Around here, elementary schools had the most basic sports programs - baseball/softball, football, basketball... My school system was in the city, but was cut out of the main city school system. Our school system also had a far smaller black population, just due to where it was cut out.
Now, now that I'm out of school, it is easier to find soccer and other sports programs. But programs not a part of the school tend to require full equipment coverage on your own, versus little had to be owned when starting in a school-provided sport.
So, in my schools, black athletes were really spread basically evenly across the sports, until high school where football was the biggest one, but our basketball team was rather evenly split. Baseball, I don't know about our baseball program... it was pretty political and run in a way I didn't approve of. I had a bad showing when trying out (injuries), plus I wasn't from the elementary school that the best players were from (their school always kicked our ass)... but regardless, I knew a lot of people bailed that and went to other leagues outside the school. But I digress...
money and popularity tend to be the factors. That and location. The Northern states, where hockey is more common with youth due to local ponds freezing and whatnot, tend to have a smaller black demographic. It seems most black hockey players are from the Northern states, and they might be from better schools with hockey programs, or just got interested in it due to hanging out, with well... likely white kids playing hockey. It's far from a popular sport amongst the demographic to be honest.
A lot of factors go into it like I mentioned... geography, school sports programs, who kids hang out with and what they like... it's not entirely an issue of race, however the way the racial demographics play out with the aforementioned factors all comes together. Nothing racist about it, it's just how things have come together. Little things here and there end up playing a big part in shaping an individual's interests. There are also the ones that break away against all common logic out of pure curiosity, but those are very few and far between. The others are just products of their surroundings.
Just like you have a few people who grow up in the ghetto and surrounded by the thug life, and eventually break away and make something for themselves, while the majority continues to live according to their surroundings.