You would use a rectangle for that. Something along the lines of: 
public static final Rectangle BUTTON_AREA = new Rectangle(413,388,58,70); // (x,y,width,height)
@Override
public void mouseClicked(MouseEvent event) {
	int x = event.getX();
	int y = event.getY();
		
	if (BUTTON_AREA.contains(x,y)) {
		powerfishing = !powerfishing;
		displayImage = powerfishing ? powerImg : normalImg;
	}
}
@Override
public void mouseMoved(MouseEvent event) {
	int x = event.getX();
	int y = event.getY();
	tooltip = BUTTON_AREA.contains(x,y);
}