Hands-on demonstration for phylogenetic comparative methods using R-package phylosem: improving stock assessment (natural mortality) and ecosystem modelling (consumption over biomass)

Hands-on demonstration for phylogenetic comparative methods using R-package phylosem: improving
stock assessment (natural mortality) and ecosystem modelling (consumption over biomass)
James Thorson, Alaska Fisheries Science Center
Tuesday October 10th, 09:30 AM PST

Comparative study across species are foundational to many topics in fisheries science, including to justify biological reference point proxies, predict natural mortality rates, or parameterize ecosystem models. Surprisingly, however, fisheries science has largely missed the research interest in phylogenetic comparative methods (PCM), which were pioneered by Joe Felsenstein at University of Washington in
the 1970s and remain a well-published topic in ecology and evolutionary biology. This is unfortunate, because PCM offers many improvements over conventional nested-taxonomic methods used in fisheries science.
In this workshop, I provide a hands-on introduction to the R-package phylosem available on CRAN. Attendees are encouraged to bring a laptop with package-install privileges, or pre-install phylosem. I will walk through vignettes which show how phylosem generalizes existing packages for phylogenetic linear models (phylolm), structural equation models (sem), phylogenetic trait imputation (Rphylopars), and phylogenetic path analysis (phylopath).
I will then provide a quick overview of results using two fisheries case studies. The first applies phylosem to the Then et al. natural mortality database, where phylosem reduces variance for out-of-sample prediction of natural mortality rates. The second replicates Palomeres and Pauly (1998), and confirms that consumption over biomass (a parameter in Ecopath with Ecosim models) is elevated for small-bodied with a high caudal-fin aspect ratio in warmer waters. I hope to demonstrate that PCM is broadly applicable for routine use throughout fisheries science.

Grant Adams coauthors population assessment of southern right whales

Current grad student Grant Adams, along with collaborators from the National Scientific and Technical Research Council (Consejo Nacional de Investigaciones Científicas y Técnicas), released a new paper in Scientific Reports. Led by Alejandra Romero, they assessed, for the first time, the population dynamics of the southern right whales from the southwestern Atlantic Ocean at the regional level to estimate the effect of whaling and the population trend and recovery level after depletion. We reconstructed the catch history of whaling for the period 1670–1973 by an extensive review of different literature sources and developed a Bayesian state-space model to estimate the demographic parameters. The population trajectory indicated that the pre-exploitation abundance was close to 58,000 individuals (median = 58,212; 95% CI = 33,329–100,920) and the current median population abundance was estimated at 4,742 whales (95% CI = 3,853–6,013), suggesting that the SRW population remains small relative to its pre-exploitation abundance (median depletion P2021 8.7%).

Citation:

Romero, M.A., Coscarella, M.A., Adams, G.D. et al. Historical reconstruction of the population dynamics of southern right whales in the southwestern Atlantic Ocean. Sci Rep 12, 3324 (2022). https://doi.org/10.1038/s41598-022-07370-6