What is your take of the impact of fishing on animal welfare? When it comes to aquatic lives, why should we only focus on farmed aquatic life, not fishing? Why not prioritise work towards the ban of all fishing, esp. industrial fishing?
Some info: fishing alone is responsible for 90% of all lives killed per year for consumption, fishing is also destroying wild aquatic life habitats more than we destroy lands, and it also is affecting all wild lives that depend on them to survive: it is pretty much the largest ecocide in the world, and it is legalized. All this destruction for less than 2% of humanity’s calories intake. Also, its current techniques to kill these animals are extremely cruel, long lasting, and in accumulation, it likely represents more suffering than in fish farms.
I agree with Michael that a ban on all fishing, or even just industrial fishing, seems politically infeasible. I think it’s possible that an island nation heavily dependent on tourism might do this, but that would probably just increase the catch of unregulated fishing ships outside of their territorial waters. I don’t see any path to the world doing this.
The other complication is that a ban on wild-caught fishing might just increase the spread of aquaculture, which is worse for each fish involved. Most wild-caught and farmed fish demand is interchangeable—people are just looking to buy fish. If the wild-caught fish becomes unavailable, I’d expect most of that demand to switch to farmed fish, which would fuel an even bigger boom in aquaculture. Sadly I expect that would be even worse for the fish involved :(
We are though funding work to reduce the suffering caused by current fishing methods. I think work to make the experience of capture and slaughter less horrific is really important.
If replacement to aquiculture is a logic, you can state the same to fight against land animal production, as this will all concentrate consumption on aquatic animals as people do not even know which fish is caught or farmed. Certainly this will mean more lives killed/ in suffering, the same way? Shall we stop talking about transitioning away from land animals? Certainly not.
You mention the unlikeliness of promoting a ban on fishing. Although there will always be traditional communities depending on fishing to thrive, from these we should never impose a ban, it is certainly true by facts that: a. aquiculture is not replacing fishing, just increasing fish consumption, as you can see in popular stats from Our world in Data; b. for fishing, you need to consider deaths of fish and crustaceans which are significantly smaller than the fish farmed, a few examples are: krill x farmed shrimp, salmon x anchovies, etc. No wonder fished animals increase number of lives killed in the order of magnitude of 10x (but represents only 1⁄2 of the current tonnage yearly). Are we ok to ignore this huge elephant in the room?
The thinking that fishing is increasing fish populations is certain on short term, but not true long term. A high spike on prey fish means less of their prey, subsequently, therefore diminishing their populations over time. There are a few studies on the effect of removing a predator from their ecosystem resulting not on increase of fish populations or biodiversity, but in fact, the opposite happening: less biodiversity, lower populations, ecosystem collapse. This can be easily noticed in scenarios before and after implementing a Marine Protected Area—I can share a few studies if this helps, let me know.
This ask is also not impossible or far fetched: we had already moved great heaps when it coms to our culture of hunting land animals. In Brazil for example 100% of native land animals are protected towards hunting. However at see, all animals can be legally caught and die as ‘bycatch’. Why not move also towards aquatic wild lives? It is massively possible to end industrial fishing: we have gone great lenghts with the international ban to the hunting of marine mammals and the hunting of sea turtles. We are starting to do the same for sharks and rays. It is only a matter of time that our dissonance between hunting wildlife on land and at sea will be fixed and we can notice how this significantly affects their welfare overall (certainly the welfare which is not ambiguous at all, of shortening their lives and killing large quantities of animals in an extreme cruel way (btw all industrial fishing techniques are extremely negative towards welfare—so if you agree on lowering the impact on fishing welfare, surely a ban on industrial fishing must be on the cards).
Also, going beyond animal welfare and animal rights: when we talk about removing wildlife in this great quantity as I mentioned before, we are also talking about ecossystemic service of the ocean for the balance of the planet and all living beings on Earth. We are already seeing a global catastrophe happening on front of our very own eyes, and if we consider that the ocean provides at least 50% of the oxygen on Earth, and it is responsible for the historical of 85% in the atmosphere today, also considering the ocean absorbs 90% of the excess heat from CO2 emissions and is responsible for 25% of the cabon sink, it is our largest ally on the fight against climate change. However it needs a balanced ecosystem for it to keep performing its role. Fishing alone, especially illegal and industrial, already had depleted more than 70% of species (which are being overfished or are on the verge of collapse), it destroys 50x more land annually than deforestation.
For me it raises an important reflection: doing all we are doing for farmed land and aquatic animals, many people will also consider going to fished animals for their animal protein intake. Is this incentive a wise one to stimulate?
Aquaculture also uses fished animals to feed their animals: therefore bans that lower fishing efforts can also make aquiculture less interesting to be pursued?
Finally, considering all of the above, shouldn’t we refrain from stimulating consumption of wild animals completely? For their welfare, but also for our planet? Ignoring this issue for me certainly shows a huge area of neglect and efficiency gap, IMO.
Not clear Michael what you mean y saying ’making fishing more sustainable = more fishing, can you elaborate? (Remembering I mention here to ban industrial fishing, not increasing its welfare, which for me is an oxymoron).
Happy to evolve this conversation further with you both. Thanks!
Aquaculture also uses fished animals to feed their animals: therefore bans that lower fishing efforts can also make aquiculture less interesting to be pursued?
I think this would be true for species caught primarily for fishmeal. While those caught for direct human consumption also contribute to fishmeal/fish oil/feed (through byproducts/processing waste, e.g. OECD/FAO, 2023, Figure 8.4), they seem more likely to compete with rather than support aquaculture overall (World Bank, 2013, Table E.2, scenario 5 Capture growth vs Baseline).
On the other hand, shrimp are major fishmeal consumers, so a decrease in fishmeal even with a decrease in overall fish and invertebrate catch could reduce shrimp farming in particular and the number of animals farmed, even if it increases aquaculture by tonnage. The increase in aquaculture by tonnage could result from an increase in more herbivorous species, like carps, tilapias, catfishes and bivalves. That being said, I’m not confident that it would decrease the number of animals farmed.
On the other hand again, banning fishing, especially for fishmeal, could also promote insect farming for aquafeed. But we could work on that, too.
Fishing alone, especially illegal and industrial, already had depleted more than 70% of species (which are being overfished or are on the verge of collapse), it destroys 50x more land annually than deforestation.
Where did you get 70% of (fished?[1]) species are depleted? Or do you mean in the past, but things might be better now? This seems much higher than related numbers I’m familiar with.
It seems that around 66% of stocks that are fished are fished sustainably vs 34% overfished, and 79% of catch by weight comes from sustainably fished stocks vs 21% from overfished (FAO, 2022, Figure 23,Ritchie & Roser, 2021–2024).
“on the verge of collapse” suggests they are likely to collapse, but that isn’t obvious, because it’s possible to maintain stocks in an overfished/overfishing equilibrium, or governments may intervene to restrict fishing (e.g. seasonal closures, total allowable catch) to protect against collapse when it gets closer. And even if/when there is a collapse, there can be recovery, e.g. like Peruvian anchoveta, which could be supported by government. Of course, recovery may not go well, e.g. NW Atlantic cod.
All of this is the result of particular kinds of fishing and management practices. Rather than outright bans, governments will just make fishing more sustainable, and then most of these concerns will no longer apply.
Not clear Michael what you mean y saying ’making fishing more sustainable = more fishing, can you elaborate? (Remembering I mention here to ban industrial fishing, not increasing its welfare, which for me is an oxymoron).
When there’s overfishing (high fishing pressure or harvest rate, as the biomass caught divided by current biomass), marginal reductions in fishing pressure allow overfished populations to recover, allowing more fish to be caught in the long run. I elaborate inSustainable fishing policy increases fishing, and demand reductions might, too. Of course, a total ban is a complete reduction, so should in fact reduce catch in the long run. But I don’t think bans are very politically feasible, at least not on a large scale, and instead you’re likely to get marginal reductions in fishing pressure, e.g. through total allowable catch or quotas. Furthermore, I’d guess even small local bans (marine protected areas) can sometimes allow for more fishing in the long run, by reducing fishing pressure on groups that migrate and will be fished elsewhere anyway.
Most species are probably not fished much at all.Only about half of the ocean area is fished. Many species in the same fisheries are not fished much or at all. Most of the oceanby depth, especially the mesopelagic zone and regions away from coasts, is almost entirely unfished.
I am at a conference at the moment, happy to respond when I leave the conference. What I would love to do is to have a session with you once you have an opportunity. I have been talking to organizations such as Faunalytics to have a deeper look into fishing and animal rights and it would be great to have someone like yourself onboard to work on this matter. Is it something you’d like to participate in?
Quick reply on one of the 70% data: sorry, I’ve made a confusion, as 70% (to be exact, it is 67%) is overfished in Brazil, not worldwide, which is in fact 34%. However, important to mention that the 60% of fish populations that are ‘fully exploited to its maximum yield’ globally actually means that it these exploited pop. have a much lower quantity of individuals than it originally used to have before exploitation (MSYs vary their limit of % of lower than original pop. per species and locations, however, they consistently are at a significant % lower than original pop. sizes). They’re still able to recover YoY, however a significant decrease in their populations is in fact changing the ecosystem balance, naturally.
Even if there are contradictory studies of some fish species growing x decreasing in studies if species are seen in isolation, I’d also encourage you to have a system’s thinking approach to this scenario, as studying animals in nature, you need to take the ecosystem context into view: a sudden change of populations of 1 species could generate growth in others, diminishment in others, but in a system’s view, this significant disruption changes the scope of the balance and interdependence of species of that particular ecosystem. In ecological terms, this is likely to result in a lower ecossystemic resilience to natural threats (in particular, climate change). I am aware, however, of the huge challenge of researching this ecological view empirically, therefore there is not so many studies taking all of these complex chains of causes and consequences to bear (it would be great to have more funding for such studies!) - but what already is a common agreement is that to protect areas from fishing is proved to increase the biodiversity of an ecosystem, and consequentially improve its resilience (and its ecossystemic role).
About the other requests for more info: I need time for this, but it may be even more productive to work as a group to distill all these data?
What we cannot deny is that this is a yet relatively overlooked and neglected area of debate, and this is surely one of the areas of more direct impact of human influence on lives, suffering and ecosystem interference and collapse.
We should not ignore it for the sake of ambiguous data or moral questionings, but see this as hugely important area of opportunity to investigate further. Let’s continue the conversation through pvt message?
The thinking that fishing is increasing fish populations is certain on short term, but not true long term. A high spike on prey fish means less of their prey, subsequently, therefore diminishing their populations over time.
I would tentatively guess that this doesn’t usually fully reverse the effect on prey fish, only dampens and slightly reverses it, so that their populations still settle higher than without fishing their predators. Furthermore, the food (mostly primary production?) of the prey (mostly crustaceans) of the prey fish should increase, too, which could have the opposite effects. I guess this can lead to algal blooms sometimes, though, which could then reduce all local animal populations.
That being said, I worry about this reasoning anyway, because it treats food webs as quite linear. A species X can eat a species Y and the prey Z of Y.
There are a few studies on the effect of removing a predator from their ecosystem resulting not on increase of fish populations or biodiversity, but in fact, the opposite happening: less biodiversity, lower populations, ecosystem collapse. This can be easily noticed in scenarios before and after implementing a Marine Protected Area—I can share a few studies if this helps, let me know.
By “removing a predator from their ecosystem”, do you mean the (near-)complete removal and therefore (near-complete) absence of the predator, or just a reduction in their biomass/populations? The latter seems more representative of fishing to me, especially as management has improved, and local extinction of a predator seems rarer (although it definitely has happened).
I’d be interested in seeing these studies, especially any globally representative aggregates, systematic reviews or meta-analyses to avoid selection bias.
I’ll note thatChristensen et al., 2014is a global aggregate (and extrapolation) of simulations (Ecopath models) spanning 100 years (1910-2010), andBell et al., 2018is a meta-analysis of observational studies of biomass data across trophic levels, each spanning at least 18 years, and with a mean length of 34 years.
Fishing pressure seems to have increased a lot around 1970, and predator biomass had been decreasing much faster since around then, according toChristensen et al., 2014(Table 3 and Figure 6). So, most of the changes to prey fish biomass should be since around 1970, too. 40 years (2010-1970) seems like it should have been long enough to see reversal in trends for prey fish from feedback on their prey, but the net effect was still an increase in prey fish biomass. That being said, I don’t know if the simulationsChristensen et al., 2014used in fact simulated the effects of prey fish on their prey and feedback from that, although I’d guess they did.
I’d guess 18 years inBell et al., 2018is long enough to see feedback from the prey of prey fish, too. We actually do see that many of the increasing trends in small fish populations (in red) reverse into decreasing trends inFigure 5inBell et al., 2018, but the trends vary substantially by survey/region and the reversals also often seems to coincide with reductions in fishing pressure (FPI, the background colour going from grey to lighter grey or white; this was the case for S St Lawrence, GSO-Fox Island, GSO-Whale Rock, Georges Bank, Mid-Atlantic), so there’s some confounding here to worry about.
FWIW, it seems reasonably likely that fishing has increased fish populations on the whole, by disproportionately reducing the populations of more predatory species and increasing the populations of their prey. See Christensen et al., 2014(only considers fish, not invertebrates) andBell et al., 2018(very limited in regional representation).
In general, the effects of fishing on welfare seem quite morally ambiguous, when you consider the effects on population sizes across species, tradeoffs between species, uncertainty about whether their lives are overall bad or overall good:The moral ambiguity of fishing on wild aquatic animal populations.
What is your take of the impact of fishing on animal welfare? When it comes to aquatic lives, why should we only focus on farmed aquatic life, not fishing? Why not prioritise work towards the ban of all fishing, esp. industrial fishing?
Some info: fishing alone is responsible for 90% of all lives killed per year for consumption, fishing is also destroying wild aquatic life habitats more than we destroy lands, and it also is affecting all wild lives that depend on them to survive: it is pretty much the largest ecocide in the world, and it is legalized. All this destruction for less than 2% of humanity’s calories intake. Also, its current techniques to kill these animals are extremely cruel, long lasting, and in accumulation, it likely represents more suffering than in fish farms.
I agree with Michael that a ban on all fishing, or even just industrial fishing, seems politically infeasible. I think it’s possible that an island nation heavily dependent on tourism might do this, but that would probably just increase the catch of unregulated fishing ships outside of their territorial waters. I don’t see any path to the world doing this.
The other complication is that a ban on wild-caught fishing might just increase the spread of aquaculture, which is worse for each fish involved. Most wild-caught and farmed fish demand is interchangeable—people are just looking to buy fish. If the wild-caught fish becomes unavailable, I’d expect most of that demand to switch to farmed fish, which would fuel an even bigger boom in aquaculture. Sadly I expect that would be even worse for the fish involved :(
We are though funding work to reduce the suffering caused by current fishing methods. I think work to make the experience of capture and slaughter less horrific is really important.
Hello @LewisBollard and @MichaelStJules thank you for your replies. Some answers to your considerations:
If replacement to aquiculture is a logic, you can state the same to fight against land animal production, as this will all concentrate consumption on aquatic animals as people do not even know which fish is caught or farmed. Certainly this will mean more lives killed/ in suffering, the same way? Shall we stop talking about transitioning away from land animals? Certainly not.
You mention the unlikeliness of promoting a ban on fishing. Although there will always be traditional communities depending on fishing to thrive, from these we should never impose a ban, it is certainly true by facts that: a. aquiculture is not replacing fishing, just increasing fish consumption, as you can see in popular stats from Our world in Data; b. for fishing, you need to consider deaths of fish and crustaceans which are significantly smaller than the fish farmed, a few examples are: krill x farmed shrimp, salmon x anchovies, etc. No wonder fished animals increase number of lives killed in the order of magnitude of 10x (but represents only 1⁄2 of the current tonnage yearly). Are we ok to ignore this huge elephant in the room?
The thinking that fishing is increasing fish populations is certain on short term, but not true long term. A high spike on prey fish means less of their prey, subsequently, therefore diminishing their populations over time. There are a few studies on the effect of removing a predator from their ecosystem resulting not on increase of fish populations or biodiversity, but in fact, the opposite happening: less biodiversity, lower populations, ecosystem collapse. This can be easily noticed in scenarios before and after implementing a Marine Protected Area—I can share a few studies if this helps, let me know.
This ask is also not impossible or far fetched: we had already moved great heaps when it coms to our culture of hunting land animals. In Brazil for example 100% of native land animals are protected towards hunting. However at see, all animals can be legally caught and die as ‘bycatch’. Why not move also towards aquatic wild lives? It is massively possible to end industrial fishing: we have gone great lenghts with the international ban to the hunting of marine mammals and the hunting of sea turtles. We are starting to do the same for sharks and rays. It is only a matter of time that our dissonance between hunting wildlife on land and at sea will be fixed and we can notice how this significantly affects their welfare overall (certainly the welfare which is not ambiguous at all, of shortening their lives and killing large quantities of animals in an extreme cruel way (btw all industrial fishing techniques are extremely negative towards welfare—so if you agree on lowering the impact on fishing welfare, surely a ban on industrial fishing must be on the cards).
Also, going beyond animal welfare and animal rights: when we talk about removing wildlife in this great quantity as I mentioned before, we are also talking about ecossystemic service of the ocean for the balance of the planet and all living beings on Earth. We are already seeing a global catastrophe happening on front of our very own eyes, and if we consider that the ocean provides at least 50% of the oxygen on Earth, and it is responsible for the historical of 85% in the atmosphere today, also considering the ocean absorbs 90% of the excess heat from CO2 emissions and is responsible for 25% of the cabon sink, it is our largest ally on the fight against climate change. However it needs a balanced ecosystem for it to keep performing its role. Fishing alone, especially illegal and industrial, already had depleted more than 70% of species (which are being overfished or are on the verge of collapse), it destroys 50x more land annually than deforestation.
For me it raises an important reflection: doing all we are doing for farmed land and aquatic animals, many people will also consider going to fished animals for their animal protein intake. Is this incentive a wise one to stimulate?
Aquaculture also uses fished animals to feed their animals: therefore bans that lower fishing efforts can also make aquiculture less interesting to be pursued?
Finally, considering all of the above, shouldn’t we refrain from stimulating consumption of wild animals completely? For their welfare, but also for our planet? Ignoring this issue for me certainly shows a huge area of neglect and efficiency gap, IMO.
Not clear Michael what you mean y saying ’making fishing more sustainable = more fishing, can you elaborate? (Remembering I mention here to ban industrial fishing, not increasing its welfare, which for me is an oxymoron).
Happy to evolve this conversation further with you both. Thanks!
On 7
I think this would be true for species caught primarily for fishmeal. While those caught for direct human consumption also contribute to fishmeal/fish oil/feed (through byproducts/processing waste, e.g. OECD/FAO, 2023, Figure 8.4), they seem more likely to compete with rather than support aquaculture overall (World Bank, 2013, Table E.2, scenario 5 Capture growth vs Baseline).
On the other hand, shrimp are major fishmeal consumers, so a decrease in fishmeal even with a decrease in overall fish and invertebrate catch could reduce shrimp farming in particular and the number of animals farmed, even if it increases aquaculture by tonnage. The increase in aquaculture by tonnage could result from an increase in more herbivorous species, like carps, tilapias, catfishes and bivalves. That being said, I’m not confident that it would decrease the number of animals farmed.
On the other hand again, banning fishing, especially for fishmeal, could also promote insect farming for aquafeed. But we could work on that, too.
So, it seems pretty messy.
On point 5
Where did you get 70% of (fished?[1]) species are depleted? Or do you mean in the past, but things might be better now? This seems much higher than related numbers I’m familiar with.
It seems that around 66% of stocks that are fished are fished sustainably vs 34% overfished, and 79% of catch by weight comes from sustainably fished stocks vs 21% from overfished (FAO, 2022, Figure 23, Ritchie & Roser, 2021–2024).
“on the verge of collapse” suggests they are likely to collapse, but that isn’t obvious, because it’s possible to maintain stocks in an overfished/overfishing equilibrium, or governments may intervene to restrict fishing (e.g. seasonal closures, total allowable catch) to protect against collapse when it gets closer. And even if/when there is a collapse, there can be recovery, e.g. like Peruvian anchoveta, which could be supported by government. Of course, recovery may not go well, e.g. NW Atlantic cod.
By land destroyed by fishing, I assume you mean bottom trawling/dredging. Unlike deforestation, this is mostly the same land being affected each year, and recovery could be faster. Governments are also likely to eventually limit bottom trawling separately from fishing as a whole, because it’s much less sustainable.
All of this is the result of particular kinds of fishing and management practices. Rather than outright bans, governments will just make fishing more sustainable, and then most of these concerns will no longer apply.
When there’s overfishing (high fishing pressure or harvest rate, as the biomass caught divided by current biomass), marginal reductions in fishing pressure allow overfished populations to recover, allowing more fish to be caught in the long run. I elaborate in Sustainable fishing policy increases fishing, and demand reductions might, too. Of course, a total ban is a complete reduction, so should in fact reduce catch in the long run. But I don’t think bans are very politically feasible, at least not on a large scale, and instead you’re likely to get marginal reductions in fishing pressure, e.g. through total allowable catch or quotas. Furthermore, I’d guess even small local bans (marine protected areas) can sometimes allow for more fishing in the long run, by reducing fishing pressure on groups that migrate and will be fished elsewhere anyway.
Most species are probably not fished much at all. Only about half of the ocean area is fished. Many species in the same fisheries are not fished much or at all. Most of the ocean by depth, especially the mesopelagic zone and regions away from coasts, is almost entirely unfished.
Hello @MichaelStJules,
I am at a conference at the moment, happy to respond when I leave the conference. What I would love to do is to have a session with you once you have an opportunity. I have been talking to organizations such as Faunalytics to have a deeper look into fishing and animal rights and it would be great to have someone like yourself onboard to work on this matter. Is it something you’d like to participate in?
Quick reply on one of the 70% data: sorry, I’ve made a confusion, as 70% (to be exact, it is 67%) is overfished in Brazil, not worldwide, which is in fact 34%. However, important to mention that the 60% of fish populations that are ‘fully exploited to its maximum yield’ globally actually means that it these exploited pop. have a much lower quantity of individuals than it originally used to have before exploitation (MSYs vary their limit of % of lower than original pop. per species and locations, however, they consistently are at a significant % lower than original pop. sizes). They’re still able to recover YoY, however a significant decrease in their populations is in fact changing the ecosystem balance, naturally.
Even if there are contradictory studies of some fish species growing x decreasing in studies if species are seen in isolation, I’d also encourage you to have a system’s thinking approach to this scenario, as studying animals in nature, you need to take the ecosystem context into view: a sudden change of populations of 1 species could generate growth in others, diminishment in others, but in a system’s view, this significant disruption changes the scope of the balance and interdependence of species of that particular ecosystem. In ecological terms, this is likely to result in a lower ecossystemic resilience to natural threats (in particular, climate change). I am aware, however, of the huge challenge of researching this ecological view empirically, therefore there is not so many studies taking all of these complex chains of causes and consequences to bear (it would be great to have more funding for such studies!) - but what already is a common agreement is that to protect areas from fishing is proved to increase the biodiversity of an ecosystem, and consequentially improve its resilience (and its ecossystemic role).
About the other requests for more info: I need time for this, but it may be even more productive to work as a group to distill all these data?
What we cannot deny is that this is a yet relatively overlooked and neglected area of debate, and this is surely one of the areas of more direct impact of human influence on lives, suffering and ecosystem interference and collapse.
We should not ignore it for the sake of ambiguous data or moral questionings, but see this as hugely important area of opportunity to investigate further. Let’s continue the conversation through pvt message?
Hi Nathalie, on point 3
I would tentatively guess that this doesn’t usually fully reverse the effect on prey fish, only dampens and slightly reverses it, so that their populations still settle higher than without fishing their predators. Furthermore, the food (mostly primary production?) of the prey (mostly crustaceans) of the prey fish should increase, too, which could have the opposite effects. I guess this can lead to algal blooms sometimes, though, which could then reduce all local animal populations.
That being said, I worry about this reasoning anyway, because it treats food webs as quite linear. A species X can eat a species Y and the prey Z of Y.
By “removing a predator from their ecosystem”, do you mean the (near-)complete removal and therefore (near-complete) absence of the predator, or just a reduction in their biomass/populations? The latter seems more representative of fishing to me, especially as management has improved, and local extinction of a predator seems rarer (although it definitely has happened).
I’d be interested in seeing these studies, especially any globally representative aggregates, systematic reviews or meta-analyses to avoid selection bias.
I’ll note that Christensen et al., 2014 is a global aggregate (and extrapolation) of simulations (Ecopath models) spanning 100 years (1910-2010), and Bell et al., 2018 is a meta-analysis of observational studies of biomass data across trophic levels, each spanning at least 18 years, and with a mean length of 34 years.
Fishing pressure seems to have increased a lot around 1970, and predator biomass had been decreasing much faster since around then, according to Christensen et al., 2014 (Table 3 and Figure 6). So, most of the changes to prey fish biomass should be since around 1970, too. 40 years (2010-1970) seems like it should have been long enough to see reversal in trends for prey fish from feedback on their prey, but the net effect was still an increase in prey fish biomass. That being said, I don’t know if the simulations Christensen et al., 2014 used in fact simulated the effects of prey fish on their prey and feedback from that, although I’d guess they did.
I’d guess 18 years in Bell et al., 2018 is long enough to see feedback from the prey of prey fish, too. We actually do see that many of the increasing trends in small fish populations (in red) reverse into decreasing trends in Figure 5 in Bell et al., 2018, but the trends vary substantially by survey/region and the reversals also often seems to coincide with reductions in fishing pressure (FPI, the background colour going from grey to lighter grey or white; this was the case for S St Lawrence, GSO-Fox Island, GSO-Whale Rock, Georges Bank, Mid-Atlantic), so there’s some confounding here to worry about.
FWIW, it seems reasonably likely that fishing has increased fish populations on the whole, by disproportionately reducing the populations of more predatory species and increasing the populations of their prey. See Christensen et al., 2014 (only considers fish, not invertebrates) and Bell et al., 2018 (very limited in regional representation).
In general, the effects of fishing on welfare seem quite morally ambiguous, when you consider the effects on population sizes across species, tradeoffs between species, uncertainty about whether their lives are overall bad or overall good: The moral ambiguity of fishing on wild aquatic animal populations.
I also suspect efforts to make fishing more sustainable actually just increase fishing, while outright bans seem politically infeasible; see my other recent post Sustainable fishing policy increases fishing, and demand reductions might, too.