fishing for words

(and tossing out random thoughts)


Leave a comment

more on CA DFG’s conversion to triploids: all of California’s stocked rainbow trout soon to be dumb(er)?

Just last week we posted that nearly all of California’s hatchery-raised rainbow trout will be triploids within two to three years.

Now we can’t help but wonder what it really means.

According to U.K. Salmon and Freshwater Fisheries Consultant David J. Solomon:

Apart from having three sets of chromosomes, as opposed to the usual two in trout, there are a number of other relevant differences [between diploid and triploid trout].

Many organs and tissues have larger but fewer cells in triploids, including the brain, muscle, retina, liver and kidney (Benfey, 1999). This appears to arise because the extra set of chromosomes dictates an increase in cell nucleus dimensions which in turn affects overall cell size.

Fewer brain cells doesn’t mean will mean you’ll hook a triploid trout on every cast, particularly if diploid trout (with the normal chromosomal configuration) are present in the same water. Solomon goes on…

However, this rather fundamental difference appears to have remarkably little knock-on effect upon physiology, behaviour and general performance. Development rates appear very similar, until the onset of sexual maturity in diploids. Diet utilisation and energetics appear unaffected. Triploids are generally less aggressive than diploids, which leads to poorer performance when the two are reared together in intensive culture – but these differences disappear when the two are reared separately.

It’ll be interesting…

Advertisements


1 Comment

why the California trout you might catch will be different, though not to your naked eye

Chances are that in the sordid noble history of nearly all fly fishermen, trout were caught, cleaned and eaten. It’s just as likely that these fish were born in a hatchery, raised in concrete runways and trucked to that river, stream, or lake from which they were plucked.

Writing without the encumbrances of real journalism, I can can step out on a limb and offer definitive word that nearly all of the stocked rainbow trout in California soon could be triploids. Yup, them fish that should be asterisk’d in any claim of a record.

Hatchery Upwelling Jars

Hatchery Upwelling Jars

Shifting to triploids by 2014 is the goal, according to California Department of Fish & Game’s Dr. William T. Cox*, Program Manager: Fish Production and Distribution, thanks in part to the 2006 lawsuit filed by the Pacific Rivers Council and the Center for Biological Diversity claiming that CA DFG’s fish stocking did not comply with the California Environmental Quality Act. The nut of the lawsuit was the impact of stocked trout upon anadromous fish populations and other native aquatic species.

While the resulting hatchery environmental impact reports called for the protection of steelhead in anadromous waters below rim dams, CA DFG will expand rainbow triploid production to approximately 90% of the state’s stocking program. The few exceptions will include Eagle Lake, an understandably unnamed southern Sierra source of Kamloops Junction Rainbow broodstock, and hatchery broodstock that will be placed in certain waters when three to four years old.

Triploids aren’t new to California. They were first brought in from out-of-state suppliers, such as Sumner, Wash.-based Troutlodge, then reared in CA DFG hatcheries. The department later developed its own program, with a single apparatus and borrowing methodology from other states that have had success with trout triploidy. This single apparatus was trucked up and down the state, following the spawning of the different rainbow strains.

That will change near the end of this month when additional triploidy pressure shocking machines should arrive from Europe, allowing for the placement of two machines at the Mt. Shasta Hatchery and single machines at the San Joaquin Hatchery and Hot Creek Hatchery. (You can get a good, easy-to-understand outline of triploids and their production at Get Hooked.)

There Be No Monsters Here (and Good News for Natives?)

It seems you can set aside concerns that genetically engineered monster rainbows will be dumped into California waters. These triploid trout will be still be stocked when ½ to ¾ of a pound. (Trivia: The size of trout stocked by CA DFG rose to a target of ½ pound when the general daily limit on trout was reduced to five, from 10 fish. Before that, stocked trout often were smaller.)

Although mandated by 2005’s Assembly Bill 7 — now California Fish and Game Code §13007 — and not directly related to the PRC/CBD lawsuit, Dr. Cox expressed hope that up to 25% of CA DFG’s stocked fish will be heritage species (in terms of numbers) by 2012-13. State hatcheries currently raise Eagle Lake Rainbow (Oncorhynchus mykiss aquilarum), Lahonton Cutthroat (Oncorhynchus clarki henshawi), California (or Volcano Creek) Golden Trout (Oncorhynchus mykiss aguabonita) and Steelhead (Oncorhynchus mykiss).

A fifth heritage trout species should be in production by January 2012. Spelled out in the California Fish & Game Commission’s Current Issues Fall 2010 document are plans to upgrade the infrastructure at the Kern River Hatchery for the production of the native Kern River Rainbow Trout (Oncorhynchus mykiss gilberti). Dr. Cox said that Kern River rainbow broodstock should be collected this fall. Long-term plans include the possibility of rearing Lahontan cutthroat trout for the Lake Tahoe basin restoration.

Regardless of one’s opinion of stocked trout, it’s fair to say that those with boots on the ground in California’s hatcheries honestly aim to better the angling experience. Here’s to hoping.


* Yes, he’s a fisherman who spent much of last month fly fishing in Wyoming and Montana.


Leave a comment

what we see this Wednesday… (2011-06-01)

  • Great video of #flyfishing in the Eastern Sierra Nevadas, in California and Nevada. http://ow.ly/57CJ5 #
  • Global Sporting Safaris’ new website offers fly fishing guides by county in every state. So far a bit slow and awkward. http://ow.ly/57AZw #
  • Not all blog posts come from nowhere; interviewing CA DFG Fish Production/Distribution Program Manager. Post to follow. #