# How do fisherman catch only the fish they want? **URL:** \ **Category:** Factual Questions\ **Created:** [May 25, 2009, 3:50am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529 "2009-05-25T03:50:31Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [May 25, 2009, 3:50am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/1 "2009-05-25T03:50:31Z")
I’m watching Deadliest Catch, and I have to wonder: how do only King Crab get into the pots? I mean…I’m sure there’s the odd shrimp or lobster or other crab species in there, but in watching the show it looks to be 99% king crab. And for fishing boats for actual fish, ones that swim, I assume they use large nets? How do they only get mackerel, or tuna, or salmon? Are their fish finders, instincts, and knowledge of what fish congregate where that good? ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [May 25, 2009, 3:55am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/2 "2009-05-25T03:55:32Z")
It’s too cold for lobster up there. I would assume that the shrimp have a preferred area that isn’t where the king crabs are. I’ve also heard that male king crabs and female king crabs tend to congregate separately, but I can’t vouch for that. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 25, 2009, 4:37am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/3 "2009-05-25T04:37:32Z")
> [@bouv](#): > > And for fishing boats for actual fish, ones that swim, I assume they use large nets? How do they only get mackerel, or tuna, or salmon? Are their fish finders, instincts, and knowledge of what fish congregate where that good? Well, they don’t just catch the fish they want. If they set their nets on a school of tuna or mackeral, that’s mostly what they will get. However, often there will be a good deal of what is called “bycatch,” non-commercial fish that are simply discarded, often in a dead or dying condition. Commercial fishing can sometimes be very wasteful. ---
**Author:** ![IAmNotSpartacus](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@IAmNotSpartacus](https://boards.straightdope.com/u/IAmNotSpartacus)\ **Post date:** [May 25, 2009, 4:51am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/4 "2009-05-25T04:51:54Z")
Keep watching. They find some pretty big octopuses (octopi?). ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 25, 2009, 5:00am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/5 "2009-05-25T05:00:10Z")
> [@IAmNotSpartacus](#): > > octopuses (octopi?). Octopuses. “Octopi” is not a correct Latin plural (which is octopodes), although it has been mistakenly used for so long it appears in some dictionaries. ---
**Author:** ![Markxxx](https://avatars.discourse-cdn.com/v4/letter/m/5daacb/32.png) [@Markxxx](https://boards.straightdope.com/u/Markxxx)\ **Post date:** [May 25, 2009, 5:14am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/6 "2009-05-25T05:14:25Z")
Can’t they sell the byproducts? I know cats are pretty fussy but there must be some poor cats in China that would be happy to get any kind of “fish mash” ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 25, 2009, 5:25am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/7 "2009-05-25T05:25:21Z")
> [@Markxxx](#): > > Can’t they sell the byproducts? I know cats are pretty fussy but there must be some poor cats in China that would be happy to get any kind of “fish mash” Generally it’s discarded because 1) it’s not economically worthwhile in terms of time to sort through for the few saleable species, and 2) the low-value stuff would take up cargo space that could be used for the valuable species. You’re not going to fill up your hold with species suitable for cat food when you need it for tuna. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 25, 2009, 5:27am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/8 "2009-05-25T05:27:52Z")
[Here’s](http://seagrant.gso.uri.edu/factsheets/Bycatch.html) some discussion of bycatch issues. ---
**Author:** ![Dallas\_Jones](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dallas_jones/32/3277_2.png) [@Dallas\_Jones](https://boards.straightdope.com/u/Dallas_Jones)\ **Post date:** [May 25, 2009, 5:28am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/9 "2009-05-25T05:28:53Z")
> [@Colibri](#): > > Well, they don’t just catch the fish they want. If they set their nets on a school of tuna or mackeral, that’s mostly what they will get. However, often there will be a good deal of what is called “bycatch,” non-commercial fish that are simply discarded, often in a dead or dying condition. Commercial fishing can sometimes be very wasteful. It is not that the incidental bycatch is not marketable, (there is a market for most all fish) but that the bycatch are species that are protected and not allowed to be kept. And they must be thrown overboard to prevent the boat from profiting by ‘accidental’ catches. Even though these fish are dead and valuable they must be discarded. This incidental bycatch can determine when the fishing season must end. _numbers below are used for example only_ Say it is bottomfish season here in the Pacific NW and a million pounds is the seasonal quota for the sole, flounder, etc that can be caught. But yellow-eyed rockfish are endangered and an incidental bycatch of 10000 lbs is the limit. Once that 10000 lbs is caught (and discarded) the season is OVER for the entire fleet, even if 600,000 lbs of the allowable sole, etc is still uncaught. The gives the fleet incentive to fish in areas where they are less likely to catch the yellow-eye. The industry is highly regulated including onboard cameras and GPS. As far as crab and the Deadliest Catch goes, crab pots are designed to allow for escape for non-target species, and under-size and females can be safely tossed back without harm to the crab. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [May 25, 2009, 5:31am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/10 "2009-05-25T05:31:07Z")
How far down to king crabs live? ---
**Author:** ![Dallas\_Jones](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dallas_jones/32/3277_2.png) [@Dallas\_Jones](https://boards.straightdope.com/u/Dallas_Jones)\ **Post date:** [May 25, 2009, 5:47am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/11 "2009-05-25T05:47:51Z")
> [@Markxxx](#): > > Can’t they sell the byproducts? I know cats are pretty fussy but there must be some poor cats in China that would be happy to get any kind of “fish mash” Yes the byproducts are desireable. I spent 29 years working as a manager at a plant that used the scrap and otherwise undesireable human food grade fish to make fishmeal, fishoil, pet food flavors and hatchery fish feed among other things. The hatchery feed was mainly for salmon and required a high level of fish protien since that is what salmon eat, other fish. What protien we could not make ourselves had to be imported from South American as fishmeal. Fish meal is a huge worldwide commodity. White fish from Alaska, anchovy from Peru and Chile, menhaden from the gulf of Mexico. But these are caught fairly close to shore in one or 2 day trips. If you are fishing tuna the boats go very long distances and you would not want to use the space to keep so called ‘trash’ fish. ---
**Author:** ![Jormungandr](https://avatars.discourse-cdn.com/v4/letter/j/a6a055/32.png) [@Jormungandr](https://boards.straightdope.com/u/Jormungandr)\ **Post date:** [May 25, 2009, 8:20am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/12 "2009-05-25T08:20:28Z")
The captains tend to have spots where they caught large loads of crabs in the past. However, this doesn’t alway work as there can be few crabs or the wrong type. I remember one episode where a ship caught a huge load of crab. Unfortunately, the crab were all female and had to be thrown back. ---
**Author:** ![Argent\_Towers](https://avatars.discourse-cdn.com/v4/letter/a/e8c25b/32.png) [@Argent\_Towers](https://boards.straightdope.com/u/Argent_Towers)\ **Post date:** [May 25, 2009, 9:32am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/13 "2009-05-25T09:32:49Z")
I have an uncle who caught crabs. He was in the Navy, though. ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [May 25, 2009, 11:03am UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/14 "2009-05-25T11:03:51Z")
> [@Johnny\_L.A](#): > > How far down to king crabs live? [As deep as 500 fathoms (3000 feet)](http://www.adfg.state.ak.us/pubs/notebook/shellfsh/kingcrab.php): > [@](#): > > In Alaska there are three commercial king crab species. **Red king crabs** , _Paralithodes camtschaticus,_ have been the commercial “king” of Alaska’s crabs. It occurs from British Columbia to Japan with Bristol Bay and the Kodiak Archipelago being the centers of its abundance in Alaska. **Blue king crabs** , _P. platypus,_ live from Southeastern Alaska to Japan with the Pribilof and St. Matthew Islands being their highest abundance areas in Alaska. **Golden king crabs** , _Lithodes aequispinus_, are distributed from British Columbia to Japan with the Aleutian Islands their Alaska stronghold of abundance. Red and blue kings can occur from the intertidal zone to 100 fathoms or more. Golden king crabs live mostly between 100-400 fathoms, but can occur from 50-500 fathoms. ---
**Author:** ![Turek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/turek/32/18782_2.png) [@Turek](https://boards.straightdope.com/u/Turek)\ **Post date:** [May 25, 2009, 12:33pm UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/15 "2009-05-25T12:33:44Z")
> [@bouv](#): > > I’m watching Deadliest Catch, and I have to wonder: how do only King Crab get into the pots? I mean…I’m sure there’s the odd shrimp or lobster or other crab species in there, but in watching the show it looks to be 99% king crab. They will use the occasional cod that slips into the pots as fresh bait. They can also adjust the pots to catch cod. ---
**Author:** ![LH75](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lh75/32/4438_2.png) [@LH75](https://boards.straightdope.com/u/LH75)\ **Post date:** [May 25, 2009, 12:54pm UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/16 "2009-05-25T12:54:32Z")
> [@Johnny\_L.A](#): > > How far down to king crabs live? I wondered about this also. One of the guys on the show was talking about the rope tied to the pot as 600 feet long. ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [May 25, 2009, 2:41pm UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/17 "2009-05-25T14:41:38Z")
> [@Colibri](#): > > Octopuses. “Octopi” is not a correct Latin plural (which is octopodes), although it has been mistakenly used for so long it appears in some dictionaries. Actually, it IS a correct [Latin ending](http://en.wikipedia.org/wiki/Latin_declension#Second_declension_.28o.29), but it’s not a correct Greek plural, which is where Octopus comes from. ---
**Author:** ![kaylasdad99](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kaylasdad99/32/3398_2.png) [@kaylasdad99](https://boards.straightdope.com/u/kaylasdad99)\ **Post date:** [May 25, 2009, 4:38pm UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/18 "2009-05-25T16:38:03Z")
Why do they call them “pots” when they are clearly not made from pottery materials, such as porcelain or ceramic (some of them _could_ be made of cast iron, I suppose, but the pictures I’ve seen don’t really look like it)? In fact, they look a lot like cages. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [May 25, 2009, 10:45pm UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/19 "2009-05-25T22:45:34Z")
> [@bouv](#): > > Actually, it IS a correct [Latin ending](http://en.wikipedia.org/wiki/Latin_declension#Second_declension_.28o.29), but it’s not a correct Greek plural, which is where Octopus comes from. It’s a correct ending for second declension nouns. Since octopus is third declension, it’s an incorrect Latin plural. See the [Staff Report](http://www.straightdope.com/columns/read/2139/what-is-the-plural-of-penis) by **bibliophage** on Latin plurals. ---
**Author:** ![Bijou\_Drains](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bijou_drains/32/2814_2.png) [@Bijou\_Drains](https://boards.straightdope.com/u/Bijou_Drains)\ **Post date:** [May 25, 2009, 11:13pm UTC](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529/20 "2009-05-25T23:13:59Z")
I think pots is just the slang term they use for the crab traps. I have never seen them talk about why they use pots rather than traps. [Next page](https://boards.straightdope.com/t/how-do-fisherman-catch-only-the-fish-they-want/497529.md?page=2)