SEMINAR: MBF 602 Student Seminar Series Presents Marc Nadon Friday 11/19 Slab seminar room 4:00p

["Sidney Hartley" <shartley@rsmas.miami.edu>]

Status and baselines of Pacific reef sharks

Sharks are economically important marine fishes that are heavily exploited despite their known vulnerability to over-fishing due to their long life spans, slow growth rates, late maturity, and small brood sizes. This is especially true for pelagic sharks as significant declines in their abundance have been reported in the recent literature, notably in the Northwest Atlantic and the Gulf of Mexico. Much less is known about the status of coral reef-associated shark populations or even what levels/types of anthropogenic pressure they are experiencing. As these populations are not generally commercially exploited, few fisheries-dependent datasets exist. However, reef shark populations can be quantified using fisheries-independent methods, such as underwater visual surveys. Here, I analyzed a large dataset of reef shark densities from towed-diver observations around 46 reef areas in a vast region of the Central Pacific. These areas ranged from highly remote, uninhabited locations with exceptionally undisturbed coral reef ecosystems to areas with relatively dense human populations. We develop a statistical model of reef shark density using large-scale oceanographic and anthropogenic variables as covariates. Our analyses suggest that reef shark abundance has declined to 4-7% of their unexploited levels around inhabited U.S. Pacific islands. Our study provides insights into baseline shark densities that can be used to guide the management of these species.

 

Marc Nadon

BSc Biology

McGill University, Montreal, Canada

 

MSc Marine Ecology

Laval University, Quebec City, Canada

 

Entered PhD: Fall 2009

Advisor: Dr. Jerry Ault