National Marine Mammal Laboratory, 7600 Sand Point Way, N.E. Bldg. 4, Seattle, WA 98115.
IMPLICATIONS OF NON-LINEAR DENSITY DEPENDENCE
Article first published online: 26 AUG 2006
Marine Mammal Science
Volume 9, Issue 4, pages 360–371, October 1993
How to Cite
Taylor, B. L. and Demaster, D. P. (1993), IMPLICATIONS OF NON-LINEAR DENSITY DEPENDENCE. Marine Mammal Science, 9: 360–371. doi: 10.1111/j.1748-7692.1993.tb00469.x
- Issue published online: 26 AUG 2006
- Article first published online: 26 AUG 2006
- Received: September 23, 1992 Accepted: March 28, 1993
- density dependence;
- marine mammal;
- nonlinear dynamics;
- population dynamics
Abstract: Ranges of the ratio of maximum net productivity level (MNPL) to carrying capacity (K) are explored in general models for pinnipeds and odontocetes. MNPL/K is used in management of marine mammals but no empirical evidence exists to limit the range of values expected. Density dependent changes in age-specific birth and death rates have been used to infer MNPL/K. Non-linearities in these rates do not translate directly to population growth curves. The simple models demonstrate: (1) density dependence is likely to involve more than a single parameter (such as birth rate), (2) MNPL/K can be greatly reduced from that inferred from one strongly non-linear parameter when changes in other parameters are linear, (3) ranges of MNPL/K depend on biological limits on ranges of fecundity and survival rates, and (4) the magnitude and sign of bias incurred by inferring MNPL/K from functional forms of single parameters cannot be determined. Given current empirical evidence the range of MNPL/K for marine mammals as a group is large. Although MNPL/K should not be inferred from single parameter non-linearities, distributions of MNPL/K values can be generated through models which account for single species ranges for birth and death rates and maximum population growth rate.