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To be short in answer Yes you need a NY Saltwater Lic, $15 and can get it on line.
If you are fishing
Raritan Bay or Southern shore along Long Island 1 Fish over 28" up to 40" and 1 Fish over 40"
If you fish from a Charter/Party Boat that is licensed in NY Waters you may take 2 fish 28" and over.
If you fish from a Charter/Party Boat that has a NY Lic. you do not need a Saltwater Lic, the boat has it (just sent my $650 to the wonderful State of NY).
Parts of the Hudson and Delaware River in NY have differant regulations.
Hope it helps
From the NY DEC Web Page
Species Open Season Minimum Length Possession Limit
Striped Bass (except the Hudson River north of the George Washington Bridge) Apr 15 - Dec 15 Licensed Party/Charter Boat anglers 28" TL 2
All other anglers 28" to 40" TL 1
>40" TL(Total Length) * 1
Red Drum All year No minimum size limit No limit for fish less than 27" TL
Fish greater than 27" TL shall not be possessed
Tautog Oct. 1 - Dec. 20 and Jan. 17 - Apr. 30 14" TL 4
American Eel All year 6" TL 50
Pollock All year 19" TL No limit
Haddock All year 19" TL No limit
Atlantic cod All year 22" TL No limit
Summer flounder May 15 - June 15 and July 3 - Aug 17 21" TL 2
Yellowtail Flounder All year 13" TL No limit
Atlantic Sturgeon No possession allowed
Spanish Mackerel All year 14" TL 15
King Mackerel All year 23" TL 3
Cobia All year 37" TL 2
Monkfish (Goosefish) All year 17" TL
11" Tail Length # No limit
Weakfish All year 16" TL
10" Fillet length+
12" Dressed length** 6
Bluefish All year No minimum size limit for the first 10 fish; 12" TL for the next 5 fish. 15, no more than 10 of which shall be less than 12" TL.
Winter Flounder April 1 - May 30 12" TL 2
Scup (porgy) Licensed Party/Charter Boat anglers **** June 12 - Aug. 31 11" TL 10
Sept. 1 - Oct. 15 11" TL 45
Scup (porgy) All other anglers May 24 - Sept. 26 10.5" TL 10
Black Sea Bass June 1 - June 30 and Sept 1 - Sept 30 12.5" TL 25
American Shad All year No minimum size limit 1
Hickory Shad All year No minimum size limit 5
Oyster toadfish Jan 1 - May 14 and July 16 - Dec 31 10" TL 3
Large & Small Coastal Sharks ##, ### As per Title 50 CFR,Part 635### As per Title 50 CFR, Part 635### As per Title 50 CFR, Part 635###
Pelagic Sharks ++,### As per Title 50 CFR, Part 635### As per Title 50 CFR, Part 635### As per Title 50 CFR, Part 635###
Prohibited Sharks***,### No possession allowed
* Total length is the longest straight line measurement from the tip of the snout, with the mouth closed, to the longest lobe of the caudal fin (tail), with the lobes squeezed together, laid flat on the measuring device, except that black sea bass are measured from the tip of the snout or jaw (mouth closed) to the farthest extremity of the tail, not including the tail filament.
# The tail length is the longest straight line measurement from the tip of the caudal fin (tail) to the fourth cephalic dorsal spine (all dorsal spines must be intact), laid flat on the measuring device.
+ The fillet length is the longest straight line measurement from end to end of any fleshy side portion of the fish cut lengthwise away from the backbone, which must have the skin intact, laid flat on the measuring device.