No abstract

Fishways have traditionally been designed to provide safe passage for jumping fish and only recently have nonjumping species been considered. Concern over dwindling populations of lake sturgeon, Acipenser fulvescens, has focused attention on fishway designs that accommodate its swimming abilities. The objective of this study was to derive a model that relates swimming endurance of lake sturgeon to length and flow characteristics of fishways. Endurance at sustained and prolonged swimming speeds (those maintainable for more than 20 s) increased with water temperature but was independent of temperature at higher burst speeds. Endurance increased with total length at all swimming velocities. Swimming performance of lake sturgeon, relative to body length, is inferior to that of most salmonids, particularly at burst speeds. Fishway designers need to consider swimming ability, space requirements, and behavior of lake sturgeon to ensure that they can ascend potential migratory obstacles safely.

The sea lamprey (Petromyzon marinus) in the western Atlantic Ocean adjacent to North America is usually found within a depth of 200 m between latitudes of 30 and 53°. Spawning size lampreys have been recorded in 116 rivers between 32 and 48° latitude. The upstream spawning migration which may extend to several hundred kilometres, takes place between March and September, the actual time varying directly with latitude. Fecundity of the anadromous P. marinus (approximately 124 000–305 000) is the highest for any lamprey species. Energy requirements for migration and reproduction are discussed in the context of parental investment. The larval phase lasts 6–8 yr and is followed by a highly synchronous period of metamorphosis. On completion of metamorphosis in late autumn some juveniles migrate downstream to the estuary or ocean and commence feeding. In at least some rivers, a portion of the young juveniles overwinter in the natal stream without feeding. Subsequent to a short feeding period in May these young juveniles leave the river for the sea. Sea lampreys attack a variety of marine elasmobranchs and teleosts. Only swordfish, Xiphias gladius, and striped bass, Roccus saxatilis, are reported to eat lampreys. During the marine interval, which lasts from 23 to 28 mo, the calculated instantaneous growth rate is 0.645–0.785 g∙d−1. Lamprey scarring frequency on Atlantic salmon, Salmo salar, in the St. John River, New Brunswick, increased from 2.6 to 15.0% between 1972 and 1975 coincident with a dramatic rise in the number of migrant salmonids. Scars were most prevalent on larger salmon, particularly females. Most scars were recorded on the right side of salmon, particularly in the ventral regions.Key words: sea lamprey, Atlantic Ocean, distribution, life cycle, growth, energetics, fecundity

Standard oxygen consumption, as estimated by simultaneously measuring spontaneous activity and oxygen consumption, for five species of freshwater fishes, was measured in relation to weight and temperature. The fish studied were brown trout, Sulmo trutta; brook trout, Salvelinus fontinalis; common white sucker, Catostomus commersonii; brown bullhead, Ictalurus nebulosus; and carp, Cyprinus carpio. When expressed on a logarithmic grid, standard oxygen uptake increased linearly with weight for all species. The proportionate change in standard oxygen consumption for a given change in temperature appears to be independent of size within each species. The mean slope values of the regressions found for brown trout, brook trout, common white sucker, brown bullhead, and carp are 0.877, 1.052, 0.864, 0.925, and 0.894, respectively.The standard rates of oxygen consumption found in the present investigation are less in most cases than the lowest applicable values that could be found in the literature.Spontaneous activity, expressed in terms of average oxygen consumption over the standard rate, varied with temperature. Maximum spontaneous activity for a given species coincided roughly with its preferendum temperature.

Changes in growth and proximate body composition of largemouth bass (Micropterus salmoides) were examined for fish of 8–150 g, between 18 and 30C. For most weights, growth of fish (grams/day) was highest at 25C, and lowest in fish at 18C. This was attributable in part to a higher satiation (maximum) feeding level at 25C. For a fixed level of feeding, growth rate (percentage wet weight/day) was highest for fish held at 18C.Lipid content (percentage wet weight) increased with feeding level and was highest at 18C, Moisture content varied inversely with lipid. Protein and ash content did not vary appreciably with temperature, body weight, or feeding level.Maintenance requirement of bass, expressed as grams/day, was about twice that lost during food deprivation, but only slightly different when expressed as kilocalories/day.Energy requirements for nonfecal losses were estimated as 10% of intake energy at all feeding levels. Standard metabolism accounted for 50% of intake energy near maintenance, but only 10% at the satiation feeding level. Growth requirements increased From zero at maintenance to 40% of intake energy at satiation feeding.