Partnership between researchers and whale-watch operators makes for big whale behaviour insights

Partnership between researchers and whale-watch operators makes for big whale behaviour insights

by Riley Tjosvold

The tourism industry of Pleasant Bay, N.S. depends on guided whale-watching expeditions. However, over the past two decades, tour companies reported that the area’s flagship species, the long-finned pilot whale, has been appearing less frequently and moving farther from shore.

Researchers from the Institute for the Oceans and Fisheries (IOF) and Dalhousie University partnered with whale-watching companies in Pleasant Bay to collect data on the whereabouts and behaviours of this social, matrilineal whale species known for mass stranding events.

Their findings not only confirmed whale-watch operators’ suspicions, but also provided insights for keeping whales in the area.

It is also one of the first studies to show that whale-watch data can give researchers a focused picture of where whales spend their time. The reliability of this data was a question mark because whale-watching boats don’t survey entire marine areas – instead, they go where the whales are.

“The methods that we use in this study can be applied to other researchers who are searching for an inexpensive way to get out on the water and can’t pay for their own, solely research-dedicated boat,” said Sarah McComb-Turbitt, the study’s lead author and a graduate of the IOF’s master’s program

To create an accurate map of how the whales were using the waters of Pleasant Bay, the researchers used GPS to keep track of where whale sightings happened, and, crucially, where they did not see whales.

They noticed some key changes in the whales’ behaviour when they examined the data, which was collected between 2003-2016.

“It’s an interesting story because the whales have moved farther from shore, they have decreased their foraging activity, but they’re still foraging in their very traditional, historic areas at two cove locations,” McComb-Turbitt said. “Local fishermen and local whale-watch operators say that the abundance of pilot whales is changing, and the spatial data that we had been collecting complements this knowledge.”

“The community wants what’s best for the whales. They’re very responsible whale-watchers out there… they’re so proud of the whales.”

Based on their findings, the researchers recommended that whale-watchers keep some distance from the two foraging areas to avoid disturbing the whales while they eat. Studies on other whale species have shown that whales are particularly sensitive to noise and disruption when they forage.

“We didn’t want the message of this paper to be about recommending a marine protected area,” McComb-Turbitt said. “Because pilot whales are abundant, we believe the population is doing well. The reason we were looking into this was to address the concerns of the whale-watching operators about the continued viability of the local pilot whale population and the whale-watch industry.”

Partnerships between researchers and whale-watch operators have a long history. McComb-Turbitt said working with the operators gave her the chance to get close to the animals and to attend a few “pilot whale parties” – events in which hundreds of the whales gather to socialize and give lucky spectators an acrobatics show as they leap out of the water.

“The community just wants what’s best for the whales. They’re very responsible whale-watchers out there… they’re so proud of the whales,” McComb-Turbitt said.

Studies in which scientists work alongside community members who have a stake in policy decisions make for more actionable research, according to Dr. Marie Auger‐Méthé, an assistant professor at the IOF and co-author of the study.

“I think a key takeaway is the power of using data from the whale watch operators, that is collected with them, to help management,” Auger‐Méthé said. “In the end, when a government makes rules, you want people to buy in. If you involve them in all steps of the process, it’s more likely they’re going to be happy with it and have their voice heard and understand the process. I think that’s the key.”

The study “Small‐scale spatial distributions of long‐finned pilot whales change over time, but foraging hot spots are consistent: Significance for marine wildlife tourism management” was published in Marine Mammal Science.

All pilot whale photos: © Sarah McComb-Turbitt

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Pilot whale – © Sarah McComb-Turbitt

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In Memoriam – Josef (Joe) Bauer

We mourn the loss of Josef (Joe) Bauer, who passed away on May 11, 2021.

Joe was a much loved fisherman, teacher, student, researcher, environmentalist, and social justice advocate, as well as a long-time Adjunct Professor with the Institute for the Oceans and Fisheries, and its previous incarnations.

Joe Bauer with his Queen Elizabeth II’s Diamond Jubilee Medal (2012)

Joe was a British Columbian fisherman for more than six decades, and he was fiercely proud of that moniker. He started fishing at age seven and worked his way up and down the Fraser River and out to the ocean chasing salmon, eventually piloting his own 350 ton vessel on the Salish Sea and northern BC waters. He could tell stories about fishing salmon both in rivers and the ocean, as well as being an active fisher of shrimp along the B.C. coast.

The ecosystem was his classroom, and he joyously shared his knowledge. He researched innovations in fisheries around the world and brought his findings to fishermen and fisheries managers, working to make fisheries more easily understood and sustainable. He also brought this passion to his work with graduate students at the University of British Columbia to help them better understand fishers, fisheries management, our fisheries, and our coupled socio-ecological systems.

As a child, his German background led to some difficulties, particularly during the time of the World War II, however Bauer was quick to befriend and accept others, including Japanese Canadians who had been sent to internment camps. He also established strong friendships with the local Indigenous communities, which led to his being accepted by Coast Salish First Nations, and being adopted by the Nisga’a Nation. He has been mindful and respectful of Indigenous knowledge throughout his interactions with the natural world. This, in addition to his self-education through reading and his hands-on working experience, have made him a naturalist, passionate about marine biology and ichthyology

Fish truly were his passion. Friends tell stories about the huge aquarium set up that Joe had in his basement at his house in Steveston; at the time one of the largest private collections in the province. As the years went on most of the collection moved from his basement to the Vancouver Aquarium; in deed, Joe spent many years collecting specimens for the Vancouver Aquarium. Also, while most of his career was spent on the water he also worked for the Department of Fisheries.

In 1976, Joe was a member of the preservation group that helped rejuvenate the Gulf of Georgia Cannery in Steveston. On December 11, 1986, the Gulf of Georgia Cannery Society was incorporated and this abandoned fish cannery is now a thriving tourist attraction, working to preserve and promote the history of Canada’s West Coast fishing industry.

A long-time member of the auxiliary Coast Guard, Joe worked with the agency to increase fishermen’s safety at sea that foreshadowed the development of FishSafe protocols. He worked to memorialize those who did perish in our waters and designed the Steveston Fisherman’s Memorial, a giant fishing net needle inscribed with the names drowned fishermen raised in 1996. A member of the BC Council of Professional Fish Harvesters and United Fishermen & Allied Workers Union, he had also been a generous legacy supporter for aquatic life.

Joe Bauer with students from BIOL 420 course on ocean conservation and sustainability

UBC’s Fisheries Centre (now the Institute for the Oceans and Fisheries) recognized Bauer’s expertise, and made him an Adjunct professor, often calling on him to provide his hard-earned knowledge with graduate students from around the world. Until recently, Joe was a regular visitor and was always surrounded by a bevy of students hanging off his every word as he relayed his real world fisheries experience. In recent years Joe was also active in habitat protection and pollution prevention campaigns with the T. Buck Suzuki Environmental Foundation, treasuring food production on land and sea.

Joe was deeply loved by British Columbia’s fishing community, and his impact on our knowledge, community and ecosystems will be felt for years to come.

Joe’s funeral service will take place on May 18, 2021 at 3:00 pm and can be livestreamed at http://www.livememorialservices.com/Home/ServiceDetail/13250

Some memories of Joe sent in by IOF community members

Tony Pitcher, professor: A couple of things about Joe. First he had a contract from FAO to go to Belize to show them how Canadian fishing gear is used sustainably. He often talked of his central America experience and was very proud of it. Second, Joe once saved a seal from being shot by other fishermen. It lived in his bathtub for some time with him and often travelled in his truck much to the intrigue of bystanders. He called it Josephine. Eventually he donated the seal to Vancouver Aquarium where it lived for some years.

Rashid Sumaila, professor: Joe was such a big fan of the Fisheries Ccentre, and later, the IOF. He was so proud to be the first and only local Steveston fisher to be named an Adjunct Professor at UBC! Joe would probably win an award for the one who attended the most Fish 500 seminars if there was one.

Joe Bauer teaching Dr. Mimi Lam, then a graduate student, how make a net.

Mimi Lam, affiliate assistant professor: This is sad news, indeed. Joe was such an ardent believer of the importance of respecting other ways of knowing and educating the next generation in his efforts to help sustain fisheries. I was privileged to get to know Joe on our many trips with the students to the Gulf of Georgia Cannery.

William Cheung, professor: Joe was indeed one of our most consistent FISH500 Seminar attendees. Even back in the days when I was a grad student and was the coffee-making/donut-cutting person, he would be there early, waiting for the seminar, while I was preparing the refreshment. The chat with Joe, often mixed with his recount of fishing stories and knowledge, was always very enjoyable. Missing him.

Amanda Vincent, professor: I, too, was terribly sad to hear this news. Joe was so immensely knowledgeable and generous in sharing his experiences and understanding. I learned a lot, very enjoyably, from Joe. And was really impressed by his vast array of leadership contributions. Joe was hugely kind and wonderful in engaging with my BIOL 420 course on ocean conservation and sustainability. Joe also provided great support when students, UBC Food Services and I were working with SEEDS to more UBC towards only using sustainable seafood on campus. I well remember him talking - very compelling, it was too - to our gathering of Food Service providers from university and colleges from BC to California. He drew them wonderfully into sustainable seafood.

Andrés Cisneros-Montemayor, research associate: This is really sad news. I really grew close with Joe during my tour setting up the FISH500 seminar and snacks. We traded fishing stories (his were always more interesting) and just really chatted about whatever. When my parents (also in fisheries) came to visit from Mexico we would meet Joe in Steveston and talk fisheries all day. I remember one year Rhona Govender and I surprised Joe with a birthday lunch at a Steveston sushi restaurant and were both blown away with how he seemingly knew every person in that town, and was usually able to trade at least a few words back and forth in their first language. He was incredibly insightful about the changes to his community over the years and always embracing new people, new cultures and experiences. I'm really, really sad to hear this and will miss him sorely.

Maria (Deng) Palomares, research associate: A person of integrity and honor … and this is how I know Joe … nothing less …

Sarah Foster, research associate: Just wanting to echo everything being said here. I had many great conversations with Joe on a wide range of topics over the years - but the most memorable was when we met to discuss my upcoming PhD field season for which I was to spend six months at sea on an industrial shrimp trawler in the Mexican Gulf of Californiza. We were to talk logistics, but I was really nervous about it all (ok, terrified) and he saw right through me. Our meeting lasted much longer than planned as he listened to and discussed my concerns. I might not have gone if it weren’t for that conversation!! He definitely left the world a better place. Forever grateful to have known him.

Villy Christensen, professor: I come from fishing families and found it so easy to connect with Joe; always something to discuss, often about life as a fisher and fishing families. All of these emails highlight his unique ability to make one feel appreciated. I have the impression that we talked almost every Friday when he was out for our seminars, and somehow I only fully realize now, how many he made feel special and appreciated. And we are but a few of those he touched. I will miss him too.

Juan Jose Alava, research associate: Very sad news, indeed. I just knew Joe for a little while when he was always early and waiting for the opening of the seminar series each Friday morning, usually sitting outside or inside of the seminar room or coffee room. He was a charismatic and humble person with a gentle soul full of wisdom and experience, sparking through his eyes and presence. A special memoir about him was a day when he wrote me a kind message in 2016 by e-mail and warmly asking for a ppt copy of a seminar presentation to know more about marine pollution and climate change interactions. He was really eager to pursue more knowledge and understand the nature of things affecting fisheries and our oceans. Missing him, we will…

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China and the E.U. aren’t the only ones to blame for harmful fisheries subsidies

By Riley Tjosvold

Researchers, policy makers and environmentalists have scrutinized the amount of money that the world’s top fisheries-subsidizing entities spend on harmful subsidies.

Taken together, these eight entities (China, the European Union, the United States, South Korea, Japan, Russia, Thailand, and Indonesia) provide 65 per cent of the global total harmful subsidies on things like fuel and fishing vessel upgrades.

However, a new study from the Institute for the Oceans and Fisheries (IOF) and the School of Public Policy and Global Affairs (SPPGA) asked if the focus on top-subsidizers has been at the expense of evaluating the “real” damage these subsidies do to the sustainability of fisheries.

“The provision of harmful subsidies is ubiquitous — everybody is doing it, obviously some countries are doing it a lot more,” said the study’s lead author and postdoctoral research fellow Daniel Skerritt. “We wanted to ask: ‘Is it right we’re just focusing on these top countries?’ and ‘Are there different ways to look at fisheries subsidies?’”

To that end, the researchers created a series of indicators to measure not only the total amount of money each entity spent on harmful subsidies but also the amount spent relative to how many fish they caught, both in their own waters and waters outside their exclusive economic zones (EEZ).

The study, published in Marine Policy, yielded some surprising results.

“Don’t think that just because you’re not providing six billion dollars that you’re not impacting, or potentially impacting the sustainability of the fish stock.”

When considering the amount of money spent on harmful subsidies compared to the total value of all of the fish caught, China, for example, dropped from No. 1 on the list of most harmful subsidizers to No. 20. When accounting for fish caught only within China’s EEZ, the country dropped to No. 34 – although, this drop is at the expense of the waters in which China’s distant water fishing fleet operates.

The study’s authors said small countries that provide harmful subsidies often don’t feel obligated to pursue more sustainable investments. This is because they see themselves as contributing a negligible amount to the problem of overfishing.

“Don’t think that just because you’re not providing six billion dollars that you’re not impacting, or potentially impacting the sustainability of the fish stock,” Skerritt said. “Any amount of harmful subsidies provided could be having detrimental impacts, so don’t provide them. Find another way to support fishers.”

Rashid Sumaila, University Killam Professor at the IOF and SPPGA, co-author of the study, said that he and his colleagues and students have been fighting to get rid of harmful subsidies since the World Trade Organization (WTO) began talks to end the contributions 20 years ago. In those two decades, WTO member countries still haven’t found consensus.

Sumaila said that he hopes the study will help broaden the debate about harmful subsidies and reveal the need for all coastal countries to remove or redirect their harmful subsidies.

“We hope this will open the eyes of all coastal countries, not just those who give a lot of subsidies,” Sumaila said. “In this business there are always little pieces. You never know what will break the proverbial camel’s back. We’ve been piling information; we’ve been looking at this from different angles – so who knows. This might just add a little bit more, which might get a few more countries to see why removing harmful subsidies is important for them.”

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PROFILE: A universe of undiscovered viruses: Inside the Marine Virology and Microbiology Lab

By Riley Tjosvold

While some oceans researchers spend their time studying charismatic marine mammals like seals, launching tracking devices at whales, or monitoring the migration patterns of vital human food species like salmon, Curtis Suttle, the professor and principal investigator of the Marine Virology and Microbiology Lab (or Suttle Lab), along with his long-time partner, Amy Chan, a research scientist in the Department of Earth, Ocean and Atmospheric Sciences, have, for the past 30 years, focused on aquatic life that can only be seen with an electron microscope: marine viruses and bacteria.

Viruses and bacteria in a drop of seawater from the Arctic Ocean stained with a fluorescent dye (image credit: Jerome Payet)

It is not the larger and ostensibly more impressive species like seals, whales and salmon that comprise most of the ocean’s biomass (the weight of all living organisms in the ocean). The organisms that make up most of the weight — 95 per cent — are the ones we can’t see. Microbes, usually a single cell or even a virus, dominate life in the ocean — at least in terms of sheer scale.

The smallest microbes are viruses, particles that infect and replicate themselves in a host organism’s cells. According to Suttle, “Our knowledge of marine viruses is very remedial, mainly because no one has looked.”

At the Suttle Lab, researchers’ primary goals are to identify previously unknown viruses to understand how those viruses affect marine life. This is a Pacific-ocean-sized task, as the vast majority — millions upon millions — of these infectious agents are unknown to us.

Three different types of viruses that infect phytoplankton (image credit Amy M Chan)

Up until the 1990s, many researchers didn’t believe that viruses even existed in ocean environments. Now that we know where they’re hiding, Suttle and his colleagues are finding them everywhere – inside fish, zooplankton, plankton, and sometimes even falling from the sky.

“When we recently did work looking for viruses in salmon, we found several new viruses that no one knew infected salmon, some of which no one knew infected fish,” Suttle said.

Amy Chan has been working alongside Suttle since before they were at Stony Brook University, New York, where they witnessed the discovery of abundant viruses in the sea.

That initial partnership led Chan to dedicate her professional life to uncovering viruses and bacteria that live in water.

“It’s exciting — when you find something that no one else has found before, when it’s the first ever,” Chan said. “Here at UBC, I isolated the first RNA virus that infects and kills a red tide, bloom-forming algae.”

Chan’s viral-discovery career has sent her on journeys thousands of feet deep into the earth down old mine shafts in Timmins, Ontario; into the burning hot [50-degree hot] “crystal caves” of Chihuahua, Mexico; and on countless research cruises throughout the Gulf of Mexico and the Pacific Ocean.
 

She’s also seen the field grow into what it is today.

“It’s a pretty new field still,” Chan said. “It started in the early 90s. The first decade it was a small, intimate group, but now we have huge meetings.”

Identifying all of these viruses may seem daunting, but for Tianyi Chang, a PhD student in the Suttle lab, the opposite is true.

Giant virus inside a microzooplankton (image credit Matthias Fischer)

“Before we only found one or two new viruses from an organism and we were really happy and we’d write a paper about that,” Chang said. “But when you have so much unknown biodiversity, it’s really exciting.”

Chang went on a month-long expedition aboard a research ship travelling from Hawaii to Chile to collect samples of zooplankton for virus identification. He and his colleagues found dozens of viruses infecting copepods, a group of near-microscopic crustaceans. What’s more, the viruses they identified were mostly RNA viruses, viruses that use RNA and not DNA to encode their genetic information, and that tend to mutate faster than DNA viruses. It was the first study that Chang knows of to find RNA viruses in copepods.

Chang also recently found over 30 RNA viruses inside sea lice, parasitic copepods that latch onto salmon and can kill them when they suck up blood and mucous and leave lesions on salmon flesh. He thinks the viruses may be used to control sea lice populations and save salmon.

“We’re not able to identify the one magic answer”

Microzooplankton infected by viruses (image credit Matthias Fischer)

Even more difficult than isolating and identifying viruses is uncovering whether they cause fish to get sick or die.

“In the wild you don’t find many sick fish because sick fish don’t survive very long. If you’re a bit slower, a seal or an orca is going to come eat you,” Suttle said.

Although researchers can see viruses replicating inside fish, fish deaths could be a consequence of any number of things, including ocean pollution and ocean warming.

Pinpointing the exact cause of mortality in sea organisms is a challenge that Jan Finke, a post-doctoral researcher with the Suttle Lab and Hakai Institute, understands well. For the past three years, he has tried to uncover what’s been killing oysters in B.C.’s oyster farms.

“Pathogens are natural but in oyster farms, where you have a really high density of oysters, that disease and mortality turn out to be bigger problems. Entire stocks will just die off within short timespans, sometimes days and then everything’s just gone,” Finke said.

Finke hoped that he would be able to identify one or a few viruses and bacteria that were clearly responsible for wiping out racks of oysters. However, the problem turned out to be much more multi-faceted than Finke expected, and he’s still reckoning with the mystery.

“We got ideas but we’re not able to identify the one magic answer to everything yet,” he said.

Unlike oyster farms in Australia and France, where researchers found specific pathogens that were linked to large oyster mortality events, B.C.’s oyster problem seems to involve a “cascade” of many different viruses and bacteria, as well as environmental stressors such as ocean acidification and warmer ocean temperatures.

“Even in human diseases it’s more and more of this concept of, well, you’ve got a primary pathogen and then you’ve got a secondary infection on top of that, and that second infection is what really complicates things,” Finke said.

Amy Chan next to submarine exploring alkaline lake for NASA project

“We need them to survive”

Curtis Suttle thinks it’s important for people to know that viruses, despite their frightening reputation, have a role to play in Earth’s many ecosystems.

“We’ve lived with them for forever; our most ancient ancestors coevolved and coexisted with viruses,” he said.

When viruses kill organisms in the environment, they help recycle nutrients that sustain other life. Thus, they perform the essential task of resupplying nutrients to the various ecosystems they are a part of.

“The thing that I always try to get across with everything we do, is that viruses are part of the natural world,” Suttle said.” If there were no viruses, we would not be alive. We need them to survive.”

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Ecosystem modelling indicates that adding fertilizer to water reservoirs pays off

By Riley Tjosvold

Researchers and fisheries management have been adding nutrients to nutrient-deprived freshwater systems since the 1970s. These additions of nitrogen and phosphorous stimulate the growth of aquatic plant life, which sustains the tiny zooplankton that feed larger fish.

However, the usefulness of the practice under high water flow conditions has come under question, especially for reservoirs, controlled environments that can be drawn upon to power hydroelectric dams.

Researchers from the Institute for the Oceans and Fisheries (IOF) set out to discover whether nutrient additions truly help maintain fish populations in reservoirs with variable flows in a new study published in Fisheries Management and Ecology.

Because reservoirs are managed by people to produce energy, water flow changes within them are more dramatic than a typical lake and do not follow a natural cycle.

“There was concern that the nutrients were going in and then in a year when you needed more power, they’d just sweep right through the system and there would be no impact from them, so it was just throwing everything away,” said Patricia Woodruff, a zoology PhD student with the IOF and the study’s lead author.

Arrow Lake

Using the modelling software Ecopath with Ecosim, the researchers created a model of the Arrow Lakes Reservoir, an important basin in the Columbia River.

“Arrow reservoir was formed in the late 1960s, and then two other reservoirs were formed upstream of it,” Woodruff said. “What happens in that case is a lot of the natural stream flow and a lot of the natural nutrient flow get trapped upstream and don’t make it into the downstream reservoirs.”

In the 1990s, Arrow Lakes Reservoir had so few nutrients, fisheries were collapsing, prompting a new experiment to manually release nutrients.

The researchers’ model simulated various amounts of nutrient additions paired with combinations of high, medium and low water-flows, and projected the abundance rates of Kokanee salmon, bull trout and rainbow trout under these different water-flow scenarios. Each of these fish are the basis for important recreational fisheries in the reservoir.

Juvenile bull trout

“We found that it’s always helpful to have nutrients in there,” Woodruff said. “As soon as we didn’t have nutrients, the populations we were looking at — the bigger kokanee and the older bull trout and rainbow trout — the abundance declined.”

In the simulated Arrow Lakes Reservoir, fish fared better when nutrients were added to the water, regardless of whether the water flow was high or low.

Adding the correct amount of fertilizer to lake systems requires precision, according to Woodruff. Add too much of one nutrient, and the result is long chains of useless, inedible algae; add too much of another, and the result is a toxic blue-green algae bloom.

“You have to monitor it,” Woodruff said. “But it should work towards producing higher abundances and higher biomasses of the fish — as long as you’re careful.”

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Small-scale fisheries can back food security efforts in Arabian sea countries

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IOF researchers find simple solution to Kuwait’s blood snapper woes

By Riley Tjosvold

A straightforward fisheries management change could help repopulate Kuwait’s waters in the Persian Gulf with Malabar blood snapper, a fish stock whose numbers dropped by 95 per cent between 1995 and 2009.

Ralf Roletschek, CC BY 3.0 , via Wikimedia Commons

Using Kuwait’s fisheries sector as a case study, Institute for the Oceans and Fisheries (IOF) researchers created a computer model to test whether Malabar blood snapper populations in the region would be restored if fishers limited their catch to mature snappers.

Malabar blood snappers can live to about 46 years but do not reach sexual maturity until about five or six years, at which point they tend to be around an average length of 61. Currently Kuwait fisheries management prohibits catching fish under 40 centimeters and has no measures in place to prevent fishers from catching juvenile fish that are unable to reproduce.

“This reduces the reproductive capacity of the fish stock,” said Abdulrahman Ben Hasan, the study’s lead author and a PhD candidate at the IOF. “It will eventually collapse, which is what happened in Kuwait.”

The researchers offered two recommendations to Kuwait’s fisheries sector: impose a strict size limit of above 61 centimeters on all blood snapper catches, and modify fishing gear so that fish smaller than 60 centimeters don’t get caught in them.

“I think these measures are easily implemented,” Ben Hasan said. “Enforcement is a different matter — I think enforcement is difficult, and critical in situations where the discard mortality of undersized fish is high. But we still can go about that by changing the mesh size of the traps. We can also enforce higher minimum size limits by co-management, where fisheries management as well as the fisheries would work together. Fisheries management can communicate the substantial gains of catching snappers at older ages with the fishers.”

Malabar blood snapper biomass would increase by at least 300 per cent and catch by 130 per cent if the measures are enforced, according to the study.

“Fishers would lose a substantial fraction of the current gains on the short term by transitioning to a higher minimum size limit, but it is expected they would more than offset that in the coming years relative to continue fishing business-as-usual,” Ben Hasan said

Photo by SenuScape from Pexels

The size limits would not have a severe impact on the livelihoods of fishers, as fishers would not be limited to a set amount of catch or prevented from fishing in certain areas.

Ben Hasan said that he hopes that Kuwait’s fisheries management will consider the approach outlined in the study and combine it with strict enforcement.

“In cases where there are weak management institutions and high dependency on fisheries, where there is little data on fisheries, we can implement these easy changes to rebuild fish stocks and to also avert overexploitation of resources.”

“Alleviating Growth and Recruitment Overfishing through Simple Management Changes: Insights from an Overexploited Long-Lived Fish” was published in Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science.

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Podcasts from FISH 500 class 2020/21

Listen to podcasts prepared by students in the FISH 500 class for academic year 2020/21

Art and Science

by Ana Pozas and Karly McMullen


Different Ways of Knowing

by Samantha Ramirez and Natalie Benoit

Equity, Diversity, and Inclusion in Marine Sciences

by Adepa Anyang and Charity Justrabo

Not so Convenient, Flags of Convenience

by Taryn Scarff and Julia Adelsheim

The Ocean Decade Revolution

by Alicia Andersen and Spencer Chaisson

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Ecosystem modelling paints a devastating picture for top marine predators by 2099

Using computer simulations to peer into the uncertain future of Earth’s oceans, researchers from the Institute for the Oceans and Fisheries (IOF) produced a model that depicts how energy moves up the food web from primary producers – organisms like phytoplankton – to top ocean predators like sharks and tuna.

Their goal: to see how this energy transfer would change by the last decade of the century under contrasting levels of climate change mitigation.

The findings paint a bleak picture.

They found that in a scenario without effective carbon mitigation resulting in continuous increases in greenhouse gas emissions in the 21st century, the ocean would lose 18 per cent of animal biomass by 2099 relative to the present day, which also means less fish available for people to draw from oceans’ already-limited supply.

The study, published recently in Global Change Biology, took a unique approach that differed from other research examining the effects of climate change on marine life.

“In our model, instead of considering species, we considered the position of the species in the food web,” said Hubert du Pontavice, the study’s lead researcher, who completed the project as part of his PhD at the IOF. “This is very interesting because we have a very simple model and we can predict relatively easily the changes of biomass.”

Du Pontavice collaborated with colleagues studying biology and food webs to make a model of Earth’s oceans that consisted of 40,000 unique “cells” containing climate and biological information.

“It’s huge. It’s a huge quantity of data we had to handle, understand well, and use well,” he said.

Top ocean predators will lose most acutely if governments make no effort to curb greenhouse gas emissions.

“It’s the butterfly effect,” said Gabriel Reygondeau, a co-author of the study and research associate at the IOF who assisted in developing the statistical methods behind the model. “A butterfly in Australia can cause a tsunami in Japan. That’s exactly what we have studied here. The change of temperature alters the production of ocean vegetation. The change could be not that important, but even a minor alteration cascades to a significant perturbation in the food web dynamic and ends up with huge decrease of top predators.”

According to William Cheung, an IOF professor and Canada Research Chair in Ocean Sustainability and Global Change who co-supervised du Pontavice’s project, “we’re already at the maximum capacity in harvesting fish from the ocean… this means we will not be able to get more fish by fishing harder. Meanwhile, climate change is further reducing the ocean’s capacity to support biodiversity and provide fish for human communities.”

Like other modelling that has examined how climate change will impact oceans, the researchers’ simulation predicted that tropical waters will see the greatest reduction in the amount of marine life they contain as fish there die or move poleward. Once again, it is people in tropical countries who are set to lose the most to climate change.

“This research adds to the evidence of previous studies,” Cheung said. “We now have strong evidence that climate change will also impact the ocean ecosystems and we need to tackle these problems for the oceans. Our study underscores it is essential for immediate actions to reduce greenhouse gas emissions that can substantially reduce climate impacts in the ocean.”

By Riley Tjosvold

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Tilapias are not precocious, they are just resilient

Nile tilapia. Photo by Germano Roberto Schüür, Wikimedia Commons

Tilapias living in crowded aquaculture ponds or small freshwater reservoirs adapt so well to these stressful environments that they stop growing and reproduce at a smaller size than their stress-free counterparts.

A new study by researchers at the University of Kelaniya in Sri Lanka and the University of British Columbia in Canada, explains that while most fishes die when stressed, tilapias survive in rough environments by stunting and carrying on with their lives in dwarf form.

“Tilapia and other fish in the Cichlidae family do not spawn ‘earlier’ than other fishes, as it is commonly believed,” Upali S. Amarasinghe, lead author of the study and professor at the University of Kelaniya, said. “Rather, they are uncommonly tolerant of stressful environmental conditions which, however, elevate their oxygen demand.”

As it happens with other fishes, when tilapia’s metabolism accelerates, it needs more oxygen to sustain its body functions. But the interaction between an increased metabolism and a growing body leads to gills reaching a point where they cannot supply enough oxygen for a larger body, so the fish either dies or just stops growing.

Tilapia fish farm in California. Photo by USDA NRCS, Flickr.

“Gill surface area grows in two dimensions, that is, length and width, but they cannot keep up with bodies that grow in three dimensions – length, width and depth,” said Daniel Pauly, co-author of the study and principal investigator of the Sea Around Us initiative at UBC’s Institute for the Oceans and Fisheries. “As fish get bigger, their gills provide less oxygen per unit of body weight. Thus, to stay alive in stressful conditions, which increase their oxygen demand, fish have to remain smaller. This theme is further developed in what I called the Gill Oxygen Limitation Theory.”

In the case of tilapias, the stress they experience under suboptimal conditions adds to the stress they experience from the surface of their gills not keeping with the increasing oxygen demand of their growing bodies. In consequence, the hormonal cascade that leads to maturation and spawning is triggered at smaller sizes than under optimal conditions.

But the spawning doesn’t occur at a ‘younger age,’ as the fish’s growth process has already ended.

To reach this conclusion, the researchers analyzed the length at first maturity and maximum lengths reached in 41 populations of nine fish species such as tilapia and other cichlids found in lakes and aquaculture ponds across the world, from Brazil to Uganda, and from Egypt to Hong Kong.

When looking at the ratio between the maximum lengths these fishes can reach and their lengths when they reproduce for the first time, they found it was the same ratio previously identified in other freshwater and marine fishes.

“This ratio tells us that tilapias in stressful conditions don’t spawn ‘earlier,’ they just adjust their size downward, but their life cycle continues,” Amarasinghe said.

“These findings will matter to fish farmers, notably in Asia, whose ponds are often full of wildly reproducing, small tilapia for which there is no market,” Pauly said.

The study “The relationship between size at maturity and maximum size in cichlid populations corroborates the Gill Oxygen Limitation Theory” was published in the journal Asian Fisheries Science.

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