Dr. Mark Bravington (CSIRO Marine Lab – Hobart)

Title: Close-Kin Mark-Recapture: Counting Fish (etc) by Modern Magic

Abstract: Counting animals is difficult--- hard enough on land, even harder in the sea, and very hard for fish that don't bother with breathing air. But figuring out how many there are, and how fast they reproduce, is central to practical marine conservation and the sustainable management of fisheries. Beginning in 2006, CSIRO has pioneered a completely new way to tackle that question: Close-Kin Mark-Recapture. We start by using modern genetics to find pairs of close relatives (e.g. parent-and-offspring) in large samples of biopsies from dead or living animals. Then the number of pairs found, and their arrangement in space and time, can be analysed in a modified mark-recapture framework for estimating not just absolute abundance, but also survival rates, fecundity, and connectivity. Close-Kin Mark-Recapture bypasses the need to rely on problematic and/or expensive data sources which bedevil much of marine (and terrestrial) management. In this talk I'll explain the principles, give a couple of examples of our work on tuna, sharks, and bats, and say something about the statistical issues that arise in genetics, in demographic modelling, and in project design with Close-Kin Mark-Recapture: it is quite a magical thing!