Create a new layer and clip it to the shark layer. Change the blending mode to Overlay. With a 3px brush at 50% opacity paint over the indicated areas.
Create a clipped Curves Adjustment layer. Drag the curve down to darken. Fill the layer mask with black. With a white brush paint over the indicated areas in the layer mask.
Create a clipped Hue/Saturation Adjustment layer. Drag the saturation slider all the way to -100. Fill the layer mask with black and with a white brush paint in the layer mask only inside the mouth to keep the redness.
Create a new layer. Choose a chalk brush. With a white color draw some little waves crashing into the body of the shark like I did in the image below.
On a new layer create some bubbles in the underwater portion of the shark.
On a new layer with a yellowish color draw something like a hook in the mouth of the shark.
Import the blood brush. Create a new layer and with a red color create a red splash near the mouth of the shark. You donï¿½t have to use the same brush I use or the same splash, most blood splashes out there will do. Use a layer mask to hide unwanted parts of the red splash.
Create a new layer and clip it to the splash layer. With a soft white brush draw some highlights on the splash.
On a new layer create another red splash using the blood splatter brush. Group the blood layers together.
On a new layer create some blood marks on the side of the shark using either the blood brush or the standard chalk brush.
Make another layer and draw some blood hanging from a tooth of the shark. Make another clipped layer to the hanging blood layer and create some shadows and highlights to make the blood look more real.
On a new layer create some blood flying from the mouth of the shark using the blood brush.
Add some shading (highlights and shadows) to the blood layer you just created. I used a couple of layers to draw with white and black and a curves layer, all clipped to the blood layer.
On a new layer cover with red the surface of the sharkï¿½s eye. Use a dark red.
Now on another layer create with a brighter red the iris.
At this step I feel that I can add more wounds to make the scene more realistic. Create a new layer and with the blood brush or the standard chalk brush create some red marks on the sharks nose. Double click the layer to enter blending mode and use the settings shown below.
On a new layer draw by hand with a black and white brush some more shading for the wounds on the nose.
Now letï¿½s make some underwater wounds. On a new layer create some wounds near the tail of the shark with a dark red. Lower the opacity of the layer to 64%.
With a round soft brush at 10% Opacity draw some red blood dispersing in the water near the wounds. Group all the layers associated with the shark and name the group “Shark” to keep the document tidy.
Open the image “Boat”. Copy and paste the boat into our working document. Convert the boat to a Smart Object. Resize the boat as shown below.