Temporary Allee effects among non‐stationary recruitment dynamics in depleted gadid and flatfish populations

Abstract

The knowledge of how a depleted population recovers is essential for conservation biology and sustainable harvest of natural resources . In aquatic systems, collapses and impaired recovery have been particularly well documented (Hutchings, 2015;Neubauer et al., 2013), often in the absence of substantial reductions in habitat carrying capacities. For example, the abundance of the northern Atlantic cod (Gadus morhua, Gadidae) was estimated to be 2% of the maximum estimated population size (N max ) in 1992 (Hutchings, 2015) and a moratorium on the Northern Cod fishery was declared. Despite the moratorium, the abundance

Atlantic salmon survival at sea: temporal changes that lack regional synchrony

“…The model we used describes step-wise changes in the marine survival parameters, ignoring, e.g., continuous linear changes that can also be present in the data Pardo et al (2021). Moreover, regarding our results, it should be noted that the change-point prior and the amount of random variation around the average relationship between the number of smolts and returning fish, that was assumed to be present in the data, may have had a considerable impact on change-point inference (Tirronen et al, 2021). Nonetheless, we carried out sensitivity analyses in terms of the priors of the variance 17 parameters as well as the change-point prior, and the obtained posterior predictive distributions suggest that the change points we reported yield a good model fit to the data (Supplementary Material, Section S3).…”

“…for non-1SW-dominated populations. The change-point inference may considerably depend on the amount of random variation that we assume to be present in the empirical time series (Tirronen et al, 2021). Thus, the priors of σ a having been set to…”

“…The method is sensitive to changes in sequential data and provides a potential tool for detecting temporal changes in the underlying processes that generate ecosystem data. It has been extensively validated for stock-recruitment models (Tirronen et al, 2021;Perälä et al, 2017), and its performance in parameter inference in short segments has also been found decent (Tirronen et al, 2021).…”

“…Moreover, a high amount of scatter among successive years in the data can affect parameter inference and consequently, the accuracy of change-point detection (Tirronen et al, 2021).…”

Spawner weight and ocean temperature drive Allee effect dynamics in Atlantic cod, Gadus Morhua: inherent and emergent density regulation

“…strengthened or masked. This questions the common assumption that Allee effects are time-invariant, but requires a model that can adjust to such temporal changes in productivity (Perälä and Kuparinen, 2017;Tirronen et al, 2022).…”