Counting the vertebrae on a blacktip shark

Life history of the common blacktip shark, Carcharhinus limbatus, from central eastern Australia and comparative demography of a cryptic shark complex

Marine and Freshwater Research

This paper was motivated by my PhD study on the Australian blacktip Carcharhinus tilstoni and the Common blacktip Carcharhinus limbatus, which included discovery of (now likey ancestral) hybridisation between the two species. I was always frustrated by the perception, particularly among managers and some scientists, that because the two species could not readily be distinguished using external morphology that they were probably similar enough to be lumped together for management purposes.

This work originally started off as a collaboration with Pascal Geraghty based on some of his unpublished PhD data for C. limbatus, and it presented an opportunity to finally publish something concrete on the life history of this species from Australia. I was later able to chase up another two important data sources from Steve Taylor and Paul Butcher, in addition to my own PhD data. Together this provides a reasonably comprehensive picture of the life history of the species. The paper includes a simple demographic analysis that shows how the different life history traits in these species potentially influence productivity.

In this paper I also used an R-based reproducible workflow. The entire paper is written in R and R-Markdown. In theory it can be reproduced by downloading the Github repository and running the top level script: source(run_all.R) A Packrat library has also been added to assist in reproducible package management.