Quote:
Originally Posted by Mr. Sandman
There are conflicting views on this matter. On the surface it appears that big fish will produce more...well in general that is true but as a fish moves beyond its peak fecundity age its eggs are not as ripe as a younger fish. Most other species have trouble reproducing when they get old. (A 19 year old hottie vs a 75 year old grandma) I know fish reproduce through-out their life but if you have ever opened up a 20#er and a 50#er you will see the color of the eggs in the 50 are indeed different, some look dead. I am not a fish biologist but I would rather bet the biomass future of a species on three 20#ers than one 60#er. As I think 3 20's will produce more than 1 60 and also, If the 60 dies for any reason, you have nothing. If a single 20 dies, you still have 2 more. IMO More is better in this case.
Again I am no expert but I like the idea of protecting everything instead of a subset.
Lastly, Fishery guys have proven they don't know jack%$%$%$%$. If they did we would not have the problems we have now. They have been managing fisheries for decades without results.
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I've always wondered about this myself, and have done a little homework...
What you're talking about is called senescense- biological aging. It's a common theory used among fishermen to justify keeping large fish. One old cow is not as fertile as two younger females, and therefore it's better to have more 20-30 lb fish in the population, and OK to keep the large ones.
Unfortunately this is comparing fish to people- they aren't. There's surprisingly little research done on striped bass fecundity (the ability to reproduce), which is weird seeing as they're such a valuable and important fish. One study by Richards, Fogarty & Teichberg (
Density-dependent Growth and Reproduction of Chesapeake Bay Striped Bass) found that as the total length and weight of striped bass increased, fecundity increased. Monteleone & Houde at UMD also did a study entitled
Influence of maternal size on survival and growth of striped bass Morone saxatilis Walbaum eggs and larvae- they found that small females produced small larvae, while large females produce large ones. Additionally, the larvae from large females grew faster than those from the smaller ones. They did note that a significant difference in survival to 25 days post hatch was not noticed.
So what does that mean? Large fish produce more fertile and viable eggs than small fish, and large fish produce larger larvae that grow faster. In a laboratory setting, survival was not influenced by female size... However in the wild the larger you are when born and the faster you grow will have a direct effect on survival (less things can eat you).
So basically, while the research on striped bass is limited, the common understanding among icthyologists is that the larger the fish, the more valuable it is to the population and sustainablility. The growth is fairly linear- a 10kg fish is about half as fecund as a 20kg fish.
So, don't think that the old cows aren't providing as much to the population as the smaller ones- they're providing much more. However I wholly agree that protecting just a subset isn't the answer.