Woodmorappe estimates the ark contents by weight to show that the carrying capacity of the ark was more than enough for its cargo.

The dimensions of the ark and a draft of 15 cubits (Gen 7:20) give it a cargo mass of 17,000 tons (Hong et. al. 1994).

Biomass refers to the weight of the animals (and people). This increased significantly during the year as the animals grew bigger. Some reproduction would also have taken place.

The increase in biomass would have been more than offset by the consumption of the food and water supplies initially on the ark.