-Can we make any inferences about what percent of wild-caught fish were originally stocked in specific areas? Or has any research been done (via tagging, genetic markers, species, etc) to try to estimate that? I guess a question would be does reducing the number of stocked fish in commercial fisheries have an impact on the commercial fishing industry that we’d expect to help animals in other ways (e.g. if it made it less commercially viable to do commercial fishing if there were fewer stocked fish it might in turn reduce the fishing of truly wild fish). While the impact of that on wild animals is unclear, it seems like a consideration.
-On the large numbers of juvenile fish that mysteriously don’t seem to be making it to adulthood—is it possible this is a species specific thing? I know in China, there is a dish called 银鱼 (silverfish) that is just dozens or hundreds of fry in a bowl (also called whitebait?). It looks like they are called Icefish in English—https://en.wikipedia.org/wiki/Salangidae—I wonder if the stats are somehow not accounting for fish being eaten at a younger age or stocking specifically for whitebait dishes? Also, it looks like whitebait is eaten a ton of places—https://en.wikipedia.org/wiki/Whitebait
Another possibility is tons of young fish are being used for fishmeal or stocked to feed other fish? They might not make it into stats about fish produced then.
Regardless, thanks for doing all these pieces—they’ve all been really informative and needed for way too long!
I didn’t know about whitebait. It’s an interesting theory. I haven’t found much information about whitebait/Salangidae farming or fisheries. I only see one species of icefish in fishcount aquaculture statistics—Clearhead icefish (Protosalanx hyalocranius). All of them are produced by China. Fishcount certainly underestimated their numbers by assigning a generic mean weight of 322-1,081 grams. If their mean weight is 10 grams (this is just a guess), there would be 2.1 billion of them produced every year—a lot, but not nearly enough to explain those huge numbers. But there are many tonnes of farmed fish with no species specified in fishcount and it could be that some of them are icefish.
Can we make any inferences about what percent of wild-caught fish were originally stocked in specific areas? Or has any research been done (via tagging, genetic markers, species, etc) to try to estimate that?
Yes, I’ve seen such statistics in many articles. For example, Stopha (2018) claims that “[o]ver the past decade (2008–2017), hatcheries contributed an annual average of about one-third of the total Alaska commercial salmon harvest. By species, Alaska hatchery fish contributed an annual average 66% of the chum, 40% of the pink, 23% of the coho, 20% of the Chinook, and 5% of the sockeye salmon in the total commercial harvest over the decade.” I remember tagging being mentioned as a way to estimate it.
According to an investigation report in 2001, there were 16 435 fish seed production units and of these, about 8 072 were well equipped for hatching and juvenile rearing. Total production of all the hatchery is 13 385 billion individuals which meet the need for grow-out production. There are 8 171 hatcheries of the “four major domesticated fish”, 6 700 hatcheries for common carp and crucian carp and 499 for tilapia. The rest of the hatcheries are for river crab (515), reptile (203) and shellfish (1 017).
According to the same article, “four major domesticated fish” are black carp, grass carp, silver carp and bighead carp.
I think this and other sources would mention that most of the fish are of one tiny species that is relatively unimportant commercially and produced by a small number of hatcheries. Or maybe they would exclude them from statistics. But this is not a very strong evidence.
That makes sense—thanks for sharing these. I’m honestly surprised the icefish count is so low, but that’s just because it seems popular as a dish and requires a lot of fish. One other theory—is there much information on the fishmeal market? It seems possible that the statistics (I didn’t look too far into methods so this might be wrong) are representing fish sold (or leaving facilities) and that hatcheries are processing fish into fishmeal on site and using it to feed fry and fingerlings? Just a thought about other ways lots of fish might be produced but not represented in counts—especially if the methods for counting are different.
Icefish might weigh less than 10 grams, they really look tiny. Also, I see some wild-caught icefish in a fishcount table but it’s ten times less in weight than farmed icefish. It could be that these stats don’t include all the icefish though.
Fishcount also estimated that each year 0.45-1 trillion wild-caught fish are used to make fishmeal and fish oil, and that between 140 and 490 billion wild-caught fish are fed directly to farmed fish. But all of these fish seem to be wild-caught. This article also seems to assume that (although I only skimmed it). I haven’t seen evidence that fish are farmed to feed other farmed fish, I’m not sure if that could be economically viable.
Hey Saulius!
This is awesome! I have a few questions:
-Can we make any inferences about what percent of wild-caught fish were originally stocked in specific areas? Or has any research been done (via tagging, genetic markers, species, etc) to try to estimate that? I guess a question would be does reducing the number of stocked fish in commercial fisheries have an impact on the commercial fishing industry that we’d expect to help animals in other ways (e.g. if it made it less commercially viable to do commercial fishing if there were fewer stocked fish it might in turn reduce the fishing of truly wild fish). While the impact of that on wild animals is unclear, it seems like a consideration.
-On the large numbers of juvenile fish that mysteriously don’t seem to be making it to adulthood—is it possible this is a species specific thing? I know in China, there is a dish called 银鱼 (silverfish) that is just dozens or hundreds of fry in a bowl (also called whitebait?). It looks like they are called Icefish in English—https://en.wikipedia.org/wiki/Salangidae—I wonder if the stats are somehow not accounting for fish being eaten at a younger age or stocking specifically for whitebait dishes? Also, it looks like whitebait is eaten a ton of places—https://en.wikipedia.org/wiki/Whitebait
Another possibility is tons of young fish are being used for fishmeal or stocked to feed other fish? They might not make it into stats about fish produced then.
Regardless, thanks for doing all these pieces—they’ve all been really informative and needed for way too long!
I didn’t know about whitebait. It’s an interesting theory. I haven’t found much information about whitebait/Salangidae farming or fisheries. I only see one species of icefish in fishcount aquaculture statistics—Clearhead icefish (Protosalanx hyalocranius). All of them are produced by China. Fishcount certainly underestimated their numbers by assigning a generic mean weight of 322-1,081 grams. If their mean weight is 10 grams (this is just a guess), there would be 2.1 billion of them produced every year—a lot, but not nearly enough to explain those huge numbers. But there are many tonnes of farmed fish with no species specified in fishcount and it could be that some of them are icefish.
Yes, I’ve seen such statistics in many articles. For example, Stopha (2018) claims that “[o]ver the past decade (2008–2017), hatcheries contributed an annual average of about one-third of the total Alaska commercial salmon harvest. By species, Alaska hatchery fish contributed an annual average 66% of the chum, 40% of the pink, 23% of the coho, 20% of the Chinook, and 5% of the sockeye salmon in the total commercial harvest over the decade.” I remember tagging being mentioned as a way to estimate it.
Also, the full quote from Honglang (2007) is:
According to the same article, “four major domesticated fish” are black carp, grass carp, silver carp and bighead carp.
I think this and other sources would mention that most of the fish are of one tiny species that is relatively unimportant commercially and produced by a small number of hatcheries. Or maybe they would exclude them from statistics. But this is not a very strong evidence.
That makes sense—thanks for sharing these. I’m honestly surprised the icefish count is so low, but that’s just because it seems popular as a dish and requires a lot of fish. One other theory—is there much information on the fishmeal market? It seems possible that the statistics (I didn’t look too far into methods so this might be wrong) are representing fish sold (or leaving facilities) and that hatcheries are processing fish into fishmeal on site and using it to feed fry and fingerlings? Just a thought about other ways lots of fish might be produced but not represented in counts—especially if the methods for counting are different.
Icefish might weigh less than 10 grams, they really look tiny. Also, I see some wild-caught icefish in a fishcount table but it’s ten times less in weight than farmed icefish. It could be that these stats don’t include all the icefish though.
Fishcount also estimated that each year 0.45-1 trillion wild-caught fish are used to make fishmeal and fish oil, and that between 140 and 490 billion wild-caught fish are fed directly to farmed fish. But all of these fish seem to be wild-caught. This article also seems to assume that (although I only skimmed it). I haven’t seen evidence that fish are farmed to feed other farmed fish, I’m not sure if that could be economically viable.
Thanks! That makes sense.