The lake sturgeon is one of the largest North American freshwater fish and was once common in most inland rivers and lakes of the US and Canadian Midwest. World demand for caviar and sturgeon meat led to a dramatic decline of lake sturgeon populations throughout much of its range. Along with overfishing, lake sturgeon populations have been negatively affected by habitat degradation. Recruitment factors and early life history are poorly understood. Today, renewed interest in lake sturgeon restoration has led to numerous state and federally-funded research activities. Research has focused on identifying and assessing the size structure of remnant stocks, the availability of spawning habitat, and factors affecting reproductive success. Additional studies are needed to improve hatchery techniques, to better understand recruitment mechanisms, and how genetic diversity among and within meta-populations may affect long-term recovery of depleted populations.

Greenland shark Somniosus microcephalus is a potentially important yet poorly studied cold-water species inhabiting the North Atlantic and Arctic Oceans. Broad-scale changes in the Arctic ecosystem as a consequence of climate change have led to increased attention on trophic dynamics and the role of potential apex predators such as S. microcephalus in the structure of Arctic marine food webs. Although Nordic and Inuit populations have caught S. microcephalus for centuries, the species is of limited commercial interest among modern industrial fisheries. Here, the limited historical information available on S. microcephalus occurrence and ecology is reviewed and new catch, biological and life-history information from the Arctic and North Atlantic Ocean region is provided. Given the considerable by-catch rates in high North Atlantic Ocean latitudes it is suggested that S. microcephalus is an abundant predator that plays an important, yet unrecognized, role in Arctic marine ecosystems. Slow growth and large pup sizes, however, may make S. microcephalus vulnerable to increased fishing pressure in a warming Arctic environment.

We present digital imaging methods for geometric morphometric analysis of shape, and we describe issues associated with improper image acquisition by using lake trout Salvelinus namaycush as an example. The choice of imaging equipment, the configuration of that equipment, and the orientation of the specimens with respect to the camera lens can lead to inaccurate imaging and ultimately to error in landmark placement during morphometric analysis. Lake trout that were imaged at 15‐mm focal length and 0.5‐m focal distance (treatment 1) were distorted in comparison with fish that were imaged at 50‐mm focal length and 2‐m focal distance (treatment 2). Deformation grids showed dramatic variation in the horizontal plane along the length of the fish, especially midbody, suggesting that barrel distortion was occurring at the 15‐mm focal length. Partial warp scores resulting from geometric analysis of body shape differed for all fish on all 18 warps as a result of the different focal length and distance treatments for image capture. To minimize perspective (orientation) and distortion (equipment) errors, we recommend using a digital single‐lens reflex camera (>5 megapixels) with a lens that has a focal length exceeding 35 mm, a horizontal tripod to position the lens directly over the specimen, a mesh cradle to create a planar imaging surface, and dissection pins to display the fish in a standard orientation. The method presented herein will aid in reducing measurement error associated with landmark homology and will promote comparability of geometric shape data among studies.

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