GAMs of blue crab distribution

In a paper published in Marine Ecology Progress Series (Jensen et al. 2005), we develop generalized additive models (GAMs) of female blue crab distributions in Chesapeake Bay during winter. The models are based on thirteen years of data (1990 - 2002) from a winter dredge survey conducted co-operatively by the Virginia Institute of Marine Science and the Maryland Department of Natural Resources. In the paper, the distribution and abundance of blue crabs was modeled as a flexible function of depth, salinity, water temperature, distance from the Bay mouth, distance from submerged aquatic vegetation (SAV), and bottom slope for each of the 13 years of data available. Depth and distance from the Bay mouth and the interaction of these two terms were found to be the most important environmental determinants of mature female blue crab distributions. The response curves for these two variables displayed patterns that are consistent with laboratory and field studies of blue crab/habitat relationships. The generality and transferability of the habitat models was assessed using intra- and inter-annual cross-validation. Although the models generally performed well in cross-validation, some years showed unique habitat relationships that were not well predicted by models from other years. Such variability may be overlooked in habitat suitability models derived from data collected over short time periods.

Here we provide graphs, including some not found in the paper, showing response curves for all independent variables and years. Note: response curves are conditional, i.e., they reflect the response given the other variables in the model. Therefore response curves for individual independent variables that are also included in an interaction (indicated by an I in the table below) should be interpreted with caution. To go to the figures, follow the link to the table and select any term view the corresponding response curve.

GAM Table

QuaFEL research areas


Blue crab ecology

Multispecies interactions

Fisheries Oceanography

Elasmobranch ecology


Last revised: 4/3/2015