Globally, croplands and rangelands are major land uses and they have altered lands and waters for millennia. This continues to be the case throughout the USA, despite substantial improvements in treating wastewaters from point sources—versus non-point (diffuse) sources. Poor macroinvertebrate assemblage condition occurs in 30% of conterminous USA streams and rivers; poor fish assemblage condition occurs in 26%. The risk of poor fish assemblage condition was most strongly associated with excess nutrients, salinity and sedimentation and impaired riparian woody vegetation. Although the Clean Water Act was passed to restore and maintain the integrity of USA waters, that will be impossible without controlling agricultural pollution. Likewise, the Federal Land Policy and Management Act was enacted to protect the natural condition of public lands and waters, including fish habitat, but it has failed to curtail the sacred cows of livestock grazing. Although progress has been slow and spotty, promising results have been obtained from basin and watershed planning and riparian zone protections.
The Amazon sailfin catfish Pterygoplichthys pardalis is native to the Amazon River basin. It has since expanded its range to North America, the Caribbean, and more recently to South Asia, as with some of its congeners. Our paper reviews recent data from Bangladesh, clarifies taxonomic identification, and examines the potential effects of P. pardalis and congeneric species on local aquatic ecosystems and elsewhere in South Asia. Range expansions there probably reflect aquarium releases and escapes from aquaculture farms, as exacerbated by dispersal due to storm flooding and in impacted waters like irrigation canals. Given their potential ecosystem-level effects, we also review potential control mechanisms and human use for these invasive loricariids.
20 July 2016 in North American Journal of Fisheries Management
During 2001–2003, we counted redds of Coastal Cutthroat Trout Oncorhynchus clarkii clarkii and measured microhabitat variables at fresh redds in Irely Creek upstream of Irely Lake in a largely undisturbed watershed within Olympic National Park, Washington. Redd numbers declined abruptly in 2003, the year after a dry summer caused the dewatering of Irely Lake; therefore, we continued the redd counts during 2004–2012 to determine whether pond dewatering was a factor in the decline and whether redd counts would track Irely Lake surface area. The estimated number of redds varied from a high of 51 (in 2002) to a low of 2 (in 2006, 2007, and 2010); increases in estimated redd number occurred after wetter summers, and decreases were observed after drier summers. This pattern was significant in chi-square tests for redd number and the change in redd number with Irely Lake condition in the preceding year (dry, semi-dry, or wet). Rather than indicating juvenile mortality, the lack of a lag in response suggests the mortality of adults that would otherwise have spawned during the subsequent spring. The clear impact of dry summers in one of the wettest regions of North America underscores the important influence of hydrology on fish, even in the absence of other disturbances. Received September 16, 2015; accepted March 15, 2016 Published online July 20, 2016
Globally, native migratory and resident fishes are declining from aquatic and terrestrial ecosystem degradation resulting from physicochemical habitat alteration, migration barriers, over-exploitation, hatchery supplementation, non-native species introductions, and the climate crisis