Fishing for Answers: Learning About Fishery Research Volunteers Through Surveys

By Oliver Topel, SRC Intern

Today’s blog revolves around a group of researchers who interviewed volunteers from the California Collaborative Fisheries Research Program (CCFRP). Their paper, “Long-term participation in collaborative fisheries research improves angler opinions on marine protected areas,” examines how the volunteers’ time in the program impacts their views on marine protected areas (MPAs). The survey showed a clear relationship between time as a volunteer and perceptions of marine resource value and fishery management. 

Let’s start with a quick little history lesson, shall we? In 1999, California passed the Marine Life Protection Act, which directed the state to increase the protection of their local marine habitats, which led to several marine-focused organizations coming together under this unifying law, and in 2006 the CCFRP was created. The California Collaborative Fisheries Research Program monitors groundfish populations, such as rockfish, groundfish, skates, and rays. It uses the data collected to make future predictions of species diversity and catch rate. According to the article, “Between 2007 and 2016, CCFRP annually surveyed four sets of MPAs along the central coast including Año Nuevo State Marine Reserve (SMR), Point Lobos SMR, Piedras Blancas SMR, and Point Buchon SMR” (Mason et al., 2020).  

While the benefit of the CCFRP is more than evident, what’s not as clear-cut as the volunteers’ perception of the work they do. This where the survey comes in. To conduct this experiment, the researchers distributed a 29-question survey to 722 volunteer anglers in CFRP. The survey consisted of several different types of questions, such as multiple choice and ordinal scale. They were distributed through email in the Spring of 2018 (Mason et al., 2020). The questions themselves ranged from being about CCFRP, MPAs, and personal demographic data about the individual taking the survey. Despite so many recipients, only 15% of the volunteers completed and sent in their survey. A majority of the responses were positive, with volunteers not only believing that the CCFRP is a beneficial organization but that they have learned from and contributed to the work the organization does. To learn more about these results, you can look at Figures 2-4 below.  

Figure 1: From Mason et al. (2020, pg. 2): “Marine Protected Areas in central California monitored by CCFRP between 2007 and 2016”


Figure 2: From Mason et al. (2020, pg. 15): “Predicted probability of CCFRP volunteer anglers having an opinion change on MPAs relative to time”

Overall, this article portrays who CCFRP volunteers are and how they have been affected by the program. Results show that positive change in opinion became significant after an extended time with the program (sometimes up to 7+ years) (Mason et al., 2020). Hopefully, this article, and maybe even this blog, encourages people to volunteer with programs such as the CCFRP and put some real-time in, and you might even have a change of viewpoint.


Work cited

Mason ET, Kellum AN, Chiu JA, Waltz GT, Murray S, Wendt DE, Starr RM, Semmens BX. 2020. Long-term participation in collaborative fisheries research improves angler opinions on marine protected areas. PeerJ 8:e10146. DOI 10.7717/peerj.10146

Traditional knowledge of Fishers versus an environmental disaster from mining waste in Central Brazil

By Rebecca Varnam, SRC intern

In recent years, the depths of human impacts on the environment have become even more clear (Nyssen, 2004). These impacts are not just specific events that occur in single, isolated locations, but rather multiple events that occur around the world, and in multiple different forms (Phillips, 2001). Here, I am going to focus specifically on a study from Oliviera et al. (2020) on how mining waste released into the Doce River affected artisanal fisheries, following the collapse of a dam associated with the Samarco Mineração (SA) mining company (Figure 1). Assessed are the three different regions in Central Brazil; Conceição da Barra (CB), Regência (RG), and Barro do Riacho (BR). 

Map of Doce River, including the Southeastern Brazil dam setup and the collapsed dam location that caused the release of mining waste closest to the three regions assessed in this paper: CB, RG, and BR (Magris, 2019).


Scientists spent about four months performing assessments and interviews in the three central Brazilian regions mentioned above. The procedure began with habitat assessments in each location based on observation and research on the areas before, during, and after the disaster. They completed 120 interviews-to avoid bias, these were performed individually and using a standard questionnaire (Oliviera et al., 2020). The information was then gathered and organized to allow scientists to make conclusions on the impacts this disaster had within this area. 

Overall, most fishers mentioned the following, “1) fishing was suspended, 2) the catch was contaminated and its volume decreased and 3) there was degradation in the Doce River basin as far as the river mouth” (Oliviera et al., 2020, p. 4) (Figure 2). These three impacts play a role in not just the environmental health of these designated regions, but also success in the fishing market.

Doce River after the dam collapse in Central Brazil, (B) “Toxic Mud” that accumulated in Doce River (Oliviera et al., 2020).

You may wonder why it was important for these scientists to perform this study. First, there are about 40 million people worldwide that have livelihoods that rely on marine fisheries (FAO, 2018). With this many people relying on fisheries, it is important that changes to this industry are available to not only help the environment but also to protect these families from economic deficits. Second, mining companies establishing in a region can increase aquatic environmental concerns such as increased pollution, contamination, and changing landscapes and ecosystems, which can also affect fisheries within the region (Kossoff et al., 2014). With these environmental concerns and impacts on fisheries, there is an increased need for more research to find the most sustainable and safe methods for mining and dam usage.

In conclusion, this environmental disaster, recognized by most to be the fault of SA mining company, has affected fishers in CB, RG, and BR regions to reduce their fishing practices to only supply for their families as they do not have the money to access other food sources. Fishers are also struggling, as a majority do not have the education to access other job opportunities. Further assessments on the continued impact of this disaster is necessary along with more employment opportunities provided by the SA mining company for those struggling to provide for their families (Olivier et al., 2020). 

Works cited

Kossoff, D., Dubbin, W. E., Alfredsson, M., Edwards, S. J., Macklin, M. G., & Hudson-Edwards, K. A. (2014). Mine tailings dams: Characteristics, failure, environmental impacts, and remediation. Applied Geochemistry, 51, 229-245. doi:

FAO, The State of World Fisheries and Aquaculture 2018 – Meeting the Sustainable Development Goals, Food and Agriculture Organization of the United Nations, Rome, Italy, 2018.

Nyssen, J., Poesen, J., Moeyersons, J., Deckers, J., Haile, M., & Lang, A. (2004). Human impact on the environment in the Ethiopian and Eritrean highlands—a state of the art. Earth-Science Reviews, 64(3), 273-320. doi:

Oliveira, P. D. C., Di Beneditto, A. P. M., Quaresma, V. d. S., Bastos, A. C., & Zappes, C. A. (2020). Traditional knowledge of Fishers versus an environmental disaster from mining waste in Central Brazil. Marine Policy, 120, 104129. doi:

Magris, R. A., Marta-Almeida, M., Monteiro, J. A. F., & Ban, N. C. (2019). A modelling approach to assess the impact of land mining on marine biodiversity: Assessment in coastal catchments experiencing catastrophic events (SW Brazil). Science of The Total Environment, 659, 828-840. doi:

Phillips, J. D. (2001). HUMAN IMPACTS ON THE ENVIRONMENT: UNPREDICTABILITY AND THE PRIMACY OF PLACE. Physical Geography, 22(4), 321-332. doi:10.1080/02723646.2001.10642746


Mapping the global network of fisheries science collaboration

By Julia Saltzman, SRC intern

Collaboration is something which we all learn about as children. We are taught to work together in teams, to share our toys, and that ideas are better when many individuals contribute to them. As science has become increasingly internationalized, scholars investigating the shifting spatial structure have posed questions to whether networks of research collaboration are actually expanding despite the argument that broad-based collaboration is crucial to solving the challenges ongoing with respect to fisheries (Syed, ní Aodha et al. 2019). The global marine catch is approaching its upper limit, the number of overfished populations and the indirect effects of fisheries indicate that fisheries management has failed to achieve any sort of sustainability. This failure is primarily due to the continued increase in harvest rates in response to global pressure for greater harvests and the inability to accurately model sustainable catch amounts. Nevertheless, fisheries provide the direct employment to about 200 million people and account for nearly 19% of the total human consumption of animal protein (Botsford, Castilla et al. 1997). Fisheries are a crucial resource, and the only way to promote comprehensive management is with collaboration on a global level.

Figure 1: The global marine catch is approaching its upper limit, the number of overfished populations and the indirect effects of fisheries indicate that fisheries management has failed to achieve any sort of sustainability.

With the imperativeness of this collaboration in mind scientists mapped and examined the landscape of scientific collaboration across fisheries science. The results were quite interesting, the collaboration has become more extensive and more intensive in various places. However, the fisheries science landscape is one where the centers of knowledge production and the collaboration across scientists is far more regional than global. The regional manner of collaboration in fisheries science is likely to limit the potential benefits of collaboration. Collaboration which is regionally limited in such a global field will have consequences such as preventing the innovation which is necessary to address the ongoing challenges within fisheries management. There are several different aspects of fisheries management which can be learned from this study. First and foremost, collaboration on a global level is crucial for sustainable fisheries management. This collaboration should manifest itself in several different ways whether it be direct collaboration between various fisheries, collaboration among scientists who work in different fisheries, and collaboration among governments and fisheries management organizations.

Figure 2: Collaboration is something which we all learn about as children. We are taught to work together in teams, to share our toys, and that ideas are better when many individuals contribute to them. As science has become increasingly internationalized, scholars investigating the shifting spatial structure have posed questions to whether networks of research collaboration are actually expanding despite the argument that broad-based collaboration is crucial to solving the challenges ongoing with respect to fisheries.

Works cited

Botsford, L. W., J. C. Castilla and C. H. Peterson (1997). “The Management of Fisheries and Marine Ecosystems.” Science 277(5325): 509.

Syed, S., L. ní Aodha, C. Scougal and M. Spruit (2019). “Mapping the global network of fisheries science collaboration.” Fish and Fisheries 20(5): 830-856.

Securing Sustainable Somali Fisheries

By Peter Aronson, SRC intern

Lots of people know about the issue of piracy in Somali waters in recent years, with mass coverage from American media and even Hollywood focusing on it with the 2013 movie Captain Phillips. However, many people don’t know that the loss of secure fisheries to illegal foreign vessels was the root cause of these conflicts (Beri, 2011). In the 1980’s, when the Somali Civil War first broke out, the central government collapsed and the Somali Navy disbanded. As a result, foreign fishing boats took advantage of the lack of security and fished Somali waters heavily, leading to great erosion of fish stocks. With no government intervention to help, artisanal Somali fishermen banded together to protect their own resources. At first, violence was not threatened or used. However, as events escalated, weapons were used, both poor fishing vessels and wealthy cargo vessels were taken over, and in some cases hostages were held for ransom. As this became profitable, pirate activities became widely funded by financiers and militiamen on land. The cause of all this was illegal foreign fishing.

Illegal, unreported, and undocumented (IUU) fishing from foreign fleets declined in Somalia in the mid 2000’s due to piracy, but increased again when foreign naval fleets began patrolling Somali waters to reduce piracy (Oceans Beyond Piracy, 2014). Seeing foreign fleets off the coast angered the public and increased support for piracy, as sustainably developing artisanal and subsistence fisheries became much more difficult with pressure from foreign operations. Due to uncertainty of the legality of foreign fishing for decades, unregulated fishing with ineffective enforcement of decades-old policy, and catch that hasn’t been reported to the United Nations since 1988, there is a widespread perception that any foreign fishing activity in Somalia is illegal (Glaser et al., 2015).

Apart from poor fisheries management, there is justified anger towards foreign vessels due to violent conflict. They have been accused of hiring armed guards to shoot at Somali fishers, blasting hot water at Somalis, and destroying fishing gear in domestic artisanal fisheries (Glaser et al., 2015). Additionally, Somalis are upset at the foreign fleets’ destruction of fish stocks at the expense of domestic fishing, and using destructive methods, such as bottom trawling, that destroy coral reef and other habitat. As a result, Somalia has removed fishing rights from many foreign vessels, and have even captured vessels and imprisoned the fishermen aboard them (Glaser et al., 2015).

Using satellite data, the Secure Fisheries group with the One Earth Future Foundation estimated the amount of foreign fishing vessels in Somali waters between 1981 and 2013, and the amount of fish they took. It was estimated that 3.1 million metric tons of marine life was taken in this time frame by foreign vessels, more than twice the amount that domestic Somali fishermen took at 1.4 million metric tons. The heaviest fishing nations in the time frame are Iran, Yemen, Spain, Egypt, and France, though in 2013 Spain, Seychelles, France, South Korea, and Taiwan dominated.

Trawling has had a great impact on Somalia’s marine habitat. Trawling from foreign nations continued for decades following the collapse of Somalia’s government, with bottom trawling even continuing beyond Somalia’s ban of it in the new Somalia Fisheries Law. It was mainly Italian and Egyptian vessels trawling until 2006, when South Korean ships replaced the Italian ones. Italian and Korean vessels fished 220 and 229 days of the year respectively. Some trawlers are actually licensed to Puntland, a coastal region in Somalia on the Horn of Africa. Due to its wide continental shelf and high fish availability, as well as licensing in the region, most trawling occurred in shallow waters here. Over the time period that data was collected, 120,652 square kilometers were trawled, an area slightly larger than the neighboring nation Eritrea (Glaser et al., 2015). This doesn’t account for areas of seafloor that were trawled multiple times. Several areas that experienced this underwent significant ecosystem damage.

In Somalia, foreign fleets are larger, better equipped, and more technologically advanced, giving them a competitive edge over smaller Somali vessels. Globally there is a similar trend of large, distant, industrial fleets outcompeting small, artisanal and subsistence fishers. These small-scale fishers are some of the world’s poorest people and are extremely vulnerable to changes in resource availability (Béné, 2009). The current sustainability of fish stocks were estimated by Secure Fisheries using methods designed for data-poor fisheries. It was found that 8 of 17 fish groups analyzed are currently fished unsustainably, including swordfish, emperors, sharks, snappers, and groupers. This data must be used cautiously, as categories were analyzed at different levels, such as striped marlins at the species level, to sharks at the family level. Additionally due to little available data, estimations of migratory species used catch reconstruction and the classification of whether or not a stock was sustainable was based on comparison to an exact calculated value.

Optimistically, a lower proportion of fish stocks are being fished unsustainably in Somalia than globally, and no stocks are collapsed whereas 24% of stocks are globally. This advantage is due to delayed industrial fishing in Somali waters. However, if trends continue and follow the preceding global pattern, it is estimated that over half of Somali stocks will be overexploited by 2025 (Glaser et al., 2015). It is important to move towards sustainable fisheries in Somalia. With the full effects of postcolonialism pressing down on the nation, sustainable fisheries could promote the Somali economy, provide food, and nourish many for years to come.

Works Cited

Béné, C. (2009). Are Fishers Poor or Vulnerable? Assessing Economic Vulnerability in Small-Scale Fishing Communities. Journal of Development Studies, 45(6), 911–933. doi:10.1080/00220380902807395

Beri, R. (2011). Piracy in Somalia: addressing the root causes. Strateg. Anal., 35 (3), 452-464.

Glaser SM, Roberts PM, Mazurek RH, Hurlburt KJ, and Kane-Hartnett L (2015) Securing Somali Fisheries. Denver, CO: One Earth Future Foundation. DOI: 10.18289/OEF.2015.001

Oceans Beyond Piracy. (2014). The State of Maritime Piracy Report 2014. Denver, Colorado: One Earth Future Foundation.

Predicting Fisheries Collapse

By: Chris Schenker, SRC Intern

Figure 1: Some fisheries, such as skipjack tuna (left) remain profitable. Shown to the right, blue bars indicate fisheries that remain close to target biomass, while red bars indicate fisheries that generate profit. Predictions for 2050 are shown based on business as usual (BAU), maximum sustainable yield through catch limits (MSY), and maximum profit through rights-based fisheries management (RBFM). (Worm et al., 2009)

Hundreds of millions of people around the world depend on wild harvests from the ocean as both a livelihood and source of protein (Srinivasan et al., 2010). Ensuring the long term sustainability of fisheries is therefore a matter of utmost importance for global resource security. However, according to a 2016 paper in PNAS, global fish stocks are on average poor and declining (Costello et al., 2016). Of the 4,714 fish stocks analyzed by Costello et al. in 2012, 68% were below the biomass target that supports maximum sustainable yield (referred to as BMSY). Considering a level of 63% of assessed stocks measuring below BMSY  in 2006 (Worm et al., 2009), there has been a clear decrease in fisheries health worldwide. Furthermore, the finding that only 35% of stocks in decline are being fished at a rate that puts them back on target to achieve BMSY indicates that this trend is set to worsen (Costello et al., 2016).

In order to avert a collapse in the world’s fisheries, it is therefore important to understand which species are at greater risk than others. Terrestrial surveys suggest that large bodied, high trophic level species are the most susceptible to population decline due to human pressure. While this was long assumed to also be the case for marine species, recent evidence has suggested otherwise. Pinsky et al. analyzed two independent fisheries databases and global landings from 1950 to 2006 as reported by the UN Food and Agriculture Organization (FAO) in order to test this hypothesis (Pinsky et al., 2011).

Neither the assessment data nor the landings data supported the idea that fisheries collapse across only a small range of life history traits. In the analysis of the assessment data, 12% of stocks of high trophic level species experienced collapse, but 25% had collapsed among low trophic level species. When comparing by size, 16% of large species collapsed versus 29% of small species. While these figures suggest a higher likelihood of collapse in smaller, low trophic level species, linear regression models did not support any significant relationship between stock collapse and trophic level (P = 0.15), weight (P = 0.26), longevity (P = 0.10), age of maturity (P = 0.92), fecundity (P = 0.77), or investment in offspring (P = 0.99). The landings data supported the conclusion that small, low trophic level species are just as vulnerable as large, top predators, and individual life history traits alone did not explain significant variation in stock collapse (Pinksy et al., 2011).

Figure 2: Global variation by large marine ecosystem in (a) proportion of stocks that have ever collapsed, and (b) climate variability from season to season. (Pinsky et al., 2015)

In a 2015 paper, Pinsky et al. created boosted regression trees for 154 populations of fish worldwide in order to analyze the effects of harvesting, life history traits and climate variability on the risk of collapse. As expected, overfishing was the most important predictor of collapse. Chronic overfishing correlated to depletion, while acute overfishing correlated to collapse (Pinsky & Byler 2015). However, certain life history traits and climate variability were found to predispose populations for collapse.

Fast-growing species in variable climates appeared particularly sensitive to overfishing. Species with short generation times can rebound faster than longer generation species, but they can only tolerate smaller lags in harvest rate reductions. When coupled with productivity lows caused by climate variability, fast growing species become difficult to manage and require proactive oversight. There are limitations to the datasets used to arrive at this conclusion, such as the low number of tropical climates assessed, but it is clear that more variability exists than can be explained by simple extinction models (Lande, 1993). More complex models incorporating multiple, interacting drivers of stock declines appear useful for better predicting future collapses.

Stock assessments are an important component of most management systems, but their prohibitive cost often means they can only be completed infrequently. It is therefore imperative to maximize the value of an assessment by deriving as much information about as many species as possible. In PNAS, Burgess et al. (Burgess et al. 2013) suggest a new system for predicting future population declines. The theory assumes that the species in any multispecies fishery are connected to each other by the shared threat of effort. This means that the fate of all species can be predicted if the fate of one species can be predicted.

Figure 3: Comparison of assessment histories and points of earliest identifiable threat based on T-score. (Burgess et al., 2013)

The logic behind this assumption is that in any fishery, most of the harvesting will be directed at key species, and this will drive future mortality from fishing for all species. Target species are usually monitored more consistently and have more extensive datasets of past and present stocks (Burgess et al., 2013). By using differences in life history traits between key and other species and projections of future mortality from fishing, the authors created a T-score or “eventual threat index” for any given species across all of the fisheries in which it is caught. A T-score < 1 means a species is not at risk, while greater than one means a weak stock is on track to become overfished. Once T increases to > 2, the species is at risk to become extinct due to incidental fishing pressure.

This new approach promises to boost the effectiveness of fisheries management worldwide. Eight populations of Pacific tuna and billfish were analyzed with this technique, four of which are severely depleted. Had this method been available then, the authors claim that the decline of these populations could have been predicted in the 1950’s (Burgess et al., 2013). Such early detection could have positive economic impact and save decades in recovery time. However, alternative solutions are still needed in less developed countries lacking sufficient assessment and regulation. If depleted fish populations in these countries are ever going to recover, new sources of income and nutrition must be found to supplement the role that fishing has traditionally filled. Saving global fisheries from collapse is possible, but it will require innovative new science, strict regulation, and engagement with less developed communities that rely on the sea for livelihood.

Works Cited:

Burgess MG, Polasky S, Tilman D (2013) Predicting overfishing and extinction threats in multispecies fisheries. Proc Natl Acad Sci USA110:15943–15948.

Costello C, et al. (2016) Global fishery prospects under contrasting management regimes. Proc Natl Acad Sci USA 113:5125–5129.

Lande R. 1993 Risks of population extinction from demographic and environmental stochasticity and random catastrophes. Am. Nat. 142, 911–927

Pinsky ML, Jensen O. P. , Ricard D., Palumbi S. R. 2011 Unexpected patterns of fisheries collapse in the world’s oceans. Proc. Natl. Acad. Sci. U.S.A. 108, 8317–8322. doi: 10.1073/pnas.1015313108; pmid: 21536889

Pinsky ML, Byler D. 2015. Fishing, fast growth and climate variability increase the risk of collapse. Proc. R. Soc. B 282:20151053

Srinivasan, U.T., Cheung, W.W.L., Watson, R. et al. J Bioecon (2010) 12: 183. doi: 10.1007/s10818-010-9090-9

Worm B, et al. (2009) Rebuilding global fisheries. Science 325(5940):578–585.

Local taboos could help conserve marine fisheries in Tanzania

By Jess Daly, SRC Intern

In developing nations it is often difficult to effectively enforce marine conservation laws because of a lack of staff and funding. With so little government intervention, it may be unclear to what extent the rules are being followed. A 2017 study by Shalli et al. examined how alternative methods of management might be affecting fisheries in Tanzania.

Specifically, the focus of this project was how traditional knowledge and local taboos alter the behavior of local fisherman. Traditional knowledge is wisdom that is passed down through generations, and taboos are a subcategory that includes the belief that certain actions are either too immoral or too sacred to be done in good conscience. The study examined six different Tanzanian fishing communities (4 rural and 2 urban), and used a wide variety of survey methods to gather information, including observation of fishing practices, a questionnaire given to fishers, and interviews with village leaders.

Figure 1

A fisherman goes out with his boat in the waters off of Dar-es-Salaam, Tanzania. [Grant, Milton. “Fishing in Tanzania.” United Nations Photo. 01 May 1991. /un_photo/34848229512]

Those who were given the questionnaire were also asked to provide their ages, genders, education levels, and lengths of residency. Across all of the villages, the majority of fishers were men who were between the ages of 30-40 and had a primary school education or less. However, when asked about local taboos, it was the uneducated elders who were able to provide the most information.

It was discovered that a wide variety of taboos exist within the Tanzanian fishing communities. The first is that certain fish species should not be eaten; reasons given for non-consumption included religious beliefs and fear of toxicity. Specific species and explanations of the taboos varied in the different villages, but all of them discussed dietary restrictions in one way or another. While the trend was present, however, the study found that nearly 50% of respondents did not comply with this taboo. A second class of taboos includes several actions involving the creation and deployment of fishing gear (such as women not touching new nets). These rules were more closely followed, with 44% of respondents claiming that they stringently complied with them, partially because of fear of social backlash. Almost 77% of fishers admitted noncompliance with taboos related to restrictions before or during fishing. More than 97% did not adhere to local taboos that prohibit fishing on certain sacred reefs, and nearly 47% claimed that they fished on certain prohibited days (such as religious holidays).

Figure 2

A graph depicting the levels of compliance to six different “categories” of taboos by different groups of fisherman as either strong, weak, or none. [Shalli et al. /sh/iyrngyxjy05qhm5/ AACAfkJqi4aOBqumSsEb0cZNa? dl=0&preview=shalli+et+al+2017.pdf]

Many of the local taboos, if they were widely followed, would aid in marine conversation by limiting things like fishing days, target species, fishing in sensitive reef areas, and catch size. While it appears that the majority of taboos are ignored in practice due to growing village populations and an increased demand for fish, it is believed that if local fishermen were educated in how these taboos actually affect population sizes, they would be more likely to observe them. In addition, local conservation laws should be aligned with existing taboos to highlight just how much they could aid in successful fisheries management.

Work Cited

Shalli, Mwanahija Salehe, et all. 2017. The role of local taboos in management of marine fisheries resources in Tanzania. Marine Policy 85: 71-78.

A Bird’s Eye View of Illegal Fisheries

By Mitchell Rider, SRC Intern and MS student

Seabirds have been attracted to vessels for centuries, but more recently, they have been observed to aggregate in large quantities near fishing vessels to feed on fish scraps or bait (Croxall et al. 2012; Phillips et al. 2016). Their interactions with fishing vessels have been observed and quantified using Global Positioning System (GPS) combined with vessel monitoring-system (VMS) data, however, this type of analysis can only be carried out with declared vessels whose position can be tracked within exclusive economic zones (EEZs). Therefore, there is little information available on the interaction of seabirds and fishing vessels outside the EEZs. In their study “Use of radar detectors to track attendance of albatrosses at fishing vessels”, Weimerskirch et al. (2017) set out to estimate the efficiency of fitting newly developed GPS loggers to wandering albatrosses (Diomedea exulans) (Fig. 1), foraging from the Crozet Islands, to detect fishing vessels at sea in addition to observing the extent to which the fishing vessel operations were overlapping with D. exulans foraging range.

Figure 1

Photo of Diomedea exulans [ /Diomedea_exulans#/media/File:Diomedea_ exulans_in_flight_-_SE_Tasmania.jpg]

Birds from Possession Island, Crozet Islands, were hand caught and an XGPS radar logger was taped to their back feathers. These radar loggers could detect interactions between the birds and fishing vessels by measuring radio emissions at a certain frequency that is used in marine radars. From this interaction data, the authors could determine three different types of behaviors of birds associated with the radar detections: fly pasts, follows, and vessel attendance (Fig. 2). Fly pasts occurred if there were a few successive radar detections but no significant change in the route of the bird, however, successive radar detections associated with a linear direction was noted as a follow. Vessel attendance was noted as successive radar detections in a restricted area where the bird alternated between flying and sitting on the water. This data was combined with VMS data of French long-line fishing vessels to note the distance between the GPS tagged birds and the fishing vessels.

Figure 2

Movement pattern of wandering albatrosses (yellow and orange lines) equipped with biologging devices that detect radar emissions and record the position of boats (green dots): (a) attending behavior, (b) fly-past behavior, and (c) follow behavior where the red line is the track of the vessel (Wiemerskirch et al. 2017).

A total of 43 foraging trips were recorded from with the XGPS radar loggers and Wimerskirch et al. (2017) discovered that 79.5% of the loggers recorded interactions with vessel radars. Among the three types of interactions with ships, D. exulans was noted to spend the highest percentage of radar detections in attendance of the ships (64.7%), followed by fly pasts (23.9%), and follows (8.8%). In general, the birds spent a large amount of time behind the vessels, which suggested more of an attraction to the vessel, instead of a spatial overlap. Even though there is this significant interaction between D. exulans as fishing vessels, the answer as to why these birds are attracted to fishing vessels is not clear. However, these findings suggest that this method of radar detection on seabirds could become an effective way to manage marine ecosystems. More specifically, radar detection on seabirds could be used to detect the location of illegal fishing vessels outside of EEZs.

Works Cited

Croxall, J. P., Butchart, S. H., Lascelles, B., Stattersfield, A. J., Sullivan, B., Symes, A., & Taylor P. (2012). Seabird conservation status, threats and priority actions: a global assessment. Bird Conservation International 22:1–34.

Phillips, R., Gales, R., Baker, G., Double, M., Favero, M., Quintana, F., Tasker, M., Weimerskirch, H., Uhart, M., & Wolfaardt, A. (2016). The conservation status and priorities for albatrosses and large petrels. Biological Conservation 201:169–183.

Weimerskirch, H., Filippi, D. P., Collet, J., Waugh, S. M., & Patrick, S. C. (2017). Use of radar detectors to track attendance of albatrosses at fishing vessels. Conservation Biology.

Bait worms: a valuable and important fishery with implications for fisheries and conservation management

By Brenna Bales, SRC intern

Historically, bait fisheries around the world have been perceived as low-value, and their often limited, local extent makes large-scale management and conservation policy difficult to implement. Watson et. al 2016 explored three ragworm fisheries in the United Kingdom to investigate these claims, based on both evidence gathered scientifically and from an analysis of published literature. The data on polychaete bait fisheries is extremely limited, causing inaccurate estimates of catch amounts and collection efforts. In order to accurately assess the three bait fisheries of focus and other fisheries worldwide, Watson and other researchers assessed the following: retail value of bait species collected, extent of collection efforts both geographically and quantitatively, bait storage methods, and the choice and amount of bait used by angler fisherman on an average fishing trip.

The five most expensive (£/kg) species of marine animals sold on the global fish market are polychaetes (Glycera dibranciata, Diopatra aciculata, Nereis (Alitta) virens, Arenicola defodiens, and Marphysa sanguinea). The values of these bait species were quantified using retail prices of the species online and from data gathered from other literature sources. It was concluded that N. virens landings alone in the UK annually are worth approximately £52 million. Globally, this number is around £5.8 billion, with 121,000 tonnes of N. virens being landed worldwide. This demonstrates the high value of polychaete bait, contrary to popular opinion.

Nereis (Alitta) virens, commonly known as a sand worm, are a popular polychaete worm collected for bait purposes in UK tidal fisheries. (source:

Nereis (Alitta) virens, commonly known as a sand worm, are a popular polychaete worm collected for bait purposes in UK tidal fisheries. (source:

The three UK sites surveyed were Fareham Creek, Portsmouth Harbour; Dell Quay, Chichester Harbour; and Pagham Harbour. They were monitored over a period from August to September 2011, using remote closed circuit television recordings. The time for each digger on-site was recorded, and based on the number of times they placed a worm in their collection bucket, the biomass (mass of live worms) collected was estimated. The mean removal rate per bait collector per hour was 228 ± 64 worms. This large amount of collection can lead to things like environmental disturbance (trampling), over-exploitation of collection species, and the depletion of food resources for bird species that consume these worms.

This Japanese coastal bird feeds off a small ragworm, species that are globally collected as bait. When too many worms are removed by collectors, it can have serious consequences for the animals that rely on them for food. (source:

This Japanese coastal bird feeds off a small ragworm, species that are globally collected as bait. When too many worms are removed by collectors, it can have serious consequences for the animals that rely on them for food. (source:

An investigation as to how long certain species could be kept fresh before being used as bait on fishing trips was also conducted. The amount of time that N. virens could be maintained as viable bait was at the least 2 weeks. Given the average amount of N. virens used on angling trips per week was 0.33 kilograms, that amount of bait could be collected in only 28 minutes during a tidal cycle, based on the mean removal rate per bait collector per hour.

In conclusion, Watson et. al. proved that there needs to be a re-examination of the importance of polychaete bait fisheries worldwide, in order for better conservation initiatives to be launched. Seeing as the majority of these bait fisheries are located in MPAs (marine protected areas), better regulations must be enforced. There are several proposals in the study, such as personal catch limits, surveillance conservation, and stakeholder involvement. Overall, these fisheries are worth a lot more than is currently thought, and the implications of continuing poor management could have serious consequences.

Works Cited

Watson, Gordon J., et al. “Bait worms: a valuable and important fishery with implications for fisheries and conservation management.” Fish and Fisheries (2016).

Why do Fishers Fish?

By Emily Rose Nelson, SRC Graduate Student

Humans have been fishing for over 40,000 years. Initially, the world’s waters were thought of as a resource with no bounds. However, intensification of fishing pressure over the last 100 years has decimated fish populations, forcing us to realize that the oceans’ resources indeed do have limits. Today, fish make up more than 16 percent of the global human protein intake, whether it is in the form of subsistence fishing in developing countries or extravagant restaurants in wealthy countries. As demand for marine resources continues to grow, pressure on fish populations is also increasing. Governments around the world have started making efforts to slow the decline of ocean resources, but in many cases the success of these initiatives is dependent on compliance of the fishermen. Essentially, conservation efforts are in direct conflict with fisher objectives. For this reason, it is important to understand why a fisher is fishing in the first place – knowledge of fishers’ motivations will help policy makers identify the most effective conservation methods.

Young et al. 2016 set out to answer the question, “Why do fishers fish?” using an ethnographic approach. They conducted semi-structured interviews of experienced male fishermen at two sites, Australia and the Solomon Islands. The interviews gathered information about their general background, fishing methods, motivations for fishing, and feelings upon return from a fishing trip.

The interviews identified an overwhelming split in motivation to fish between the two study sites. 100 percent of fishers in the Solomon Islands were motivated by food and 93 percent were motivated by income. In contrast, 96 percent of the fishers in Australia were motivated by a connection to the environment. Recognizing these differences in incentives can help managers to form the best conservation policy for each region. For example, one could not realistically set in place a no-take marine reserve throughout the Solomon Islands without providing the fishermen and their families with an alternate source of food and income.

Motivations for fishing in Australia (gray bars) and the Solomon Islands (black lines).

Motivations for fishing in Australia (gray bars) and the Solomon Islands (black lines).

Despite the drastic difference in ‘primary reason to fish’ between the Solomon Islands and Australia, interviews revealed that many other drivers were the same. When fishers in the Solomon’s were given a hypothetical situation in which they had secured an alternate income, 100 percent of interviewees indicated that they would still continue to fish whenever possible. This shows that the fishers are getting enjoyment out of their work and indicates the presence of a somewhat recreational mindset. Therefore, if economic conditions were to improve in the area there would likely be a growth in recreational fishing. In Australia, where recreation is the primary reason for fishing, 80 percent of fishers identified food as a secondary incentive. For those people, fishing provides an escape from their stressful day to day lives, with the added bonus of catching a fresh meal for a price much cheaper than what is available at local fish markets.

Young et al. were not only able to identify clear-cut cultural differences in fishing motivations, but also recognize that fishing may provide benefits to individuals and communities that transcend these traditional motivations. In both the Solomon Islands and Australia, mentions of social bonds with fellow fishers and camaraderie were widespread in interviews. Lastly, the interviews revealed that fishing might not be as far off from conservation as some may think. The values identified of many fishers in this study, such as “teach children to appreciate nature” and “foster respect for the environment” are very similar to those of conservationists. As said by an Australian fisher, “fishing provides environmental benefits because we like to protect things that are dear to us.”


Young, A.L., Foale, S., & Bellwood, D.R. (2016) Why do fishers fish? A cross-cultural examination of the motivations for fishing. Marine Policy, 66: 114-123.

Why have global shark and ray landings declined: improved management or overfishing?

Paper by Lindsay N K Davidson, Meg A Krawchuk, Nicholas K Dulvy


By Pat Goebel, SRC Intern

A drop in shark and ray landings may be thought of as a success for in improved management strategies. However, in the case of Davidson et al (2015), that is too good to be true. Unfortunately, the decline in global shark and ray landings has been attributed to overfishing and other ecosystem influencers.

Sharks and rays are commercially valuable for their fins, meat, liver, oil and skin with their fins and meat. The demand for shark products is relatively new concept, as their commercial value has increased with the decline of other valuable fisheries. As on could assume with supply and demand, the high demand of shark products leads to an increase in fishing pressure. The increase in fishing pressure combined with the lack of laws regulating the shark and ray fishery, lead to the depletion of shark and ray populations. The rapid decline in shark and ray populations resulted in new management strategies. Davidson et al (2015), investigated these new management strategies to determine if declines in shark and ray catches were a result of the fisheries management performance or overfishing.

Figure 1 - Shark_fins_Taiwan

Shark and ray landings peaked in 2003 and have declined by about 20% in the past decade. Davidson et al. (2015), noted that the decrease is more likely related to overfishing than management implementations. The official harvest number used in this study is possibly two to three times below the actual number of sharks and rays being caught. This study highlights the fact that sharks and rays are being harvested at an unsustainable rate. Moreover, Davidson et al (2015), stressed several countries that warrant prioritization for conservation and management action. The greatest declines were reported in Pakistan and Sri Lanka, both of which have little to no management or enforcement. If new management strategies are not implemented into these countries, elasmobranch populations will continue to be harvest at a detrimental scale.

Figure 2. Global distribution of (a) country-specific shark and ray landings averaged between 2003 and 2011 and mapped as a percent of the total. (b) the difference between the averages of landings reported in 2001-2003 and 2009-2011

Figure 2. Global distribution of (a) country-specific shark and ray landings averaged between 2003 and 2011 and mapped as a percent of the total. (b) the difference between the averages of landings reported in 2001-2003 and 2009-2011