Our Herp Class: Article Review: Buoyless Nets Reduce Sea Turtle Bycatch in Coastal Net Fisheries

Bycatch has been a negative consequence of fishing nets for many years since the nets have resulted in high mortality rates of many air breathing marine mammals and sea turtles. As human populations continue to grow, this problem is only increasing and now has been identified as the main reason for bycatch and overfishing around the world. The fishing nets are known to cause populations to decline so this is very problematic for sea turtle species such as the loggerhead sea turtles since they are already globally endangered. In fact, in Baja California Sur, Mexico, fishing nets move through a popular juvenile and subadult loggerhead foraging spot that sadly is the source of the highest recorded bycatch around the world.

The current nets being used are not adequate to combat this growing problem. Therefore, a research team with representation from leading universities in California, Arizona, and Mexico decided to conduct a study to test an innovative net solution to try and reduce the amount of bycatch. They came up with the idea of buoyless nets, which simply involved detaching many of the existing buoys from the float lines of the already existing nets. The team decided to test this new net design by setting both the buoyless net and the original control net at the same depths and side-by-side in an area where bycatch was known to occur. It is known that decreasing the vertical profile of the net in the water has yielded lower sea turtle bycatch since it decreases encounters, therefore underwater, the buoyless net is able to be lower in the water column and have less of this undesirable vertical profile.

The 136 trials with the controlled net and buoyless net set next to each other resulted in a total of 36 sea turtle captures - with 32 being loggerheads, 3 green turtles and 1 olive ridley. However, the turtle bycatch rate was much lower in the buoyless nets with, “a 68% reduction in mean turtle bycatch rates and 67% fewer turtles caught in buoyless nets (9 turtles) than in control nets (27 turtles).” This study has shown that by removing the buoys it has allowed for a decrease in bycatch while maintaining target catch rates. An interesting idea presented was that if sea turtles use the buoys on traditional nets as a visual cue for where to eat out of the nets, then the removal of this cue could have decreased the rate of sea turtle interactions.

While the buoyless net does not completely eliminate bycatch, it can serve as a good option since the fisheries are still able to bring in money but also reduce bycatch. Implementing the nets does not cost much either since all a company needs to do is remove the buoys from the float line if they need to make a net that costs less than a traditional net. Lastly, there is not additional training needed by the fisherman since the buoyless nets function the same as traditional nets. Overall, this buoyless net can be easily adapted by commercial fishers. While this solution may not be the ideal, it does decrease bycatch and provide an easy adaptation for fishers, and that is more than what is currently being done to protect our sea turtles.