Biology of Cystidicola farionis Fischer, 1798 (Nematoda : Cystidicolidae) in salmonid fishes

Morphological studies, experimental cross-infections and host specificity data suggest that the species of swimbladder nematode which matures in Coregonus clupeaformis, from inland lakes is not distinct from Cystidicola farionis which matures in Coregonus artedii and other salmonids from Lakes Superior and Nipigon. Adult worms in Coregonus clupeaformis are morphologically indistinguishable from those in other hosts. However, eggs of worms in Coregonus clupeaformis have predominantly lateral filaments, while those in other hosts have predominantly polar filaments. Larvae which accumulate but do not mature in the swimbladder of Coregonus clupeaformis from Lake Nipigon, grew and developed toward maturity in hatchery-reared Coregonus clupeaformis of Lake Simcoe origin. One, mature, male worm was found 77 days after experimental infection. Only female worms containing unshelled eggs were found after 120 days. This suggests that the development of C. farionis may depend on host strain. Uncertainty remains as to whether variations in egg morphology are host-induced or due to genetic differences of the worms involved. Filaments on the eggs of C. farionis readily adhere to the setose areas on the appendages of amphipod intermediate hosts. Presumably, this increases the probability of the intermediate host ingesting eggs. Eggs stored in water or saline for periods of two weeks or more do not hatch in the gut of amphipods. Only eggs recently released from female worms hatch and develop. Mature swimbladder nematodes were found in Coregonus clupeaformis from all of seven inland lakes examined in northwestern Ontario. Coregonus artedii was present in three of these lakes but was not infected, perhaps due to the lack of amphipod intermediate hosts in its diet. Cystidicola farionis matures in Salvelinus namaycush from Pettit Lake, Ontario and has eggs resembling those from worms in Coregonus clupeaformis from the same lake. Prosopium coulteri from Lake Superior are infected with C. farionis (new host record) but are not considered to be a suitable host for the worm as no mature worms were found. Infections in Coregonus clupeaformis from Pettit Lake and in Salmo gairdneri from Lake Superior exhibited similar seasonal periodicity with largest worm numbers occurring in the spring. The cephalic structures of C. farionis and its close relative, C. stigmatura, were studied using a scanning electron microscope and are compared with those of other cystidicolids

First record of Ammocrypta pellucida (Agassiz, 1863) (Actinopterygii: Perciformes) from the Lake Ontario drainage basin

The objective of this paper is to document the first occurrence of Ammocrypta pellucida in the Lake Ontario basin from samples collected in West Lake, Ontario (Canada) in 2013. Prior to this record, the known range of this imperilled species consisted of two disjunct elements in eastern North America separated by about 500 km. The new occurrence is in the middle of these two distributional elements and suggests that further inventory efforts are warranted in the intervening area

Monitoring lake populations of Eastern Sand Darter (Ammocrypta pellucida): a comparison of two seines

For many imperiled fishes in the Laurentian Great Lakes basin, detection protocols and population monitoring programs are lacking. In this study, we used a repeat-sampling approach to compare the effectiveness of two seines (bag and beach) to detect and characterize the abundance of lake-dwelling populations of Eastern Sand Darter (Ammocrypta pellucida); a threatened species in Canada. Compared to the bag seine, the larger beach seine collected a greater number of Eastern Sand Darter and detected the species at more sampling sites. Model-averaged estimates of detection probability were also greater for the beach seine (p = 0.72) than bag seine (p = 0.48). A decline in catch over repeated seine hauls occurred at less than a third of the sample units. Mean capture probabilities were 0.41 in units sampled by beach seine, and 0.37 in units sampled by bag seine, when depletion occurred. Sizes of Eastern Sand Darter collected by each seine were significantly different, with fewer small (<40 mm total length) individuals found in bag seine hauls. Power analyses indicate that data collected with either seine are expected to detect changes in local distribution of 50% or greater. Power to detect future changes in Eastern Sand Darter abundance of 50% or greater is predicted to be higher for the beach seine, and to increase with the number of seine hauls at a site. Catch differences between seines are interpreted to reflect the greater area sampled by the larger beach seine

Generic ecological impact assessments of alien species in Norway: a semi-quantitative set of criteria

The ecological impact assessment scheme that has been developed to classify alien species in Norway is presented. The underlying set of criteria enables a generic and semi-quantitative impact assessment of alien species. The criteria produce a classification of alien species that is testable, transparent and easily adjustable to novel evidence or environmental change. This gives a high scientific and political legitimacy to the end product and enables an effective prioritization of management efforts, while at the same time paying attention to the precautionary principle. The criteria chosen are applicable to all species regardless of taxonomic position. This makes the assessment scheme comparable to the Red List criteria used to classify threatened species. The impact of alien species is expressed along two independent axes, one measuring invasion potential, the other ecological effects. Using this two-dimensional approach, the categorization captures the ecological impact of alien species, which is the product rather than the sum of spread and effect. Invasion potential is assessed using three criteria, including expected population lifetime and expansion rate. Ecological effects are evaluated using six criteria, including interactions with native species, changes in landscape types, and the potential to transmit genes or parasites. Effects on threatened species or landscape types receive greater weightings

Reintroduction of fishes in Canada: a review of research progress for SARA-listed species

Fishes are among the most threatened taxa in Canada with over 70 species, subspecies, and/or designatable units presently listed for protection under the Species at Risk Act (SARA). Protecting these species requires a diverse set of strategies based on the best-available data and information. One approach identified under SARA and in Canadian federal recovery strategies for improving the status of SARA-listed fishes is species reintroduction, which involves the release of individuals into areas from which they have been extirpated with the goal of re-establishing self-sustaining populations. The success of reintroduction relies on a comprehensive understanding of species life history and ecology, with considerations around population genetics and genomics. However, SARA-listed species are some of the most poorly known species in Canada due to their rarity and relative lack of research investment prior to the enactment of SARA. As a result, SARA-listed species have the most to lose if reintroduction activities are not carefully researched, planned, and executed. Therefore, the purpose of this review is to present an accessible summary on the state of reintroduction science for SARA-listed fishes in Canada with the hope of motivating future research to support reintroduction activities. We focus our review on 14 SARA-listed freshwater or anadromous fishes identified as candidates for reintroduction in federal recovery strategies. We follow the species-specific summaries with guidance on how basic research questions in population ecology, habitat science, and threat science provide a critical foundation for addressing knowledge gaps in reintroduction science. Subsequently, we identify the importance of genetic and genomic techniques for informing future research on the reintroduction of SARA-listed species. We conclude with recommendations for active, experimental approaches for moving reintroduction efforts forward to recover Canadian fishes.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

What evidence exists for evaluating the effectiveness of conservation-oriented captive breeding and release programs for imperilled freshwater fishes and mussels?

Captive breeding programs are widely applied by conservation practitioners as a means of conserving, reintroducing, and supplementing populations of imperilled freshwater fishes and mussels. We conducted a systematic map to provide an overview of the existing literature base on the effectiveness of captive breeding and release programs. A key finding is that there is limited evaluation of the effectiveness of such programs at all three stages (i.e., broodstock collection, rearing/release methods, and post-release monitoring). We identified clusters of evidence for supplementation evaluations related to rearing/release methods for fish growth and survival metrics, and the monitoring stage for fish genetic diversity, growth, and survival metrics, primarily focused on salmonids. However, many studies had inadequate experimental designs (i.e., lacked a comparator). Overall, there was a paucity of studies on the effectiveness of captive breeding programs for imperilled freshwater mussels, highlighting the need to make such information broadly available when studies are undertaken. Outputs from this systematic map (i.e., the map database and heatmaps) suggest that the effectiveness of captive breeding and release programs requires further systematic evaluation.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author