No abstract

Stomach content data on 14,796 spiny dogfish (Squalus acanthias) from British Columbia waters are presented. The major dietary components based on occurrence were 55% teleosts, 35% crustaceans, and 5% molluscs. The principal food items were herring (22%) and euphausiids (14%). Prey was largely pelagic (80%), with fishes predominating in winter and invertebrates in summer. Fishes became more important in the diet with increasing dogfish size. Dogfish consumed twice as much food in summer as in winter. Annual consumption varied from 5 times biomass for small dogfish to 2.5 times for larger animals. Preliminary analyses suggest that dogfish consume over 5 times the current annual commercial catch of herring, but insignificant quantities of salmon. Key words: dogfish, Squalus, feeding, food, biomass, predation, metabolism, seasonality, survivorship, digestion

In this article, operational definitions of resiliency used in previous studies are reviewed. Data from a sample of 56 maltreated school-age children are then explored to highlight how variations in the source, type, and number of assessments obtained affect the rates of children classified as resilient. Assessments were obtained in three domains: academic achievement, social competence, and clinical symptomatology. Two sources of information were used to assess each domain, and three different data integration procedures were used to calculate rates of resiliency in the maltreated cohort. It is concluded that the most appropriate definition of resiliency to be used in future investigations depends on the aims of the study. If the goal of the study is to assess overall functioning, there is an advantage to using more broad, multidimensional assessments. If, in contrast, the goal of the study is to determine why some high-risk children develop particular types of problems, to identify underlying etiological processes associated with different outcomes, there is an advantage to using narrower definitions.

Lengths at 50% maturity of spiny dogfish (Squalus acanthias) in the Strait of Georgia, B.C., are 78.5 and 93.5 cm, corresponding to ages 19 and 29 yr, for males and females, respectively. Modal lengths of mature males and females are 85 and 100 cm, respectively.Mating occurs from October to January, with a peak in December. Males are capable of mating every year, with smaller dogfish mating earlier in the year than larger ones. Females mate every 2nd yr. Ovulation of 4 cm diam eggs closely follows mating. The fertilized eggs are enclosed in gelatinous capsules for 4 mo after which the embryos are released into the uterine cavity. The external yolk supply of the embryos is totally absorbed by parturition, although the internal yolk is not fully utilized until 2 mo later. Parturition occurs from September to January, with a peak in November. Gestation is roughly 23 mo. Breeding females produce a mean of 7.14 progeny.These population characteristics indicate that regulation of a future fishery should be by total catch limit rather than net mesh size selection. Key words: spiny dogfish, reproduction, length distribution, survivorship, fecundity, fishery regulation

Ages of spiny dogfish (Squalus acanthias) in the Strait of Georgia, B.C., have been estimated by an X-ray spectrometric technique which involves measuring variations in the element composition within vertebrae.