This paper presents the results of the first attempt to estimate and identify factors influencing individual reproductive success in a fish species, under natural conditions, after the progeny have dispersed from their site of origin. Using family-specific DNA fingerprints, the reproductive success of male smallmouth bass in Lake Opeongo, Ontario was estimated and evaluated at the point when their offspring were fall young-of-the-year (YOY). For the 1992 spring spawning season, we generated family-specific fingerprints using DNA of fry captured from 116 nests in Jones Bay. In the fall of the same year, 283 YOY were captured by electrofishing along the shoreline of the study area. Using DNA obtained from fin tissue, a fingerprint was generated for each fall YOY and compared to the family fingerprints to determine the family of origin. Males were considered successful if at least one of their offspring survived to the fall YOY stage. Although 27.7% of all males who acquired eggs (N ϭ 57) had at least one offspring surviving to the fall YOY stage, only 5.4% of all spawning males (N ϭ 11) produced 54.7% of the total number of fall YOY captured. If recruitment frequently depends on the success of such a small number of males, then population abundance will be extremely vulnerable to adverse natural and anthropogenic impacts. Because natural resource managers cannot differentiate these few successful males a priori, they cannot differentially protect them from potentially adverse human activities, such as opening the fishing season on a preset date that may fall before the end of brood-guarding in a given year.The evaluation of variables that might influence differences in male reproductive success included male length and age, spawning date, number of eggs and fry within a nest, nest depth, and dominant substrate type both within and surrounding the nest. Logistic regression analysis indicated that none of these variables were significant predictors of male reproductive success (P Ͼ 0.05). Additionally, linear regression analysis suggested the lack of a relationship between the number of fall YOY produced per male and these variables. However, a goodness-of-fit test to the Poisson distribution indicated that the number of YOY produced per male does not occur at random (P Ͻ 0.001), suggesting that reproductive success was influenced by factors not measured in this study.
Largemouth (LMB: Micropterus salmoides) and Smallmouth Bass (SMB: Micropterus dolo-mieu) are important species in the recreational fisheries of the Laurentian Great Lakes. The invasion of the Round Goby (Neogobius melanostomus) into these lakes has changed several facets of black bass biology, but there is still much to learn about the relationship between these species. Previous dietary analyses have shown Round Goby to be important prey for bass, but have been limited by low visual identification rates of dissected stomach items. Within the present study, DNA barcoding and stable isotope analysis improve prey identification and provide a more quantitative dietary analysis of adult black bass in Lake Ontario, comparing the importance of Round Goby as prey between these two species. Eighty-four LMB (406mm fork length ±4mm SEM) and two hundred sixty-four SMB (422mm ±2mm) obtained as tournament mortalities had prey identified using DNA-based methods. Round Goby was the most prevalent prey species for both predators. The diet of LMB was three times more diverse than that of SMB, which almost entirely consists of Round Goby. Our results provide further support that recent increases in the size of Lake Ontario bass are a result of Round Goby consumption, and that the effects of this dietary shift on body condition are greater for SMB. Techniques developed in this study include reverse-oriented dual priming oligonucleotides used as blocking primers for predator DNA, and an automated design approach of restriction fragment length polymorphism tests for identifying prey DNA barcodes.
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