By Hans Kristian Strand – Institute of Marine Research (IMR) – Norway
As the project’s journey continues and we have already witnessed the first field actions taking place, it is now time to get to know each of the five pilot sites. As highlighted in the first OCEAN CITIZEN comic, each pilot site faces a unique environmental pressure.
In this series of articles, we will present the five pilot sites to gain a deeper understanding of the problems they are facing, how the project aims to help, and the restoration techniques that will be used.
We will begin with Norway, where overfishing is creating an ecological imbalance that is ultimately affecting the cod population.
Fisheries are an integral part of coastal communities, providing food, livelihoods, and maintaining cultural identity. However, overfishing and its cascading effects have disrupted marine ecosystems, leading to long-term, often irreversible changes. In Porsangerfjord, Norway, overfishing has decimated local cod populations, triggering a series of ecological consequences. The Institute of Marine Research (IMR), as part of OCEAN CITIZEN, is poised to help restore these cod populations using innovative methods such as Smart Enhanced Reefs (SER®).
The problem: Overfishing and ecological imbalance
Overfishing in Porsangerfjord, particularly from the 1950s onwards, has drastically reduced populations of key species like cod, haddock, and wolffish. This reduction has had far-reaching effects, one of the most notable being the explosion in sea urchin populations. Sea urchins, whose predators were significantly reduced due to overfishing, proliferated and overgrazed the kelp forests. These kelp forests were crucial habitats for juvenile cod, providing both food and shelter.
With the kelp forests decimated, the seabed transformed into barren landscapes. These “urchin barrens” are inhospitable to many marine species, including juvenile cod, who rely on the complex structure of kelp forests for protection from predators and foraging. This loss of habitat has probably been devastating for cod recruitment and survival.
Kelp forests are productive, species-rich, and important nursery areas for several commercial fish species. Large areas were grazed down by sea urchins (Strongylocentrotus droebachiensis) in the 1970s, and many are still barren. Photo credit: IMR
Meso-Predator release and cod recovery challenges
When populations of top-predators like cod are heavily fished, it might create an ecological imbalance known as meso-predator release. Smaller predators, such as sculpins, thrive in the absence of larger predatory fish. These meso-predators may, in turn, prey heavily on juvenile cod, further hindering the recovery of cod populations even if fishing pressure is reduced. This feedback loop might prevent the cod population from rebounding naturally, necessitating active intervention to restore balance.
IMR’s role in OCEAN CITIZEN: Deploying Smart Enhanced Reefs (SER®)
The Ocean Citizen project, with IMR as a partner, aims to address these complex ecological issues through innovative restoration techniques. One of the primary strategies involves deploying Smart Enhanced Reefs (SER®) in the Porsangerfjord. These artificial reefs are designed to provide immediate and effective shelter for juvenile cod, protecting them from predators like sculpins.
SER® are not just static structures; they are designed to mimic the natural complexity of kelp forests. Made from composite materials that do not harm the environment, these reefs offer hiding spaces and a complex habitat that can be quickly colonised by kelp and associated marine life. As the reefs become overgrown with kelp, they will further enhance their role as protective and nourishing environments for juvenile cod.
Figure 1. Based on traditional scientific surveys and conversations with fishermen and other fjord users, the IMR has created a map with detailed information about the various species that occur in the fjord. Spawning sites for capelin and cod are marked with red and blue circles, respectively. The three innermost spawning sites for cod are now abandoned and are targeted in the recovery efforts. Photo credit: IMR
Broader ecological benefits
The benefits of deploying SER® extend beyond the immediate survival of juvenile cod. Restoring the kelp forests and cod populations will have a cascading positive effect on the entire ecosystem. Kelp forests are biodiversity hotspots, supporting a wide range of marine life. As top predators and kelp forests recover, they will enhance the overall productivity and resilience of the Porsangerfjord ecosystem.
IMR’s comprehensive approach
IMR’s tasks in OCEAN CITIZEN are multifaceted. In addition to deploying SER®, IMR will conduct extensive monitoring and research to evaluate the effectiveness of these and other artificial reefs and restoration activities. The local cod stock recovery plan also includes the establishment of a spawning cage on an abandoned spawning site, stocked with genetically tested local cod. Additionally, the creation of a Marine Protected Area (MPA) will help secure foraging grounds for the growing cod population and is also part of the plan.
IMR’s involvement in Ocean Citizen exemplifies a holistic approach to marine conservation. By combining advanced technology with ecological understanding, IMR aims to create sustainable solutions that can be replicated in other regions facing similar challenges.
Conclusion
The restoration of the cod population in Porsangerfjord is not just about bringing back a single species; it is about reviving an entire ecosystem that has been disrupted by human activities. The IMR’s partnership with OCEAN CITIZEN represents a significant step towards achieving this goal. Through the deployment of SER® and other innovative measures, there is hope that the once-abundant cod populations, along with the kelp forests and overall marine biodiversity, can be restored to their former glory. This project underscores the importance of active intervention and collaborative efforts in addressing complex environmental challenges and ensuring the health and sustainability of marine ecosystems for future generations.
