Google N-gram Corpus Counts
╭─ーーー─┬────────┬───────╮
│ 五十集 │    830 │100.0% │
│ いさば │ 12.660 │  N/A  │
╰─ーーー─┴────────┴───────╯
Daijr:
〔近世語〕
①魚を売買する店。また、魚市場や海産物を扱う商人。
②江戸時代、近距離航路で使われた百石積み前後の小型回船。いさばぶね


Daijisen confuses me a bit, not sure how well this nuance can be incorporated:
1（東日本で）魚商。また、その商品。
2（西日本で）行商や運搬に用いられてきた和船。いさばぶね。

Koj: ④江戸時代、水産物や薪炭などを主に運送する小廻船の一種。いさば船。磯場船。磯辺舟。

.

Kojien has 5 senses, but that's overkill. The 2 that are also in other references are enough, although the archaic one could be split perhaps.
Unabridged nikkoku also has a third sense, but I don't see it in other refs so I have left it out for now.
I have preliminarily added daijisen's notes

@@ -11,0 +12,8 @@
+<misc>&hist;</misc>
+<s_inf>in western Japan</s_inf>
+<gloss>small Edo period short-distance transport vessel (of marine products, fuel, etc.)</gloss>
+</sense>
+<sense>
+<pos>&n;</pos>
+<misc>&arch;</misc>
+<s_inf>in eastern Japan</s_inf>
@@ -13,0 +22 @@
+<gloss>marine products</gloss>

三省堂　スーパー大辞林; デジタル大辞泉; 広辞苑 第七版