Northern elephant seals, equipped with advanced sensors, are playing a crucial role in understanding the health of our oceans, particularly the mysterious "twilight zone." This dimly lit ecosystem, teeming with fish, is attracting the attention of commercial fisheries, making its monitoring more critical than ever, researchers explained to ABC News.
A study published in Science details how marine biologists at the University of California Santa Cruz have tagged thousands of these seals with smart sensors. These devices collect a wealth of data, including water temperature, salinity, the seals' location and dive depth, and even audio and video recordings of their surroundings.
Photo Credit: D. Costa
These seals, unlike fully aquatic marine mammals, spend significant time on land during their migrations, making them accessible to researchers. Twice a year, thousands gather at California's Año Nuevo Natural Reserve for breeding and molting, providing researchers a unique opportunity to tag them. The breeding season is a particularly vibrant time, with females fiercely protecting their pups and males competing for mates and territory.
Photo Credit: D. Costa
Researchers focus on adult females, tracking their journeys as they breed, give birth, and embark on foraging trips. After the breeding season, the seals undertake a shorter 2.5-month foraging trip north, followed by a longer 7-month migration into the vast Northeast Pacific, a journey that takes them halfway to Japan and back.
Photo Credit: D. Costa
During these migrations, the seals dive into the "twilight zone" or mesopelagic zone, a layer of the ocean between 656 and 3,280 feet deep, rich in fish. The sensors, equipped with sophisticated algorithms, track the seals' foraging attempts, providing valuable data on their hunting success and the environmental factors influencing it.
Photo Credit: D. Costa
This research comes at a crucial time, as the twilight zone's untapped resources are attracting interest from commercial fisheries. Exploiting this ecosystem could have significant consequences for the elephant seals and the broader marine environment. The seals' reliance on this zone's abundant fish stocks makes them vital indicators of the ocean's health.
Photo Credit: D. Costa
The long-term study of elephant seals at UC Santa Cruz, spanning decades and involving thousands of seals, has provided invaluable insights into the changing health of the ocean. This ongoing research underscores the importance of continuous monitoring and scientific support, especially in the face of increasing threats to our oceans.
Photo Credit: D. Costa
