Humans commercially harvest many marine animals because a booming market exists above the ocean’s surface. Unfortunately, some these same animals are at risk of being overharvested, an issue that could prove dire for their populations if left unchecked. The unfavorable circumstances raise a pressing question: is there any way we can sustainably reduce our impact on these animals’ communities?
Image Credit: Charles Boch
New research published this month in the journal American Naturalist indicates that we could and that Marine Protected Areas (MPAs) would play an instrumental role in making it happen. Just as the name implies MPAs are protected regions in which human restrictions are enforced for conservation purposes – this often comprises of barring or limiting activities that would disturb local wildlife, such as fishing.
The researchers purportedly reached their conclusion after using computer models to predict green abalone population influences with and without MPAs. Perhaps unsurprisingly, effective fisheries management resulted in sustainable green abalone populations, whereas unrelenting overharvesting of the species showed a continuous decline in population numbers.
Notably, overharvesting isn’t the only factor that contributes to population declines in various marine animals – so too do natural catastrophic events such as oil spills, tropical storms, and viruses. In the unfortunate circumstance that one of these devastating natural events do occur, immobile animals like abalone, sea stars, and sea urchins are some of the hardest-hit because they can’t move out of the way.
“For many species, reproductive failure may occur if abundance drops below critical Allee thresholds for successful breeding, in some cases impeding recovery,” the authors wrote in the paper. “At the same time, extreme environmental events can cause catastrophic collapse in otherwise healthy populations.”
Related: Can effective fisheries management prevent the extinction of marine fish stocks?
This detail is particularly significant to the study because the researchers also found that green abalone populations bounced back to normal much more quickly in MPAs after natural catastrophes than they did in non-managed regions where the animals were subjected to a combination of natural disasters and human-centric overharvesting.
To make matters worse, the green abalone doesn’t breed as effectively when population counts get too low, which has implications for the species in regions where the animals face all these suppressive challenges at one time. That said, when population counts get too low, they tend to stay low if/until the threats are neutralized.
“We found that MPA networks dramatically reduced the risk of collapse following catastrophic events (75-90 percent mortality), while populations often continued to decline in the absence of spatial protection,” the authors continued. “For species with Allee effects, the use of protected areas can ensure persistence following mass mortality events while maintaining ecosystem services during the recovery period.”
Given all the challenges that appear to be working against their favor, it seems from the results that green abalone and other immobile marine animals could benefit momentously from protected regions. Unfortunately, it remains to be seen at the time of this writing whether improved fisheries management will be implemented anytime soon.
Source: Monterey Bay Aquarium Research Institute, American Naturalist
