Spearfishing and Blackouts

Disclaimer: The information in this article is not intended to replace the education and training from a freedive course taken at a professional agency. The Monterey Bay Tritons encourage all divers to take a freedive course as the most proactive and important approach to safe and responsible diving.

If you have not watched a freediving competition, do yourself a favor: prepare some homemade gyoza appetizers, open up YouTube, then search for “AIDA World Championship Freediving”. Now, invite some of your freediving friends over and nerd out on one of the various 3+ hour competition videos covering different disciplines. Even if you are not interested in competitive apnea, it is valuable for any breath-hold diver to be aware of signs and symptoms of hypoxia. A competition exposes a person to an array of other divers that are pushing themselves to their absolute physical and mental limits. An overlooked benefit to the observer is that you can see how professional divers are managing hypoxia after surfacing.  Some of these athletes are not so lucky. After surfacing they may experience a loss of motor control (LMC) or a blackout (BO) event. While an athlete who is competing may be diving deeper and longer than a person spearfishing, we cannot undermine the reality of BO events in spearfishing. While they are just as real as the BOs in competitions, they are more dangerous due to the wild, uncontrolled environment that spearos are usually diving in.

Terminology + Misconceptions

Adam Stern returns to the surface after a line dive.

Before going deeper, let’s pause for a dumpling so we can define terminology and clarify certain misconceptions. A diver may experience a near BO event, also known as a loss of motor control or LMC - if they are hypoxic enough to show signs and symptoms of hypoxia, but they are not hypoxic enough to lose consciousness. So how do we define a BO event? It is the state at which the diver has lost consciousness, and it sets in when hypoxia continues to carry on after the diver exhibits signs/symptoms of LMC. Hypoxia can creep in when the oxygen supply to the tissues in the body decreases below safe levels. Euphoria or confusion as well as contractions are characteristic symptoms linked to hypoxia. We know of two types of hypoxia in the world of apnea diving. Various agencies define these differently: one type is observed when the diver engages in static apnea (where they are not diving) and thus are not exposed to varying hydrostatic pressures, and the other type is seen when the diver descends to and ascends from depth. For the sake of this article, let’s call the two types of hypoxic events no-depth and depth hypoxia, respectively. 

A diver engaging in static apnea may be able to hold their breath for over 4 minutes with no signs or symptoms of hypoxia, but the same diver may experience strong hypoxia only after a 30-40 second dive to 15-20m depth. During descent the pressure exerted on the diver increases, and so does the oxygen pressure within their tissues and blood. As a result, it is easier for the respiratory and cardiovascular systems to use the oxygen present in the body the deeper one descends. As the diver ascends they are no longer exposed to great pressure of depth, and given the fast rate of ascent/descent, oxygen absorption by tissues becomes more difficult. Onset of hypoxic symptoms may be observed without the gradual warning signs one may experience while they are doing a static breath-hold. Due to the rapid change in pressure, the diver may experience BO without feeling very hypoxic.

“Shallow Water Blackout”

You may have heard the term Shallow Water Blackout before. Generally speaking, BO events happen at shallower depths. From recorded history, 90 percent of BO’s happen once the diver has reached the surface, with 9 percent on the ascent within 15 feet of the surface. Only 0.9 percent of BO’s occur between 15ft and 85ft range and 0.1 percent occur deeper than 85ft. From this data we can infer that 99 percent of BO’s happen between the surface and 15ft of depth, hence the term shallow water blackout. What causes a blackout? Myriad variables can contribute to a blackout. Pinning down the exact reason why a diver has experienced BO is not easy, it can be anything from the increase in CO2 levels creating blood flow restriction, or excessive hyperventilation and reduction in O2 levels, or the sharp change in hydrostatic pressure in the last stage of ascent. Regardless of the reason, disastrous results of a BO can be avoided under the watchful eyes of safety diver(s).

In a freediving competition, it is not uncommon for a significant number of competitors to experience BO. Generally, divers are queued up and once the first athlete finishes the dive, the second diver prepares to dive on the same line, and the queue continues until all divers get a chance at attempting their target dives. Do not be surprised if you come across competitions where almost one third of competitors are disqualified due to a BO event, one after another surfacing and falling back into the water like sacks of potatoes. 

The beauty of competition is the presence of a controlled environment. Yes, the divers are diving to ungodly depths, but they are tethered to the dive line, a trained safety team is always present, live streaming underwater cameras are always running, safety divers have scooters, and the medical personnel to care for the diver in case of an emergency is on call at the site. In such a controlled environment a BO event can be resolved within seconds. The question you need to now ask yourself is, “does the same hold true when spearfishing?”

Blackouts + Spearfishing

While it is true that a large number of athletes may experience BO in a freediving competition,  the percentage of participants that BO in a spearfishing competition is comparably lower; BO events are rarely recorded in spearfishing competitions. A competitive diver may be pushing beyond their physical limit for a single dive, while an apnea hunter might swim around with a speargun for hours at a time making endless drops to find fish and forage seafood. Both divers are exposed to hypoxia as they engage in apneic activities, therefore they are both at risk for blacking out, and thus their activity must be done under the watchful eyes of a trained safety diver(s). 

Even though a freediving athlete may be diving substantially deeper and stay down considerably longer than a person spearfishing, blackouts in spearfishing are more dangerous. When spearfishing, more than likely the underwater hunter is driven by the desire to find good quality fish. Unfortunately, the seas are not always inviting, and it is unlikely that every session will be ideal - free from current, wind, poor visibility and surge. Surface currents, wind chop, boat traffic and marine life are all added variables that may introduce different levels of complexity, requiring you to constantly create solutions while diving. This is already stressful enough, adding a BO event to the mix significantly complicates the outcome.

Dive Stages

While hunting underwater, if a diver is “staying within their limit” and experiencing symptoms of hypoxia, it is true to assume something is incorrectly executed. The diver could be pushing past their capacity, lacking sleep, being sick, hung over, dehydrated, suffering from bad diet, poor technique, experiencing fatigue, incorrectly breathing up, not spending enough time during their surface interval, or unable to relax, ect. BOs or hypoxic events should not be occurring. If the diver is physically and mentally prepared and dive-fit, every drop should feel clean and relaxing, in other words, no dive should feel uncomfortable, intimidating or tiring. Before each dive, an appropriate amount of time on the surface must be spent ventilating, relaxing and re-oxygenating the blood. When the hunter feels ready to dive, all stages of the dive must be executed seamlessly to avoid injury. These stages can be grouped into 3 categories. Pre-dive stage, dive stage, post-dive stage. 

In the pre-dive stage, the hunter just needs to relax and ventilate. Everyone has a different breathing regimen before a dive but generally is something to the tune of “inhale for 4-5 seconds” and “exhale for 8-10 seconds.” During this stage, the idea is to lower the heart rate and oxygenate the blood while relaxing. After the hunter has finished ventilating on the surface, a peak inhale is taken and the snorkel removed (this is important!), and with a proper “duck-dive”, the descent begins while kicking wide and strong to achieve depth. As the diver descends during the dive stage, they are paying close attention to head position, keeping the chin tucked into the chest and avoiding looking up or down will allow for the safest dive. During this stage, the goal is to relax, get to the bottom, find the fish, and return to the surface. As one can imagine, this is where the action happens.  

The most important stage has yet to come. Finally, we enter the post-dive stage, where the diver has finished the hunt and reached the surface after significant anabolic activity. From a systematic viewpoint, the muscles have built up lactic acid, CO2 levels have increased, O2 levels have decreased, blood pressure has changed. The hunter is at a critical point, and may experience hypoxia if the post-dive stage is not handled properly. This is where the all important “hook breaths” and “cleansing breaths” come into play. Together they make up recovery breathing. After each dive, the diver must engage in three hook breaths, followed by three cleansing breaths.  Hook breaths are done by taking a full inhale and filling the top of the lungs, ie. the intercostal muscles, and holding for 3 seconds to increase blood pressure, then exhaling in one second, and repeating this for 3 times. Cleansing breaths are executed by taking one second inhale and one second exhales for 3 times. This will help naturally offset the variables that may cause the diver to experience a BO. A wise diver would make this process a habit after every single dive no matter how shallow or short their dives are. It should become muscle memory so that if or when a hypoxic event occurs, it is second nature to accomplish.

Team Work

While spearfishing, dive buddies should always be diving in one-up-one-down fashion, regardless of where or what conditions they hunt in, whether the hunt takes place in cold and dark waters of California amongst the thick kelp beds or warm and clear waters of Hawaii. As a safety diver, awareness of your buddy’s dive time is essential; if the diver exceeds average active dive time by dangerous levels, a safety can immediately go down to assist. As discussed earlier, the probability of an apnea diver experiencing a BO at depth is low, but it is not zero. Chances of a BO on the surface are very high, and in addition to knowing the average active dive of the hunter engaged in apneic activity, a safe dive buddy should also at all times remain within an arm’s reach of the hunter when on the surface. If the surfacing diver experiences a BO, immediate recovery of the head/neck and protection of the airways is very possible if the safety remains vigilant and within an arm’s reach of the surfacing diver. After surfacing, if the diver feels fine proceeding the recovery breathing, then an OK sign should be relayed to the safety to indicate they are lucid. After the safety observes the diver for 30 seconds, they can switch and now the diver can act as safety and the safety can go through the pre-dive, dive, post-dive stages, while the previous hunter is watching and counting the dive time of their buddy. With a game plan that involves hunters paying close attention to each other, it is very much possible to minimize the risks of BO. Other key components of safe diving practice is both divers using a floatline so the safety diver can keep an eye on the position of the hunting diver. Dive watches have algorithms to provide recommended surface intervals and freedive recovery vests auto inflate after a certain time at depth has occurred. Most importantly, however, there is nothing that will contribute to the safe and successful dive more than for both dive buddies to have taken a freedive course with a reputable institution and an experienced instructor. There is no amount of reading, watching videos, listening to podcasts or equipment you can dive with, that will benefit you as much as an instructor that can teach, watch, assist and correct your diving technique in the pool and ocean. For more information on freedive certifications, click here.

Avoiding the Black Out

Avoiding BOs during spearfishing and recreational freediving should be top priority. You should strive to be educated on what causes black outs, proper dive technique, know your limits, never dive alone and always have a safety diver vigilantly watching, while staying within an arm’s reach. Spearfishing is an activity that demands a high fitness level. Progress should be gradual. Before focusing on hunting deeper, it is more important and safer to concentrate on “owning” the current depths one operates at. BO’s are not a myth, they are as real as it gets, if no safety is present, a BO can easily have a fatal outcome. A diver trained by a professional agency such as NAUI or PFI will be more capable of assessing the situation and responding accordingly. It is a good investment to enroll in a freediving course to better understand the safety skills discussed in this article in more detail with the opportunity to practice them under the watchful eye of a trained instructor.