Vital population rates across multiple spatial scales: A geostatistical analysis

Abstract

Population and community level processes change across multiple spatial scales. Understanding these patterns and the factors that drive them are essential for the development of spatial approaches in fisheries management. Determining appropriately-resolved spatial scales is further complicated in temperate marine ecosystems by the generally high mobility and low site fidelity of temperate species compared to those in tropical reef systems. Spatial variability in per capita vital population rates (e.g., consumption, mortality, growth, survival) can directly affect the population level dynamics of managed species. Benthic habitat characteristics also change across spatial dimensions and may contribute to the differential spatial variability in vital rates. We used a set of bioenergetic equations to compute the daily per capita rate of consumption and mortality for individual groundfish species. These estimates used data from the US National Marine Fisheries Service Northeast Fisheries Science Center bottom trawls and food habits data sets. A geographic information system (GIS) was created to map these vital rates at multiple spatial scales. The spatial variability and spatial independence of vital rates were then explored using geostatistical techniques. Multivariate statistical approaches were also used to examine how habitat characteristics may be influencing spatial patterns in vital rates. Our results demonstrate the challenge of evaluating key population processes at the most appropriate spatial scales. Yet the demonstrated ability to integrate individual, population, and habitat information across multiple spatial scales should enhance our ability to manage our living marine resources. Keywords: spatial statistics, consumption, mortality, groundfish, fisheries management, essential fish habitat, NW Atlantic