[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[escepticos] Salmones transgénicos: no es eso....

Recordareis que muy recientemente los medios de incomunicación se
hicieron eco de que una empresa "tenía a punto" el sistema para obtener
salmones gigantes, que iban a comerse de vivo en vivo a los "naturales"
y mil peligros más.... Por lo visto, los periodistas británicos, que fueron
los primeros en "informar" sobre el hecho, son tanto o más torpes que
los de casa....

Os paso el escrito del presidente de aquella compañía, en el que, o mi
inglés es peor del que creo, o entiendo que lo que se pretende no es
conseguir "salmones monstruosos", sino reducir el tiempo de cultivo
en piscifactoria hasta llegar al tamaño "normal".

Saludos ictiológicos.

Josep Català
___________________Mensaje del "señor presidente"_______________

> "The recent debate in the British press regarding GM salmon ("advanced
> hybrids") has been mirrored to some extent in this forum. As the CEO of the
> company that is developing these fish, I wish to make a couple of points and
> clarifications based on comments I have read:
> 1. Fast vs Big. The Atlantic salmon we have been working on do not grow
> larger, just faster. They reach smolt size (about 50gm-70gm) and are
> biologically capable of transitioning from fresh to salt water in about 3 to
> 4 months from first feed. Standard Atlantics reach this point at about 12 to
> 15 months. Under proper conditions a commercial size of 3kg to 4kg is reached
> well before 24 months -in comparison with 36 months for the standards. The
> specific growth rate (i.e., daily growth rate) of our fish is well above that
> of standard Atlantics for at least a year, but thereafter the slope of the
> curve diminishes relative to the non-transgenics. By the time 3 or more years
> has elapsed and sexual maturity achieved, our fish weigh in at 5kg to 7kg -
> pretty standard for farm raised Atlantics at maturity. The biggest fish we
> have ever had, (7 years old, I beleive) weighed in at 15kg or so - not
> particularly large for a fish this age.
> 2. Survival in the Wild? The issue of relative competence in the wild of
> transgenic fish in general is the subject of at least one very good article (T
> ransgenic Research?) by Dr. Wayne Knibb. His thesis about the selective
> disadvantage of transgenic organisms and fish in particular is powerful and
> based in both empirical studies and theoretical considerations. The overall
> conclusion is similar to that mentioned by many here (and not diputed by many
> serious environmentalists who are not favorable towards GM fish): these fish
> are at a selective disadvantage, and absent repeated and widespread releases
> of fertile transgenics, their effect on the environment and the survival of
> conspecifics would be limited in time and scope. As an aside, we have had one
> academic study of the behavior of our (young) fish and it showed that in
> contrast to the control group (non-GM), our fish had such a desire to feed
> that they did not flee from introduced predators. ( I will provide cites for
> this and all other mentioned articles once I have returned to my office this
> week. Sorry for the inconvenience.)
> 3. The Trojan Gene Hypothesis. The thesis that GM fish have a survival
> disadvantage coupled with a greater ability to attract mates because they are
> larger at maturity  underly Dr. William Muir's theory (PNAS)  that the
> confluence of these two factors will lead to the extinction of the wild
> conspecific within 36 to 40 generations. The theory is based on his
> understanding of the mating behavior of medaka (the lab rat of the fish
> world), but without any empirical evidence regarding transgenics: he grew
> some GM medaka but although they rapidly reached adult size, they failed to
> get larger - as in our case with salmon. Dr. Muir has since agreed that his
> hypothesis would be of no effect if the transgenics did not achieve that
> increase in mating size. In particular, he agrees that it is doubtful his
> work applies to our salmon both because we do not see any increase in final
> size and also because the mating behavior of salmon in the wild is far more
> complex than that of the medaka in the lab. In the wild, Atlantic salmon eggs
> are fertilized by males who may be anywhere from 6 inches long and a year or
> so old (precocious males) to lunkers weighing in at over 20kg who may be
> many years old.
> 4. The Need for Terminator Genes? Unlike plants, a technology to create
> sterile organisms from fertile eggs is well developed in fish farming.
> Triploidy, which results in sterility, is induced via pressure shocking the
> eggs shortly after fertilization. The success rate for this technology - in
> use for 20 or more years - approaches 100% in salmon if done properly. Salmon
> farmers don't like to do this (as opposed to trout farmers) because they feel
> it slows down the growth rates, despite the potential advantage of
> eliminating precocious maturity (resulting in a non-performing fish) and
> despite pressures from environmentalists who want fish farmers to raise
> triploid salmon to avoid gene introgression into the wild. (e.g., the North
> Atlantic Salmon Farmers Organization - an intergovernmental body charged with
> overseeing the wild stocks.) It is interesting that on this issue, there is a
> real likelihood that the introduction of transgenics can help solve an
> existing environmental problem.
> For those who want more information, we have a web site - afprotein.com which
> provides access to scientific data, as well as providing the more tradiitonal
> commercial info. As an aside, I would tend to avoid using the British press
> as an authoritative source on this subject - particularly The Guardian, whose
> environment reporter claimed we have 200 lb, 12 foot salmon - an assertion
> based only on his fevered dreams".
> Elliot Entis
> Aqua Bounty Farms
> (previously A/F Protein)