Welcome, Guest. Please login or register.
March 28, 2024, 09:32:24 AM

Login with username, password and session length

Recent Topics

[Today at 08:17:00 AM]

[Today at 08:02:19 AM]

[Today at 05:07:22 AM]

[March 27, 2024, 07:25:42 PM]

[March 27, 2024, 07:05:39 PM]

[March 27, 2024, 04:18:57 PM]

[March 27, 2024, 12:35:34 PM]

[March 27, 2024, 11:18:23 AM]

[March 26, 2024, 07:45:07 PM]

[March 26, 2024, 06:19:03 PM]

[March 26, 2024, 05:47:06 PM]

Support NCKA

Support the site by making a donation.

Topic: What makes for good/bad crab years?  (Read 1854 times)

0 Members and 1 Guest are viewing this topic.

HobieSport

  • Salmon
  • ***
  • Let us go fishing together
  • View Profile
  • Location: Mendocino, Calif
  • Date Registered: Oct 2007
  • Posts: 577
Anyone have an idea of what conditions make for good and bad crab years?   From what I've read on the forum, most of the crabs seem to be out in deep water to far this season.   Any ideas BSteves (fish nerd)?  Hawk/Swellrider?  Or are the various environmental/ecological factors just too complex to really tell?   Thanks; just curious.


bsteves

  • Fish Nerd; AOTY Architect
  • Moderator
  • *****
  • Better Fishing through Science!
  • View Profile Northwest Kayak Anglers
  • Location: Portland, OR
  • Date Registered: Jan 2005
  • Posts: 2267
There are several researchers working on that (Dr. Steven Morgan at the Bodega Marine Lab being one of them).  This all boils down to what is known as fish/crab recruitment dynamics.

Recruitment can be considered at various life stages.  Fisheries recruitment, (the number of fish/crabs of legal size) is what most fishermen are interested in.  In other words, why aren't there as many crabs this year?   But recruitment can occur when a fish or crab makes a major life history change (e.g. sexual maturity) as well.

Researchers like Dr. Steven Morgan feel that larval recruitment may play a large role in determining overall crab recruitment. Dungeness crabs have pelagic larvae and it is believed that when oceanographic conditions are favorable (food availibility and the right currents) the larval crabs can make it to the right spot when they settle to the bottom and become little crabs.  Because of this, this hypothesis is sometimes referred to as "environmental forcing".  This pelagic larval stage is considered the most treacherous in the crabs life so it is thought that if more crabs can make it through this stage in a given year that the fisheries recruitment might be higher several years down the road when the little crabs become big crabs.

Another popular hypothesis is called "density-dependent recruitment" in which at low adult numbers the little crabs settling to the bottom have lots of free space and recruitment goes up in a few years as these crabs mature.  At higher adult densities the little crabs settle to the bottom to find that they have lots of competition with all the adults and don't do as well, in a few years recruitment goes down because many of these small crabs don't survive.

In the end, it's probably a combination of environmental forcing and density-dependence and both are nearly impossible to measure let alone predict.

Brian


Elk I Champ
BAM II Champ


HobieSport

  • Salmon
  • ***
  • Let us go fishing together
  • View Profile
  • Location: Mendocino, Calif
  • Date Registered: Oct 2007
  • Posts: 577
Thanks for all the info Brian.   Interesting stuff.  We met Juan, from Willits (NCKA) crabbing on his drift boat at Big River today.  He had two legals and said he was pulling up lots of undersized.  We'll see how the crabbing develops in the new year.   -Matt