The Nonlinear Library EA - The moral ambiguity of fishing on wild aquatic animal populations by MichaelStJules
May 7, 2024
13:09
Welcome to The Nonlinear Library, where we use Text-to-Speech software to convert the best writing from the Rationalist and EA communities into audio. This is: The moral ambiguity of fishing on wild aquatic animal populations, published by MichaelStJules on May 7, 2024 on The Effective Altruism Forum.
Summary
The net welfare effects of fishing, changes to fishing pressure and demand for wild-caught aquatic animals on wild aquatic animals seem highly morally ambiguous, in large part because there are
1. tradeoffs between species due to predation, e.g. larger (respectively smaller) populations and life expectancies for one species results in smaller (respectively larger) populations and life expectancies for their prey and competitors, and this cascades down the food chain,
2. uncertainty about moral weight tradeoffs between affected species, and
3. depending on the moral view, uncertainty about whether the directly and indirectly affected animals have good or bad lives on average.
Acknowledgements
Thanks to Brian Tomasik, Ren Ryba and Tori for their feedback on an earlier draft. All errors are my own.
For prior related writing that is more comprehensive and suffering-focused, see Tomasik, 2015-2017. This piece focuses on population effects, overlapping largely with Tomasik, 2015.
Population effects and welfare uncertainty
Increasing the fishing of a species will tend to decrease their population, and decreasing their fishing will tend to increase their population, all else equal.
For a given species, the marginal and average effects of fishing on the number of them alive at any time are typically at least several times greater than the effects on their annual catch under standard single-species fishery models.[1] With fishing deaths making up such a small share of a life on average, even if intense (although stunning during capture may be more widely used in the future), the effects on the size of the population and resulting welfare effects could be more ethically
important than the effects on the number of fishing deaths.
And then the effects on the populations could be morally ambiguous. First, it may be ambiguous whether the average individual has a good or bad life, so that reducing their population through fishing and increasing their population by reducing fishing could be morally ambiguous.
Second, there are also population (and life expectancy) tradeoffs between species due to predation, with increasing the population of one species reducing the populations of its prey species.[2] Fishing reduces the populations of the directly fished species and (I'd normally guess) species up the food chain that depend on them,[3] while increasing the populations of the (unfished) prey (and competitors) of the directly fished species.
But then the increased populations of the (unfished) prey (and competitors) may result in decreased populations for their prey. And so on.
For example, Peruvian anchoveta, the species most wild-caught for feed and the most wild-caught fish species by numbers of individuals and tonnage (Mood & Brooke, 2024, Supplementary material 3, Supplementary material 6, Borthwick et al., 2021), primarily eat krill and copepods (Espinoza & Bertrand, 2008, Espinoza & Bertrand, 2014), so fishing Peruvian anchoveta presumably decreases Peruvian anchoveta populations but increases krill and copepod populations.[4]
I illustrate with the effects of fishing on the fished pieces and their (unfished) prey:
Fished animals have good lives
Fished animals have bad lives
Unfished prey have good lives
Bad for fished animals
Good for unfished prey
Good for both
Unfished prey have bad lives
Bad for both
Good for fished animals
Bad for unfished prey
Effects of fishing on fished animals and their unfished prey, in a simple model ignoring the rest of the food web. Fishing decreases the populations of the fished animal populations and increases the populations of their unfished prey, and these lives could be good or bad. Similarly, fi...
Summary
The net welfare effects of fishing, changes to fishing pressure and demand for wild-caught aquatic animals on wild aquatic animals seem highly morally ambiguous, in large part because there are
1. tradeoffs between species due to predation, e.g. larger (respectively smaller) populations and life expectancies for one species results in smaller (respectively larger) populations and life expectancies for their prey and competitors, and this cascades down the food chain,
2. uncertainty about moral weight tradeoffs between affected species, and
3. depending on the moral view, uncertainty about whether the directly and indirectly affected animals have good or bad lives on average.
Acknowledgements
Thanks to Brian Tomasik, Ren Ryba and Tori for their feedback on an earlier draft. All errors are my own.
For prior related writing that is more comprehensive and suffering-focused, see Tomasik, 2015-2017. This piece focuses on population effects, overlapping largely with Tomasik, 2015.
Population effects and welfare uncertainty
Increasing the fishing of a species will tend to decrease their population, and decreasing their fishing will tend to increase their population, all else equal.
For a given species, the marginal and average effects of fishing on the number of them alive at any time are typically at least several times greater than the effects on their annual catch under standard single-species fishery models.[1] With fishing deaths making up such a small share of a life on average, even if intense (although stunning during capture may be more widely used in the future), the effects on the size of the population and resulting welfare effects could be more ethically
important than the effects on the number of fishing deaths.
And then the effects on the populations could be morally ambiguous. First, it may be ambiguous whether the average individual has a good or bad life, so that reducing their population through fishing and increasing their population by reducing fishing could be morally ambiguous.
Second, there are also population (and life expectancy) tradeoffs between species due to predation, with increasing the population of one species reducing the populations of its prey species.[2] Fishing reduces the populations of the directly fished species and (I'd normally guess) species up the food chain that depend on them,[3] while increasing the populations of the (unfished) prey (and competitors) of the directly fished species.
But then the increased populations of the (unfished) prey (and competitors) may result in decreased populations for their prey. And so on.
For example, Peruvian anchoveta, the species most wild-caught for feed and the most wild-caught fish species by numbers of individuals and tonnage (Mood & Brooke, 2024, Supplementary material 3, Supplementary material 6, Borthwick et al., 2021), primarily eat krill and copepods (Espinoza & Bertrand, 2008, Espinoza & Bertrand, 2014), so fishing Peruvian anchoveta presumably decreases Peruvian anchoveta populations but increases krill and copepod populations.[4]
I illustrate with the effects of fishing on the fished pieces and their (unfished) prey:
Fished animals have good lives
Fished animals have bad lives
Unfished prey have good lives
Bad for fished animals
Good for unfished prey
Good for both
Unfished prey have bad lives
Bad for both
Good for fished animals
Bad for unfished prey
Effects of fishing on fished animals and their unfished prey, in a simple model ignoring the rest of the food web. Fishing decreases the populations of the fished animal populations and increases the populations of their unfished prey, and these lives could be good or bad. Similarly, fi...