Fishing for Fun? It Has a Bigger Environmental Impact Than We Thought
By David Shiffman
Let's go fishin'! After all, a lone angler fishing from a dock or a few friends going out to sea can't have all that much of an effect on fish populations … right?
"When you're floating in the open ocean, it can be hard to imagine that your hobby will have an impact on the overall health of a fishery," said Sepp Haukebo, who works on recreational fisheries conservation issues for the Environmental Defense Fund. "But multiply the number of fish a single angler catches and discards in a day by millions of anglers and you have a significant harvest on your hands."
Haukebo echoes points made in two new studies, published in the journals Fish and Fisheries and Frontiers in Marine Science, that show recreational fishing has a much bigger collective effect on oceanic species than previously realized, with nearly one million tons of fish caught every year.
Far from being an insignificant drop in the proverbial ocean, this is a massive amount of fish — about 1% of total global marine fisheries catch, a much higher number than many scientists and managers used to believe.
So how is it that the actions of individuals can have such a far-reaching effect? Recreational anglers usually catch just a few ocean fish in a whole day, while industrial-scale commercial fishing often uses miles-long gear and catches tons of marine life at a time.
Part of the answer is scale: Previous research has shown that there are a lot more recreational anglers than there are commercial fishing vessels — at least 220 million people go fishing for fun every year all around the world.
The marina in Valencia, Spain. Mark Chinnick (CC BY 2.0)
That number is expected to grow as people and countries become more affluent, said Jessica Meeuwig, a professor at the University of Western Australia and a coauthor on the Frontiers in Marine Science paper.
Another part of the answer involves economics: For people and companies trying to make a profit from fishing — like with commercial fisheries — there's an incentive to stop fishing when populations get low.
But if you're fishing for fun, you're paying for the experience, and the experience of catching a relatively rare fish is often considered worth paying extra.
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Indeed there are many threatened populations of fish where commercial fisheries are banned but recreational angling continues.
Additionally, a subset of recreational anglers called trophy anglers intentionally target the biggest individuals in a population, often with the goal of getting a perceived-as-prestigious certificate that says they hold a record for catching the biggest fish of that species.
This can affect entire species populations, explained Meeuwig.
"Recreational fisheries targeting larger fish means they are taking the most fit individuals, the big breeders, out of the population," she said. Bigger fish tend to reproduce more often and have a greater number of young at a time. This culling preference is different from commercial or subsistence fishing, which aim to catch as many fish as possible, but not necessarily the largest individual member of a species.
There are other factors are play, although those aren't always as clear.
"Recreational catch of threatened species is an issue that's poorly understood," said Peter Kyne, a senior research fellow at Australia's Charles Darwin University who was not affiliated with either of the new papers. "In Australia, this is a significant issue for the grey nurse shark on the east coast," he said. "Their habitat is close to major cities where recreational fishing levels are high. Even in remote areas of northern Australia, catches of river sharks are an issue — although they are protected, they're similar in appearance to a number of common non-threatened species and anglers may not recognize them."
A Regulatory Failure?
The research also found that most nations don't do a very good job managing their recreational fisheries — especially when compared to their commercial fisheries.
"Governments fail to recognize that recreational fisheries can decimate populations" or that they can be as important to monitor as commercial fisheries, said Warren Potts, a professor of fisheries science at Rhodes University and lead author of the Fish and Fisheries paper. "This ignores or underappreciates recreational fishing's economic and ecological effects and causes governments to fail to prioritize regulating the practice."
The paper looked at the global state of management regulations for recreational fishing and found that only 86 nations define recreational fisheries in their national fisheries-management legislation.
More than half of experts surveyed for the paper raised significant concerns about their nation's recreational-fisheries management. No experts from developing nations, where the popularity of recreational fisheries has exploded as international tourists seek out "exotic" places to fish, believed that their countries effectively manage those fisheries.
But Robert Arlinghaus, a professor of fisheries management at Humboldt University in Germany who was not involved with either paper, pointed out that many countries do employ a basic fisheries-management regulation called a minimum size limit — in other words, you can't land a fish if it's below a certain size and hasn't had the chance to reproduce yet. This isn't exactly the cutting edge of adaptive science-based management, but it's a lot better than nothing.
Arlinghaus feels that characterizing the majority of the world's recreational fisheries as ineffectively managed may be taking things a little too far.
"Recreational fisheries might not be managed optimally," he said, "and I do think the governance and management systems could be improved in many areas of the world, but I'm not sure that recreational fisheries are generally managed poorly."
By the Numbers
Another major issue with recreational fisheries management boils down to numbers — or lack of them. In most places nobody knows exactly how many fish are caught.
That's another difference from commercial fisheries — it's just easier to gather data when you're dealing with a limited number of fishing vessels than with hundreds of millions of individual people.
Cod in a commercial net. Derek Keats (CC BY 2.0)
"Some countries keep detailed data on their recreational fisheries catch, but others don't," said Daniel Pauly, principal investigator of the Sea Around Us project at the University of British Columbia and a coauthor on the Frontiers in Marine Science paper. He added that some countries use different agencies to collect data from recreational and commercial fisheries, and those groups don't always speak with each other or consolidate their findings.
"If you know there are recreational fisheries in a country, but there's no data, you have to be creative," said Pauly. "You can't say 'there's no data, so we'll assume nothing has been caught.'"
To resolve this data gap and estimate the global catch of marine recreational fisheries, the paper used a method called "catch reconstruction" — a mix of computer analysis and good, old-fashioned detective work.
Catch reconstruction, he explained, assumes that fishing doesn't happen in a vacuum. Even if you don't have data on how many fish are caught or brought to shore, there's often other information showing things like how many boats used a marina, how much fuel they used, and how much seafood was for sale in local markets.
That's where Pauly and his team came in. They consolidated information from a variety of sources and built a bigger picture.
Pauly provided an example of how they accomplished this.
"In West Africa, many people thought there weren't any substantial recreational fisheries, because there's no catch data available," he told me. "But there are fishing lodges there for tourism, and those lodges post images of what people catch on social media and websites. We know how many people go to those lodges, because tourists entering the country are reported and they fill in where they're staying. If we know how many people visit, how long they stay and what's usually caught, we can estimate catch even with an absence of official statistics."
This isn't foolproof. Potts pointed out that this kind of formulation can cause complications. He noted that the paper estimated the catch from one fishing lodge and extrapolated it to two others, including one lodge that exists on paper but hasn't actually been built yet. Pauly responded to this concern by pointing out that "we were able to generate first estimates of the catch of West African recreational fisheries … but the fact these these estimates can be improved goes without saying."
Even though the results are estimates, they suggest two potentially troubling trends. First, all recreational fisheries catch is significantly increasing in developing-world nations, especially in Africa and South America. For example, the number of recreational fishing licenses in Brazil jumped from 276,500 in 2011 to more than 400,000 just two years later.
Fishing off the coast of Brazil, with dolphins swimming nearby. Felipe Vaduga (CC BY 2.0)
Second, recreational fisheries targeting sharks and rays are on the upswing worldwide. Sharks and rays represented less than 1% of total recreational catch in the 1950s, but about 6% today, and are especially increasing in South America, the Indo-Pacific and West Africa.
"This is a cause for concern given the threatened status of many species of sharks and rays," Meeuwig said. Previous research has shown that about 24% of sharks and related species are threatened or endangered. "The capture of large sharks is particularly worrisome," she adds, because of their importance as breeders.
Arlinghaus said he feels the Frontiers in Marine Science paper represents a "Herculean effort" to gather global recreational catch.
It's also an opportunity to shift our attention to a previously invisible or ignored problem. Increasingly, as scientists and environmentalists have been raising the alarm about commercial and industrial overfishing, they've implicitly or explicitly sent the message that fishing for fun has so little environmental impact that it wasn't worth considering.
And Arlinghaus cautioned that the papers' recommendations about recreational fishing have already been misinterpreted in some circles. A widely shared Nature News article about this paper claimed "hobbyists' harvest of sharks and rays have soared, and catch and release is no solution,"— despite the fact that the paper did not address catch and release. Additionally, some on social media claimed that this paper was proof that all recreational angling needed to be shut down, which was not a recommendation issued by the paper.
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Arlinghaus warned against making those leaps in logic based solely on the data from these papers. "We can't learn much about the conservation concerns associated with a fishery just by looking at landings," he pointed out.
But the Fish and Fisheries paper did contain some recommendations for improvement.
"There are some basic guidelines for improving governance that can be followed and should improve the quality of a governance of a country's recreational fisheries," Potts said. These include clearly defining recreational angling in national legislation and stressing how its management differs from commercial fisheries. The paper also calls for increased cooperation with stakeholders to gather more effective data and ensure compliance with rules, and scientific monitoring of populations of fishes targeted by recreational fisheries — all things that are currently done relatively well in the U.S. and Australia, but done relatively poorly in large parts of the developing world.
"I want to commend these authors for their recommendations," Haukebo said. "This framework is a great reference for any nation that is aspiring to improve, or even just establish, responsible management of their recreational fishery."
While Haukebo and other experts say you don't have to feel bad about "goin' fishin'" with family and friends just yet, the science presented in these papers makes it clear that in some places individual actions can collectively pose a significant threat to marine species — and that's something governments and conservationists around the world, not to mention anglers, need to start to address.
David Shiffman is a marine biologist specializing in the ecology and conservation of sharks.
Reposted with permission from The Revelator.
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From the mythical minotaur to the mule, creatures created from merging two or more distinct organisms – hybrids – have played defining roles in human history and culture. However, not all hybrids are as fantastic as the minotaur or as dependable as the mule; in fact, some of them cause human diseases.
When Looking Through a Microscope Isn’t Close Enough.<p>For the last few years, <a href="http://www.rokaslab.org/" target="_blank">our team at Vanderbilt University</a>, <a href="https://www.researchgate.net/lab/Gustavo-Goldman-Lab" target="_blank">Gustavo Goldman's team at São Paulo University in Brazil</a> and many other collaborators around the world have been collecting samples of fungi from patients infected with different species of <em>Aspergillus</em> molds. One of the species we are particularly interested in is <a href="https://doi.org/10.1006/rwgn.2001.0082" target="_blank"><em>Aspergillus nidulans</em>, a relatively common and generally harmless fungus</a>. Clinical laboratories typically identify the species of <em>Aspergillus</em> causing the infection by examining cultures of the fungi under the microscope. The problem with this approach is that very closely related species of <em>Aspergillus</em> tend to look very similar in their broad morphology or physical appearance when viewing them through a microscope.</p><p>Interested in examining the varying abilities of different <em>A. nidulans</em> strains to cause disease, we decided to analyze their total genetic content, or genomes. What we saw came as a total surprise. We had not collected <em>A. nidulans</em> but <em>Aspergillus latus</em>, a close relative of <em>A. nidulans</em> and, as we were to soon find out, <a href="https://doi.org/10.1016/j.cub.2020.04.071" target="_blank">a hybrid species that evolved through the fusion of the genomes</a> of two other <em>Aspergillus</em> species: <em>Aspergillus spinulosporus</em> and an unknown close relative of <em>Aspergillus quadrilineatus</em>. Thus, we realized not only that these patients harbored infections from an entirely different species than we thought they were, but also that this species was the first ever <em>Aspergillus</em> hybrid known to cause human infections.</p>
Several Different Fungal Hybrids Cause Human Disease.<p>Hybrid fungi that can cause infections in humans are well known to occur in several different lineages of single-celled fungi known as yeasts. Notable examples include multiple different species of <a href="https://doi.org/10.1002/yea.3242" target="_blank">yeast hybrids</a> that cause the human diseases <a href="https://rarediseases.info.nih.gov/diseases/6218/cryptococcosis" target="_blank">cryptococcosis</a> and <a href="https://www.cdc.gov/fungal/diseases/candidiasis/index.html" target="_blank">candidiasis</a>. Although pathogenic yeast hybrids are well known, our discovery that the <em>A. latus</em> pathogen is a hybrid is a first for molds that cause disease in humans.</p>
(Left) Candida yeasts live on parts of the human body. Imbalance of microbes on the body can allow these yeasts, some of which are hybrids, to grow and cause infection. (Right) Cryptococcus yeasts, including ones that are hybrids, can cause life-threatening infections in primarily immunocompromised people. Centers for Disease Control and Prevention<p><a href="https://doi.org/10.1371/journal.ppat.1008315" target="_blank">Why certain <em>Aspergillus</em> species are so deadly</a> while others are harmless remains unknown. This may in part be because <a href="https://doi.org/10.1016/j.fbr.2007.02.007" target="_blank">combinations of traits, rather than individual traits</a>, underlie organisms' ability to cause disease. So why then are hybrids frequently associated with human disease? Hybrids inherit genetic material from both parents, which may result in new combinations of traits. This may make them more similar to one parent in some of their characteristics, reflect both parents in others or may differ from both in the rest. It is precisely this mix and match of traits that hybrids have inherited from their parental species that <a href="https://www.nytimes.com/2010/09/14/science/14creatures.html" target="_blank">facilitates their evolutionary success</a>, including their ability to cause disease.</p>
The Evolutionary Origin of an Aspergillus Hybrid.<p>Multiple evolutionary paths can lead to the emergence of hybrids. One path is through mating, just as the horse and donkey mate to create a mule. Another path is through the merging or fusion of genetic material from cells of different species.</p><p>It is this second path that appears to have been taken by our fungus. <em>A. latus</em> appears to have two of almost everything compared to its parental species: twice the genome size, twice the total number of genes and so on. But unlike other hybrids, which are often sterile like the mule, we found that <em>A. latus</em> is capable of reproducing both asexually and sexually.</p><p>But how distinct were the parents of <em>A. latus</em>? By comparing the parts contributed by each parent in the <em>A. latus</em> genome, we estimate that its parents are approximately 93% genetically similar, which is about as related as we humans are with lemurs. In other words, <em>A. latus</em>, an agent of infectious disease, is the fungal equivalent of a human-lemur hybrid.</p>
How A. Latus Differs From its Parents.<p>Elucidating the identity of closely related fungal pathogens and how they differ from each other in infection-relevant characteristics is a key step toward reducing the burden of fungal disease. For example, we found that <em>A. latus</em> was three times more resistant than <em>A. nidulans</em>, the species it was originally identified as using microscopy-based methods, to one of the most common antifungal drugs, <a href="https://www.drugbank.ca/drugs/DB00520" target="_blank">caspofungin</a>. This result provides a clear example of the potential importance of accurate identification of the <em>Aspergillus</em> pathogen causing an infection.</p><p>We also examined how <em>A. latus</em> and <em>A. nidulans</em> interact with cells from our immune system. We found that immune cells were less efficient at combating <em>A. latus</em> compared to <em>A. nidulans</em>, suggesting the hybrid fungus may be trickier for our immune systems to identify and destroy.</p><p>In the midst of the COVID-19 pandemic, our quest to understand <em>Aspergillus</em> pathogens is becoming more urgent. Growing evidence suggests that <a href="https://doi.org/10.1111/myc.13096" target="_blank">a fraction of COVID-19 patients are also infected with <em>Aspergillus</em>.</a> More worrying is that these <a href="https://doi.org/10.3201/eid2607.201603" target="_blank">secondary <em>Aspergillus</em> infections</a> can worsen the clinical outcomes for those infected with the novel coronavirus. That being said, we stress that little is known about <em>Aspergillus</em> infections in COVID-19 patients due to a lack of systematic testing, and none of the infections identified so far appear to have been caused by hybrids.</p><p>So, when it comes to hybrids, some are fantastic (the minotaur), some are helpful (the mule) and some are dangerous (<em>Aspergillus latus</em>). Understanding more about the biology of <em>Aspergillus latus</em> may help in our understanding of how microbial pathogens arise and how to best prevent and combat their infections.</p>
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