There are a lot of strong arguments to be made against bible stories that people insist are literally true, and it's gotten a bit boring. The believers come up with all kinds of pseudo-scientific ways to validate impossible stories, and the arguments to contradict them are predictable. So I thought I'd come up with a new one for the story of Noah's ark, specifically how there shouldn't be any dolphins (or whales, great white sharks, etc.) if the story were true. Let's establish a couple points first.
1) According to the bible, the ark was 300 cubits (about 450 feet) long (Gen 6:15). We can safely assume that Noah didn't fit two 98 foot whales on the ark, and there's no mention of any onboard aquarium.
2) God says: I will wipe from the face of the earth every living creature I have made (Gen 7:4 New International Version). In the King James Version it's: every living substance that I have made will I destroy from off the face of the Earth.
Now, I'm no stranger to semantic rationalization. Keen observers will focus on the use of the phrase "face of the earth," and argue that it doesn't include aquatic creatures. This leads me to point three.
3) And the waters prevailed exceedingly upon the earth; and all the high hills, that were under heaven, were covered. Fifteen cubits upward did the waters prevail; and the mountains were covered.
So all the mountains on earth were covered. So what? you may ask. Well, let's do some basic geometry, finding the volume of a sphere. (Yes, I know the Earth is not perfectly spherical, but for the point I'm going to make, this will have to do.)
The radius I'm using (in case you want to check my math) is 20,925,524.9 feet. To find the volume we use the formula 4/3 * pi * r^3, or four-thirds times pi time radius cubed. The number I got was 38,381,124,220,494,286,091,421.9. So what? you're asking, more irritably this time. I'll tell you. We're going to calculate the volume of water from the flood. Go back to point three. We're going to add the height of the highest mountain (Everest at 29,029 feet) plus 15 cubits to the radius of the Earth and find the volume. We can then subtract one from the other to find the change in volume. The more scientific among you will note that this does not take into account the volume of naturally existing land formations, but this is negligible in relation to the scope we're dealing with. So, if you've done the math you should have found a difference of 160,078,848,019,995,137,560.4 cubic feet. That's 1,087,507,504 cubic miles. The volume of the oceans currently is approximately 321,000,000 cubic miles. So to answer the question you're probably dying to know, (i.e. what about the gosh darn fish) the simple fact is that saltwater fish can't survive in brackish water. Even if we accept that half of the water from the flood was saltwater from "the fountainsf of the great deep" (Gen 7:11), the water would still be so diluted that any living thing that needed salt water to survive would die.
"But," I imagine someone saying, "if most of the water were salt water from the fountains of the great deep, then the water wouldn't be diluted enough to kill all the saltwater fish." That's true. It would only kill all the freshwater fish. But, overall, it's not really about the fish.
It's about the plants.
As in, Noah didn't take any with him.
As in, they need sunlight, carbon dioxide, and fresh water.
As in, enough sunlight for photosynthesis can't penetrate more than about 200 feet into water.
As in, 2,400 feet of water pressure is enough to crush a modern submarine, let alone a tree.
As in, most plants can't survive in brackish or salt water.
As in, all the land plants would have died by the time the floods receded.
So if you want to believe your stories, go right ahead. But don't try to pass them off as scientific fact.