You write 'Who will inform them if strangers fish in their waters and walk off with the Chilazon without paying their fishing dues?' I saw (I think in the ArtScroll English) that the chilazon would come out of the sea and creep up into the mountains, where passersby could collect them without being detected more easily.
Pinchos Osher Rohr, Yerushalaim
Very nice. (That will not explain the Tuna and white glass, though.)
Perhaps they learned to explain that way from Rashi, who finds it necessary to point out that the Chilazon climbs up to the mountains. However, I think Rashi had something else in mind. Hash-m appeased Zevulun for the shoreline he received by giving him the tuna of the sea and glass from the beach. However, we don't find that he was appeased for the mountains and hills. Rashi thus explains that the Chilazon was gathered from the mountains (see Sanhedrin 91a and Rashi there).
Be well,
Mordecai Kornfeld
Rabbotai,
The fact that the chilazon crawls up the moutains lends credence to the view that the chilazon is a Medditeranean snail know as murex trunculus (or related murex species) and not the cuttlefish identified by the Radzyner Rebbe or any type of actual fish. Those species can't live out of the water. (I don't think the murex can live out of the water for long either but it should be easy to harvest if it crawls up a mountain.)
The P'til Tekhelet foundation http://www.tekhelet.com/ has done extensive research on the subject and produces the "modern" techelet used by many today.
B'kavod,
Sam Kosofsky