Significant declines in the recruitment of American eels Anguilla rostrata to formerly productive habitats in the upper St. Lawrence River and Lake Ontario resulted in the implementation of an experimental conservation stocking program. Nearly 3.8 million American eels (glass eel and elver stages) were stocked during 2006–2009. Our study objectives were to (1) assess the adequacy of sampling procedures for following temporal changes in stocked eel abundance, (2) examine captured eels for evidence of spinal trauma, (3) qualitatively evaluate whether stocked eels would disperse outside of stocking locations, and (4) provide initial data on biological variables describing young stocked yellow eels. Boat electrofishing was successful at capturing all four stocked year‐classes, and the densities of stocked eels in the main stocking locations ranged from 25 to 275 eels/ha. Estimated sampling precision ranged from 0.15 to 0.28, and the estimated sample sizes required to detect a 50% change in stocked eel densities ranged from 27 to 112 electrofishing transects depending on location and season. The stocked American eels dispersed throughout Lake Ontario and demonstrated among the fastest recorded growth rates for this species: 60 to 123 mm/year. The first male American eels ever identified in the St. Lawrence River watershed were among the stocked individuals assessed for gender. We conclude that boat electrofishing for yellow American eels has the potential to measure stocking effectiveness along shallow shorelines with limited aquatic vegetation. We also recognize that the ultimate assessment of the conservation stocking experiment will not be made until future studies on the population demographics, migratory behavior, and spawning physiology of stocked American eels are complete. Received December 10, 2010; accepted May 11, 2011

An experimental stocking program in the St. Lawrence River–Lake Ontario system provided a unique opportunity to compare reproductive fitness of migrant silver American Eels Anguilla rostrata from the stocking program (SM) and wild migrants (WM), both of which were grown in the same location. Body size, muscle lipid stores, oocyte development, and morphometric indices of silvering were compared between SM and WM eels captured in the St. Lawrence River estuary. Migrant eels from the stocking program were smaller than wild migrants from the estuary, but their size was similar to migrating wild silver American Eels from their site of original capture on the Atlantic coast of New Brunswick and Nova Scotia. A bioenergetic model was used to estimate the costs of migration and reproduction and the duration of migration. The adequacy of the measured lipid reserves to meet these estimated energetic costs was assessed for SM and WM eels. Gonad maturation and stage of silvering for SM eels were less advanced than that for WM eels, and they had lower initial muscle fat reserves and higher estimated energetic requirements for migration as a consequence of their smaller size. It was estimated that 100% of the SM eels would not have adequate fat reserves for migration and reproduction, whereas 57% of the WM eels would have adequate reserves. Smaller‐sized SM eels would take 1.6 times longer to reach the spawning grounds than WM eels and, thus, may not arrive in synchrony with these wild migrants. Thus, smaller‐sized, out‐migrating, stocked eels from the upper St. Lawrence River are less likely than wild migrants to complete successfully their migration and reproduction. These results support the recommendation to source and stock American Eels at sites where they have similar life strategies to increase the likelihood of successful silver eel escapement. Received November 27, 2013; accepted April 9, 2014

The age and growth of lake sturgeons (Acipenserfulvescens) were investigated in the lower Moose River system in the Hudson Bay lowland. The effects of current fishing methods also were reviewed in order to recommend procedures for a sustained-yield fishery. The population estimate of lake sturgeon in the study area was 7,088 with 95ø/o confidence limits of 5,774-8,919. Sex ratios of all fish sampled throughout the summer were 1:1 and the length-weight relationship showed allometric growth with no significant differences between sexes. The age of first spawn for females was approximately 20 years but that for males was suspect due to small sample sizes of ripe males. Tissue memury analyses showed relatively high levels of mercury in lake sturgeons longer than 102 cm. Growth was calculated from the Brody-Bertalanffy relationship that was employed in the Beverton-Holt yield model. This model indicated that increases in fishing intensity under present fisheries regulations would result in overexploitation. An alternative commercial fishery management plan for sustained yield is proposed.

Although many fish habitat suitability models (HSMs) have been developed and used in wildlife management and conservation planning, comparatively few have been independently validated. Given the importance of such models in habitat management and conservation policy, the extent to which they accurately predict population parameters (e.g., abundance or recruitment) is a critical issue. Here we apply an HSM recently developed for lake sturgeon Acipenser fulvescens in northern rivers to three reaches of the Ottawa River, using measurements of the model's key variables (substrate type, water depth, and velocity) to generate spatially explicit predictions of habitat suitability. We then test the predictive power of the model by comparing lake sturgeon catch per unit effort (CUE) when using short‐set gill nets in areas predicted to have good (habitat suitability index values >0.6) and poor (values < 0.3) adult and juvenile foraging habitats. Consistent with model predictions, significantly more lake sturgeon were caught at sites within river reaches predicted to be of high quality than at those predicted to be of low quality. Moreover, the average CUE at the reach scale correlated positively with the average predicted habitat foraging quality. On the other hand, the predictive power was generally low, such that most of the variation in CUE was unexplained by the fitted models. These results suggest that although the lake sturgeon HSM developed for northern rivers has some predictive power in other contexts, the uncertainty of its predictions is still rather high. We suggest that (1) considerably more effort be devoted to the independent validation of both existing HSMs and those still in development and (2) in the absence of independent validation and bona fide estimates of their predictive power, such models be used circumspectly in conservation management and planning.

The 240-h NaCl LC50 for goldfish, Carassius auratus, was estimated as 201.1 (SE 6.7) mmol∙L−1, a concentration well in excess of one recently published value, but consistent with earlier observations on the tolerance of this species for hypersaline conditions. Evidence for operation of several lethal effects that vary in intensity with time, the absence of a well-defined relationship between dose and mortality within an intermediate range of lethal NaCl concentrations, and the strong likelihood of size-related variation in individual sensitivity to NaCl suggest that NaCl is an inappropriate reference toxicant for use in static bioassays involving this species.Key words: NaCl, goldfish, toxicity