IBRAHIM, Ahmed G.; Univ. of California, Irvie: The Metabolic Rate of the Little Skate Raja erinacea

Skates are dorsoventrally flattened carnivorous fish that inhabit deep and shallow waters of marine environments (Leonard, et al.). Like all elasmobranches (i.e. sharks, rays), skates lack a bony structure, instead they have a skeleton comprised of a matrix of soft, white or translucent chondrin called cartilage. All skates are oviparous (egg-laying), laying flat, rectangular shaped egg capsules with a pair of posterior and anterior horns emanating from the corners of the single-embryo capsule. The little skate (Raja erinacea) is a common species of the North Atlantic marine ecosystem. Though the species is well known and frequently studied, its bioenergetics have not been fully investigated. We measured the metabolic rate of the little skate �Raja erinacea� using two approaches to bioenergetics. The first method was respirometry, where live individuals (n=10) where placed in chambers and oxygen consumption was measured in uniform increments of 15 or 30 minutes. Data were recorded in mg O2�hr-1�g-1. The second approach used homogenized skate tissue (n=20) for the measurement of energy content via micro-bomb calorimetry. The mean recorded metabolic rate was 0.0543 mg O2�hr-1�g-1. Oxygen consumption over the nine month development period was calculated to be 0.352 g O2�g-1 .Results for calorimetry were recorded in kcal/g or kcal for crude measurements. The mean recorded calorie content among the individuals was 4.25 kcal/g and 4.22 kcal/g in yolk samples. Using regressional analysis the yolk conversion efficiency of the skate embryo was found to be over 100%, which might suggest an alternate quota than yolk. More work into the bioenergetics of Raja erinacea is still underway.