…for making our study a success!

In 2012-2013, with the help of many fishermen associations along eastern Canada, several key fishermen advisors, social scientists and biologists, we surveyed 195 active and retired fishermen regarding their interactions with and observations of grey seals. Upon completing our analyses, we determined:

1) There are four interactions (other than grey seal predation) that impact fishermen financially: stealing “fish off the line,” bait raiding, gear damage and seal worm infestation of catch.

2) Bait raiding, gear damage and seal worm infestation severely impact the southern Gulf and the Scotian Shelf.

3) These interactions were directly related to reported grey seal sightings in respective Lobster Fishing Areas.

4) When we plotted these interactions on a map of the Gulf of St. Lawrence, they were consistent with grey seal, groundfish, and fishing fleet behaviors.

5) Lobster Fishing Area 24 (northern PEI) is the hardest hit by all three interactions types (see map). LFA 24 also overlaps a known summer groundfish feeding area.

6) Unless seal worm infestation declines, the cost of labour for food processors will continue to climb. We predict these higher costs will necessarily be passed to fishermen to maintain financial viability.Image

This map shows how Lobster Fishing Areas are related to one another in regards to bait raiding, gear damage, parasite infestation and the presence of grey seals. Similar shades of blue match regions that are alike. LFA 24 did not group with any other region due to overwhelming reports of gear damage, bait raiding, seal worm infestation and grey seal sightings.

Next Steps:

1) We would like to assign dollar values to these interactions to evaluate the realized cost of grey seal interactions with fisheries.

2) We have a manuscript in draft to document these findings in the peer reviewed literature.

Thank you to all the fishermen who completed this survey, FA reps that helped us successfully recruit and distribute to fishermen and numerous individuals that helped create the final questionnaire through a collaborative consultation process. Your participation was crucial!

If you have any questions or suggestions, please feel free to contact the researcher.

Warmest Regards,

Rachel Neuenhoff

PhD Candidate



Canadian Fisheries Research Network 2014 AGM

Fresh from a presentation in Truro Nova Scotia, I stepped off the plane in Montreal with a momentous energy and my first assignment was no less the challenge. I had until the next morning at 8AM to develop a pitch for the student led initiative, “Predator Pit.” Based on the concept of “Dragon’s Den,” this game similarly pitted future fisheries scientists against each other through bids on contracts that addressed problems faced by commercial fisheries and fishery communities. The day proved to be an invaluable exercise in bridging natural and social scientists with ideas such as feasibility, budgets and targeted grant writing; skills completely overlooked in formal education settings. Feeding on the success of the “Predator Pit” exercise, many groups capitalized on presence of key industry, government and academics to weave their ideas into reality, myself and “Predator Pit” teammate included.

The AGM opened with a review of updates, key successes and avenues that deserved greater exploration. I really feel that this is a critical time for the network. Not only are partners delivering on their promises, they are also looking into the foreseeable future for longstanding relationships, products and potential projects. The AGM has become so much more than a required perfunctory gathering of conservation minded individuals. There is a richer, more tangible value in the relationships developed now, particularly with industry (from my personal perspective) and I can feel an engine turn over as a number of smaller projects simultaneously gain momentum. At times, the synergy can feel intoxicating.

This was the first year that our group, Project 3.2 participated with all members present. Ben Nelson is continuing his project on interactions between pinnipeds and key salmon stocks on the west coast of Canada. I gave results of the fishery survey questionnaire for grey seals and fisheries interactions on the east coast.  Sarah Fortune contributed her expertise of bioenergetics to provide a model that could account for uncertainty in activity factors for pinnipeds on the east and west coast. Together we presented a great story that is not yet complete but the plot is well seeded. For more about the meeting, navigate to:

ALSO! If you represent a fishermen association that is interested in receiving the results of the fishery questionnaire, please send me a message or comment!

Next up: Laura Ramsay of the PEI Fishermen Association has graciously invited me to participate in the upcoming Small Pelagics Advisory Meeting on the 6th.  My hope is that I will be able to circulate the results of the questionnaire analyses in an upcoming post! Stay tuned!

Fishermen and Scientists Research Society 21st Annual Conference

Okay, I’m ditching what I had originally written–a jargon-laced, self-contained capsule of my research prowess and general scientific spewings–in favor of a different kind of blog post…of the human interest variety. So, if you’re not prepared to commit twenty minutes of “connect the dots of Rachel’s humanity” I recommend that you forgo this post and go watch a Netflix original series. Otherwise, proceed at your own risk. 

I had the great privilege of speaking at the annual FSRS meeting in Truro, Nova Scotia this week. Truro, affectionately known as “hubtown” owing to the fact that all major highways in Nova Scotia intersect there, is just south of Halifax. Truro has been bitterly cold on both occasions I have had to visit it. In fact, if it weren’t for the few blocks that I jog each time I come here, Truro proper would remain a nebulous idea of a town that existed only between my hotel and the highway back to Halifax. Yet, Truro still gives me the warm fuzzies simply as the humble host to the annual FSRS meeting.

I enjoy this meeting a great deal more than other meetings for a number of reasons: First, most if not all the science presented here has immediate practical applications. There is concerted and established effort to use a common language between fishermen and scientists; A subject that is commonly brought up a meetings but rarely addressed so openly. This is also one of the few meetings where I have seen overviews of successful, ongoing fishery management plans: paid for, implemented and maintained solely by fishermen relying on the resource. “Taking ownership of a resource” is a phrase that sounds very nice in presentations, but these folks live it, with tremendous success I might add. Gone is the era of fishermen waiting around for government and academia to throw them the occasional nugget of management ingenuity. They are surpassing outdated regimes of “contract-based” science that fizzles and wanes on a political whim or ever-capricious agendas, where success is measured by voter turnout rather than voter well-being. There is a sense of safety and security at this meeting. Fishermen can be a vociferous bunch but tend to button their lips around scientists who many have grown to distrust over time due to, among other things, the tendency of managers to eat away at the ever precious and expensive quota in response to fishermen input on key issues such as bycatch or marine mammal interactions. This is a fact that I am reminded of again and again, but I oblige the annual ribbing because at the end of the day, I’m still impressed with a community that I do not come from and am only beginning to understand. The meeting is sort of a safe venue to express frustrations, concerns, propose new projects and really pick and probe the working parts of science; An opportunity that is often lost in the mire of lofty scientific and statistical jargon that really only journal editors or reviewers care about. In short, it is one of the few places where the intersections of policy, culture and biology are discussed in earnest.  

…I should also mention that the FSRS has never failed to put me up in a hotel room with a TV that is wider than my bed. Watch Blue Planet on that baby and you will realize that it was never meant to be viewed any other way. 


West Coast Node Meeting at UBC

Hello loyal followers! UBC recently hosted the Canadian Fisheries Research Network (CFRN) West Coast Node meeting where all of the west coast study component investigators updated CFRN project partners on project progress and any results. On the menu were several projects ranging from socioeconomic aspects of fisheries, management strategy evaluation and constructing policy parameters (fmsy, bmsy, etc.) for commercially important species. I was in the unique position of presenting my preliminary results for the survey distributed on the east coast of Canada. I’m part of project 3.2 which focuses on pinniped interactions with commercially important fisheries on both coasts. My counterpart is conducting a similar study on the west coast. There are several key differences that characterize how east and west coast fisheries are managed, and many folks were interested to know how these differences played out in reality. I was also able to present the survey as a CFRN supported and packaged product, that included a consultation process that I hope should be the basis for any study where fishermen and scientists collaborate. 

Here were the key outcomes:

Partners were please with the outcome of the collaborative consultation process.

We received 300 completed surveys. 

We achieved almost 100% coverage of the Gulf and the Scotian Shelf.

We would like to see more participation by fishers in the Gaspe.

We were able to evaluate significant differences that occurred between fishing zones with respect to fisher interactions with grey seals.

We showed that fisher concerns extend beyond simply grey seal consumption of catch species and are ready to evaluate how other interactions may fit within the same evaluation framework.

We need more input from food processors willing to speak with us about parasite infestation, and how to address infestation in practice within reasonable time frames.

Within a larger context, project partners identified key issues and discussions that did not or were not occurring at other meetings, either due to communications barriers, scope of experience or (un)common perspectives. 

That being said, our hope is that we are more aware of communication barriers so that we can work toward a more holistic perspective through discussion and cross student collaboration exchanges (e.g. student experiences on fishing boats, fishermen meetings). 

I will be presenting an in depth report of preliminary results from my fishermen survey at the CFRN AGM in Montreal as well as the Fishermen and Scientists Research Society Meeting in February in Truro, NS. Because these are two of many groups that were instrumental in making the survey a resounding success, I would like to present the results to these groups as soon as possible. It is also my hope that I can speak to fishers in PEI as they providing overwhelming support in terms of response and representation. 

You can find a review of the CFRN West Coast Node meeting either on the CFRN Facebook page or the CFRN wesbite:

I hope my readers will take a look around, and if you have any questions or comments on how we could improve our coverage, scope or project framework, please feel free to comment here or message me directly.

Best wishes and happy responsible fishing! 


My sincerest apologies for flying a bit below the radar lately. I have been diligently studying for my comprehensive exam and coding fishermen surveys. My goal is to complete the survey analysis by September and present preliminary results to the PEI Fisherman Association in late September. I have some interesting trends emerging from my very early analyses, and it has been tough to keep these exciting developments under wraps! Recently, I have had a few discussions with a seafood processor that is very concerned about future fishing and processing prospects. He has been keeping internal records that have proved invaluable for fleshing out my Bayesian belief network, a model that quantifies socioeconomic and ecological variables based on ever-changing states of nature and management decision processes. These data are giving us unprecedented insights into several challenges faced by east coast communities aside from falling total landed catch.

I am currently scheduled to complete my comprehensive examination on September 9. My committee includes renowned experts on grey seal foraging ecology, life history, physiology, as well as fisheries experts that are versed in both social and biological implications of management decision. It is, to say the least, a tough crowd, but I am confident that there is no better handful of folks to guide me in accurately representing biological and social spheres of a very serious crisis.  I am excited for the opportunity and it is my dearest hope that I can do this topic justice.

I will be joining the crew of the southern Gulf Bottom Trawl Survey in mid-September to gain first hand experience collecting fish data that are used in east coast stock assessments. This survey is crucial. Given the uncertainty in grey seal diet data, the bottom trawl survey offers an alternative approach: fish abundance estimates can be used to assess the compatibility of what is observed in grey seal stomachs versus what the survey indices are telling us about recruitment, population production, and stock status of countless species.

My last task is to find a fishing boat to work on in order to document obstacles that fishermen face, particularly marine mammal interactions. This has been the most challenging project to tackle. Although east coast fishermen are by and large, quite supportive of a student shadow, travel funds are always tight with the notable exception of CFRN funding for students. However, travel is prohibitively expensive for coast to coast flights. While I could easily approach west coast fishermen that would be willing to allow me to tag along during the season, east and west coast fishery structures are vastly dissimilar. The west coast operates mainly on ITQ’s (Individual Transferable Quota) where quota owners may not even be fishermen or involved with any part of landing catch or selling to dealers. The east coast system is primarily owner/operator so that a majority of owners are also captains of their boats. ITQ holders have an interest in maximizing a single individual’s return on investment, whereas owner/operators have broader interests that are focused on bringing profit to small fishing communities. In short, there are vastly different objectives that characterize each type of quota allocation system that have a direct impact on how fishery conflicts are managed.

Thank you for following, and I will be providing future updates as my plate clears in the very near future. I am open to any suggestions and especially east coast fishery connections that are willing to flesh out the financial logistics with me. I am particularly interested in participating in fisheries where grey seal interactions are commonplace.

What are functional feeding responses?

Welcome to my first installment of comprehensive examination hell. Don’t worry, it may actually be fun. Today, I’ll be giving a basic intro to the Holling “Disc” equations and how well they may or may not describe the relationship between grey seals and cod on the east coast. There are two ways to read this post: You can jump over the mathematical proofs and jump right to an easy explanation of how different modeling approaches impact your view of the grey seal cod issue. It is my belief that most explanations to date are inaccessible to the non-science crowd, and that doesn’t seem fair. If you want to skip to implications, you can start reading after the graphic near the bottom. If you prefer to relive all the grisly modeling details with me, then keep reading. Choose wisely.

It is important to remember that there are several fundamental assumptions built into these “models of reality” and we may or may not have reasons to justify these assumptions. Functional feeding responses don’t necessarily help to describe other issues, like the prevalence of seal worm in cod fillets, but they can imply circumstantial connections. Predator-Prey models simply address one part of the world–a building block that needs to be in context to understand its full implications. The non-math people can stop here if they wish.

In C.S. Hollings’ early work, he designed a very simple and intuitive experiment. He blindfolded a group of people then asked them to search for sandpaper “discs” that he placed at random on a smooth floor. He discovered that early on in the experiment, the poor blindfolded souls did a reasonable job of finding the discs. As time wore on, the subjects spent more time “searching” for discs simply because there were fewer available to be found. He developed a very simple equation to describe this phenomenon:

Tt = Ts + Th

where Tt was the total time spent “foraging” or engaging in seeking out discs, Ts was the time spent in active search, and Th was the time needed to physically pick up or “handle” the discs. From this simple equation, we can derive three different functions based on different lines of logic. These, Holling “Disc” equations describe different types of predator prey interactions that require different assumptions to analytically solve. Here’s the Type I:

Type I Assumptions: Handling time and search time are negligible. We know this to be rare in nature and is more commonly a situation that arises in laboratory experiments (more on this later). We can simply describe Type I as:

NE = mNo

where NE is the number of prey eaten by the predator and is proportional to prey density/abundance only up to some maximum (when predators can eat no more).

Type II Assumptions: predators eventually become “satiated,” but in this case, it is because the predator becomes limited by the time spent “handling” the prey. We can start with Hollings’ original time budget equation:

Tt= Th+ Ts

Now, we can express handling time as:


where h is the time lost to handling and NE is the number of prey eaten. Next we can express the number of prey eaten, NE as:


where a is some “rate of attack” and N_0 is the total density or abundance the prey. Substituting NE into the time budget equation:

Tt=ahTsN0+ Ts which is the same as:

Tt= Ts (1+ahN0) when expressed in terms of Ts, it becomes:


And finally, substituting this into the equation for NE:

NE=(ahTt N0)/((1+ahN0))

And Voila! We have a Hollings Type II equation.

Type III Assumptions: As in the Type II equation, predators become “satiated” but at low prey densities/abundances, the time spent searching (T_s) increases as prey become harder to find and encounter rates become lower. To graphically display this behavior, we simply square the denominator:

NE= (ahTt N0)/((〖1+ahN0)〗^2 )

Here is what we can expect to see graphically from the Type I, II, and III equations:


Photo Credit: Wikimedia Commons

Now back to cod and grey seals. We can exclude the Type I equation. We know from natural experiments that handling time and search time are extremely important considerations. That leaves us with two views of the cod and grey seal world.

The argument for a TYPE II response

The first view, a Type II has serious implications for a severely depleted cod stock. Referencing the graph above, a Type II response suggests that grey seals could potentially consume cod to near extinction. That means that cod as a population either, a) have no habitat refuges (hiding spots) to escape grey seal predation so as to reduce encounter rates (increase searching time), or b) cod do have refuges but their life history is such that they aggregate so that they are easily found or grey seals have learned to find them when they aggregate. There is support for b) because cod aggregate to spawn in the summer months, making them far more vulnerable than at other times of the year. Cod may be doubly vulnerable in areas where past trawling activity has destroyed bottom cover.

The argument for a TYPE III response

There is the general belief among many (scientists and non-scientists alike), that depletion of fish populations is unnatural and only happens in response to fishing pressure. In fact, this isn’t always the case. Some fish life histories are such that their populations may crash in response to factors such as El Niňo. These stocks have evolved to sustain these periodic crashes by having high rates of production when environmental conditions are favorable again. In these cases, fish populations may have evolved to sustain periodically high predation rates. Fish often rely on refuges to hide from predators. The predators, in turn, experience low encounter rates with prey. There tends to be an increase in search time and handling time as predators have less and less experience efficiently handling prey. If we reference the graph about, this results in the characteristic “inflection” at low prey densities, where consumption rates are nearly zero due to lower encounter rates.

When we see a curve such as this, it could suggest that predators need to engage in active “prey switching” in order to survive. This may be what we are seeing today in the Gulf of St. Lawrence. Grey seals are encountered with increasing frequency by fishermen engaging in fisheries other than depleted groundfish species. Herring and mackerel fishermen report grey seal “herding” behavior to feed on shoals. This is possibly a response related to learning a new “handling” strategy because the encounter rates with herring are now much higher than they are for cod and other groundfish.

The modeling to date suggests that a Type II response for cod and grey seals for the Eastern Scotian Shelf. However, the key weakness in these studies has been a lack of agreement between the grey seal diet information and a Type II feeding response. How does this happen?

Because we essentially use two different methods to assess the feeding response and grey seal diet. Due to the incompleteness of the diet data, functional feeding responses are built around results from stock assessment modeling which provides detailed information on natural mortality rates. Operating on a different set of assumptions (which I will not go into here), modelers can estimate cod mortality attributed to grey seals. This information can help us make inferences about grey seal consumption that can be quite robust IF we can rely on the inherent assumptions of those models. Conversely, the dearth of long-term and more importantly spatially representative diet data from grey seals do not allow us to “ground-truth” functional feeding response models. Consequently, the problem becomes circular, and we are reduced to relying on assumptions about diet. Whether right are wrong, these diet assumptions remain the most contentious and divisive issue among scientists.

Countdown to the Comprehensive

Countdown to the Comprehensive

So if you weren’t already aware, there is a horrible rite of passage inflicted upon all PhD students called the comprehensive exam. In a nutshell, about two years into your program, you stand up in front of a firing squad of academic monsters and answer questions from every corner of their merciless minds. This process is designed solely to make the poor victim sweat under pressure, lose their composure and then somehow out of the depths and recesses of long forgotten knowledge, come up with brilliant responses on the spot. My inquisition is coming up September 9. Do you feel sorry for me yet? Well, fear not because I’m tapping into this blog for help organizing my thoughts. You see, when I post something, I commit a lot of time to doing background research and tying information together to make it entertaining and relevant (whether or not I accomplish that is up to you to decide). I’ve decided to do just that with my comprehensive exam “reading list.” I have a list of topics that I need to review in depth, and I’m going to tie those topics to relevant fishery issues in such a way that it’s new and fresh for my fishery audience. Basically, I want to connect several ideas back to the Gulf of St. Lawrence, the condition of the fisheries there, and the socioeconomic concerns.

Here’s an idea of the things you can expect me to write about:
-Southern Gulf Atlantic cod
-Predator Prey relationships
-Foraging Arena Theory
-Biomass Dynamics Models
-Adaptive Management
-Decision Analysis
-Bayesian Statistics

Don’t worry! It’s my job to make each of these topics sound as “un-boring” as possible. I’ll use plain language but present concepts in a way that makes us all think critically. Let the learning begin!

Iceland gets cheeky: Fishery fail or finders keepers?

This week, I decided to step outside of east coast fisheries to look at an ongoing debate over fishing rights between Iceland and the European Union that has received global coverage.  Recently, Iceland withdrew from negotiations to join the EU after several charged exchanges over Iceland’s mackerel quota. In a blunt statement by Icelandic Minister for foreign affairs, Gunnar Bragi Sveinsson simply offered, “This is how democracy works” ( Sveinsson, whom is part of the newly elected administration in Iceland, is placing the blame for failed negotiations squarely on the EU, which he claims needs to prove its usefulness to Iceland–not the other way around.  However, is Iceland just standing up to a “bully” as the Minister implies or is the island nation taking more than their fair share of fish?

The previous Icelandic administration sought economic refuge in negotiations to join the EU in 2010 when Iceland’s banking sector (like much of the rest of the world) failed. During initial discussions, Iceland even agreed to cut their mackerel quota by 15 per cent. According to the government, this would leave the people of Iceland with a paltry 16% of the total catch IF and only if, other EU member states also reduced their quotas ( This was a substantial concern considering that after the failure of Iceland’s banking industry, fishing represented a substantial proportion of total GDP. In short, aligning with the EU dictates could mean another financial blow.  EU accession was starting to look far less appealing.

But why are mackerel a sticking point? Scientists for the EU argue that Iceland’s fishing practices are unsustainable. Iceland’s scientists, by contrast, say migration patterns have simply changed due to climate change, and Icelanders are seeing a larger share of mackerel venture into Iceland’s exclusive economic zone.  What is the truth? Have mackerel migration patterns changed? If so, this means that we have to accept the EU is sticking Iceland between a rock and a hard place for the sake of other member states that want to catch more fish. If mackerel migrations are not changing, then member states, such as Scotland, which has vehemently decried Iceland’s “unreasonably high” fishing quotas, have a vested interest in fishing harder to compete for less income per fisher.

This is not the first time the UK and Iceland have engaged in acrimonious debates over fishing rights. The so-called “Cod Wars” brought both countries into conflict when Iceland extended exclusive fishing rights from 4 miles to 200 miles in order to force out British fleets. During the last conflict (1975-76) Icelandic coast guards used “trawl cutters” to thwart British fishing boats caught fishing within Iceland’s EEZ. Iceland eventually succeeded in defending their exclusive fishing zone with a few shots fired and no casualties (for more information:  Despite freshly healed wounds, British and Icelandic fleets have managed to share the same stocks with minimal bickering, until now.

I have tried to wrap my head around this new confrontation…trying to determine if this is a battle based on reasonable scientific differences of opinion or political posturing. So like the good little scientist I try to be, I delved into the mackerel literature. Traditionally, mackerel have only been a substantial boon to Icelanders when their population reaches some threshold abundance. More or less, the “extras” find themselves in Icelandic waters by 1) density dependence (i.e. too many fish at the same party so they find another) or 2) stochastic (random) chance (i.e. a great number of confused mackerels get lost, or take a vacation) (Hannesson 2013). However, the most recent influx of mackerel into Icelandic waters may be the result of a recent warming period, climate change, and oceanic processes favoring a more westerly distribution of the original stock (Arnason 2012, Astthorsson et al. 2012, Hannesson 2013), rather than overfishing by Iceland as Scotland claims. Iceland’s government says mackerel stock size is being underestimated because fish surveys occur where mackerel are no longer present during that time of year. In other words, Iceland is the new locale of choice if you are a mackerel that once preferred EU waters.

There are several assumptions that we must accept to be in favor of the EU: 1) There is no change in mackerel migration patterns. 2) The increased presence of mackerel in Icelandic waters is the result of overfishing, not actual abundance of fish. 3) Current fish survey data are reliable. That means that surveys are in no way biased and when vessels change, the new vessel is properly calibrated. To accept Iceland’s explanation, we must assume: 1) changes in migration patterns, 2) climatic anomalies, 3) unreliable survey data (or the survey has become unreliable). The difficulty with relying on survey data is easy to understand. Data from research vessels are preferred because they are random, commercial vessels are nonrandom and target certain species of fish. However, due to the migratory nature of mackerel, scientists must use a research vessel during a quarter of the year, and use commercial fishing data for the remainder of the year when the research vessel is not in operation (Jansen et al. 2012). To understand why this can be problematic, simply research the decline in the Newfoundland cod fishery, where the population was consistently overestimated because managers used commercial fishing data to assess the stock (Schrank 2005)—a situation known as “hyperstability” (Walters & Maguire 1996). So if the use of commercial fishery data results in the overestimation of fish abundance, why bemoan the survey at all? Well, as it turns out, the opposite is quite true too. Catches can be quite low even though overall population abundance is high—a condition known as “hyperdepletion” (Walters & Martell 2004). There are several ways to test for hyperstability and hyperdepletion but it’s more involved than what is necessary here. Suffice it to say, the faceoff between Iceland and the EU is probably a good mix of political and scientific uncertainty, replete with the same arguments we hear regarding grey seals and cod along eastern Canada.

This is probably why I am most reluctant to form an opinion (on either Iceland or Canada). As a budding natural scientist, I’m still trying to develop ways to handle biological uncertainty, now you want me to consider socioeconomic and political variables too? What is fair? What is relevant? What are the consequences of my personal weighting system on hundreds of thousands of individuals? How does that stack up against millions of others? The key difference that I see between these two situations is philosophical: Canada seems to be going of the way of, “give us a reason NOT to join the EU,” while Iceland, with a fraction of the population of Canada and almost exclusively dependent on fishing is saying, “give us a reason TO join the EU.” Regardless of whether or not the weight of the scientific evidence supports their stance, I have to give it to Iceland, they wear their cajones on the outside.  That sort of conviction, whether or not it is shown to be misplaced, short-sighted, or ultimately vindicated, is admirable…according to my personal weighting scheme, of course.


Arnason R (2012) Global warming: New challenges for the common fisheries policy? Ocean Coastal Manage 70:4-9

Astthorsson OS, Valdimarsson H, Gudmundsdottir A, Oskarsson GJ (2012) Climate-related variations in the occurrence and distribution of mackerel (Scomber scombrus) in Icelandic waters. ICES Journal of Marine Science 69:1289-1297

Hannesson R (2013) Sharing the Northeast Atlantic mackerel. ICES Journal of Marine Science 70:259-269

Jansen T, Campbell A, Kelly C, Hatun H, Payne MR (2012) Migration and Fisheries of North East Atlantic Mackerel (Scomber scombrus) in Autumn and Winter. PLoS ONE 7

Schrank WE (2005) The Newfoundland fishery: ten years after the moratorium. Marine Policy 29:407-420

Walters C, Maguire J-J (1996) Lessons for stock assessment from the northern cod collapse. Review in Fish Biology and Fisheries 6:125-137

Walters CJ, Martell SJD (2004) Overview of single species assessment models. In: Fisheries Ecology and Management. Princeton University Press, Princeton