This post belongs to a series written by students in the Conservation Biology course BSC4052 at the University of South Florida. This course provides an overview of major themes in conservation practice and related applied problems in biology, including: population ecology in the context of conservation, patterns of diversity, valuing diversity, threats to diversity, management actions and strategies for preserving diversity.
Taylor Mattson is a junior majoring in Environmental Biology with a minor in Geographic Information Systems and Technology at the University of South Florida. Learning about the environment and ways to protect it has been a passion for Taylor ever since she was young. She currently volunteers in an ecology lab at her school and after graduation she plans to pursue a master’s degree. In her free time Taylor enjoys drawing and skateboarding
Reference Article: Cardeñosa, D. 2019. Genetic Identification of Threatened Shark Species in Pet Food and Beauty Care Products. Conservation Genetics 20:1383–1387 https://doi.org/10.1007/s10592-019-01221-0
There’s power behind every purchase we make. Companies make and sell products based on consumer demand, and we as consumers have a right to know what we are putting our dollars behind. Recently, a study has identified trace levels of threatened shark species in various pet food and cosmetic brands. While this alone is troubling, what’s more concerning is that these products have failed to include shark products on the ingredient label.
Importance of Sharks in Ecosystems
Sharks play an important role as an apex predator in their environment. Apex predators are at the top of the food chain and regulate the prey populations below them. For example, sharks keep the fish populations they hunt from growing too large. Therefore, if a shark species were to vanish from an area, the populations of its prey in that area are likely to increase and this in turn can have consequences for other parts of the food web (e.g. the prey of the sharks’ prey, or other predators that feed on the same prey as the sharks).
Sharks are very sensitive to human exploitation. As top predators, they usually have small population sizes. Individual sharks grow and reproduce at a slow rate which means that their populations do not increase quickly. For these reasons, it is difficult for shark populations to replenish from over harvesting. It is well known that sharks are often caught for their fins and meat. Less known is that sharks are also harvested for squalene, a common ingredient in cosmetics.
Many species of shark are now threatened or endangered as a result of human influence (over harvesting, habitat degradation, etc.). Great effort should be put into conserving shark populations due to both their critical role as predators and their fragile populations. This effort includes informing consumers, through proper ingredient labeling, of products that are potentially contributing to the unsustainable harvesting of sharks. To better understand the extent to which shark components are contained in products, a scientist at Stony Brook University , Diego Cardeñosa, conducted an experiment utilizing a technique called genetic barcoding to identify shark DNA in pet foods and cosmetics. Genetic barcoding involves analyzing the DNA of an organism to identify the species it belongs to.
How Shark DNA was Identified
All the pet foods and cosmetics tested in Cardeñosa’s experiment were purchased in the United States. After purchase, DNA was then extracted from samples of each product. The extracted DNA was then amplified using a technique called PCR, which stands for Polymerase Chain Reaction. Basically, this technique involves isolated DNA that is copied over and over to create many copies of the desired DNA fragment, in a process known as “amplification”. Amplifying the DNA makes it easier to identify the species to which the DNA belongs. The DNA sequences that were isolated and amplified from the samples were compared to a DNA database called BLAST to determine what species were present in the products.
Sharks are Friends, Not (Pet) Food
In his study, Cardeñosa analyzed 87 pet food products from 12 different brands for traces of shark DNA. All the pet foods tested were generically labeled with ingredients such as “ocean fish” and gave no indication of containing meat from sharks. Of the 87 different pet foods analyzed, 21 pet food products were identified as containing shark DNA. The two shark species identified in these pet foods were the shortfin mako shark and the blacktip shark. These results are particularly alarming, since the shortfin mako shark is an endangered species.
Shark Squalene in Cosmetics
Squalene used in cosmetics can either come from plant sources or from sharks, however many products fail to specify where the squalene is sourced from. Cardeñosa tested 24 cosmetics from 15 different brands which did not indicate on their labels whether the squalene they contained was plant- or shark-based. Of the products tested, three were found to contain shark DNA. Traces of blue shark, scalloped hammerhead shark, and blacktip shark species were found in these products. Of which, the scalloped hammerhead shark is an endangered species.
Looking to the Future
Only a small proportion of pet foods and cosmetics on the market were tested, but the fact that a substantial proportion of products tested contained shark is alarming and suggests that more widespread testing should be done to better assess the extent of this problem. As genetic techniques continue to improve, the proportion of products found to contain sharks might increase.
This study was able to highlight a weakness in regulation and enforcement of labeling. The consumer has a right to know what they are purchasing and where it comes from. When enough consumers are not satisfied with what is in their products, they can motivate industry to change their practices by refusing to support companies that mislabel their goods.