Actualizaciones sobre las supuestas ocurrencias de tiburón toro (Carcharhinus leucas) en la cuenca superior del río Mississippi de América del Norte

A previous paper in this journal by Shell and Gardner assessed various factors around the exploration of the Mississippi River by bull sharks (Carcharhinus leucas Müller and Henle, 1839) based on two twentieth-century occurrences. Recent evidence has suggested one of these occurrences is a probable hoax. Here, we provide a correction to our earlier paper, as well as additional comments on extralimital euryhaline vertebrates in the Mississippi River system, the environmental and historical contexts for their exploration into riverine systems, and suggest steps for any future effort to detect the usage of these river systems by bull sharks.En un artículo anterior de Shell y Gardner en esta revista, se evaluaron varios factores en torno a la exploración del Río Mississippi por parte de los tiburones toro (Carcharhinus leucas Müller y Henle, 1839) basados en dos sucesos del siglo XX. La evidencia reciente sugiere que una de estas ocurrencias es un probable engaño. Brindamos aquí una corrección a nuestro artículo anterior, así como comentarios adicionales sobre los vertebrados eurihalinos extralimitantes en el sistema del Río Mississippi, los contextos ambientales e históricos para su exploración en los sistemas fluviales, y sugerimos los pasos para cualquier esfuerzo futuro en detectar el uso de estos sistemas fluviales por los tiburones toro

Incorporating basic and applied approaches to evaluate the effects of invasive Asian Carp on native fishes: A necessary first step for integrated pest management

Numerous studies throughout North America allege deleterious associations among invasive Asian Carp and native fishes; however, no empirical evidence on a system-wide scale exists. We used Mississippi River Basin fish community data collected by the Long Term Resource Monitoring program and the Missouri Department of Conservation to evaluate possible interaction between Asian Carp and native fishes. Results from two decades of long-term monitoring throughout much of the Mississippi River suggest that Silver Carp relative abundance has increased while relative abundance (Bigmouth Buffalo [F 3, 8240 = 6.44, P\u3c0.01] and Gizzard Shad [F 3, 8240 = 31.04, P\u3c0.01]) and condition (Bigmouth Buffalo [slope = -0.11; t = -1.71; P = 0.1014] and Gizzard Shad [slope = -0.39; t = -3.02; P = 0.0073]) of native planktivores have declined. Floodplain lake qualitative evaluations yielded similar results; floodplain lake fish communities were likely altered (i.e., reductions in native species) by Silver Carp. Furthermore, laboratory experiments corroborated field evidence; Silver Carp negatively influence native planktivores through competition for prey (all comparisons, P \u3e 0.05). To this end, this study provides evidence that Silver Carp are likely adversely influencing native fishes; however, mere presence of Silver Carp in the system does not induce deleterious effects on native fishes. To the best of our knowledge, this evaluation is the first to describe the effects of Asian Carp throughout the Mississippi River Basin and could be used to reduce the effects of Asian Carp on native biota through an integrated pest management program as suggested by congressional policy. Despite the simplicity of the data analyzed and approach used, this study provides a framework for beginning to identify the interactions of invasive fish pests on native fishes (i.e., necessary first step of integrated pest management). However, knowledge gaps remain. We suggest future efforts should conduct more in depth analyses (i.e., multivariate statistical approaches) that investigate the influence on all native species

Maturation and Reproduction of Shovelnose Sturgeon in the Middle Mississippi River

Shovelnose sturgeon Scaphirhynchus platorynchus in the middle Mississippi River provide one of the last commercially viable sturgeon fisheries in the world, yet their maturation and reproduction have not been linked. During 2005 and 2006, we sampled adult and age-0 shovelnose sturgeon to link age at maturation, the timing and periodicity of spawning, age-0 sturgeon production, and the resulting age-0 growth rates. Age at maturity was later than previous estimates, the minimum age of first maturation being 8 years for males and 9 years for females. Total egg count was slightly lower than previously reported (mean = 29,573 per female; SE = 2,472). Males and females typically spawned every 2 and 3 years, respectively. Peaks in mature fish coincided with rising river stages and water temperatures at which shovelnose sturgeon probably spawn. Peaks in spent adults followed. Age-0 shovelnose sturgeon occurred during June and July 2005 and May and June 2006, confirming successful spawning. Age-0 sturgeon grew between 0.69 and 1.69 mm total length/d; four distinct weekly cohorts occurred each year. During fall 2006, females contained ripe eggs, males were milting, and a single age-0 sturgeon (total length = 55 mm) was captured, suggesting that shovelnose sturgeon spawn during fall as well as spring. Management must consider the protracted nature of spawning within seasons as well as differences in spawning activity between seasons

Turtle communities in the Upper Mississippi River System

The fisheries component of the Long-Term Resource Monitoring Program (LTRMP), which utilizes many sorts of collecting methods, began sampling in 1989. Beginning in 1992, fisheries component specialists at each of six field stations began to systematically record data on turtles collected as a by-product of fisheries monitoring. Herein we summarize data collected on turtle communities in the UMRS from 1992 to 1995. Our analysis is important because it is the first based on long-term collections that encompass a wide geographic area made in any large river. Overall, we caught 4,414 individual turtles of 10 species from all reaches and in all years. Species of chelonians collected included the common map turtle (Graptemys geographica), the false map turtle (G. pseudogeographica), the Ouachita map turtle (G. ouachitensis), the painted turtle (Chrysemys picta), the red-eared slider (Trachemys scripta elegans), the river cooter (Pseudemys concinna), the common snapping turtle (Chelydra serpentina), the smooth softshell (Apalone mutica), the spiny softshell (A. spinifera), and the stinkpot (Sternotherus odoratus). The number of species collected tended to increase from north to south. We found the southern reaches to contain more species, but with reduced diversity indices due to decreased evenness in the sample and with increased density as measured by catch per unit (CPU) effort. Apparently, increased density accrued from increased number of individuals from one or two dominant species present rather than a general increase in all species present. Species diversity as measured by number of species collected did not vary with habitat type. We sampled tributaries, backwaters, impoundments, channel borders, side channels, and tailwater zones. Habitat was an important determinant in the sorts and proportions of turtle species collected. Backwaters and impoundments were dominated by C. picta and T. s. elegans. In contrast, species of Graptemys dominated main channel border and side channel borders. Tailwater habitats differed from other habitats in species composition due to the importance of A. spinifera. Species composition within particular habitats was strongly affected by sampling location within the system. Among all the gear types used by fisheries components at the LTRMP field stations, fyke nets were by far the most effective at catching turtles. This gear type accounted for 65% of all turtles collected. Temporal variation accounted for a significant amount of variation in carapace length for some species. Turtles collected earlier in the year (i.e., June, July, or August) tended to be larger than those collected later in the year (i.e., September or October). Overall our models on the influence of variables on turtle size accounted for 28 to 48% of the variance excepting the A. spinifera model, which accounted for 82% of the variance in carapace length. Sexual size dimorphism was found for many of the species collected. In such cases males were smaller than females. Dimorphism was most pronounced in the two softshell species and least pronounced for the Stinkpot and common snapping turtle. Navigation dams such as those found in the UMRS create impoundments that have different ecological features than the more natural habitat types such as backwaters, channel borders, etc. We found effects that may be attributable to impoundment. We found no effect on the number of species in impoundments as all major habitats for all reaches combined contained nine species. However, species diversity indices were greater for backwater habitats than impoundments. The difference seems to be due to greater unevenness in impoundments where one or two species dominate collections. Despite this, the number of individuals collected in impoundments was fewer than those collected in backwater habitats. This suggests that protection of backwater habitats from alteration and maintaining their riverine nature is important in maintaining species diversity and density among aquatic turtles in the UMRS.INHS Technical Report Prepared for National Biological Survey via Environmental Management Technical Center, Onalaska, Wisconsi

Incorporating basic and applied approaches to evaluate the effects of invasive Asian Carp on native fishes: A necessary first step for integrated pest management.

Numerous studies throughout North America allege deleterious associations among invasive Asian Carp and native fishes; however, no empirical evidence on a system-wide scale exists. We used Mississippi River Basin fish community data collected by the Long Term Resource Monitoring program and the Missouri Department of Conservation to evaluate possible interaction between Asian Carp and native fishes. Results from two decades of long-term monitoring throughout much of the Mississippi River suggest that Silver Carp relative abundance has increased while relative abundance (Bigmouth Buffalo [F 3, 8240 = 6.44, P 0.05). To this end, this study provides evidence that Silver Carp are likely adversely influencing native fishes; however, mere presence of Silver Carp in the system does not induce deleterious effects on native fishes. To the best of our knowledge, this evaluation is the first to describe the effects of Asian Carp throughout the Mississippi River Basin and could be used to reduce the effects of Asian Carp on native biota through an integrated pest management program as suggested by congressional policy. Despite the simplicity of the data analyzed and approach used, this study provides a framework for beginning to identify the interactions of invasive fish pests on native fishes (i.e., necessary first step of integrated pest management). However, knowledge gaps remain. We suggest future efforts should conduct more in depth analyses (i.e., multivariate statistical approaches) that investigate the influence on all native species

Contents

partners with scientific and technical support. All reports in this series receive anonymous peer review. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the U.S. Department of the Interior, U.S. Geological Survey

Contents

partners with scientific and technical support. All reports in this series receive anonymous peer review. Mention of trade names or commercial products does not constitute endorsement or recommendation for use by the U.S. Department of the Interior, U.S. Geological Survey