Rebecca Lewison: For as long as fishers have put gear in the water, they catch things they haven’t meant to catch. That is, in essence, what bycatch is.
Rebecca Lewison is a conservation ecologist at San Diego State University. She studies what happens when long-lived marine populations – such as sea turtles, sea birds and seals – get snared in fishing gear.
Rebecca Lewison: All of these organisms are either trying to eat the bait that’s on the hooks or going after the fish that are caught in nets. Just hitting gear can cause mortality events.
Lewison said that long-lived species are particularly affected by accidental entanglement in fishing lines, because these species take so long to reproduce. She added that it’s difficult to estimate numbers of this unintended catch, or even how it impacts ocean health.
Rebecca Lewison: It sounds like a very simple question: How much is too much? How much bycatch in this population is too much?
In order to answer that question, Lewison is studying the complex interactions between fishers, marine species, and the ocean landscape. Ultimately, she said, the goal is to reduce bycatch, in order to make sure that there’s fish to catch in the future.
Rebecca Lewison: Bycatch of these large marine organisms is just another indicator that we are fishing unsustainably.
Lewison added that new fishing technologies and practices are currently being developed, with the help of fishing experts. She is the lead researcher of Project GloBAL, a large scale research initiative to improve and understand the impact that fisheries bycatch has on protected marine species like the loggerhead turtle, the monk seal, the albatross, and the harbor porpoise, among many other species of concern.
Rebecca Lewison: The project itself was really designed to fill in as much as we can, from a scientific perspective, the research that we needed. How can we take existing bycatch data and develop new quantitative approaches? How can we fill in data gaps where there is no information on bycatch, or there is no information on fishing efforts?
Lewison said that bycatch has been around since fishing gear has been in the water, but the field of research is relatively new. Project GloBAL is using a new approach that they call the “bycatch triangle”: Studying the human activity in fisheries, understanding how the marine species’ behaviors leads them to interact with fishing gear, and the overall context of the ocean. Lewison said progress has been made with the project.
Rebecca Lewison: We’ve been able to identify, for particular populations – using them as case studies – likely population impacts. If someone comes and says, ‘I’m catching 300 sea turtles. Should I be concerned?’ That is a challenging question. We’ve worked to try and develop techniques to answer these simple, applied questions. Also, we’ve tried to put together global estimates of how many individuals, for example, how many sea turtles, worldwide, have been taken, based on the information that we have. That sounds like this is just a numbers game, but I think for people to realize the scope and magnitude of bycatch, those numbers are really important.
She said ultimately, reducing bycatch is a matter of keeping fisheries sustainable – making sure marine populations remain healthy and viable into the future. Lewison believes that this will take an international effort, because many of these species swim across oceans. But she believes there’s support to reduce bycatch, from both a conservation and fisheries perspective.
Rebecca Lewison: From the perspective of the fishers, there are two things they don’t want to do. They don’t want to catch a sea turtle or marine mammal that is going to damage their gear. And if you talk to small-scale fishermen, they are all concerned about the fact that catches have been reduced. One of the most important take-home messages is that we may be concerned about conservation of these species – that’s an important issue – but for many people, that’s not their primary concern. Their primary concern is that we are fishing unsustainably around the world. Bycatch of these large marine organisms is just another indicator that we are fishing unsustainably, and that’s an important starting point with many communities.
Learning to love science. As a producer for EarthSky, Lindsay Patterson interviews some of the world's most fascinating scientists. Through EarthSky, her work content is syndicated on some of the world's top media websites, including USAToday.com and Reuters.com. Patterson is also charged with helping to stay in steady communication with the thousands of scientists who contribute to EarthSky's work of making the voice of science heard in a noisy world. She graduated from Colorado College with a degree in creative writing, and a keen interest in all forms of journalism and media.