Density-dependent habitat selection and the ideal free distribution in marine fish spatial dynamics: considerations and cautions

The ideal free distribution (IFD) of behavioral ecology has been used in the study of the distribution of fishing effort since the 1990s. Concurrently, evolutionary perspectives on forager distributions have led to the development of theoretical curves of equal fitness, named isodars, to test IFD hypotheses. We develop isodars, based upon catch rates and unknown costs, to quantify regularity in the distribution of fishing effort among alternative areas. Our analyses indicate that these isodars provide significantly better predictions than a simple IFD without costs. Autocorrelation in the catch and effort data necessitates the use of generalized linear least squares when estimating model parameters. Differences in costs that are proportional to effort are more clearly identified in the model than nonlinear effects, which may arise from extreme interference competition. The isodar approach provides a new tool for examining the spatial dynamics of catch and effort data. It improves the accuracy of predictions and provides new parameters related to costs and vessel interactions that can be applied to rapidly identify situations where effort dynamics have changed.

Download Full-text

The Ideal Free Distribution and Evolutionary Stability in Habitat Selection Games with Linear Fitness and Allee Effect

Springer Proceedings in Mathematics & Statistics - Interdisciplinary Topics in Applied Mathematics, Modeling and Computational Science ◽

10.1007/978-3-319-12307-3_66 ◽

2015 ◽

pp. 457-463 ◽

Cited By ~ 7

Author(s):

Ross Cressman ◽

Tan Tran

Keyword(s):

Habitat Selection ◽

Allee Effect ◽

Ideal Free Distribution ◽

Evolutionary Stability ◽

Free Distribution ◽

Ideal Free ◽

The Ideal

Download Full-text

Density-dependent host choice by disease vectors: epidemiological implications of the ideal free distribution

Transactions of the Royal Society of Tropical Medicine and Hygiene ◽

10.1016/j.trstmh.2006.08.009 ◽

2007 ◽

Vol 101 (3) ◽

pp. 256-269 ◽

Cited By ~ 21

Author(s):

María-Gloria Basáñez ◽

Karina Razali ◽

Alfons Renz ◽

David Kelly

Keyword(s):

Ideal Free Distribution ◽

Host Choice ◽

Disease Vectors ◽

Density Dependent ◽

Free Distribution ◽

Ideal Free ◽

The Ideal

Download Full-text

Distributionabundance relationships for North Sea Atlantic cod (Gadus morhua): observation versus theory

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f05-109 ◽

2005 ◽

Vol 62 (9) ◽

pp. 2001-2009 ◽

Cited By ~ 78

Author(s):

Julia L Blanchard ◽

Craig Mills ◽

Simon Jennings ◽

Clive J Fox ◽

Brian D Rackham ◽

...

Keyword(s):

Habitat Selection ◽

North Sea ◽

Gadus Morhua ◽

Atlantic Cod ◽

Ideal Free Distribution ◽

Density Dependent ◽

The North ◽

The North Sea ◽

Density Dependent Habitat Selection ◽

Ideal Free

Density-dependent habitat selection has implications for fisheries management and for the recovery of depleted fish populations. According to ideal free distribution theory, populations contract into areas of highest habitat suitability as their abundance decreases. This can increase their vulnerability to fishing and predation. We detected density-dependent habitat selection by juvenile Atlantic cod (Gadus morhua) (ages 1 and 2) in the North Sea and compared the observed distributionabundance relationships with those predicted from a model based on ideal free distribution theory and knowledge of optimal temperatures for growth, where temperature was used as a measure of suitability. As predicted by the model, in years when stock size was low, the catches were largely confined to regions with near-optimal bottom temperatures. Conversely, when population size was high, catches were spread across a larger area including regions with suboptimal temperatures. The spatial extent of optimal habitat appears to have decreased from 1977 to 2002, reflecting a gradual warming of the North Sea. The combined negative effects of increased temperature on recruitment rates and the reduced availability of optimal habitat may have increased the vulnerability of the cod population to fishing mortality.

Download Full-text