USC Dana and David Dornsife College of Letters, Arts & Sciences > Blog

August 25, 2015

The Stressful Side of Catch-and-Release Fishing

Filed under: Graduate,Wrigley Institute — Jessica Dutton @ 7:33 am

USC Wrigley Institute

By: Caitlin McGarigal

I am a Graduate student at CSU Long Beach and I have spent this past summer as a Wrigley Institute Summer Fellow conducting my research in Big Fisherman’s Cove on the effects of catch-and-release fishing on kelp “Calico” bass (Paralabrax clathratus) and barred sand bass (P. nebulifer). The objectives of my Master’s Thesis project are to 1) Determine how the trauma from being caught and released affects fish physiology and behavior, 2) Measure survival rates and how rapidly fish recover once released, and 3) Identify specific things fishermen can do to minimize stress and promote recovery in these valuable recreational species.

Recreational fishing has historically been an important part of California culture, and every year more people are heading out on the water to enjoy this activity. Fishing regulations (e.g. minimum size limits, daily bag limits, etc.) are common tools used by fisheries managers to prevent the overfishing of popular gamefish, and these policies often result in the mandatory release of fish after they have been caught and handled.


Kelp bass (with spaghetti tag near upper fin) swimming in the water column in Big Fisherman Cove

But catch-and-release can be a traumatic experience for fish which are stressed from fighting to escape, being exposed to air, and possible physical injury from fishing tackle or the handling process. The stress can affect fish growth, reproduction, and behavior as well as potentially reduce the growth or recovery of the entire population. For many important recreational gamefish, these species regulations are used without any knowledge of how fish respond and recover after being released –yet these are critical things to know to ensure that the most effective measures are being employed. Understanding the impacts of recreational fishing activity on kelp bass and barred sand bass is particularly important right now, given the large declines in population size observed in recent years and their value as two of the most caught species in southern California.

My research aims to relate physiological stress responses (e.g. hormonal and metabolic changes) with behavioral responses (e.g. movement and activity) of fish that are caught and released. I have spent this past summer catching kelp bass and barred sand bass in Big Fisherman’s Cove, a local marine reserve. From blood samples collected after fish are caught on hook and line, I can measure the levels of cortisol (the major hormone that regulates the stress response), glucose (i.e. energy), and lactate (i.e. indicator of exhaustion) to determine how stressed these individual fish are from being caught and handled. The fish are tagged with a unique ID number, released, and then recaptured after varying hours or days in the wild to determine how quickly the fish recover back to their normal, unstressed state.


Kelp bass being weighed and measured

Preliminary results suggest that kelp bass and barred sand bass are extremely hardy species, and are often able to recover physiologically within 24 hours. However, the data also suggests that the longer fish are fought on the line and exposed to air, and the rougher fish are handled (e.g. dropped, carried by gills or jaw, etc), then the longer it takes for those individuals to recover.

I hope to continue my research at Wrigley Marine Science Center throughout the fall and spring, and return next summer as a Wrigley Fellow. Upcoming research will involve capturing and tagging fish with a small acoustic transmitter that is detected by listening stations (i.e. receivers) that are set out around Big Fisherman’s Cove; these transmitters provide information on the fish’s location and depth over time, allowing me to observe how behavior is altered when fish are released and how long it takes before individuals return to normal activities and movements.


Three of the receiver “listening stations” (out of water for maintenance)

Ultimately, this research will help inform fisheries managers of the effects of catch-and-release fishing on kelp bass and barred sand bass. The work will also provide information that will educate recreational fishermen to promote survival and recovery of these important gamefish, ensuring future opportunities for generations of California fishermen.

Caitlin is a Masters student at California State University Long Beach in the “Shark Lab‘ under Professor Christopher Lowe.

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July 23, 2015

The Social Side of Science

Filed under: Graduate,Wrigley Institute — Jessica Dutton @ 9:41 am

USC Wrigley Institute

By: Nathan Churches

Driving down one of Catalina’s dirt roads can be a very dusty endeavor, but they are one of my favorite venues for scientific discussions. Often, I find myself in company of enthusiastic researchers while driving to various collection sites on the island, and good conversation inevitably ensues.

This last week, for example, I had planned to take an undergraduate colleague James Duffy, a young scholar working with me in the Research Experience for Undergraduate (REU) program, on a collection trip to Shark Harbor for some California mussels (Mytilus californianus). Before the trip began I was contacted via email by a graduate student from UC Davis, Micah Freedman, who would be on island to look at the Catalina Island Conservancy’s deer exclosure sites: could he tag along on our trip? Of course I obliged, and we set off. What followed was a few hours of discussion between us three regarding our various research topics and interests. Conversation meandered between the genetics of orchid bees, to the evolution of plant volatiles, to plant responses to herbivore predation, to aquaculture production bottlenecks, to west coast bird populations, to chemical cues of predation in fish, to name a few. Wrigley vans: a science lover’s ideal conversation site.


Our dusty Wrigley Institute van fleet

But these kinds of interactions aren’t simple waxings of topics philosophical, a nice meta-benefit of life on the island; they often have tangible outcomes. Through our interactions, I was able to understand what kinks needed to be ironed out for my new graduate student colleague’s research, and I happened to know a few people that could help him solve said problems. Introductions were made, and my new friend has an easier path toward reaching his scientific goals. What I gained from our interaction is a new connection with a terrestrial lab doing cool science at a university that I knew only by name just hours before. And this is the spirit of the Wrigley Institute for Environmental Science: great minds (if I can take such a liberty) convening to the betterment of the scientific community. Consider that this is just one example of a single interaction! I see and experience these types of bonds being made on a daily basis at WIES.


Nathan running a mussel embryo experiment

I study aquaculture, the genetics of bivalves, and how we can produce more sustainable protein from California’s coastal waters. Among other projects, I am working this summer to develop a protocol with REU student James to create the first cryopreserved eggs for the extremely economically important blue mussel. And though my studies are mostly marine based, they are supported from a network of scientists and thinkers that span many academic disciplines. I had the chance to expand my support network this past week, and you never know where that may lead. These kinds of opportunities are one reason why I look forward to continuing my work at WIES.

Nathan is a graduate student in the research group of Professor Sergey Nuzhdin, studying the genetic traits that contribute to successful sustainable bivalve aquaculture. He is a member of the USC Department of Biological Sciences Program in Molecular and Computational Biology.

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