Bycatch can be defined as the act of unintentionally catching certain living creatures using fishing gear. A bycatched species is distinguished from a target species (the animal the gear is intended to catch) because it is not sold or used. Marine mammals (whales, dolphins, porpoises), seabirds, sea turtles and unwanted or undersized fish are some examples of animals caught as bycatch. The incidental capture of these animals can significantly reduce their populations. The most well known example of bycatch may be the unintentional mortality of spotted and spinner dolphins in the tuna fishing industry. "Dolphin-Safe" tuna was a result of this interaction (Be prepared to discuss how this came about with students, as it is something close to their daily lives). One important aspect to consider when discussing this issue is that laws protect some of the animals caught as bycatch (Marine Mammal Protection Act and Endangered Species Act). In this lesson, students will first be shown pictures of entangled marine animals and will discuss the definition of bycatch. This will lead to discussions on why bycatching exists, how it impacts specific animals as well as humans, whether the students believe it is an important issue, and how bycatch can be reduced.

Students will study bycatch from an engineering perspective to design technological solutions for addressing the problem. Bycatch Target Species explain what is meant by "bycatch" explain how bycatch affects their lives describe ways to reduce bycatch describe key issues relating to bycatch, such as fishermen's rights, ownership of the sea, and the economic impact of eliminating bycatch If you have access to the video "Empty Oceans Empty Nets," produced by Habitat Media in 2002, this should be shown to the class as a great introduction to what bycatch is and how it affects the lives of different species. If you do not have access to the video, pass around pictures of entanglements, such as the ones in this curricular unit. Have the students comment on how the pictures make them feel, why they think that this type of entanglement occurs, and whether or not people should do anything about this. This will lead them to the definition of bycatch and discussions with a broader scope that combine marine science with government policies. Review the explanation of bycatch (see Summary above). Also review the following material, so that you can explain to students the different types of fishing gear that result in bycatch. Note also which species are affected the most by commercial fishing. Vaquita, striped, common, and bottlenose dolphins, harbor porpoises, pilot whales, humpback whales, and right whales can get caught in these stationary nets comprised of webbing. This is a diagram of a TED, or Turtle Excluder Device, used within a trawl net (note the cod end on the right). TEDs allow turtles to escape through a hole in the net, thus excluding them from entering the cod end of the net. BRDs, or Bycatch Reduction Devices, such as "fish eyes" in this drawing let certain fish species to swim out through panels in the net. Note that the target species is preferentially caught in the cod end on the right. The vaquita is a small porpoise that lives only in the Gulf of California and is in imminent danger of extinction as a result of gillnet fisheries (See earlier chart). Because gillnets are of uniform mesh size, they can entrap much larger non-target species and result in death. The total population of vaquita is now less than 1,000 animals, after declining by approximately 20% each year between 1986 and 1993. The North Atlantic right whale population has been reduced to approximately 300 individuals due to bycatch and ship strikes, primarily off the New England coast. Albatrosses in the Southern Ocean suffered a decrease by 44,000 birds per year due to the Japanese longline fishery. 1. Acoustic alarms (pingers): deter marine mammals by emitting noise. 2. Modification of gear: Breakaway links- allow large whales to break out of nets when they struggle and exert force. Reflective nets- More detectable to marine mammals. Turtle Excluder Devices (TEDs)- allow turtles to escape through a built-in hatch in trawl Modification of mesh size- May allow marine mammals to detect nets more effectively. 3. Time- area closures: setting nets at different times of the day (setting longlines at night minimizes seabird bycatch); setting nets in areas that are less heavily frequented by mammals, birds, and turtles The portion of a fishing catch that is discarded as unwanted or commercially unusable. Single sheet of webbing that hangs between a float line and main line. Stationary net. Consists of three parts: a conical bag- shaped net, "wings", and a cod end. Pulled by a boat. Large curtain-type nets with small mesh size. Pulled by two boats to encircle fish. Consists of a long, mainline to which smaller, baited hooklines are attached at regular intervals All Caught Up Bycatch is the unwanted capture of unprofitable species obtained during fishing attempts for a specific 'target species.' Animal populations such as dolphins, whales, and seals, to name a few, are significantly affected by bycatch and can become endangered as a result. Students will probably have different opinions on this. Some may think that humans have no responsibility to reduce bycatch. They may believe that humans should have unlimited control over marine environments to fish and hunt, and it is acceptable to catch and kill animals that we are not going to eat. Some students may have relatives that are fishermen and believe that bycatch avoidance methods are too expensive for small businesses who are trying to remain profitable and competitive. If students do not have such acquaintances, you as a teacher can present this point of view. Others may strongly believe that people need to help reduce bycatch so that endangered species are preserved for future generations and/or because the loss of species may have unforeseen affects on the food chain. Encourage a discussion surrounding this topic that encourages a wide variety of viewpoints to be shared. Ask the students to propose measures that can be taken to reduce bycatch. These should not be limited to engineering solutions like different types of fishing gear or modified gear. Other potential methods include governmental legislation and policy surrounding fishing methods or the reduction of commercial fishing in general. Hopefully the students will think of very creative solutions that others may not have thought of before. Encourage them, if they have an innovative idea, to write to their governor, congressman, or even the president about their idea and the importance of the bycatch issue. As long as the students are actively engaged in discussion and appear to understand the definition of bycatch, then they comprehend the most important aspects of this lesson. You can encourage creative thought on the issue of bycatch by having each student write in his or her journal after the discussion. Students should reflect on the classroom lesson, answering prompts such as: What is bycatch? Do you think it is important for fishermen to try to reduce it? Why or why not? Can you think of any ways that the government, fishermen, and/or the average person could help to reduce bycatch? Biology of Marine Mammals Biology of Marine Mammals. 1999. Edited by: J. Reynolds III and S. Rommel. Smithsonian Institution, WDC, USA. The Bottlenose Dolphin The Bottlenose Dolphin. 1990 Eds. S. Leatherwood and R. Reeves. Academic Press, Inc. London, U.K. Conservation and Management of Marine Mammals Conservation and Management of Marine Mammals.1999. Eds. Twiss and Reeves. Smithsonian Institution, WDC, U.S.A. "Empty Oceans Empty Nets" "Empty Oceans Empty Nets" (video). Produced by Habitat Media. 2002. www.shoppbs.org Shop PBS Marine Mammal Biology, An Evolutionary Approach Marine Mammal Biology, An Evolutionary Approach. 2002. Ed. R. Hoelzel. Blackwell Science, Ltd., Oxford, U.K. Seabird Bycatch: Trends, Roadblocks, and Solutions. Seabird Bycatch: Trends, Roadblocks, and Solutions. 2001. Eds. E. Melvin and J. Parrish. Univ. of Alaska Seagrant.