Herring and other clupeid fishes are very common in fish meal.
However, a number of other fish could be added if available, as rendering plants will take whatever meat or offal they can get their hands on.
NLS has fancy ingredients, but we just ran a study using fish meal from another species and it performed even better than herring fish meal. I can't reveal the species yet, as I won't be publishing the study for another 6-12 months.
In aquaculture you usually see fish meal, but also poultry by-product meal, feather meal, bone meal, blood meal, etc...This is because the fish meal in your pet food is NOT SUSTAINABLE. These fish are at the base of the food chain and their numbers are dropping due to the fish meal market. Prices have doubled in the past decade or so if I remember correctly. In aquaculture there is a huge push for finding fish meal replacements. Sturgeon have been grown well without any fish meal using mixes of the other stuff I mentioned. Tilapia can be grown on mixed plant / soybean meal. Casein works well with lots of species but it's super expensive since it comes from milk.
Prices for products like NLS will rise unless they can develop other protein and fat sources, but it is unlikely that they can since nutritional needs beyond fish meal vary so much from one species to another!