I assume you mean that the "them" in your sentence means fish farms. The problem is that the people all over the rest of the Province that want them gone are not concentrated in any particular riding, unlike the folks in the North Island who rely on the industry for their livelihood and is unlikely to vote for the Party that has a position that would negatively affect the industry. So the "anti fish farm" vote in the rest of the Province is pretty much diluted and not likely to have much influence one way or the other in the election.
According to the Salmon Farmers Web Site the total province numbers are “ …more than 6000 people who work on salmon farms and provide services or supplies for our industry”. Let’s take into consideration that is a number from an industry PR organization which has a vested interest in having that number as high as possible for existence justification propaganda purposes. When you are an industry so under the gun for so many negatives you tend to focus on a few selling points. Two of them are almost always how much you contribute to the economy and how many jobs you are providing. I will hold the economic argument in abeyance for now.
Is that 6000 well paid full time fish farm jobs. I hardly think so. How many seasonal, how many part time, how many not on the north island, how many less is it with the closed farms, how many supplier employees who provide say toilet paper and for which those net pens represent only a tiny % of their business insufficient to have them throw their common sense and conscience out the window.
I have a young relative who once work on a fish farm as a starter job. Kind of like you first, part time, low pay job at MacDonald’s. He got himself some education and a good job real quick after that eye opener, but he counted in their numbers. Consider all that and then compare the number of workers and their families and contrast that against the total population of the north island. I have family in the north island and know a fair number of people there, fish Pacific salmon and attend fish and wildlife fund raising events there. You may just find that there are a lot more people who oppose this industry out of informed concern than support it out of financial self interest, even in the North Island.
No political party would want to alienate even a single voter, especially before an election but don’t over estimate the power of a handful of fish farm employees and their families. The NDP is not unsupportive of the Industry but they also are going to continuously feel the same political pressure that pushed the liberals towards this pre election announcement.
The political power of the industry is not in the votes it more or less directly influences because of jobs; it is in the dollars they have available to influence political parties and conduct massive professional PR campaigns including on this forum. Even with that in my opinion they are not winning the PR war and slowly losing ground. If that continues parties of all political strips are going to begin to distance themselves from the industry and that money may look a little less inviting.
To put your argument about the “anti” fish farm vote (and you have their terminology down) being watered down and inconsequential in the rest of the province into perspective; please consider within a few kilometers of where I live that are hundreds of thousands of voters across a number of ridings. I believe the majority of them have concerns about this industry and even the Greens can elect down here. They are certainly not all single issue voters by any means but there are many for whom this is a very significant issue. Their numbers are orders of magnitude higher than the single issue self interest fish farm voters of the North Island. All parties would be foolish not to take that into consideration.