Density maps/kernel density maps

Question

I am trying to create a map from latitude and longitudes of catch locations. I was able to plot this on the map, however I would like to make densities of these locations. Therefore I have a few questions...

1. Would that require me to zoom in on only the Atlantic ocean?
2. Should the points be smaller?
3. How the heck can I map kernel densities or densities of the most used locations of these coordinates?

library(maps)
library(ggplot2)
library(stringr)
world_map <- map_data("world")
#Creat a base plot with gpplot2
p <- ggplot() + coord_fixed() +
  xlab("") + ylab("")

#Add map to base plot
base_world_messy <- p + geom_polygon(data=world_map, aes(x=long, y=lat, group=group),
                                     colour="black", fill="light green") + 
                                      ggtitle("striper reports")

base_world_messy

#Strip the map down so it looks clean 
cleanup <- 
  theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank(), 
        panel.background = element_rect(fill = 'blue', colour = 'blue'), 
        axis.line = element_line(colour = "white"), legend.position="none",
        axis.ticks=element_blank(), axis.text.x=element_blank(),
        axis.text.y=element_blank())

base_world <- base_world_messy + cleanup

base_world


map_data <- 
  base_world +
  geom_point(data=striper, 
             aes(x=Long, y=Lat), colour="Red", 
             fill="Red",pch=1, size=.2, alpha=I(0.5)) + ggtitle("striper report")
map_data