The spider cracks are in the non skid portion , it appears. It is very difficult to replace that to look like the original.. and pretty expensive. I would consider just resurfacing the entire nonskid area with a product like
KiwiGrip.... I recently covered all my non skid with it.... my old decking was worse than yours...and I was very pleased.... made the 40 year old boat look like new.
Another popular method is to cover the areas with a tile like product such as this Treadmaster.
If you google "yacht non-skid systems" you will find many choices.
That said.... I would not be afraid to try brushing on a thinned primer that will sink into the cracks... then finish with a similarly thinned coat of non skid deck paint.... if that doesn't work to your satisfaction you can go to the cover method.