Fishing-induced changes in adult length are mediated by skipped-spawning:
Journal
Ecological Applications
Journal Volume
27
Journal Issue
1
Pages
274
Date Issued
2017-01-01
Author(s)
Abstract
© 2016 by the Ecological Society of America. Elucidating fishing effects on fish population dynamics is a critical step toward sustainable fisheries management. Despite previous studies that have suggested age or size truncation in exploited fish populations, other aspects of fishing effects on population demography, e.g., via altering life histories and density, have received less attention. Here, we investigated the fishing effects altering adult demography via shifting reproductive trade-offs in the iconic, overexploited, Pacific bluefin tuna Thunnus orientalis. We found that, contrary to our expectation, mean lengths of catch increased over time in longline fisheries. On the other hand, mean catch lengths for purse seine fisheries did not show such increasing trends. We hypothesized that the size-dependent energetic cost of the spawning migration and elevated fishing mortality on the spawning grounds potentially drive size-dependent skipped spawning for adult tuna, mediating the observed changes in the catch lengths. Using eco-genetic individual-based modeling, we demonstrated that fishing-induced evolution of skipped spawning and size truncation interacted to shape the observed temporal changes in mean catch lengths for tuna. Skipped spawning of the small adults led to increased mean catch lengths for the longline fisheries, while truncation of small adults by the purse seines could offset such a pattern. Our results highlight the eco-evolutionary dynamics of fishing effects on population demography and caution against using demographic traits as a basis for fisheries management of the Pacific bluefin tuna as well as other migratory species.
Subjects
adult demography | eco-genetic individual-based modeling | fisheries selectivity | fishing-induced evolution | life history trade-offs | Pacific bluefin tuna, Thunnus orientalis
adult demography; eco-genetic individual-based modeling; fisheries selectivity; fishing-induced evolution; life history trade-offs; Pacific bluefin tuna, Thunnus orientalis
Other Subjects
adult; catch statistics; demographic survey; exploitation; fishery management; fishery survey; fishing mortality; individual-based model; life history trait; longlining; migratory population; perciform; population dynamics; size effect; spawning ground; sustainable development; trade-off; Scombridae; Thunnus orientalis; animal; biological model; body size; energy metabolism; fishery; Japan; life history trait; Pacific Ocean; physiology; reproduction; Taiwan; tuna; Animals; Body Size; Energy Metabolism; Fisheries; Japan; Life History Traits; Models, Biological; Pacific Ocean; Reproduction; Taiwan; Tuna
Publisher
WILEY-BLACKWELL
Type
journal article