Course:EOSC270/2023/Group 11- Impacts of shark chumming (for research & ecotourism)

From UBC Wiki

What is chumming?

Chumming is a practice used to attract larger fish by luring them with a form of baitfish. Chum refers to a mixture of prey-fish segments and shedding tissues, including blood, fat, skin, etc.[1] This differs from bait, which is the full fish or large segments like fish heads. The act of chumming often uses both chum and bait in combination. Chumming is particularly common during shark diving operations because it brings sharks to the surface and has been associated with sharks spending more time in close proximity to the boat[2]. There is ongoing concern and debate about the effects of attracting sharks to boats and humans in the ocean, which has led to some regional prohibitions of shark provisioning tourism; tourism that involves unnaturally feeding a predator to promote their aggregation. However, there currently lacks sufficient data to quantitatively confirm these effects[3].

Interns from Oceans Research are chumming to lure Great White sharks for research purposes. Above, frozen baitfish heads attached to a rope and buoy are used, and below, frozen fish guts are being poured overboard to create a scent trail to the boat for sharks to follow. (Source: Jenna Lehocki, Date: June 2022, Location: Mossel Bay, South Africa)

Some common chumming techniques include:

  • Frozen and fresh chum: Chum can be made by adding frozen and fresh fish chunks to water, then stirring and breaking apart the chunks to create a slurry of decomposing fish. The watery chum mixture is dumped overboard, creating a scent trail that attracts predators toward the boat. Although often effective at attracting a target species, chum can also affect the local water’s nutrient balance because it increases biological oxygen demand, thus reducing levels of dissolved oxygen in the water[4].
  • Frozen bait: Frozen bait is used in shark provisioning when frozen fish segments, like heads or tails, are tied to rope and a flotation device, and casted manually to lure predators as the bait is pulled in towards the boat. Frozen bait and chum may also be used in combination, and one study showed that when sharks interact with both, there is a significant transition toward feeding behaviours that was not clear when only frozen bait was used[1].
  • Bait bucket: Bait may also be put into a plastic bucket with holes that let the scent out[5] or an organic fibre bag, and tied to a line and buoy[1]. This is a common practice used for baited shark dives, where the divemaster drags along the bait bucket to attract sharks toward the divers.

Common motivations for chumming include:

  • Scientific Research: Chumming can be used to attract sharks to the boat so researchers can collect photo IDs or tag the individuals for studies of shark movement and migration patterns. One effective way of identifying sharks is through dorsal fin ID because individuals have unique pigmentation and scarring patterns. Thus, chumming is used to bring the shark to the surface near the boat, so researchers can capture a clear and identifiable photo of the dorsal fin.
  • Ecotourism: As discussed, chumming and baiting are very common practices within the shark-diving industry. Shark ecotourism has both economic and conservation potential[2]. For example, shark cage-diving in Guadalupe alone is estimated to make more than US$4.5million each season in revenue[1]. The industry often promotes shark education and profits can contribute to further research or conservation efforts.
  • Fishing: Chum is evidently a useful tool for attracting more fish thus increasing catch amounts, and also depending on the type of bait used, fishermen can target the specific species they are after[6].

The effects of chumming are not well-studied and the debate of whether benefits outweigh the costs is ongoing.

What are the impacts?

Negative Impacts

As mentioned above, Chumming is a technique used to lure in sharks for research benefits as well as ecotourism. Although, with its popularity, it is a very controversial topic because of its risk to humans and other ecological impacts, including[7]:

Change in Behavior

Studies have proven that chumming can have a negative impact by conditioning the sharks to associate humans with food as well as altering their behavior[8]. Sharks can become dependent on chumming as their source of food, causing sharks to become detached from their natural habitat[9]. With chumming, sharks lose the urge to hunt on their own –they become accustomed to being fed by humans. This can cause problems because once the chumming stops, the sharks will lack the skills to hunt on their own and they will starve. It has also been discovered that there was an increase in aggressive behavior towards other species, as well as their own[10]. This was linked to the reduced migration of the surveyed sharks because they no longer had to hunt for food. This reduced migration can eventually lead to inbreeding within the surveyed sharks which could potentially cause genetic disorders and mutations - harming future shark offspring[10].

A marine food chain illustrating the type of species sharks eat. Image is from Encyclopedia Britannica.

Disruption of the Ecosystem

With chumming, there is potential for more than just the sharks to experience consequences.  A shift in the dynamics of the whole food web could occur since sharks are no longer hunting for their own prey[9].  For example, if a shark stops feeding on tuna or salmon, then there will be a larger abundance of that prey species. This could cause an overpopulation of salmon or tuna which will lead to increased marine resource consumption because the overpopulated fish species are consuming a large portion of the available resources. That being said, there will be more competition for these resources within a species and between species which could be detrimental to other marine organisms because of the reduced resource availability[11].

Overall, long-term shark-baiting can have many detrimental effects on all species in the marine ecosystem as well humans above the surface of the ocean.

On a baited shark dive with Calypso Dive Charters, divers are using a bait bucket to attract Lemon sharks and Bull sharks. (Source: Jenna Lehocki, Date: January 2023, Location: Florida, USA)

Positive Impacts

Chumming, while disruptive to shark environments and natural instincts as stated above, is also often considered as a relatively safe method of gathering sharks for specific needs and concerns.[12]

Chumming for Research

There is a growing desire to fully understanding the roles apex predators undertake in day-to-day life[2].Permitting investigations on marine mammal statistics while they are still in their habitat using chumming to direct the animals prevents complete deracination or removal from their natural environment. Some expeditions, such as the Eastern Adriatic chumming in July-August 2005, use various techniques tailored to specific environments (2005)[13]. These techniques include assorted baits being sunk to specific depths to prevent as much displacement as possible[13]. This type of natural observation allows for faster results on marine issues that in turn help the populations observed[13]. Chumming also allows for studies on behavior that has limited evidence as many sharks are solitary[14].

Chumming for Ecotourism and Fishing Industries

Within the tourism industry, chumming is beneficial for economic gain of tourism-focused countries that offer marine explorations such as shark diving. In South Africa a survey found that 88.5% of tiger shark dive participants supported chumming use for a more up close experience while 95.9% felt safe throughout the dive[12]. Along with this, the recreational fishing industry is a crucial part of the economy in coastline communities[15]. Without the practice of chumming the dimmed success of these charters could negatively affect the groups with deep cultural fishing roots[15]. While not a positive impact, many systems in place for humans in some way rely on aspects of the chumming industry and would struggle to overcome adjustments made to the restrictions on chumming in the tourism, fishing and/or research industry.


Shark Cage Tourism Regulations
Permitted cage dive operation sites around Neptune Islands, Australia (shown in red)

Regulations depend on the country and local jurisdiction; many countries have been changing their restrictions to account for the developing shark dive industry. As stated in a shark cage dive management review[16], new regulations are to focus on possible long-term effects like restricting diving areas and setting temporary site closures. Restricting cage dives to naturally concentrated shark areas prevent operators from needing to lure sharks and having temporary site closures reduces the chance for sharks to become conditioned or develop expectations from cage dive groups. For example, Australia’s shark cage dive industry is restricted to Neptune Islands and has limit of 10 operation days every 2 weeks.

Regulations for cage dives in New Zealand are only restricting consumption of bait, meaning bait can be used to lure in sharks during a dive but cannot be given to sharks. In comparison, California’s shark cage tourism in prohibited to use any chum or bait, South Africa has a 25kg daily bait limit for an operator and as noted during research around Guadalupe Island, Mexico[17], chum is used during cage dives.

Enforcement and Management

The effectiveness of regulations is reliant on the country’s level of enforcement, while some countries have large restrictions, limited resources can make it difficult to monitor and enforce them[18]. These regulations are important for the health and safety of sharks and is crucial that they are consistently enforced to operators. In South Africa, the Department of Environmental Affairs and Tourism (DEAT) has been inadequate and publicly known as inconsistent with regulation enforcement[19]. They have had issues with following through on fines and have ambiguous permit guidelines to feeding sharks during shark dives, leading to poor self-enforcement for operators.

For many countries, the usage of a daily logbook is being introduced for easier management for local authorities as well as for research. The purpose is for operators to keep track of activity during their cage dives, including bait and chum usage (if permitted) and shark behavior[16]. In research done by Nazimi et al.[20], past logbook data and photos from a cage dive operator in South Australia was used to help study shark behavior patterns in reaction to the cage dives, allowing further research for shark and human interaction impacts. In countries like New Zealand and Australia, management plans have allowed only a small number of registered operators (Bruce, 2015), making it easier to manage and monitor regulations. The usage of permits allows for easier management of company operations as renewal is necessary on a yearly or multi-year basis. Permit renewal also allows or operators to review protocols set to protect sharks.

Possible Alternatives to Chumming

Even with certain regulations, chumming to attract sharks for research and ecotourism can cause damaging behavioral issues with sharks, such as aggression towards humans and dependency for food sources [21]. This can cause a negative chain reaction effect on marine ecosystems[9]. Although chumming has many negative impacts, it also has many positive impacts. Shark ecotourism is very beneficial for the economy[12], as stated above. As well, chumming allows for important research on sharks and their environments to be conducted[2]. In order to diminish the negative impacts of chumming but also continue to gain the positive impacts, an alternative method must be used. Some alternative methods include:

Aerial Surveying
Aerial Surveying of a group of basking sharks off the coast of New England. Captured on October 11th, 2022 by NEAq Aerial Survey Team using an aerial surveying plane.

One alternative is the use of aerial surveying, which uses drones, helicopters or surveying planes to help record the movements and number of sharks in a desired area. Aerial surveying can find sharks and predict their location for future research or ecotourism without using chumming, but can also be much more expensive, as an average research drone can cost from $50 to $10000[22]. Aerial surveying is being used in many different places around the world. The National Marine Fisheries Service of NOAA in the USA has seen many positive effects using aerial surveying for research purposes in order to protect marine species under the Marine Mammal Protection Act[1]. In Europe, Aerial surveying has been used in European Atlantic oceans and the Mediterranean[1].

Migration Tracking

Another alternative to chumming is using migration tracking from underwater[6]. Scientist can track the movement and location of sharks that have been previously tagged using tracking devices installed on seamounts, which can then allow them to find sharks and other species at a future time and date. This alternative works by signaling and notifying researchers the location of the sharks via the satellite tracking devices. Again, this alternative is far more expensive than chumming, but is safe to both sharks and their ecosystems. Migration tracking also allows for immense amount of research to be on the same sharks, over a long period of time.


The final alternative for finding sharks for research and ecotourism purposes is diving[6]. Diving is not nearly as expensive as aerial surveying or underwater migration tracking. This alternative requires a SCUBA qualification and a substantial amount of time to locate the sharks. It is also not a guarantee that tourist will see sharks when diving, but is highly likely with the right professionals and locals. Diving can benefit researchers and tourist to experience the true behavioral characteristics of sharks while protecting their ecosystems.

All of these alternatives are just as effective in collecting data as chumming, but have their own individual negative and positive effects. The negative impacts for these three alternatives include cost, time and experience. Although, practicing these alternative methods can protect not only sharks, but their entire ecosystems as well.


  1. 1.0 1.1 1.2 1.3 1.4 1.5 Becerril-García, E., Hoyos-Padilla, E., Micarelli, P., Galván-Magaña, F. & Sperone, E. (2020). Behavioural responses of white sharks to specific baits during cage diving ecotourism. Scientific Reports, 10. Cite error: Invalid <ref> tag; name ":9" defined multiple times with different content
  2. 2.0 2.1 2.2 2.3 Jacoby, D., Fairbairn, B., Frazier, B., Gallagher, A., Heithaus, M., Cooke, S. & Hammerschlag, N. (2021). Social network analysis reveals the subtle impacts of tourist provisioning on the social behaviour of a generalist marine apex predator. Frontiers in Marine Science, 8. Cite error: Invalid <ref> tag; name ":7" defined multiple times with different content
  3. Hammerschlag, N., Gallagher, A., Wester, J., Luo, J. & Ault, J. (2012). Don’t bite the hand that feeds: assessing ecological impacts of provisioning ecotourism on an apex marine predator. British Ecological Society, 26(3), 567-576.
  4. Babcock, H. (2007). Chumming on the Chesapeake Bay and complexity theory: why the precautionary principle, not cost-benefit analysis, makes more sense as a regulatory approach. Washington Law Review, 82(3), 505-532.
  5. Caldwell, P. (2011). Shark bait. Medical Post, 47(2), 22-23.
  6. 6.0 6.1 6.2 Brownlee, J. (2019, October 23). How to fish with chum. SaltWater Sportsman.
  7. Meyer, Carl G. (Summer 2009). "Seasonal cycles and long-term trends in abundance and species composition of sharks associated with cage diving ecotourism activities in Hawaii". Environmental Conservation. 36: 104–111 – via Science Direct.
  8. Laroche, RK (May 24, 2007). "Effects of provisioning ecotourism activity on the behaviour of white sharks Carcharodon carcharias". Marine Ecology Progress Series. 338 – via Inter-Research Science Publisher.
  9. 9.0 9.1 9.2 "Does Baiting Sharks for Photo Ops Have Long-Term Consequences?". Animals. October 16, 2016. Retrieved February 7, 2023.
  10. 10.0 10.1 Clua, E (September 13, 2010). "Behavioural response of sicklefin lemon sharks Negaprion acutidens to underwater feeding for ecotourism purposes". Marine Ecology Progress Series. 414 – via Inter-Research Science Publisher.
  11. "Why do We Need Sharks for Our Ecosystem?". Oceans Research. September 20th, 2021. |first= missing |last= (help); Check date values in: |date=, |archive-date= (help)
  12. 12.0 12.1 12.2 Dicken, M. L.; Hosking, S. G. (November 1, 2008). "Socio-economic aspects of the tiger shark diving industry within the Aliwal Shoal Marine Protected Area, South Africa". African Journal of Marine Science. 31: 227–232 – via Taylor & Francis Online.
  13. 13.0 13.1 13.2 Soldo, Alen (November 11, 2005). "Shark Chumming in the Eastern Adriatic". Annales. Series Historia Naturalis. 15: 203 – via UBC Library.
  14. Findlay, R.; Gennari, E.; Tittensor, D P. (2016). "How Solitary Are White Sharks: Social Interactions or Just Spatial Proximity?". Behavioral Ecology and Sociobiology. 70: 1735–1744 – via ProQuest.
  15. 15.0 15.1 Babcock, Hope M. (2007). "Administering the Clean Water Act: Do Regulators Have 'Bigger Fish To Fry' When It Comes To Addressing the Practice of Chumming on the Chesapeake Bay?". Tulane Environmental Law Journal. 21: 33–34 – via JSTOR.
  16. 16.0 16.1 Bruce, Barry (November 2015). "A review of cage-diving impacts on white shark behaviour and recommendations for research and the industry's management in New Zealand" (PDF). Report to the Department of Conservation New Zealand.
  17. Aquino-Baleytó, Marc; Leos-Barajas, Vianey; Adam; Hoyos-Padilla; Santana-Morales; Galván-Magaña; González-Armas; Lowe; Ketchum (October 2021). "Diving deeper into the underlying white shark behaviors at Guadalupe Island, Mexico". Ecology and Evolution. 11: 14932–14949.
  18. Ward-Paige, Christine (2017). "A global overview of shark sanctuary regulations and their impact on shark fisheries". Marine Policy. 82: 8–97.
  19. Johnson, Ryan; Kock, Alison (2006). "South Africa's White Shark cage-diving industry-is their cause for concern" (PDF). Finding a balance: White shark conservation and recreational safety in the inshore waters of Cape Town, South Africa. 3: 40–59.
  20. Nazimi, Leila; Robbins, William David; Schilds, Adam; Huveneers, Charlie (2018). "Comparison of industry-based data to monitor white shark cage-dive tourism" (PDF). Tourism Management. 66: 263–273.
  21. Brunnschweiler, Juerg M.; McKenzie, Jonathan (2010). "Baiting sharks for marine tourism: Comment on Clua et al. (2010)" (PDF). Marine Ecology Progress Series. 420: 283–284.
  22. "Guide to How Much Drones Cost". 2022.