between Georges Bank and Browns Bank, the southwestern edge of the Scotian Shelf. The Northeast Channel is the major channel between the Gulf and the rest of the Northwest Atlantic. A secondary, shallower connection to the rest of the Atlantic is the Great South Channel, located between Georges Bank and the Nantucket Shoals. The watershed of the gulf encompasses an area of , including all of Maine, 70% of New Hampshire, 56% of New Brunswick, 41% of Massachusetts, and 36% of Nova Scotia. The watershed also includes a small southern portion of the Canadian province of Quebec, which is less than 1% of the province's area. Significant rivers that drain into the Gulf include, from east to west, the Annapolis, Shubenacadie, Salmon, Petitcodiac, Saint John, Magaguadavic, St. Croix, Penobscot, Kennebec, Saco, Piscataqua, Merrimack and Charles rivers; the Saint John and Penobscot have the greatest discharge. Ecology The cold waters, extreme tidal mixing, and diverse bottom of the gulf make it one of the most productive marine environments in the North Atlantic, and it furnishes habitat for more than 3,000 marine species and birds, including most notably large fish species such as haddock, pinnipeds, the Acadian redfish (Sebastes fasciatus), the Atlantic herring (Clupea harengus), and the American lobster (Homarus americanus), which grows to famously large sizes in the gulf. The biodiversity and productivity of the area are supported by kelp forest habitats that are found along the coastal zones of the gulf. In the Gulf of Maine, different kelp macroalgae species are found at various depths. At depths less than 5 meters, Alaria esculenta is most abundant, while the Saccharina species such as S. latissima and S. digita are the species primarily seen at depths of 5–15 meters. In the deeper waters, Agarum clathratum are more abundant in the rocky subtidal zone. The waters of the Gulf of Maine system, particularly at the boundary with the Bay of Fundy, are also home to the summering grounds for many different bird and whale species, most notably the highly endangered North Atlantic right whale. The gulf was home to the sea mink until its extinction in the late 1800s. Due to rapid rising of water temperatures in the Gulf of Maine, it has become too warm for cod as well as kelp forests. Studies found that some areas, such as Ammen Rock Site 1, witnessed a 36.2% decrease in kelp between 1987 and