Shark Catch, Mortality Rates Determined Through Modeling System Of Fishing Data, Experts Say

Researchers from the College of Natural Resources and Environment at Virginia Tech are evaluating the effectiveness of shark sanctuaries by building a modeling system that uses publicly available fishing data to predict shark catch and mortality rates.

A study published in the journal Science Advances showed an essential step toward using data science to address ocean conservation concerns.

"My initial ambition was to use publicly available data to look at these sanctuaries from a high-level perspective, understanding how much fishing is occurring in these areas and what the potential risks are to sharks," said Brendan Shea, a Ph.D. student in the Department of Fish and Wildlife Conservation and the paper's lead author.

Fisheries data

To estimate capture and fatality rates for marine shark species, the research team used fishing vessel position data from Global Fishing Watch, an open-access website that provides a global view of commercial fishing activities throughout the world to enhance ocean governance.

In addition, the scientists gathered publicly available data from regional fisheries management organizations to develop a model that would assess the effects of longline fishing on seven species of open-ocean sharks.

According to the team's models, 286,820 large sharks were caught in the eight sanctuary regions targeted in 2019, with 109,729 of those sharks dying as a result of the stress of capture.

The researchers discovered that blue and silky sharks accounted for more than 70% of the sharks collected, with thresher sharks accounting for the remainder.

Shea underscored that using various streams of data to answer a specific conservation question is a significant step forward in fisheries research.

Assistant Professor Francesco Ferretti echoed this sentiment and said that research like this is a crucial step toward contemplating new techniques for understanding fish populations as well as the effects of people on open ocean species.

He further added that the study provided precise figures on how sharks are taken and how many died as a result of fishing in a certain area.

"This is an illustration of how we're transitioning from fisheries science to fisheries data science," he said in an interview.

"In the age of big data, we've demonstrated that we can do applied conservation and management research, and it is work that is applicable to many other aspects of fisheries management at large and even global scales."

Conservation efforts

Shea aims to use the data gathered to further understand the home ranges of large marine predators and accurately assess the benefits of conservation strategies such as shark sanctuaries.

He added that in order for spatial protections to be effective in conserving large pelagic species, scientists must first better understand their home ranges, or how much space they require and use over their lifetimes.

He said this is not well-studied for many wide-ranging species, and the knowledge gained will build on the initial work to better evaluate the conservation and management roles of marine protected areas.

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