Turtle excluder devices: analysis of resistance to a successful conservation policy

Conservation efforts often have an associated tradeoff, and many proposed solutions are shot down because the costs are perceived to be too high. A conservation policy that benefited a charismatic endangered species with very little cost should be popular and enthusiastically adopted. However, even though turtle excluder devices greatly reduce sea turtle mortality and have very low costs, they were vigorously opposed by shrimpers. Though many factors contributed to this opposition to turtle excluder devices, analysis of quotes from newspaper articles reveals that one of the major issues was a failure of the conservation community to educate and communicate with shrimpers.

The problem

Most species of sea turtles are either threatened or endangered. Although they face many threats, a 1990 National Academy of Sciences study reached the conclusion that “drowning in shrimp trawls kills more sea turtles than all other human activities combined”. Trawling consists of dragging a large net behind a boat to catch shrimp. This fishing method has one of the highest bycatch rates of any used today, resulting in over 11 million metric tons of bycatch a year. Sea turtles breathe at the surface, and being trapped underwater in a net can be fatal if they aren’t freed in time. Adult loggerhead turtles can hold their breath for up to 45 minutes, but trawlers often wait up to four hours before hauling in their nets. This resulted in an estimated 48,000 sea turtles caught in trawl nets each year from 1973-1984 in U.S. waters, of which 11,000 died . Gulf of Mexico shrimping was particularly hard on loggerhead and kemp’s ridley sea turtles.

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Shark Conservation: The problem, the goal, and how to get there


The problem

Sharks consistently rank near the top of lists of American’s greatest fears. In reality, they have much more to fear from us than we do from them. Because of our actions, many species of sharks are on the verge of extinction. A recent International Union for the Conservation of Nature Shark Specialist Group report shows that fully 1/3 of open-ocean species of sharks are in danger of extinction in the next few decades. Many shark species have had population declines of over 90% in the last few decades.


Fins from a blacktip shark. Photo credit: David Shiffman

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Dolphin-safe tuna: conservation success story or ecological disaster?


I used to feel warm and fuzzy inside when I saw the dolphin-safe logo on my tuna. I felt like a decision I made was helping the environment- like I was making a difference.


The commonly believed narrative about dolphin-safe tuna goes something like this: Lots of dolphins were being killed by tuna fishermen, outraged environmentalists led a massive PR campaign, legions of adorable children wrote to their elected officials, elected officials changed the rules to protect dolphins, and everything is better now. Hooray, we saved an innocent species and helped the environment!

That narrative is a great story. It shows that if a few people who care can convince others that their cause is just, there’s no limit to what we can accomplish. It’s inspiring. Too bad it’s not really true. As it turns out, we made things worse- a LOT worse.

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Ethical Debate: Bycatch and the Great Skua


Most marine conservationists and environmentally conscious citizens believe that fisheries bycatch is a major problem that needs to be solved soon. In most cases, they are correct, but an

interesting paper from Nature shows that bycatch can sometimes be good for certain species. Consider the case of the Great Skua.

Image from BritishEcologicalSociety.org

The Great Skua is a large predatory seabird that lives in northern Europe. In the past, it has been known to feed on many smaller local seabird species, including the Leach’s Storm Petrel, the Northern Fulmar, the Northern Gannet, the Lesser Black-Backed Gull, and the Herring Gull. In the last few decades, Great Skua populations have increased tremendously.

Ordinarily, when the population of a predator increases, the populations of its prey decrease. This doesn’t seem to be the case among populations of the seabird species in northern Europe. How can this be?

The answer to this apparent ecological enigma has to do with fisheries bycatch. The oceans around northern Europe support many large-scale fisheries, such as the sandeel fishery. Like most large-scale fisheries, the sandeel fishery has a significant amount of bycatch (fish that were caught merely because they were swimming near the sandeel) associated with it. Since the fishermen only have a permit to sell sandeel, the bycatch species  are dumped overboard…where they are devoured by Great Skua.

In other words, Great Skua have found a new steady source of food. Great Skua populations have increased without a decrease in the populations smaller seabirds that they ate in the past.

Modern sentiments, however, have turned against bycatch. Efforts to reduce bycatch in commercial fisheries are underway in many countries worldwide. What will this mean for the seabird communities of northern Europe?

Well, it’s possible (and for the purposes of this discussion, we’ll assume it will definitely happen) that without their new source of food (bycatch dumped over the side of fishing  vessels), Great Skua will return to eating their previous prey- the smaller seabirds of northern Europe. Since there are many more Great Skua than there used to be, this would be very bad news for the smaller seabirds in the area, and could easily make several seabird species endangered.

The question for this week’s ethical debate is simple: Do you think that we should continue with efforts to reduce bycatch in Northern Europe even if it means that local seabird species will become endangered?

I should note that the authors of this paper stated that “it would not be appropriate to maintain current rates of discarding for the sake of seabirds”.

Votier SC, Furness RW, Bearhop S, Crane JE, Caldow RW, Catry P, Ensor K, Hamer KC, Hudson AV, Kalmbach E, Klomp NI, Pfeiffer S, Phillips RA, Prieto I, & Thompson DR (2004). Changes in fisheries discard rates and seabird communities. Nature, 427 (6976), 727-30 PMID: 14973483


Four things everyone needs to know about sharks: A shark conservation documentary and lesson plan

One week after the world premier at the Benthic Ecology conference’s Beneath the Waves Film Festival, I am pleased to announce that my new shark conservation mini-documentary, “four things everyone needs to know about sharks”, is now available on YouTube.

Check it out here:

If you are an educator, the movie is intended to be part of a lesson plan about shark conservation. I have created a middle school version, a high school version, and a college version. Contact me at WhySharksMatter AT gmail DOT com with the subject “Shark Lesson Plan” and I’ll send you what I have, or we can discuss making a custom lesson plan that suits the specific needs of your class.

If you are not an educator but care about sharks, the movie can be a stand-alone way to educate your friends, family, coworkers, classmates, etc.

Please let me know what you think about the video by commenting on this blog post.

Thanks to all of my photographer and musician partners in this project!

Check out their websites:

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