Article

Studies on muscular topography and meat properties of beavers (Castor canadensis) caught in Tierra del Fuego, Chile

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Abstract

In 1946, 25 pairs of Canadian beavers were released in the Argentinean part of Tierra del Fuego. In the last decades the population increased, with negative consequences for the forest in the Chilean part of Tierra del Fuego. Reducing the numbers of beavers by hunting / trapping will result in production of furs and meat as a side-effect. The aim of this study was to generate data on muscular topography and meat characteristics of beavers in Chile and to compare these with findings on Castor fiber. Body mass, carcass mass and carcass yield (mean values ± standard deviation; n = 25) were 14.13 ± 5.02 kg, 6.79 ± 2.54 kg, and 48.07 ± 2.45 %, respectively. The contribution of hind legs, M. longissimus and front legs to the total carcass mass was 25.17, 8.05 and 11.86 %, respectively. Chemical composition of muscle tissue (n = 10) was 75.75, 22.46, 0.62, 1.12 and 0.34 % for moisture, crude protein, fat, ash and carbohydrates, respectively.

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... Our search returned a total of 18 ISI, 3 Chilean non-ISI and 2 Argentine non-ISI publications. The topics addressed in the extant scientific literature have been as varied as ethical implications of invasive species management (Haider and Jax, 2006), population genetics (Lizarralde et al, 2008), properties of beaver meat (Hofbauer et al, 2005) and general community and ecosystem ecology for both terrestrial and aquatic habitats (review in Anderson et al, 2009). Overall, we found that more research has been conducted in Chile (71 per cent) than Argentina (29 per cent), and only beginning in 2009 have investigators from both countries begun to publish their work jointly (n = 2; 9 per cent; Anderson et al, 2009; Wallem et al, 2010). ...
Chapter
The North American (or Canadian) beaver (Castor canadensis) is the largest rodent native to North America (Figure 29.1), being found in an extensive range from northern Canada to northern Mexico. It has only one other extant congener, C. fiber, distributed originally throughout western and northern Eurasia. Both species affect extensive areas by 'engineering' stream and riparian habitat through their habits of dam building and cutting streamside vegetation. They were also both prized for their pelts, leading to near extinction in their native ranges. Castor canadensis was hunted heavily and locally extirpated throughout North America by the late 1800s; subsequent conservation and restoration efforts succeeded in reintroducing the species in much of its native range by the mid-to late 20th century (Naiman et al, 1988). Simultaneously, in the 1940s and 1950s, efforts in various countries sought to introduce North American beavers outside of their native range for the perceived commercial value of its fur, including countries in Europe (e.g. Finland, Poland, Austria and Russia), where the native C. fiber had been decimated, and Chile and Argentina, where no native species occupied a similar niche (Anderson and Valenzuela, 2011). Due to the unique nature of the introduction of beavers to southern South America, this chapter will focus on the socioecological role of this invasive exotic species in sub-Antarctic forests and the policy-research response of local and international managers and scientists. The sub-Antarctic archipelago, shared between Chile and Argentina (Figure 29.2), presents a paradox. On one hand, portions of this ecoregion are some of the least disturbed ecosystems on the planet (i.e. low human population density, highly intact native vegetation cover and over 50 per cent of its territory falling within the system of state protected areas; Mittermeier et al, 2003), while at the same time, it experiences pressing global environmental threats such as invasive alien species, climate change, the ozone hole and rapid commercial development, including tourism and salmon farming (Anderson et al, 2006a; Rozzi et al, 2006). The North American beaver has large impacts across the Tierra del Fuego and Cape Horn Archipelagos. The species was introduced in a single release of 25 pairs in 1946 by the Argentine government to Isla 29
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Sixty-five percent (469 of 722) of the fecal samples collected from small rodents in the central Washington Cascade mountains were positive for Giardia spp. Trapping studies showed that microtines of the genus Microtus were heavily infected with the parasite. Morphologically the cysts and trophozoites were of the Giardia duodenalis type. Small-rodent populations appear to maintain their infection throughout the year. Our data suggest that there is no difference in the percentage of positive animals in areas receiving a lot of human use as opposed to animals in those areas receiving very little or no human use. Giardia spp. were also found in elk and beaver fecal samples. Campylobacter spp. were recovered infrequently from the small rodents inhabiting alpine meadows. Of 551 specimens cultured, less than 1% were positive for the bacterium, and the isolates were identified as Campylobacter coli. Water voles were susceptible to a human isolate of Campylobacter jejuni and shed the bacterium for several weeks. C. jejuni was also isolated from a bear fecal sample collected from a protected watershed. Our studies indicate that microtines and possibly other small rodents inhabiting mountain meadows have a potential to act as a reservoir for both Giardia spp. and Campylobacter spp. Because these animals may carry human pathogens, they should be included in animal surveys designed to assess the health risks associated with mountain watersheds.
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