The determination of whether purse seine fishing in the Eastern Tropical Pacific is hampering the recovery of the northeastern offshore spotted dolphin and eastern spinner dolphin populations is a difficult problem. The question was not answered satisfactorily by a simple consideration of population abundance estimates, despite these estimates being made using innovative methods and great care ...

Most population models assume that individuals within a given population are identical, that is, the fundamental role of variation is ignored. Here we develop a general approach to modeling heterogeneous populations with discrete evolutionary time step. The theory is applied to population dynamics of natural rotifer populations. We show that under particular conditions the behavior of the inhom...

Interacting populations exhibit complex behavior in nature. Classic quadratic iteration models with two or three populations exhibit some of the features seen in nature, but fail to account for spatial variation. Indeed, the diversity paradox is that many classic population models predict one species dominates while nature exhibits diversity. While various schemes have been presented to address...

Determining the factors that influence migratory population abundance has been constrained by the inability to connect events in different periods of the annual cycle. Carry-over effects are events that occur in one season but influence individual success the following season and recent empirical evidence suggests that they may play an important role in migratory population dynamics. Using a lo...

The early life history 7 Abstract The relationship between the biomass of reproductively mature individuals (spawning stock) and the resulting offspring added to the population (recruitment), the stock–recruitment relationship, is a fundamental and challenging problem in all of population biology. The steepness of this relationship is commonly defined as the fraction of recruitment from an unfi...

This paper studies population models which have the following three ingredients: populations are divided into local subpopulations, local population dynamics are noniinear and random events occur locally in space. In this setting local stochastic phenomena have a systematic effect on average population density and this effect does not disappear in large populations. This result is an outcome of...

Maintenance of sustainable wildlife populations is one of the primary purposes of wildlife management. Thus, it is important to monitor and manage population growth over time. Sensitivity analysis of the long-term (i.e., asymptotic) population growth rate to changes in the vital rates is commonly used in management to identify the vital rates that contribute most to population growth. Yet, dyna...

A fundamental characteristic of any biological invasion is the speed at which the geographic range of the population expands. This invasion speed is determined by both population growth and dispersal. We construct a discrete-time model for biological invasions that couples matrix population models (for population growth) with integrodifference equations (for dispersal). This model captures the ...

This paper shows, in a two-sector Malthusian model of endogenous population growth, that output per capita, population density, and industrialization depend upon the labor intensity of agricultural production. Because the diminishing returns to labor are less pronounced, high labor intensity (as in rice production) leads not only to a larger population density but also to lower output per capit...

T he Netherlands is a small country in Western Europe, located on the North Sea coastal area at the mouth of the rivers Rhine and Meuse, bordering Belgium and Germany. The territory of the Netherlands covers 41,574 km of which 7,636 km are water. About one-quarter of the country, especially the western part where land has been reclaimed from the sea since the 16th century, actually lies below s...