Question

the atlantic cod was once the mainstay of the united states fishing industry. however, warming of the ocean along the shores of new england has caused the stock of cod to disappear almost completely. according to scientists at the gulf of maine research institute, the gulf of maine is heating up faster than a majority of the rest of the planets oceans. as a result of warmer ocean waters, female cod produce fewer offspring, and these fish are less likely to survive to maturity. even though recreational cod fishing was banned in 2014, and strict limitations were placed on the number of fish commercial fishermen could catch, these measures have not been enough to protect the cod. what is the main, or central, idea of the passage? female cod are producing fewer offspring in the gulf of maine. because cod used to be abundant in the atlantic, it was once the backbone of the u.s. fishing industry. because the gulf of maine is warming unusually quickly, atlantic cod are disappearing.

Explanation:

The passage starts by stating that Atlantic cod was important to the US fishing industry but is now disappearing due to ocean - warming in the Gulf of Maine. It gives details about the effects of warming on cod reproduction and survival, and mentions that fishing restrictions haven't been enough to save them. The overall focus is on the cod's disappearance due to the Gulf of Maine's warming.

Answer:

Because the Gulf of Maine is warming unusually quickly, Atlantic cod are disappearing.