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Habitat availability and ontogenetic shifts alter bottlenecks in size‐structured fish populations
Author(s) -
Cantin Ariane,
Post John R.
Publication year - 2018
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.1002/ecy.2371
Subject(s) - habitat , ecology , density dependence , population , biology , competition (biology) , abundance (ecology) , range (aeronautics) , juvenile , population density , rainbow trout , vital rates , intraspecific competition , population model , population growth , fishery , fish <actinopterygii> , demography , materials science , sociology , composite material
For species that utilize different habitats throughout their life cycle, the habitat limitation at a given stage can act as a bottleneck on population abundance, impacting density‐dependent processes such as individual growth and survival. We explore the influence of habitat limitation on population dynamics by developing a multi‐stage population model based on lake‐dwelling rainbow trout ( Oncorhynchus mykiss ) populations where adults occupy the lake habitat but use tributaries for spawning and juvenile rearing. The model details density‐dependent ecological processes and ontogenetic habitat shifts, harvest mortality, and the impact of climate on growth. We ran model simulations using a range of early life stage habitat availabilities and climatic conditions representative of the native range of rainbow trout in Canada and compared the results to empirical data. The results suggest that (1) increases in early life stage habitat leads to increases in population abundance but, due to density‐dependent processes, also results in slower growing stunted populations; (2) population bottlenecks can occur at any life stage, even at the adult stage if spawning and rearing habitats are abundant; (3) when the level of competition for early life stages is increased, inter‐cohort competition can lead to population cycles. The model's conclusions are further reinforced by empirical data showing a similar trend in the relationship between fish density and maximum size and providing evidence that limited early life stage habitat leads to lower fish densities and larger fish size. We provide a model that links environmental conditions to population dynamics and is useful for fisheries management and habitat conservation decisions.