Regarding the number of crop deaths caused by plant agriculture, it's difficult to draw firm conclusions based on the limited data currently available, as discussed in the section "Fishing vs. Crop Deaths".

That section states

While reliable data on crop deaths is extremely limited^[27], it is plausible that these crop deaths may carry a higher total moral cost than fishing sardines and anchovies.

I thought I'd expand on this claim a bit, as I agree with @Erich_Grunewald 🔸 it seems cruxy. 

Ultimately I agree, though if I were deriving my opinion solely on the citated paper, "Field Deaths in Plant Agriculture",^[1] the initial calculation based on it makes it seem unlikely. The paper says "Our overall estimate should still be much lower than the one we mentioned at the outset [even if we are morally responsible for deaths from predation]", which is "over 7.3 billion animals killed each year". That's roughly 1 animal killed per human per year.^[2] If we estimate mean calorie intake to be 2500 kcal per day, 365.25 days per year, that's 913,125 kcal per year, for 1 death. 1 sardine is 47kcal,^[3] so the initial rough comparison of 913,125/47 means that sardines cause 19,428x as many deaths per calorie as crops, excluding insects. 

Importantly, the "7.3 billion animals" does not include insects, but, based on Tomasik 2016, cropland probably typically has lower Net Primary Productivity, and lower insect populations, which is probably a good thing (assuming the insects have net-negative lives). So that suggests eating crops has a positive moral impact, despite crop deaths.

However, considering this post, I come to agree with your position that it is plausible that "crop deaths may carry a higher total moral cost than fishing sardines and anchovies" (i.e. that it is plausible that fishing sardines has a positive impact which is greater than the positive impact of farming crops). 

1. ^{^}

   Fischer, B., & Lamey, A. (2018). Field Deaths in Plant Agriculture. Journal of Agricultural and Environmental Ethics 31, 409–428. https://doi.org/10.1007/s10806-018-9733-8

2. ^{^}

   Human population surpassed 7.3 billion in 2014: https://www.worldometers.info/world-population/world-population-by-year/ 

3. ^{^}

   https://www.nutritionix.com/i/nutritionix/fresh-sardine-1-medium-sardine-4/5b2a87a6caec4140766f457a 

Biodiversity plays a key role in maintaining ecosystem resilience by providing redundancy and adaptability. As it declines, ecosystems become more fragile, raising not only the risk of widespread species loss but also the risk of human extinction, given our dependence on functioning ecosystems.

Is it true that humans depend on functioning ecosystems, in the sense avoiding extinction -- or even in the sense of >5% of human lives relying on them? 

A lot of the examples^[1] I've seen are doubtful, e.g. pollination is sometimes given as an example of an ecosystem service, but staple crops like wheat are wind-pollinated, and domesticated bees are used for the crops that require insect pollination. 

Edit: More on the pollination example: 
Yields would decline 5-10% without pollinators,^[2] and "Non-bees performed 25–50% of the total number of flower visits [...] pollination services rendered by non-bees [are] similar to those provided by bees."^[3] So if you were to naively combine these, it might mean that yields would decline 2.5-5% if wild pollinators disappeared.

1. ^{^}

   Such as in this Claude Sonnet 4 chat

2. ^{^}

   https://ourworldindata.org/pollinator-dependence 

3. ^{^}

   Rader, R., et al. (2016). "Non-bee insects are important contributors to global crop pollination." Proceedings of the National Academy of Sciences, 113(1), 146-151. https://www.pnas.org/doi/10.1073/pnas.1517092112 

Ah yes, so I guess the comparison is roughly 1-1.2 trillion other insects yearly (2020), versus 4.2-14.4 trillion honeybees yearly (2017). So, 7-29% as many as the number of honeybees. 

(Multiplying 1.4-4.8 trillion honeybees alive at one time by 3 to get the annual number, because of the 4 month average lifespan). 

The link (which does work for me, perhaps try another browser) is to an archive of a 2018 article by Jiwoon Hwang which has a table with numbers of different animals, and states "1 trillion animals exist due to humans, 97% attributable to honey". As Bentham's Bulldog and the link itself caveats, this is not true, simply because the table does not include any other farmed insects. There were 1-1.2 trillion insects farmed to be eaten by humans or animals in 2020, plus many more silkworms and cochineals. @Jason Schukraft  estimated  "that at any given time in 2017 there were between 1.4 and 4.8 trillion adult managed honey bees", for comparison. Below is the calculation from Jiwoon Hwang:

Data for honey bees:
FAOSTAT, Livestock Primary, World, Production Quantity, Honey, natural, 2014 (http://www.fao.org/faostat/en/#data/QL) : 1,510,566 tonnes

“How much honey does the average worker honey bee make in her lifetime? – 1/12 teaspoon.” (https://www.honey.com/newsroom/press-kits/honey-trivia)

Density of Honey: 1.36 kg/l (https://en.wikipedia.org/wiki/Honey#Nutritional_and_sugar_profile)

Estimated average lifespan of honey bees: 4 months (25-35 days summer, 6-8 months winter)
(Amdam, Gro Vang, and Stig W. Omholt. “The regulatory anatomy of honeybee lifespan.” Journal of Theoretical Biology 216.2 (2002): 209.)

Calculation:
World Honey Production 2014: 1,510,566,000,000 grammes. (1,510,566 tonnes * 1000 * 1000)
One teaspoon: 5mL (metric, https://en.wikipedia.org/wiki/Teaspoon#Metric_teaspoon)
One teaspoon of honey: 6.8 gramme (5mL * 1.36 kg/L)
Honey per honey bee: 0.56666666666667 gramme (6.8 gramme * (1/12))
Honey lifetimes per year: 2,665,704,705,882 (1,510,566,000,000/0.56666666666667)
Honey years per year: 888,568,235,294 (2,665,704,705,882 * (4/12))

Edit: note that the 97% number also doesn't include shrimp. 

Diana Fleischman believes scallops are not preferable because unlike oysters and mussels they are mobile rather than sessile,^[1] and therefore have an evolutionary reason to be sentient because they are capable of moving away from painful stimuli.

Also, while oysters and mussels are usually farmed, scallops are sometimes dredged,^[2] which probably has large effect on aquatic organisms. Here is a CGI represenation I found. 

There's also footage of this and the barren-looking aftermath in the new David Attenborough film Ocean -- which is not on YouTube, although YouTube does have a separate clip from the film of bottom trawling of fish. Whereas "fishermen argue that on soft seabeds that have already been dredged the impact is far less and the effects of tides and waves may exceed the impact of fishing activities in some areas",^[3] IIRC the film argues that the pre-dredging habitats recover quickly when dredging ceases. 

Considering wild animal welfare, and assuming the welfare of the ocean animals is negative, I guess the question is whether dredging reduces net primary productivity (NPP) -- it looks like it does to me, based on the barren appearance of the ocean floor following dredging. So therefore, (wild-caught) scallops may be better than oysters or mussels for wild animal welfare? However, "aquaculture now dominates at 75-80% of production [of scallops], with wild dredging at 18-22% and hand-diving under 2%".^[4]

1. ^{^}

   (though there are some caveats to this explained in Fleischman's article)

2. ^{^}

   https://www.seafish.org/responsible-sourcing/fishing-gear-database/gear/drb-scallop-dredge/ 

3. ^{^}

   https://cornwallgoodseafoodguide.org.uk/fishing-methods/scallop-dredging.php 

^{^}

This is a quote from Claude Sonnet 4's summary of its research report, which I have not double checked: https://claude.ai/public/artifacts/5164e7de-7ff4-4952-947a-163ef13ddab7 

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But if the resource was time, which in SPI's case is free as they are volunteers, then having filed a case is consistent with operating on no budget or a shoestring budget, because of free waivers.

"Pending case" does seem to have a specific legal meaning. I am not a lawyer and wouldn't know whether there is an additional colloquial meaning (though when asked in those terms, Claude Sonnet 4 agrees that there is). Therefore I disagree that it was "sufficiently clear" -- I would say it was below a sufficient standard of clarity.^[1] I don't think the reader can be expected to infer that a legal term was being used differently from the fact it was a disclosed to be a newly-formed volunteer team. I do think readers would have expected an organisation's formal statement to be using the legal, more formal, meaning, and indeed I think many non-lawyer readers of this forum would not be aware that there is any other meaning. 

1. ^{^}

   (Though I don't get the impression this was deliberate, whereas I get the sense Vetted Causes does.)

I agree to an extent, in that I think that strictly speaking it would have been better to say "we seek to reform pesticide use" or "we are working on reforming pesticide use". I wonder if you would have found that acceptable? 

Someone should commission new moral weights work in the next year

I’d like to see it expanded to even smaller animals if possible, like @Vasco Grilo🔸 asks here.

most workers were at best indifferent between these forms of work

Wouldn't traditional economic thinking basically predict that the equilibrium for wages in industrial jobs be at the point where workers are indifferent to them? As in, there's no incentive for the wages in industrial jobs to be any higher than the level which is just high enough to compensate for the downsides (e.g. health risks) compared to the informal labour market? (I'm not an economist, and maybe this depends on what's considered "traditional".)