University | And 3 more authors.
Journal of Great Lakes Research | Year: 2010

Lake whitefish (Coregonus clupeaformis) from four stocks in northern Lakes Michigan and Huron were collected seasonally from fall 2003 through summer 2006 and examined for the presence of Renibacterium salmoninarum, the causative agent of bacterial kidney disease (BKD), using culture techniques on modified kidney disease medium (MKDM) and the quantitative enzyme-linked immunosorbent assay (Q-ELISA). R. salmoninarum was detected in 62.31% (according to Q-ELISA) of the 1284 examined lake whitefish, with some fish displaying the typical signs of BKD, such as renal congestion, swelling, and whitish nodules. Kidney cultures on MKDM yielded bacteria with morphological and biochemical characteristics identical to those of R. salmoninarum recovered from other Great Lakes fish species, as well as those from other parts of the world. Isolate identification was confirmed via nested polymerase chain reaction. Antibiograms demonstrated high sensitivity to enrofloxacin and ciprofloxacin, sensitivity to oxytetracycline, erythromycin, azithromycin, chloramphenicol, novobiocin, and carbenicillin, and resistance to polymyxin B, clindamycin, and kanamycin. Statistical analysis of R. salmoninarum prevalence and intensities revealed significant interactions among stocks, years and sampling seasons, with highest prevalence generally in fall and frequent wide variation in prevalence and intensity from one season to the next for a particular stock. It was surprising to find that the prevalence of R. salmoninarum exceeded 50% in the four stocks, much higher than originally thought. Moreover, a positive association between R. salmoninarum intensity and the abundance of the swimbladder nematode, Cystidicola farionis, was identified. Our findings suggest that Great Lakes lake whitefish are vulnerable to serious fish pathogens. © 2010 Elsevier B.V.


Brenden T.O.,Michigan State University | Ebener M.P.,Inter Tribal Fisheries and Assessment Program | Sutton T.M.,University of Alaska Fairbanks | Jones M.L.,Michigan State University | And 5 more authors.
Journal of Great Lakes Research | Year: 2010

Although lake whitefish Coregonus clupeaformis populations in the Laurentian Great Lakes have rebounded remarkably from the low abundance levels of the 1960s and 1970s, recent declines in fish growth rates and body condition have raised concerns about the future sustainability of these populations. Because of the ecological, economic, and cultural importance of lake whitefish, a variety of research projects in the Great Lakes have recently been conducted to better understand how populations may be affected by reductions in growth and condition. Based upon our participation in projects intended to establish linkages between reductions in growth and condition and important population demographic attributes (natural mortality and recruitment potential), we offer the following recommendations for future studies meant to assess the health of Laurentian Great Lakes lake whitefish populations: (1) broaden the spatial coverage of comparative studies of demographic rates and fish health; (2) combine large-scale field studies with direct experimentation; (3) conduct multi-disciplinary evaluation of stocks; (4) conduct analyses at finer spatial and temporal scales; (5) quantify stock intermixing and examine how intermixing affects harvest policy performance on individual stocks; (6) examine the role of movement in explaining seasonal fluctuations of disease and pathogen infection and transmission; (7) evaluate sampling protocols for collecting individuals for pathological and compositional examination; (8) quantify sea lamprey-induced mortality; and (9) enact long-term monitoring programs of stock health. © 2010 Elsevier B.V.

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