Ship wrecked by orcas, really? Wiki doesn't mention any https://wikipedia.org/wiki/Killer_whale#%22Killer%22_stereot... Couldn't find any other reports of this happening. Youtube has some videos of other whales but not orcas.

Low fat is a problem, because we need it or "rabbit starvation" - rabbit meat is only 8.3% fat https://wikipedia.org/wiki/Protein_poisoning.

Nutritionalist picks one food, mushrooms... which have very low calories. Great for weight loss, not great for survival.

Potatoes are surprisingly good; high calories, they even have vitamin C. Easy to grow (not in a dingy of course). The favoured survival food of the stranded Martian.