Can Seals Eat Sushi?

Question

In a story I'm writing at one point a kid's sitting on the docks and feeding the Seals sushi, and I'm wandering if that's actually possible, and what kinds of sushi they can actually eat or if it would make them sick. If no, then I plan on editing the world of my book so that seals are capable of eating sushi. (What I mean is like making it so some seals live near rice fields and eat rice and farmers need to put up barriers to keep them out and stuff like that.) If seals can eat sushi already I don't need to make those sorts of changes to make it fit.

Answer 1

Japanese and mild Americanized sushis should be fine

In a typical roll of sushi, most of the vegetable mass (the rice) is cooked. This breaks down the cellulose that makes plants difficult for carnivores to digest. We already do the exact same thing in a lot of dog and cat foods where we use cooked rice as a filler ingredient. If a dog or cat can survive off such food for every meal for years on end, then the occasional bit of cooked rice is not going to harm a seal either.

As for other possible non-meat ingredients, these won't exactly be "good" for the seal, but they won't poison it either. When I started making sushi for myself, I was often surprised at just how few actual vegetables go into a sushi roll. Even Americanized sushi is mostly rice because the area of the outside of a circle (where the rice goes) is so much greater than the area of the inside of the circle (where the meat and raw veggies go). A medium sized cucumber, carrot, or avocado can go into making about 60-200 pieces of sushi. So, for a girl to share a few pieces of sushi means she's only actually feeding the seal a couple of teaspoons of raw vegetables, tops. Other common vegetables like radish, lettuce, cabbage, and ginger should be fine too. None of these vegetables are particularly digestible, but they are not in high enough of a volume to be particularly harmful and none should be poisonous either*.

Over-all sushi is not an ideal food for seals, but it's no worse than feeding a human a cookie**.

Avoid Spicy or Saucy Rolls

The one thing you need to be careful about is spicy rolls or the kinds with sauces drizzled on top. These often contain lime, mustard, chili, garlic, and/or onion which are all toxic to most non-human animals. A bit of soy sauce should be fine, but would probably mask the smell of the fish and make the seal unwilling to eat it.

---

*Reports of Avocados being poisonous to pets are often taken out of context. It is the pit of the Avocado that can poison your dog. They can eat the flesh of an entire Avocado (the part we put in sushi) without any noticeable side effects.

**Toxicity issues aside, you should technically never feed a wild animal. This encourages the animal to expect humans to feed it which can result in behaviors that are dangerous to both humans and the animal you are feeding.

Answer 2

If we consider some recipes for sushi, and have a look at the ingredients:

https://www.allrecipes.com/recipe/24228/sushi-roll/

https://www.taste.com.au/recipes/sushi-2/0d57247f-03a6-434d-b26b-071b91614d41

We have just two ingredients that would be suitable for feeding to seals, namely salmon or imitation crab meat, which is just fish by another name.

However, seals are carnivores, and their digestive system would not be adapted to all the vegetable matter in sushi, which is mostly rice. It's not toxic, but it isn't really digestable to carnivores, so it might cause bloating.

However, the most concerning ingredient in sushi would be the avocado. Avocados contain persin, which is toxic to many animals, including dogs and cats. As seals don't regularly eat avocado, I wouldn't expect them to be any less affected by avocado than other carnivores.

So, if the OP's character is feeding sushi to seals, at the very least have the kid throw just the salmon or fake crab to the seals, and have the kid eat the rest... it isn't suitable for seals' consumption.