The Flash Debate: Are We Harming Marine Life?

In this article from The Underwater Photography Show, we'll be tackling a critical question often asked by divers and non-divers alike: Does the use of strobes harm the critters we photograph?

The concern usually centers on whether flash stresses animals, temporarily blinds them, or even damages eyesight. While as photographers we rely on flash to restore color that is lost at depth, it is vital to ask ourselves if it could be causing stress or harm.

What We See

As underwater photographers with a passion for marine life and love of capturing natural behavior, we would never want our photography to be causing undue stress to marine creatures. And that is generally what we see. Most underwater photography takes place in shallow, tropical waters, which are naturally very bright. Furthermore, light levels where we dive are not constant like on land, but constantly flickering as the sunlight plays through the surface of the sea. What every underwater photographer will tell you is that it is very, very rare for any underwater animal to show any reaction at all to flash. Importantly, if they do, you should stop shooting them and move on. This will benefit the animal, but it will also benefit your photos, because a stressed subject will never yield good images.

What the Science Says

As well as our own experiences, we are aware of two marine scientists (and their co-authors) who have set out to study this scientifically and have published their results in peer-review literature. Both David Harasti¹ and Maarten De Bruawer² have studied this issue on a variety of species. Their peer-reviewed studies have led to several consistent conclusions:

• Negligible Effects: Flash itself has almost no discernible impact on an animal’s behavior, movement, or feeding success.

• No Physical Damage: Even in laboratory conditions with light much brighter than standard underwater strobes, no permanent damage was found in the eye anatomy of the subjects.

• Natural Adaptation: In shallow water, marine life is already adapted to "flickering" light levels caused by sun rays playing through the surface, which is very similar to an instantaneous flash.

The Real Impact: Physical Contact

The most important takeaway from this research is that physical contact is far more damaging than light. While using a flash is generally okay, prodding, poking, or touching a subject with your fingers or a pointer stick causes measurable changes in behavior and stress levels.

Ethical Photography Practices

Even if the science says strobes don’t stress, we believe the empathetic photographer should always adopt a sensitive approach to every subject. Here are some guides for ethical shooting:

1. Avoid Physical Handling: Never touch or move a subject into position.

2. Monitor Reactions: If an individual animal reacts negatively to flash or flinches—move on and find another subject.

3. Mind the Species: Be more sensitive with slow moving subjects that can’t just swim away, nocturnal animals or invertebrates, as their eyes may function differently than the fish studied in current research.

4. Avoid "Spray and Pray": Just because modern strobes can fire at 10 frames per second, it doesn't mean that should be our standard way of shooting. High-intensity rapid firing should be minimized for ethical reasons, and used only when it will reveal something specific in the subject.

When to Skip the Strobe: Ambient Light Techniques

There are many situations—such as when diving with schooling hammerheads or in areas where strobes are restricted—where shooting with available light is actually the preferred technique.

In heavy currents, strobes add bulk and drag, making your camera harder to maneuver. Furthermore, strobes often just light up the "crap" or backscatter in the water between you and a more distant subject. For silhouettes of sharks or large schools of fish, ambient light captures an atmosphere that strobes simply cannot.

Positioning with the Sun

• For Detail/Color: Position yourself so the sun is behind you and hitting the subject directly.

• For Silhouettes: Position yourself so the subject is between you and the sun.

• Patience is Key: If you see a school in the distance, don't chase them. Let them come to you, while you think of where the sun is. Move slightly toward them to get light on the subjects when they pass, or swim away from it to get them in silhouette.

The Digital Darkroom: Processing Ambient Shots

Because available light shots lack the "kick" of a strobe, they require specific post-processing steps to make the subjects pop. Here are a few tips:

• Boost Contrast and Clarity: Use the Contrast, Clarity, and Dehaze sliders to overcome the lack of natural punch in ambient light.

• Subject Masking: Use subject selection tools in Lightroom to isolate the marine life.

• Refine the Mask: If the subject is lost in the murk, paint over them and then deselect the blue background to ensure your mask is accurate.

• Drain the Color: For subjects like sharks, perform a white balance adjustment on the animal and then drop the saturation so they appear grayer and more distinct from the blue background.

• Raise the Whites: Increasing the "whites" selectively on the subject can help them stand out from the water column.

Ultimately, whether you use a flash or rely on the sun, the best pictures come from a place of respect for the environment.

¹ D Harasti, W Gladstone. Does underwater flash photography affect the behaviour, movement and site persistence of seahorses?

² Maarten De Brauwer, Luke M Gordon, et. al. Behavioural and pathomorphological impacts of flash photography on benthic fishes