Updated distribution of four stenohaline fish species in Labrador, Canada

Distributions of freshwater fish species in Labrador are poorly documented as the region is remote and sparsely inhabited. Here, we update distributions of four species native to the Labrador Peninsula based on data collected over 10 years: Burbot (Lota lota), Round Whitefish (Prosopium cylindraceum), Lake Trout (Salvelinus namaycush), and Slimy Sculpin (Cottus cognatus). In northern Labrador, our findings extend their ranges inland and northwest of their formerly reported distributions. Their presence in previously unknown locations indicates an alternative post-glacial colonization pathway to one previously proposed that suggested an isolated pocket of Lake Trout in a northern coastal area colonized through marine invasion. Instead, we suggest that overland colonization occurred when glacial Lake Naskaupi withdrew across Quebec into several northern drainages. In southern Labrador, we found Lake Trout and Round Whitefish to the southeast of their previously reported ranges. The discovery of an isolated population of Lake Trout in a remote location of southeast Labrador implies that they may have existed in the area historically (6000 years ago), but have undergone a range contraction with a warming climate. In addition, 22 new locations are documented for Lake Trout within their established range.

The Pennsylvania grotto sculpin: population genetics

The Pennsylvania grotto sculpin is known from just two caves of the Nippenose Valley in central Pennsylvania, USA. They exhibit emergent troglobitic morphological traits and are the second northern-most cave adapted fish in the world. Two mitochondrial (16S rRNA and D-loop gene) and one nuclear (S7 ribosomal protein gene intron) gene in both cave and epigean populations were sequenced. For the three markers, a large proportion of cave specimens possess unique haplotypes not found in their local surface counterparts, suggesting a vicariance in their evolutionary history. The cave population also has haplotypes from two separate lineages of surface sculpins of the Cottus cognatus/bairdii species complex. Since morphology, nuclear, and mitochondrial markers are not correlated among cave individuals, hybridization with introgression is suggested.

Utility of Condition Indices as Predictors of Lipid Content in Slimy Sculpin (Cottus cognatus)

Slimy sculpin (Cottus cognatus) are increasingly being used as indicator species. This has primarily entailed measuring their condition, the assumption being that condition can be used as a surrogate for lipid content. While there is evidence to suggest this assumption is applicable to some fish, it has yet to be validated for C. cognatus. Further, there are several means by which one may calculate condition, the most commonly employed of which are indirect measurements of lipid content (namely, Fulton's K, somatic K (Ks), and Le Cren's relative condition factor (Kn)). We compared the ability of each of these morphometric indices to predict whole-body lipid content in C. cognatus. There was a moderate degree of evidence that Fulton's K, Ks, and Kn are reliable predictors (Ks and Kn in particular). Of the latter we recommend Kn be used because, unlike Ks, it does not require that fish be killed. And while Fulton's K did not perform quite as well, we consider it a sufficient substitute if the data necessary to calculate Kn are unavailable.

The biology and ecology of slimy sculpin: A recipe for effective environmental monitoring

Recently, the use of small-bodied fish in environmental monitoring has increased, particularly within the Canadian environmental effects monitoring (EEM) and other adaptive programs. Although it is possible to measure changes with many small-bodied species, interpretation is often complicated by the absence of information on the biology and ecology of fish not of commercial, recreational, or traditional interest. Knowing and understanding the basic biology of these fishes aids in the sensitivity of study designs (i.e., ability to detect change) and the interpretation of all biological levels of responses (e.g., cellular to community). The increased use of slimy sculpin ( Cottus cognatus Richardson, 1836) in impact assessment studies in North America provides a considerable amount of information on life history aspects. The slimy sculpin has the most ubiquitous North American distribution among cottids but yet has a very small home range, thus integrating environmental conditions of localized areas. This paper describes aspects of slimy sculpin life cycle that affect collection efficiency and timing, and describes and provides data collected over more than 10 years of studies at more than 20 reference study sites. This overview provides a functional and informative compilation to support adaptive environmental monitoring and provide a baseline for comparative ecological study.