It is my understanding and I am sure people will correct me if I am wrong that like Ling cod the larger fish are the ones that produce the most off spring. So in keeping those we possibly impact future fishing populations. I also understand the long liners(commercial) have more of an impact than sport fishermen.
That is true to some extent. The main difference between halibut and ling cod is the concentration of spawning and sport fishing. A large female ling will lay her eggs on a particular shallow reef and repopulate a large portion of that reef and perhaps nearby reefs. These eggs cling to the rocks or vegetation and stay in that environment. If it happens to be a popular fishing spot that one large female may be responsible for years of good productive fishing. And if she is taken out of the breeding population it could have a direct effect on the fishing in that region for quite some time.
Halibut also increase egg production with size and age. But they are not reef hatchers. Most halibut spawning is done in very deep water outside the continental shelf maybe 200 to 300 fathoms in depth. A mature female might lay between two and three million eggs in this deep water and they hatch in about 15 days. These eggs or larvae at this point are free floating and have been recorded as traveling hundreds of miles over the course of six months before mature enough to establish a home. So repopulation in a specific area has more to do with ocean currents than spawning in a particular area.
So while keeping a large female may definitely reduce the number of eggs laid in the ocean each year by a million or so this doesn't necessarily mean it will effect halibut densities in a favored fishing spot. In fact, chances are it won't effect that spot at all. It may not even effect the straights if currents change in that particular year. That is not the case with ling cod. And why it is much more important to release lingcod over 40# than a large halibut that may or may not be a female.
And relative speaking, that 192# fish in the article isn't really all that big. Probably not even consistent with the age and spawning equivalent of a 40# ling. I release every ling cod I catch over 25#! Have since I was a teenager. But, I would have whacked that barn door just the same as the chickens laying next to it!
