最近アメリカでは丼=「don」が通じる様になりましたので普通に海鮮丼=seafood(sashimi) donで良いと思います。
アメリカ以外の所ですと説明をしないといけないかもしれません。この場合[刺身](https://eikaiwa.dmm.com/uknow/questions/36737/)を使った方が連想しやすいと思います。
A bowl of rice with sashimi on top.
お茶碗一杯の[ご飯](https://eikaiwa.dmm.com/uknow/questions/41672/)の上に刺身をトッピング=海鮮丼
例：
Do you like kaisendon? It's a bowl of rice with sashimi on top.
海鮮丼は好きですか？お茶碗一杯のご飯の上に刺身をトッピングしたものです。
seafood = シーフード
sashimi = 刺身
bowl of rice = ご飯一杯
Sashimi is bite-sized pieces of raw fish.
Types of sashimi:
Tuna
Salmon
Squid
Prawn
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Kaisendon is a sashimi rice bowl.
This dish is made by placing different Sashimi on Sushi Rice.
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Example
A: What are we eating tonight?
B: Kaisendon?
A: What is that?
B: A sashimi rice bowl
Sashimi is は一口サイズの生魚です。
sashimiの種類:
Tuna
Salmon
Squid
Prawn
_____________________________________________________________________________________
Kaisendon はご飯の上にsashimiをのせたものです。
いろんなSashimiをSushi Riceの上にのせて出来ています。
_____________________________________________________________________________________
例
A: What are we eating tonight?
B: Kaisendon?
A: What is that?
B: A sashimi rice bowl
Kaisen Don is a Rice Bowl which some different Sashimi are placed on Sushi Rice. Normally, it's served at Sushi restaurants and popular for lunch. If you find fresh raw fish and make sashimi or can buy sashimi and sushi rice, you have already done to make Kaisen Don.
I hope this helps :-)
raw seafood = sashimi
Seafood is shellfish such as lobsters, mussels, and crabs, and sometimes other sea creatures that you can eat.
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This is the place to come if you like seafood.
Fresh fish and seafood is in abundance.
If you like fresh seafood the dishes here are fantastic
From what I can see in the picture, it looks like an assortment of different types of fish such as :
- Fish eggs
-Salmon
-Tuna
-Some kind of prawn
if you were to see this on a menu, it would be labeled something like, "raw fish bowl," and would probably come with rice underneath.
写真を見る限り、これは色んな魚の盛り合わせのようですね。魚卵・サーモン・マグロ・エビなどが見えます。
これがメニューにあるとしたら、"raw fish bowl" などの料理名で、下にご飯が入っていると思います。
日本 
南アフリカ 
イギリス 
アメリカ合衆国 
カナダ 
