Mapping a Smoother Fishery for Smooth Dogfish

A commonly-used quote from John Shepherd states, “Managing fisheries is hard: it’s like managing a forest, in which the trees are invisible and keep moving around.” This is particularly true for highly migratory species like sharks, for which the full range is often poorly understood even for the most well-known species. In the past, fish movements were usually defined by the time of year a species is present in an area where they’re easy to observe. Telemetry and fishery surveys have gone a long way in telling us where else a species might travel when not within sight, but it’s impossible to tag every single shark, know what’s going on at a survey site when no one’s looking, or even to make sure research efforts are encompassing the full range of the species. To further complicate things, a species’ range might differ wildly between seasons and between males and females. 

To figure out where your target species is actually distributed, you have to take the information that you do have (survey catches, fishery landings, fishing effort distribution, telemetry detections, etc.) and do a lot of math (sometimes with lots of assumptions). With any luck, the data on were the species has been found can help identify other areas where it also might be found. In a newly-published paper first-authored by Andrea Dell’Apa with Maria Grazia Pennino, Chris Bonzek, and me, we did exactly that for the second most commonly-landed shark in U.S. fisheries.   

The Smooth Dogfish (Mustelus canis) is a fairly common coastal shark endemic to the North American Atlantic coast. These sharks reach a maximum size of five feet and feed mostly on small crustaceans like crabs and shrimp, but from personal experience I can attest to them being much more wily and powerful than should be necessary for that lifestyle (most of my cases of shark burn have come from this species). They also have the distinction of being second only to the Spiny Dogfish (less closely related than you’d think) in numbers landed in U.S. shark fisheries. While this in and of itself isn’t necessarily a bad thing and both Spiny and Smooth Dogfish fisheries have been assessed as avoiding overfishing, Smooth Dogfish have the dubious honor of being exempt from the U.S. ban on removing fins at sea. With all this fishery management attention you’d think most aspects of Smooth Dogfish ecology would be pretty well-known, but aside from some studies on local movements and identified nursery habitats, little is actually known about where these sharks go when not in estuaries, or how the environment influences their distribution. To our knowledge, this hasn’t been attempted with this species before.

To get a better idea of where Smooth Dogfish are distributed, we took catch data from the Northeast Area Monitoring and Assessment Program (NEAMAP), which runs a nearshore trawl survey based out of the Virginia Institute of Marine Science. Smooth Dogfish are among the most commonly-encountered elasmobranchs on this survey, making it an ideal data source for both numbers and associations with environmental data. The cruise data gave us the numbers of Smooth Dogfish caught per trawl (the catch per unit effort, or CPUE) and catch locations, which were combined with environmental variables from other data sources including satellite-based remote sensing data and bathymetry maps to identify the ranges of those variables that were associated with higher shark numbers. Armed with this information, we could then use statistical modeling to predict what the CPUE should be across the whole U.S. Atlantic continental shelf based on the environmental conditions, season, and sex. To account for seasonal migrations, we modeled spring and fall CPUE separately, and we separated out males and females to account for differences between the sexes.

We used hierarchical Bayesian modeling to make our maps of predicted Smooth Dogfish catch. Without getting too far into the weeds, this type of modeling allowed us to account for both high numbers of survey sites where no sharks were caught and the tendency of sites where Smooth Dogfish were caught to occur near each other. These issues can affect model accuracy and are commonly-encountered when dealing with relatively rare and highly mobile species like most sharks. 

Maps of male Smooth Dogfish catch-per-unit-effort (CPUE, sharks per trawl) predicted using catch and environmental data from A) spring and B) fall. From Dell’Apa and friends (2018).

Maps of female Smooth Dogfish catch-per-unit-effort (CPUE, sharks per trawl) predicted using catch and environmental data from A) spring and B) fall. From Dell’Apa and friends (2018).

The results of all this modeling showed differences both between seasons and sexes in where you should expect to find Smooth Dogfish. Males were found at relatively low salinities and shallow depths during the spring, and at temperatures less than 15 °C and mid-level bottom rugosity (basically an index of how rough the seabed is) during the fall. Females were caught in greater numbers at more shallow, rugose areas of the seafloor during the spring, and areas of relatively low salinity and mid-range chlorophyll-a concentrations during the fall. Mapping these habitat preferences showed that both females and males are distributed widely along the continental shelf north of the mouth of Chesapeake Bay and Delaware Bay during the spring while males are distributed considerable farther north (with an apparent hot spot along southeastern Cape Cod that calls for further investigation by fishery scientists) than females during the fall. 

Aside from improving knowledge of where Smooth Dogfish are distributed, our findings have some very specific applications for fishery management. When trying to keep a fish stock sustainable, it’s often effective to limit fishing effort on mature females (referred to as “spawning stock biomass” in fisheries science) so they can survive to reproduce. For long-lived species like most sharks, a targeted fishery landing mostly males is arguably the more sustainable option. Sorry fellow dudes, when it comes to sustainable fisheries we’re just more expendable (and if you feel threatened by that I have bad news for you about differences between sexes in size and trophic level among many shark species). What our findings suggest is that during the fall a male-only fishery for Smooth Dogfish may be possible in southern New England, which would allow fishermen to continue working while giving the mature females a break.

This paper shows how, thanks to advances in scientific surveys, environmental monitoring, and statistics, we’re getting better and better at counting those invisible highly migratory “trees”. Or at least predicting where they should be.

By C. W. Bangley

This post was also published in: http://yalikedags.southernfriedscience.com/mapping-a-smoother-fishery-for-smooth-dogfish/

Cited Reference

Dell’Apa, A., M. G. Pennino, C. W. Bangley, and C. Bonzek. 2018. A hierarchical Bayesian modeling approach for the habitat distribution of Smooth Dogfish by sex and season in inshore coastal waters of the U.S. Northwest Atlantic. DOI: 10.1002/mcf2.10051

Measuring the willingness of dive tourists to pay fishers not to fish in a no-take zone

Ecosystems provide an array of direct and indirect services to human populations. In tropical marine areas, such ecosystem services often include food provision (i.e., fishing) and ecotourism (i.e., diving). In cases where there are conflicts between these services – such as where fishers want to fish but divers want to see abundant, biodiverse ecosystems – examining the economics of various alternative policy solutions may be useful.

The various ecosystem services provided by tropical marine areas worldwide – such as food provision through fishing, or ecotourism opportunities through diving – are under increasing use in general. Sometimes such uses are unsustainable or conflict with one another. One way to help ensure the continued provision of ecosystem services is through establishment of marine protected areas (MPAs), where uses are ideally planned and managed with sustainability in mind.

More than 300 km off the coast of Brazil is the small andd gorgeous archipelago of Fernando de Noronha. Around this archipelago is a 26-km2 MPA, divided into two zones. One zone, which encompasses 70% of the park, is no-take: fishing is banned but diving is allowed. The other zone is multi-use, allowing fishing, tourism, as well as diving. 

Traditionally the small population of Fernando de Noronha  has relied on fishing for its food and economy, with tuna fishing (by handline) being most common now. However, diving and snorkeling by tourists has boomed in recent years, particularly to see sharks, which also use the inshore waters as an important nursery. With 24,000 divers visiting annually, Fernando de Noronha has become a premier shark tourism destination.

Credit Sophie Bertrand

However, a conflict has arisen between these uses. For about eight months of the year, fishers use the multi-use zone to catch sardines on the wave break, which they use as bait to catch tuna in pelagic waters outside the MPA. But for the remaining four months (the actual period varies from year to year), the waters of the multi-use zone become rough and unsafe, while the waters of the no-take zone remain calm. When the MPA was designed in 1988, it was understood that local fishers would fish in the no-take zone when necessary. But federal legislation in 2000 toughened the no-take zone’s rules and fishers who disagree with the no-take zone have been very vocal in protesting such rules. As a first response, park managers stated that any fishing in the no-take zone could impact the tourism experience by catching sardines the sharks eat and by disturbing juvenile and mating sharks on the shore.

So in the last 3 years we set out to investigate this conflict and possible solutions. In our first study, we showed the economic basis of the conflict, driven by an inflated demand from tourists who want to eat tuna and large pelagic species while on the island. Funny enough, such preferences do not match their consumption when back into their places of origin. Then, given that (unplanned) tourism is part of the problem, we investigated if it could also be part of the solution. In this new phase, we focused on two aspects: 1) estimating how much revenue the local fishers would lose if the no-take zone were strictly enforced year-round, and 2) gauging whether tourists would be willing to pay the fishers not to fish in the no-take zone. If visitors paid an additional BRL 1.20 (USD 0.60) as a daily fee, it would be enough to balance the lost annual revenue of the fishers. (At the time of the study in 2016, the MPA’s daily entrance fee to the no-take zone was BRL 89 [USD 53] for Brazilians and BRL 178 [USD 107] for foreigners. So the proposed additional fee would be relatively minimal.)

We then talked to 579 tourists and we found out that most of them (67-71%) would accept paying a little more if the extra money were given to fishers. Such an alternative was generally perceived as a win-win solution, as it would encompass maintaining fisher income, shark status, and the current economic gains of tourism. Tthe study also broke down the findings according to a number of criteria, showing for example that those tourits that had seen sharks on their visit were less willing to accept the extra payment. 

We understand that, with some adjustment, such payment could fit into an already existent Payment for Ecosystem Services system, varying from state to state, that compensates fishers during closed seasons to support the reproductive period of some species. However, this exercise represents an opportunity to devise solutions with fishers. Perhaps such extra money from tourism could support the transition from a bait-based fishing to a lure-based one, as the youngest and most successful fishers in the island have already started doing.

We conclude by stating that future MPAs should outline clear compensatory mechanisms to support the transition from a resource-consumptive economy to less-consumptive alternatives for those directly affected by conservation. Such transition should be planned together with fishers, as they may be the ones with the best alternatives.

Most of the text was extracted from MarXiv: https://marxiv.org/45k96

Sources: Lopes, PFM & Villasante, S. 2018. Paying the price to solve fisheries conflicts in Brazil’s Marine Protected Areas. Marine Policy, 93:1-8
Lopes et al. 2017. Tourism as a driver of conflicts and changes in fisheries value chains in Marine Protected Areas. Journal of Environmental Management 200: 123-134

A brand new method to infer stream fish abundance

Interview with Prof. Taal Levi

Prof. Taal Levi is an Assistant Professor at Oregon State University and has one of the most diverse research profiles that we’ve ever seen. His studies range from disease ecology to seed dispersal across all sorts of environments, from the Amazon Forest to Alaska. His main peculiarity is perhaps the use of empirical data to address applied issues, such as wildlife overexploitation, overfishing, climate change and anthropogenic impacts in general.

Now, one of his projects is focusing on estimating stream fish abundance using quantification of environmental DNA. Environmental DNA (or eDNA) is the technique of detecting DNA found in the environment, like water, soil or even from stomach contents, instead of trying to extract it directly from an individual.

Here he talks about this interesting and important project (we know how important it is to have reliable fish abundance measures for fishery management!):

 

FEME: How does this method work exactly?

Taal Levi: Detection of environmental DNA using real-time qPCR or digital PCR is already being used to identify species occurrence. But now we are testing its effectiveness to infer species abundance.

Firstly, it is necessary to design species-specific primers – so, you have to decide a species focus. We are mostly using mitochondrial markers, such as COI (cytochrome oxidase I). Then, you have to collect some water samples and amplify all the DNA of the target fish you find there. Finally, you make a relation between the concentration of DNA from your target and the species abundance.

FEME: What have you found so far?

Taal Levi: We already tested this method for two salmon species and for Eulachon (a smelt) in the state of Oregon. All of them are very economically and culturally important. Actually, the Eulachon is so important for the people in that region that the Oregon’s state name was given because of how the indigenous called that fish, Ourigan. For these three species the method seems very effective.

FEME: Is it possible to test its efficacy? How?

Taal Levi: We are testing it using different forms of counts. For the salmon species, we counted the number of individuals entering the streams every day for two years. For the Eulachon, we used a different approach, a mark-recapture abundance estimative.

FEME: What are the advantages of using this methodology?

Taal Levi: Several! One is the possibility of sampling more areas very fast, because the only thing you need to do is collect water. The other is to be able to work with endangered species - usually, doing research with endangered species is very complex, and this method is very cost-effective.

 

FEME: Is there any disadvantage?

Taal Levi: The eDNA is very local and time specific, so you can only infer abundance from a small area and for the last 1 or 2 days.

FEME: Do you think that this technique can be applied in Brazilian streams?

Taal Levi: Definitely yes, you will only have some more trouble to design the markers. With that being done, it is totally posible.

If you are interested in learning more about prof. Levi and/or the methods he’s been developing and applying, check his website and his last publication on eDNA.

Tax havens, illegal fishing and Amazon deforestation

Cayman Islands, Panama, Belize, Turks and Caicos and other Central American small countries may remind some of us of little pieces of paradise, but may also remind others of tax havens and corruption. However, perhaps a question that nobody had (dared to?) asked before was about a possible link between tax havens and environmental degradation. A study recently published in Nature Ecology and Evolution gives us a good sense of how these two things may be much more related than you would have ever guessed so.

Tax havens are known for providing politically neutral and reliable arenas for institutional innovation compared with settings dominated by political turbulence and institutional legal vacuum. At the same time, however, some negative effects of these jurisdictions are evident, such as their role in ‘money laundering’ and funding of illegal activities, and the risk of amplified global systemic financial risks created by the lack of financial transparency and oversight.

But how about the potential environmental impacts of tax havens? To address this issue, Victor Galaz and collaborators have examined resource extraction from two key global environmental commons - the ocean and the Amazon rainforest. Their data shows that while only 4% of all registered fishing vessels are currently flagged in a tax haven jurisdiction, 70% of the vessels that have been found to carry out or support illegal, unreported and unregulated fishing are, or have been, flagged under a tax haven jurisdiction. Fisheries sector is particularly susceptible to the use of tax havens in three important ways. First, the use of tax havens has been proved to support aggressive tax planning and tax evasion. Second, these jurisdictions also facilitate the evasion of regulation designed to address overfishing and fisheries crime because many well-known tax havens also qualify as secrecy jurisdictions in other regards, such as flags of convenience (FOC) states. FOCs are countries to which vessel owners flag vessels and from which they can expect limited or no sanctioning mechanisms if they are identified as operating in violation to international law. Third, the secrecy afforded by combined use of tax havens and FOCs also allows companies to secure the dual identity of a fishing vessel, one of which is used for legal and the other for illegal fishing activities. Therefore, the authors claim that the use of tax havens makes tracing of fisheries resource use and allocation of accountability extremely difficult and costly, representing a major threat to the sustainability of global ocean resources.

Source: Caribbean News Service (Illegal, unreported and unregulated fishing in the Caribbean)

 

The environmental impacts of tax havens are not that different in the Amazonian reality. Galaz and co-authors’ study shows that between October 2000 and August 2011, tax havens accounted for 68% of the total foreign capital transferred to the nine largest companies operating in the soy and beef sectors of the Brazilian Amazon. Even though it is not illegal to transfer money to Brazil using tax havens, it is worth mentioning that soy and cattle production are the two sectors representing key drivers of deforestation. For some of the companies investigated, tax havens represented as much as 90–100% of the foreign capital. Channeling capital through tax havens provides three benefits to investors: legal efficiency, tax-minimization and secrecy.

Both examples explored by Galaz and collaborators show that the use of tax havens leads to environmental concerns, and poses major challenges to transparency and tracking. Furthermore, the authors claim that the loss of tax revenue through the use of tax haven jurisdictions by companies modifying the biosphere could be conceptualized as indirect subsidies to economic activities with possibly detrimental global environmental consequences. The authors conclude by highlighting that the international community should intensify its attempts to stimulate corporate transparency and collaborate to uncover and fight tax evasion, viewing such actions as important not only from a socio-political perspective, but also for environmental reasons.

Source:

Galaz et al. 2018. Tax havens and global environmental degradation. Nature Ecology and Evolution: https://doi.org/10.1038/s41559-018-0497-3

Sustainable seafood consumption in Brazil: An interview with Daniele Vila Nova

Marine fishery resources have worldwide economic, social, and ecological importance. These fisheries provide a relevant part of protein intake and income for people in the developing world, being linked directly and indirectly to the fishing sector. As the global population increases, the demand for fish increases which leads to a growing number of vessels, diversification of fishing gear, and improvements of catchability. All of these innovations are leading to crashing fish stocks and dramatically changing marine ecosystems. However, the growing number of vessels, the diversification of fishing gear and the improvements in catchability, coupled with population growth and increased demand for fish in recent decades made overfishing a global reality, not only affecting fish stocks, but entire marine ecosystems. This urgent situation should leads to the promotion of forms of sustainable resources, which should encompass fisher all the way to the final consumer.

            There are many factors that determine if fish are sustainably caught. The factors that lead to this are information about the social conditions of the fishing worker (from extraction to marketing), the ecological status of fish stocks and even the basic conditions of preparation and processing the catch. These factors should be accompanied or explicitly demanded by consumers to help with their shopping choices, although this is hardly ever the case, especially in developing countries.

            Daniele is a biologist with a master's and doctoral degree in Ecology and Conservation. She has extensive experience in coastal and marine conservation which has allowed her to work in multiple initiatives to integrate and promote stakeholder/institution engagement towards coastal and ocean sustainability in Brazil. She is currently a fishery analyst for the Seafood Watch Program (Monterey Bay Aquarium) (www.seafoodwatch.org) and the Research Director for Paiche      (instagram.com/paichebr) which is a brand-new consulting firm focused in promoting seafood sustainability in Brazil. She is also part of the Brazilian Alliance for Sustainable Seafood (www.facebook.com/abps.pescasustentavel), and her work with this organization will be further explained in the interview

1. Can you tell to us a little about “Aliança Brasileira de Pescado Sustentável” and the work being developed?

The Brazilian Alliance for Sustainable Seafood (BASS) aims to promote collective actions searching for solutions to address the many challenges of the seafood supply chain along with promoting sustainable seafood consumption. BASS was created in 2015 during the second Seminar on Fisheries and Aquaculture: Seeking Sustainable Solutions. The meeting culminated in the joint decision to create the Alliance. Attendees represented the largest ocean conservation nongovernmental organizations (NGOs) working in Brazil and included: celebrity chefs, large retailers, food service companies, industry, government, independent scientists, aquariums and some prominent universities.

2. What are the main difficulties for the fish sustainability in Brazil?

In a nutshell, there's not enough information. In a country as big as Brazil, without providing fisheries statistics at a national level for about 10 years, it really shows how great the challenge is to promote seafood sustainability here. The lack of a continuous agenda hampers promising initiatives that are also often interrupted due to changes in the government and/or lack of consistent funding. It is also worth noting that in such a large country one single solution won't be enough. We need to identify best practices/initiatives already in place across the country and replicate the methods where the conditions are similar. This would allow us to seek solutions that would ultimately meet local problems while also addressing the local social, environmental, economic and cultural components.

3. How could we convince the big companies to practice sustainable fishing?

From a global standpoint, a positive aspect that I could mention is that changes are happening outside Brazil. There's a growing movement promoting seafood sustainability that has been ongoing for about 20 years, and this wave of changes is finally arriving here. Due to a large quantity of seafood in Brazil coming from other parts of the globe, some of this seafood is already certified or evaluated within seafood recommendation programs. Also, much of what is produced here is exported, so we've been witnessing sanctions and embargos towards Brazilian companies for not providing/performing consistent information that is legally required. What may initially be a negative condition can actually become a 'wake up call' for the big companies. Is the Brazilian government responsible for not enforcing the regulations? Yes, absolutely. However, companies are also responsible for not following them many times, despite knowing such regulations. The challenge here is to enable companies understand the benefits (both financial and environmental – the latter being usually a long term benefit) of compliance and also of proactively engaging in more sustainable practices (which in turn may also increase the value of their product in the market). Whoever leads such changes will also reap the first benefits.

4. You recently attended the “SeaWeb Seafood Summit” event in Barcelona, Spain. How was it to participate to this event and how is the Brazil's situation in relation to other countries?

It was an incredible experience! To be able to meet and network with the world's leaders involved in the sustainable seafood movement was a game changer for me. I also learned many inspiring stories from other developing countries addressing similar problems that we face here (lack of data, low investments, lack of transparency, social responsibility, etc. Unfortunately, I was the only Brazilian attending the Summit. Hopefully, this will change in the coming years.

5. What can each of us do to contribute to the fish sustainability?

Be a responsible consumer! Ask what fish is when you go to a restaurant, check labels, and see where your seafood is coming from when you go grocery shopping. Be aware of species that are endangered and that shouldn't be consumed. Don't eat sharks and rays (most of them are endangered species). Vary your seafood options by trying local species that are not widely known but will likely be more abundant than other species in high demand (think tuna!). Spread your knowledge to your friends, colleagues, and family. We need more changemakers!